Cadence, stride length and Mo Farah’s finishing kick

September 5, 2015

To run faster you need to increase cadence, stride length or both.  The question of which it is best to increase is not easy to answer. In particular, the question of the optimum cadence has long been an issue of discussion among runners and coaches.

On the basis of observations of athletes racing distances ranging from 800 m to marathon at the Los  Angeles  Olympics in 1984, Jack Daniels suggested that across various distances, cadence should be at least 180 steps per minute.  The figure 180 became enshrined in folklore.  There have been two niggling concerns about this. First, many recreational athletes tend to adopt a slower cadence.  Secondly, it is clear that among both recreational runners and elites, cadence tends to increase with pace.  For example, observation of a video recordings of 5000 m races reveals that many elite athletes increase cadence to 200 steps/min or more in the final lap.

Consideration of  the effect of increasing cadence on the peak height of the centre of gravity during the airborne phase illustrates why a fairly high cadence is beneficial from the point of view of both efficiency and minimizing risk of injury.

First, we need to consider the question of what proportion of the gait cycle should be spent airborne. Much empirical evidence indicates as speed increases, a shorter time is spent of stance.  For example in his study of the factors influencing running speed, Peter Weyand found that the proportion of gait cycle spent on stance typically decreased by around 40% as speed increased from 3 m/sec to 8 m/sec.  This is understandable as the shorter the time on stance, the less the braking.  To minimize braking at high speed, at least half of the gait cycle should spent airborne.

However when airborne, after mid-flight, the  body inevitably accelerates downwards under the influence of gravity.  The total vertical distance fallen in one long hop is greater than the fall in a series of short hops of equal total duration because the body accelerates to a greater average speed in a longer fall.  As a result, the total gain in height and the energy that must be spent on getting airborne increases with increases of step duration.  In addition, the impact forces are greater the longer the step duration.  Conversely higher cadence and shorter step duration result in lesser expenditure of energy on getting airborne and lesser impact forces.

However, the saving in cost of getting airborne must be set against the increased cost in repositioning the legs, The swing leg must overtake the torso before footfall, and the cost of accelerating the swing leg increases in proportion to the product of cadence and speed (see calculations in the side bar).  The need to avoid large repositioning costs sets an upper limit to cadence. The most efficient cadence is that which minimizes the total cost of getting airborne; overcoming braking; and repositioning the legs.

However, self-selected cadence differs  greatly between individuals. Recreational runners tend to have relatively low cadence, often less than the 180 recommended by folk-lore.  A study of recreational runners  by Heiderscheit and colleagues  demonstrated that a typical recreational runner might decrease both airborne costs and braking costs by increasing the self-selected cadence by up to 10% .  Heiderscheit reported that at a pace around 3 m/sec, a 10% increase in step rate from a self-selected mean step rate of around 170 resulted in a reduction of approximately  20%  in energy absorbed at hip, knee and ankle joints., It is likely than many recreational runners would  benefit by increasing cadence.

Elite 5000 m runners

Even elites differ greatly, with typical cadence during the mid-stages of a 5000 m ranging from 180 to over 200 steps/min.  Why is there such a large range of cadence among elites? I suspect it is largely determined by the efficiency with which the athlete can capture the energy of impact at footfall as elastic energy and use it to help get airborne again.  An athlete who can achieve a greater saving through elastic recoil will require less energy to get airborne and therefore can afford a lower cadence and longer stride at a given pace.  If such an athlete can increase cadence while maintaining his/her long stride in the final lap of  a 5000m, he/she will have an awe-inspiring  powerful finishing kick.

The best illustration of this is provided by Mo Farah.  In a previous blog post, I discussed Mo’s cadence during the indoor meeting in Glasgow in 2009, when he set a British indoor 3000 m record.  In the middle stages of the race, his cadence was around 175.  For example, he covered the sixth lap of the 200 m track at a pace of 6.4 m/sec with a cadence of 175 steps / min and a step length of 2.18 m.    He made his decisive break from the field in 13th lap, by increasing pace to 6.6 m/sec. He achieved this by increasing his cadence to 185 steps / min while his step length remained virtually unchanged at 2.17 m.

It was interesting to contrast his long-loping style with that of Galen Rupp as they ran together in the middle of the pack, with Galen about metre behind Mo, along the back-straight in eighth lap of the 5000 m in the London Olympics in 2012.  Mo’s cadence was 190 steps/min while Galen’s was 204 steps/min.  In the fiercely contested final lap Galen was dropped as Mo increased his cadence to 208 steps per minute while maintaining  a step length of 2.18 m to hold off six strong contenders.

In the World Championships in Beijing in 2015, again it was Mo’s ability to maintain his long stride while increasing cadence that carried him 8 metres clear of Caleb Ndiku in the home straight.   Mo’s cadence of 204 steps per minute was only  marginally faster than Ndiku’s 202 steps per minute, but the telling difference was Mo’s step length of 2.24,m  compared with Ndiku’s 2.08 m.

The secret of Mo’s powerful finishing kick is his ability to maintain his long stride as he increases cadence to match that of his opponents in the final lap.   It is most likely that this is based on very effective elastic recoil allowing him to re-use impact energy to get airborne.  It is noteworthy that he had this ability in 2009, before he joined Alberto Salazar’s training group in Oregon. It is probable that the discipline of Alberto’s coaching took him from the status of UK record holder to World Champion, but the foundation for his later achievement had clearly been laid before 2009.  It is an intriguing question to wonder how much of this reflects his genetic endowment and how much reflects the trainable features of his running style.

At footfall, his right foot splays outwards in an ungainly manner, but perhaps more relevant, to my eye, he typically exhibits about 10 degrees of dorsiflexion of his ankle immediately prior to foot-strike.  This is clearly illustrated by contrasting the orientation of Mo and Galen’s feet an instant before footfall as they run lock-step (though with Mo landing on the left while Galen is on the right) along the back straight at 9:05 in the 5000m at London, 2012, captured in  Michael Wilson’s slow motion video.   This small degree of dorsiflexion will pre-tension Mo’s Achilles and promote efficient capture of elastic energy.

Neuromuscular coordination for distance running

July 30, 2015

It is well established that countermove jump height (CMJ) is a good predictor of sprinting speed.  This is not surprising because CMJ performance depends on powerful type 2 muscle fibres and on the ability to coordinate the recruitment of these fibres.  In the CMJ, flexion of the hips and knees produces eccentric contraction of the corresponding extensors immediately prior to the explosive concentric contraction that propels the body upwards.  It is necessary to recruit the muscle fibres in a manner that harnesses the enhancement of power generated by the eccentric contraction.

The relationship between CMJ performance and distance running performance has been less thoroughly investigated.

In assessing endurance training, aerobic capacity and lactate threshold have been the main foci of attention, but other training-related variables also predict performance.  It is has been demonstrated that difference between elite athletes in volume of zone 1 training (comfortably below LT) predicts distance race performance (e.g. 10Km). In addition, it is fairly well established that a high values of the ‘stress hormone’ cortisol sustained across a period of months predicts poorer performance.

However, somewhat paradoxically, within an individual athlete, week to week variations in training volume and cortisol values make the opposite predictions.  In a study comparing seasons best and seasons worst performance in elite athletes, total training volume  was less but volume of zone 3 training  (appreciably above LT)  was greater in the week before the seasons best performance. Cortisol tended to be higher a week before the best performance, Countermove jump height was also higher in the week before the best performance.

This apparent paradox is consistent with the evidence that a taper should involve decrease volume but not a decrease in training intensity.  The fact that CMJ was higher before the season’s best performance suggest to me that zone 3 training in the week preceding the event promotes good neuromuscular coordination.

The importance of neuromuscular coordination is clearly illustrated by the clunkiness that triathletes experience during the bike to run transition.   The rapid gains in weight lifting performance  at the beginning of a lifting program are most likely due to improved recruitment of muscle fibres.  Conversely, fatigue impairs neuromuscular coordination, and measurement of postural sway has been proposed as a sensitive measure of impaired neuromuscular coordination arising from fatigue in footballers.

Overall, the evidence indicates that neuromuscular coordination is crucial for both athletic performance and injury minimization but it is rarely the focus of attention in endurance training.  While not a specific focus of attention, when we engage in routine warm up we do in fact achieve  short-term enhancement of neuromuscular coordination, and when we accumulate miles of training, we engage in long-term enhancement of neuromuscular coordination, but we rarely think of these activities as exercises in enhancing neuromuscular  coordination.  However, we are more likely to produce effective enhancement of  neuromuscular coordination if we plan our warm-up and training activities bearing neuromuscular coordination in mind.

The elements of coordination

Recruitment of the optimal number and type of muscle fibres:  because much of our training should be at an intensity less than racing intensity, we need pay attention to the need to ensure that we do retain the ability to recruit type 2 fibres as effectively as required at race pace.  Although the importance specificity in training is sometimes over-rated, at least some specificity is essential.  As discussed in my recent post on lactate shuttling, beneficial enhancement of the ability to handle the accumulation of the lactate can be achieved by a large volume of low intensity training.  However the danger of a program focussed too strongly on low intensity running is the development of a tendency to plod slowly under all circumstances.    It is therefore crucial to do at least some training at or near race pace, especially when fatigued as is likely to be the situation in the later stages of a race.  Progressive runs that achieve a pace at or even a little faster than race pace are likely to be beneficial

Recruitment of muscles in the optimal sequence:  The action of running entails a very complex combination of muscle contractions, requiring that the extensors and flexors at each of the major joints of the leg are recruited in a precisely timed sequence.

Speed of recruitment of muscle fibres:    With increasing age, deterioration in running speed is associated with loss of stride length; not cadence.    This is accompanied by a atrophy of muscles and loss of strength.  However as I found three years ago when engaged in  intense high-load weight lifting program for several months, I was able to increase my strength to the point where I could squat a heavier load than Mo Farah, but  my stride length did not increase appreciably, and my speed remained but a very pale shadow of Mo’s speed.    Speed depends on  power: the ability to exert force rapidly.  This requires effective, rapid recruitment of muscle fibres.  It is far harder to train power than speed, though there is some evidence that focussing on a rapid contraction during the concentric phase of a lift, at moderate load, can produce a worthwhile gain in power.

Implications for warming up For most of my training sessions, I employ a warm up procedure that includes 10 activities, beginning with simple movements designed to get all of the major joints  of the leg moving freely, and proceeds though a sequence in which  power output gradually increases.

Calf raises

Hip swings, (straight front to back; rotating from foot behind to opposite side in front.)

Body-weight  squats (aiming for hips below knees)

Single leg squats

Lunge, to front and side

High knees

High knees skipping

Hopping (fast, small hops)


Surges at race pace

Time for each is adjusted according to how my body is reacting, though typically each of the first 8 activities takes 20-60 seconds; the focus is on fluent action rather than effort.

Implications for injury minimization Recent studies, reviewed by Herman and colleagues, reveal  that in a variety of different sports, poor neurocognitive performance, either at baseline or in the aftermath of a concussion, is associated with elevated risk of musculoskeletal injury. It is probable that a thorough warm-up that  sharpens up neuromuscular coordination is a good way to minimise risk of injury.

Measuring neuromuscular coordination The CMJ is widely used  in various sports, especially team games such as football, to assess fitness.  However, it has three potential disadvantages as a measure of neuromuscular coordination for the distance runner: 1) it is not a ‘pure’ measure as performance depends on type 2 fibre strength in addition to coordination; 2) maximal performance is quite demanding and creates the risk of injury; 3) accurate measurement requires special equipment.

I have been experimenting with time taken to perform 20 line jumps as a test of coordination.  It does depend on other aspects of fitness such as muscle strength  to at least a small extent, but placing the emphasis on time rather than maximal power focuses attention on coordination rather than strength.  The risk of injury is small. At this stage, the utility of timed line-jump performance as a test remains speculative as I have not tested it systematically.  Typically, I find that my time for 20 line jumps decreases from 9.0 seconds after a few minutes of jogging to 7.5 seconds after the ‘neuromuscular’ warm up described above.  Time for 20 jumps increases dramatically after a long run.  Provided I can establish that the test yields consistent results when assessing deterioration in neuromuscular coordination associated with fatigue, I plan to use it to determine whether or not light weight shoes (Nike Free 3.0) result in greater deterioration in coordination during a long run, compared with more heavily padded shoes.

Conclusion It is almost certainly true that many of the activities that athletes and coaches have traditionally incorporated into warm-up and training achieve their benefit at least partly through enhancing neuromuscular coordination.  However by focussing on the more easily quantifiable physiological variables when planning and assessing training sessions, there is a risk that endurance athletes might fail to optimise training to achieve the required combination of aerobic capacity, strength and coordination.   Perhaps we should place more emphasis on a systematic approach to enhancing neuromuscular coordination during training, and on measuring it to assess the outcome of that training.

The lactate shuttle and endurance training

June 19, 2015

Races from 5000m to marathon are run at a pace that is strongly predicted by pace at lactate threshold because the accumulation of acidity is a major factor limiting muscle performance.  During the combustion of glucose to generate energy, the major source of acid is lactic acid.   Lactic acid is a compound of two ions: negatively charged lactate ions and positively charged hydrogen ions.  Under normal circumstances within the body, lactic acid dissociates into these two constituent parts, lactate and hydrogen ions, and it is the latter that create the acidity.   At least in part, the hydrogen ions are buffered (i.e. mopped-up by  other negative ions within tissue) but once this buffering capacity is saturated, hydrogen ions accumulation creates an acid environment that impairs the efficiency of muscle contraction.

However lactate itself can be used as fuel in various locations in the body, and as it is itself metabolised hydrogen ions are removed.    Thus, understanding the mechanisms by which lactate is transported around the body and the mechanisms by which it is itself metabolised provides the basis for rational planning of training.

The orthodox view

The scientific studies of Louis Pasteur, in the nineteenth and early twentieth century, and subsequently by Hans Krebs, AV Hill and others, early in the twentieth century uncovered the mechanisms of anaerobic and aerobic metabolism of glucose, and established the orthodox view that shaped the theory of training for distance training through the second half of the twentieth century. According to this orthodox view, glucose is initially metabolized by the process of glycolysis, to produce pyruvate,  This anaerobic transformation of glucose to pyuvate releases a modest amount of energy which is transferred into the high energy bonds of the energy-rich molecule, ATP, and ultimately can be used to fuel muscle contraction.  But in the presence of oxygen much more energy can be derived via aerobic metabolism of pyruvate. The pyruvate is transported into mitochondria and converted to acetyl-CoA by an enzyme complex known as the pyruvate dehydrogenase complex.  Acetyl-CoA then undergoes a series of chemical transformations catalysed by the aerobic enzymes within mitochondria.  The acetyl group is oxidized to carbon dioxide, releasing a relatively large amount of energy which is incorporated into ATP, thereby providing a substantial enhancement of the supply of energy for muscle contraction.   In contrast, when the rate of delivery of oxygen to muscle is inadequate, muscle contraction must be fueled via the modest energy yielded by conversion of glucose to pyuvate, and the pyruvate is converted to lactate, thereby generating potentially harmful acidity.

The lactate shuttle

The orthodox view is indeed substantially correct, but is misleading because a substantial proportion of pyruvate is converted to lactate even when oxygen supply is adequate to sustain aerobic metabolism in mitochondria.   The way in which the body deals with this lactate is of crucial importance to coaches and athletes.  It was not until the final years of the twentieth century that an adequate understating of the way in which lactate in handled in the body emerged.    The newly emerging understanding was based largely on the work of George Brooks of the University of California, Berkeley Campus, who developed the concept of the lactate shuttle.  Lactate shuttling refers to a group of processes by which lactate is transported within and between cells to locations where is undergoes metabolism.   There is still debate about the details of these mechanisms but the broad principles are now clear, and these principles have major implications for optimum training for distance running.

The first key point is that a proportion of the pyruvate generated in the first stage of glucose metabolism is converted to lactate in the cytosol (the fluid medium inside cells) of muscle fibres, across a very wide range of work-rates, extending from the low aerobic to anaerobic zones.  In the low and mid-aerobic range, the majority of the lactate is transported across various membranes to various different sites where it is metabolized, so there is very little observable accumulation of lactate in blood until the rate of generation of lactate rises near to the limit of the body’s ability to transport and utilize lactate.  Beyond this point, the concentration of lactate and hydrogen ions in blood rises rapidly (the Onset of Blood Lactate Accumulation, OBLA); respiration becomes very effortful, and the ability to maintain that pace is limited by the limited ability to tolerate acidity.

It is helpful to understand the various processes by which lactate is transported out of the cytosol of muscle cells and subsequently metabolized, in order to design a training program that is likely to enhance these processes.

There are four major pathways by which lactate is transported and metabolized:

  • Transport across the outer mitochondrial membrane to a site where lactate dehydrogenase converts lactate back to pyruvate which then undergoes aerobic metabolism within the same muscle cell. This process results in dissipation of lactate and acidity in the cell where it was created and hence is merely a mechanism that ensures that acid does not accumulate when oxygen supply is adequate to sustain aerobic metabolism.
  • Transport out of the muscle fibre where it was created, into nearby fibres where is can be transported across the outer mitochondrial membrane and metabolized. This mechanism makes it possible for lactate to be generated in type 2 muscle fibres, which are powerful but have relatively low aerobic capacity, and then metabolized in type 1 fibres which have high aerobic capacity.  Training ‘at a good aerobic pace’ as advocated by Lydiard is potentially a good strategy for developing this mechanism.  Although the training pace might be comfortably below OBLA, the ability to dissipate lactate and acidity will be enhanced, leading to a an increase in pace at OBLA and improved performance over distances from 1500m to marathon.
  • Transport out of the muscle fibre where it was created into the blood and thence to other organs, such as heart and brain where it can be metabolized to generate energy
  • Transport out of the muscle fibre where it was created into blood and thence to liver where it can be converted back to glucose by the process of gluconeogenesis. This mechanism is likely to help conserve glucose stores in a manner that is useful in long events such as the marathon.

It is important to note that all of these processes entail transport across a membrane or several membranes prior to metabolism.   Transport is an active process that is performed by specialised proteins known as monocarboxylate transporters (MCTs). There are several different type of MCT located in different types of membrane.   Like many proteins in the body, utilization encourages production of increased amounts of the protein.

Aerobic base-building

Low intensity running is not merely about developing the capillaries to deliver blood to muscle and mitochondrial enzymes that perform aerobic metabolism.  Because appreciable amounts of lactate are produced, transported and metabolized even at work-rates well below OBLA, low intensity training  helps build capacity to handle lactate.

Think of the flow of glucose into the energy metabolic pathway as being like water flowing from an inflow pipe into a sink. The inflow pipe is actually the anaerobic pathway (glycolysis).  A pool of interchangeable pyruvate and lactate tends to accumulate in the sink.  There are two ways out of the sink: transport out of the cell or down the plug hole into mitochondria where aerobic metabolism occurs.  In fibres in which the aerobic system has been well developed , the flow down the plughole can accommodate a large flow of glucose into the system without the sink overflowing.  Shuttling from type 2 fibres which have less well developed aerobic capacity, into nearby type 1 fibres also helps maintain the flow.  There is minimal accumulation of acid in either muscle or blood.  So purely aerobic development, which can be achieved by low intensity training, minimizes accumulation of acid at 10K and 5K pace.   Shuttling explains why runners who only do low intensity running during base building nonetheless usually find that 10K and 5K pace improve despite doing no training near race pace.

The important conclusion for the endurance athlete is that low intensity training is an effective way to develop an aerobic base which helps raise lactate threshold.  It enhances performance at all distances for 1500m to ultramarathon.

Interval training and fartlek

Lactate shuttling also provides an explanation for the effectiveness of interval training and fartlek.  A brief intense effort epoch above threshold generates a surge of lactic acid, and is followed by a recovery epoch during which lactic acid levels fall rapidly, before the sequence of effort and recovery is repeated.  Thus, large gradients in lactate concentration develop, resolve and develop again.  It is noteworthy that the drop in lactate during recovery is likely to be facilitated by low intensity running which maintains transport and utilization of lactate during recovery.  A high lactate gradient across a membrane makes high demand on the transport process and is likely to stimulate production of the relevant transporters, the MCTs.

It is plausible that this will be achieved most effectively by ‘cruise’ intervals of the type employed by Emil Zatopek, or by fartlek sessions in which intensity is high enough during the effort epochs to ensure substantial  production of lactate, while intensity during the recovery epochs is adequate to ensure transport and utilization of the lactate produced during the preceding effort epoch


The various pathways by which lactate is transported out of the muscle cells where it is created to locations where it can be usefully metabolized provide a set of mechanisms by which either low intensity training at a pace comfortably below lactate threshold, or by interval training in which lactate is generated in brief surges, can develop  the ability to cope with lactate production at race pace.    Thus training for sustained periods at or near race pace, which tends to be quite demanding by virtue of the sustained stress, has only a relatively limited role to play in training for endurance events.  This might be an explanation for the observation that many elite endurance athletes adopt a polarized approach to training, in which the majority of training is done at a pace comfortably below threshold, together with an appreciable minority of training at higher intensity during interval sessions and  a modest amount of sustained running near to threshold.

Charles Eugster: strength or power?

March 20, 2015

Perhaps the most enigmatic of the trainable capacities required for distance running is efficiency: the ability to generate as much speed as possible from a given amount of energy.  In endurance events, when the vast majority of energy is generated aerobically, it is the ability to extract as much speed as possible from a given rate of oxygen consumption.    Somewhat confusingly, it is usually reported as oxygen consumption required for a given speed and quantified in units of ml/Kg/Km, though this is actually the inverse of efficiency. It is also referred to as economy and is sometimes reported as speed at VO2max. A proportional increase in speed at VO2max will result in a similar proportional increase in speed at sub-maximal rates of energy consumption.

The first focus in planning a training program is on increasing the ability to consume oxygen (VO2max) by increasing blood supply to muscles and increasing mitochondrial enzymes, but for well-trained athletes, the scope for improving VO2max is small.   When generating energy at VO2 max, a substantial amount of metabolism is anaerobic and results in the build-up of lactic acid. Since accumulation of acid limits muscle power output, the second focus of endurance training is reducing lactic acid accumulation, either by increasing the ability to transport lactic acid out of muscle cells and metabolise it in other tissues, such as liver and heart, or by enhancing fat metabolism, which does not generate lactate.   However there is limit to what can be achieved by improving the capacity to minimise lactic acid accumulation.   Once VO2max has been maximised and the accumulation of lactic acid has been minimised, the focus of training must shift to efficiency.

As illustrated by Andrew Jones’ account of the physiological developments achieved by Paula Radcliffe in the decade prior to her phenomenal a marathon time of 2:15:25  in London in 2003, the crucial improvement was in efficiency.  Paula’s VO2max remain approximately constant at around 70 ml/Kg/min over the decade, but her estimated pace at VO2max increased by 15%.  Andrew Jones acknowledged that mechanism by which this increase in efficiency was achieved remains a mystery.

In my recent discussion of this issue, I distinguished between improvement in metabolic efficiency: the amount of work that can be achieved by muscle contraction per unit of energy consumed; and improvement in mechanical efficiency: the pace achieved for a given amount of work by the muscles.   Metabolic efficiency is strongly dependent on the relationship between rate at which muscle fibres shorten during contraction and optimum shortening rate for the type of fibre involved. In general during endurance running, the required of rate of shortening is relatively low. Type 1 fibres are more efficient than type 2 fibres when the rate of contraction is slow.  Therefore, one goal of training is increasing the proportion of work done by type 1 fibres.  This is achieved by low intensity training.  But the need for the powerful contraction provided by type 2 fibres cannot be completely neglected because of their role in achieving mechanical efficiency.

Maximising mechanical efficiency demands optimising the balance between the three major energy costs of running: getting airborne; overcoming braking and repositioning the swinging leg.  The cost of getting airborne can be reduced by spending more time on the ground, but that inevitably increases braking cost.  Braking cost can be reduced by increasing cadence, but the cost of repositioning the swing leg increases with cadence so there is a limit to cadence.   So one cannot escape the need to get airborne – indeed getting airborne is what distinguishes running from walking.  But getting airborne requires a powerful push against the ground.   The force-plate data of Peter Weyand and colleagues indicates that a major determinant of running speed is the ability to exert a strong push to lift off from stance.

For many distance runners, but especially women and elderly men, I think that the most likely factor limiting mechanical efficiency is lack of ability to exert an adequate push.    One of the striking features of Paula Radcliffe’s running in her heyday was her ability to get airborne.   The interesting question is how she developed this ability.  Following her disappointing performance in the 10,000m in Sydney in 2000, her physiotherapist, Gerard Hartmann identified her poor ability to generate the power required to step on and off a high box rapidly.   He recommended a course of plyometrics and weight training.  It is likely that this played a substantial part in her transformation from a leading athlete who was struggling to fulfil her potential into the greatest female marathoner the world has seen.  But was it the plyometrics or the weight training that played the greater part?

Charles Eugster

I was reminded of this question last week when Charles Eugster set a new world record for the MV95 200m in London, with a time of 55.38 seconds.  Like most people, my first reaction was ‘how amazing’ though I was not entirely surprised.  He had done a very entertaining TED talk a few years ago, in which he presented an enchanting picture of a 93 year old with a very positive outlook on life, and a strong message about the virtues of weight training for the elderly.   The story behind his MV95 200m record provokes some interesting speculations about how to improve the ability to get airborne.

Charles was the child of Swiss parents and had spent his childhood in London, before returning to Switzerland.  He had become a dentist despite his parents wish that he become a doctor.  One of his teachers at St Paul’s school had said: ‘Eugster, if I were to put your brain into a sparrow’s head, there would still be room for it to wobble’. He decided that he would be better advised to focus on learning about 32 teeth rather than all the organs of the body.

He had played sport all his life, and in a particular, rowed for his school, but in his eighties, decided that it was time to smarten up his body.  In his TED talk, he says it was all due to vanity. He claimed his ambition is to impress sexy young girls of 70 on the beach.  He had wanted to start on a six pack but his personal trainer, Sylvia Gattiker, former Swiss aerobics champion, said he needed to start with work on his glutes.  She stands no slacking, encouraging him along the lines: ‘…. and breathe out, no, that’s groaning…. breathe out’.

Under Sylvia’s guidance he has developed a spectacular body.  He has won numerous body building and strength awards.  At 89 he became world 80+ Strenflex champion.  Strenflex involves a set of exercises that are scored for form and number of repetitions in a given time.  It is a test of strength, endurance and flexibility.  About two years ago, he took up sprinting, and within less than a year, was British 100m and 200m Masters Athletics 90+ sprint champion.  So his world 200m record last week was amazing but scarcely surprising.

It is nonetheless intriguing to examine his style.

He runs with a high cadence but shuffling gait.  He does get airborne, but not for long.  I suspect this is part because Sylvia’s coaching emphasized reaching forwards with the swing leg, but it is a style quite characteristic of the elderly.   Ed Whitlock, who trained for his 2:54:45 marathon at age 71 by running up to 3 hours per day in a Toronto cemetery, deliberately cultivated as slow shuffle to protect his knees from the pounding during training, but during races, he is a delight to behold: He gets airborne in a manner reminiscent of Paula Radcliffe.

By virtue of his rapid cadence, Charles Eugster reduces both the costs of getting airborne and braking costs, but to my eye, he nonetheless incurs unnecessary braking costs.  His cadence appears is to be near the practicable limit, and any further improvement in efficiency would require spending a smaller proportion of the gait cycle on stance.   His energy cost would almost certainly be less if he got properly airborne, as younger sprinters do.  Impressive as his 200m time of 55.38 seconds is, it is almost certainly limited by a loss of the power required to get airborne.

The elderly lose strength but even more noticeably, they lose power: the ability to exert force rapidly.  It has been recognised for some years that the elderly can regain strength with remarkable effectiveness by lifting heavy weights.  Charles has clearly been very successful in achieving this.  It is noteworthy that in order to become a Strenflex champion, for which it is essential to be able to perform repetitions of various strength exercises rapidly, Charles must have retained some power.  Nonetheless, it appears that in training he has placed his main focus on shifting quite heavy loads, which is not a very effective way of re-building power.

Building power by explosive contractions

There is a substantial body of evidence indicating that the most effective way to build power is to perform muscle contractions  at the rate that maximises power.  Power is the rate of doing work.  Work is the product of force by distance, so power is the product of force generated by distance the load is moved divided by the time taken, or on other words, the product of force by speed of contraction.  Speed of contraction increases as load decreases, and for young adults, peak power is typically generated at about 30% of the maximum force that can be generated:  that is 30% of one repetition maximum  (1RM).   The elderly have less scope for increasing speed of contraction, and maximum power is usually generated at a somewhat great fraction of maximum load.  Typically maximum power is generated at 60% of 1RM.

Because the risk of muscle damage is greatest during eccentric contraction when a muscle is stretched while under load, the safest way to build power is to perform the eccentric phase of the exercise slowly and then execute the concentric phase explosively with maximum  possible speed.  Encouragingly, several recent randomised controlled trials have demonstrated that high velocity power training is feasible, well tolerated, and is effective in increasing leg muscle power in the elderly.    De Vos and colleagues randomly assigned 112 healthy older adults (aged 69 +/- 6 years) to explosive resistance training at one of three intensities (20%; 50%; or 80% of 1RM) for 3 sets of 8 rapid concentric contractions , for 8-12 weeks, or to a non-training control group. Peak power increased significantly by about 15% in all three groups doing the explosive exercises, compared with 3% in the control group.   In comparison with the groups using 20% and 50% of 1RM, the group using 80% of 1RM exhibited a greater increase in strength and also a greater increase in muscle endurance (the number of repetitions that could be performed with a load of 90% of 1RM).  It is also noteworthy that injuries were rare and relatively minor during the explosive sessions.  In fact there were more injuries during the testing of 1RM than during the explosive sessions, suggesting that explosive concentric contractions at moderate load are less risky that slow eccentric contractions at very high load.

Optimising the explosive contraction

The greater increase of strength at higher load reported by de Vos was expected, while the greater endurance at higher load when assessed at 90% 1RM might largely reflect a bias towards maximal recruitment of the type 2 fibres during the endurance test that were maximally recruited during the explosive training.  However the similar gain in maximum power between the three different explosive training loads raises an interesting question about the possibility of biasing the training in favour of type 1 fibres.  At low load, during the eccentric training phase, the type 1 fibres will be preferentially recruited and hence experience gentle pre-tensioning.  During the explosive concentric contraction, it is likely that a wide-range of fibres would be recruited though the bias would usually be towards type 2 fibres.  However, if the type  1 fibres have been pre-tensioned during the eccentric phase, these fibres will tend to show relatively more enhancement of recruitment.  Thus, one might expect a somewhat greater benefit for type 1 fibres at low loads.

During the push off from stance during running (and during squats) much of the load is borne by the extensors of hip, knee and ankle.  Most of the relevant muscles cross two joints, flexing one while extending the other, and hence the fibres undergo a relatively short contraction during the triple extension.   Thus, even during quite fast running, the rate of contraction of the important muscles is relatively slow, and likely to be in the range where type 1 fibres are metabolically more efficient.  This suggests that explosive training with low load might be potentially of greater benefit for endurance athletes.

With regard to the type of exercise most useful for runners, any exercise that produces a triple extension is likely to be beneficial.  While deep squats do produce such an extension, the range of motion is different from that during running, whereas hang cleans require a range more similar to that of running.  However, it is trickier to do hang cleans safely.  It should also be noted that short, steep hill sprints and squat jumps are likely to be effective for increasing power.

The mechanism

The mechanism of the increase in power is not clear.  It is likely that improved fibre recruitment due to enhanced neuromuscular coordination plays a role.   If so, one might expect there to be a ceiling on the benefit that can be obtained over a prolonged period of training.  Nonetheless, on the principle that using a muscle prevents atrophy, there are likely to be long term benefits in ensuring that muscles can be recruited with peak efficiency.

My preliminary experiments

During the past year, during which I have focused more on increasing volume of training than on either strength training or sprinting, I have been dismayed to find that my sprinting speed has decreased yet more than in previous years.   Although I do not yet shuffle quite as noticeably as Charles Eugster (who is a little over a quarter century older than me) I too am forced to increase cadence to a very high level in order to produce speed.

About a year ago I had introduced plyometrics into my routine, but abandoned these as they appeared to be exacerbating the aches in my knees.  I am therefore eager to find a safe way to increase leg muscle power.  I have recently introduced sessions in which I do 3 sets of 8 explosive squats at 60% of 1RM. This has produced no DOMS and in fact leaves me feeling invigorated. I am even experimenting with doing 1 set of explosive squats at moderate load as part of my warm up for running sessions, with the expectation that this will enhance neuromuscular coordination.

It is too early to say whether or not this explosive resistance training has produced a worthwhile increase in ether sprinting speed or in efficiency at sub-maximal paces.  Nonetheless, the impressive gain in strength achieved by Charles Eugster though training with heavy loads has somewhat paradoxically inspired me to try a different approach with the aim not only of increasing strength but also recovering the power to get properly airborne.  But before I allow myself to become too dismissive of the approach employed by Charles Eugster, I should establish that I can run a 200m in 55 sec at age 75, let alone 95.

Endurance Training and Heart Health, Revisited

February 25, 2015

The perennial question of the benefits and risks of running has been back in the news in the past few weeks. First there was the recent publication of another paper adding to the previously reported findings from the Copenhagen heart study. The main conclusion from this long-term study of mortality among runners is that moderate amounts of running increase the probability of a longer life. However, the newspapers seized on the statement that large amounts of running were not statistically safer than a sedentary life-style. That in itself was a trivial conclusion despite its sensational appeal to newspaper editors. The number of people in the sample doing a large amount of exercise was too small to produce statistically robust evidence of either benefit or harm. While mortality rate was higher in those doing a lot of running compared with those doing a modest amount, it was nonetheless lower than in sedentary individuals, but the decrease was not statistically significant. I suspect that the somewhat sensational reporting was at least partly due to the fact that James O’Keefe joined the scientists who conducted the study, to write the paper. I have previously remarked that in my eyes, O’Keefe appears more like a snake-oil merchant than a scientist.

The other publication, a study of adverse cardiac events in over a million British women by Armstrong and colleagues from Oxford, is more measured in its reporting. It too shows that moderate amounts of exercise are beneficial, but those doing a larger amount of exercise had less good outcome than those doing a modest amount (e.g. half and hour three times per week). Nonetheless, even those exercising daily had a better outcome than sedentary individuals.

A third large epidemiological study, the Aerobic Longitudinal Study of 55,137 American adults also revealed that moderate exercise is associated with a substantial reduction in mortality, but yet again those doing a large amount of exercise tended to have higher mortality that those doing moderate exercise. Thus three large epidemiological studies have all demonstrated that moderate exercise is associated with major health benefits, but these benefits are reduced, though not entirely abolished, in those doing a large amount of exercise.  The evidence suggests that in at least some individuals a large amount of exercise is associated with harmful effects on health. This finding is not surprising in light of the very strong evidence from many studies that at least a minority of individuals who do very large amounts of exercise suffer heart damage.

Evidence of heart rhythm disturbances

The best documented adverse effect of extensive amount of endurance training and racing is disturbance of cardiac rhythm, especially atrial fibrillation. A review by Mont and colleagues revealed that long-term endurance athletes have a to 2-10 fold increase in risk of atrial fibrillation.   There is also an increased frequency of potentially more dangerous rhythm disturbances arising in the ventricles. Ventricular rhythm abnormalities are quite common in elderly endurance athletes, and also occur in a substantial minority of young athletes. For example, Verdile and colleagues observed ventricular rhythm abnormality in 367 (7.3%) of 5011 highly trained young athletes with average age 24 without other evidence of heart disease. Six of these individuals underwent successful surgical ablation of the aberrant heart tissue, while 7 with frequent or complex rhythm disturbances who declined surgery were prohibited from competitive sport.   However no adverse cardiac event occurred in any of the 367 young athletes during a follow-up period of average duration 7 years, indicating that at least in young athletes with no other evidence of cardiac abnormality, the arrhythmias are usually benign.

What are the implications for individuals who want to exercise vigorously?

Is there an upper limit to the amount of exercise that is healthy, and if so, what is it? Or can the likelihood of adverse effects on health be reduced by adjusting the way in which we train? There is a twist in the tail of the Oxford study of a million women that throws some light on this. A sub-group analysis revealed that among those who were obese, the women taking a large amount of exercise had a somewhat higher risk of cardiac events than those who exercised only three times a week. However, among those with BMI below 25, those who exercise frequently have a lower risk than those who exercise only three times week.   This suggests that it is not the amount of exercise in itself that does the damage, it is more likely that it is the amount of stress generated by the exercise that matters.    Emerging evidence about the mechanism by which excessive exercise might produce harmful health effects in runners throws a little more light on the issue.

What are the possible mechanisms of damage?

What determines who among endurance athletes is at greatest risk of damage? The mechanism of the damage remains uncertain, but a growing body of evidence provides some clues. Exercise remodels the heart.  The walls of the ventricles become thicker and the cavities become dilated. This is the typical athletes heart. Some athletes also exhibit fibrosis of the muscle. Fibrosis arises when damaged muscle is repaired with a scaffold of fibrous material.  This is a part of the normal mechanism by which inflammation repairs damaged body tissues but can become disruptive if the fibrous deposits become permanent. Fibrosis of heart muscle is likely to disrupt the normal conduction pathways via which electrical signals initiate heart muscle contraction. Although not directly proven, fibrous deposits are a prime suspect for rhythm disturbances.

What causes the damage that sets the scene for fibrosis? Some thought provoking clues come for studies of the effects of strenuous exercise on the right ventricle. The right ventricle has to pump blood through the lungs, and the capillaries in the lungs do not open up as much during exercise as the capillaries in the muscles. Hence, the right ventricle faces a relatively harder task than the left in having to push the increased volume of blood required with less benefit from an accommodating vascular system.  As a result there is demonstrable weakening of the right ventricle that persist for several days after very strenuous exercise. This weakening is associated with markers of transient heart muscle damage, such as increase in levels of cardiac enzymes in the blood stream. For a well trained athlete, the weakening is only appreciable after extremely strenuous exercise. For example, the weakening is only slight after a marathon, though more marked after an ironman, and still detectable a week later. For recreational runners, the damage can be appreciable after a marathon. But perhaps the crucial observation is that the amount of weakening appears to depends on how thoroughly the runners prepared for the marathon. In a study of runners in the Boston marathon in 2004 and 2005, Neilan and colleagues found that appreciable weakening of the right ventricle in those who had done less than 35 miles per week in the preceding moths, but no appreciable weakening in those who had done more than 45 miles per week.

What might convert transient damage into long term damage? In general when body tissues suffer transient damage the repair process includes the construction of a temporary framework of collagen fibres. If there is repeated trauma before full recovery there is greater risk that the temporary fibrous framework will be become permanent. Although there is little direct evidence that this happens in the heart, perhaps the most plausible explanation for the fibrosis observed in the heart muscle of endurance athletes is repeated trauma without opportunity for adequate recovery. Overall the evidence suggests simply that moderate exercise is beneficial for virtually everybody, but if you want to do a lot of exercise you need to build up gradually to avoid over-stressing the body.  Furthermore, it is plausible that demanding training or racing while incompletely recovered from previous strenuous training or racing creates an especially high risk of converting transient damage into long term fibrosis that might act as a precipitant of disturbance of heart rhythm.


Moderate exercise has major health benefits for virtually every one, but a large volume of endurance training diminishes the benefit for some individuals. There is no evidence indicating a fixed upper limit on the amount of exercise that is healthy.   On the other hand, the evidence suggests, but does not prove, that the risks of extensive training are likely to be low if you if you increase training load gradually and avoid demanding training or racing when inadequately recovered.

It is probably no coincidence that what appears to be the safest strategy for avoiding long term damage is similar to the widely accepted recommendation for training to improve performance: increase training load gradually and recover well after strenuous training or racing.

More reminiscences and the science of running injury free

January 5, 2015

The New Year is a time for looking forward, but in the past few days several things have also prompted me to take a backwards glance.   One of these things was the summary of the previous year’s statistics for my blog which Word-press compile each year. Two features intrigued me. First, was the very wide geographic range of the readership.  But even more intriguing was the fact that three of the most viewed pages in 2014 had been posted in 2010 or earlier.   It led me to wonder just how much my views on the topics of those posts have changed in the past five years.

Heart rate variability (HRV)

The most frequently viewed post was one of my 2010 posts on HRV. At that time I was intrigued by the possibility that regular HRV measurement might be an effective way to guide the adjustment of training load. In the preceding years, several studies by Kiviniemi and colleagues from Finland had provided preliminary evidence indicating that daily measurement of HRV was potentially useful for adjusting training load. In particular, a decrease in high frequency HRV was reported to be a useful indicator of the need for recovery. Although several recent studies have confirmed that HRV is related to the effects of training, there are inconsistencies in the findings, and I am not yet convinced that these studies provide compelling evidence that daily measurement provides a reliable basis for day-by-day adjustment of training load. Indeed a recent study by Plews and colleagues reports that daily HRV measurement is only weakly related to training status, though a weekly average was a quite strong predictor of 10K performance.

My own experience is that HRV, measured either at rest or immediately after exercise is not sufficiently consistent to provide a useful guide to adjusting training on a day to day basis. Nonetheless, I do regard a marked reduction in resting high frequency HRV as a pointer towards the need for better recovery when it occurs in association with other signs of stress. Conversely, unusually large amplitude HRV while running appears to be a fairly reliable sign of stress (as illustrated in  figure 3a from my post in 2010). However, the main reason I continue to record R-R traces during training runs is to monitor the frequency of occurrence of rogue rhythms – a common but inadequately understood phenomenon in elderly runners.

fig 3a: Expanded view of HR variability in the period 23 to 25 minutes, before (18 July) and during fatigue (31 August)

fig 3a: Expanded view of HR variability in the period 23 to 25 minutes, before (18 July) and during fatigue (31 August)


The second most frequently viewed post in 2014 was my 2010 discussion of the Dr Romanov’s Pose method of running. That post had drawn many comments at the time of the original posting and has attracted many thousands of views since 2010. Although I started the post with a list of the positive features of Pose, the main message was that Dr Romanov had seriously under-estimated ground reaction force (GRF) during running and as a result had drawn the erroneous conclusion that the net force acting on the runner’s body after mid-stance is directed forward and downwards. This led him to the erroneous conclusion that the centre of gravity falls after mid-stance. In contrast, a realistic estimate of GRF indicates that the net force after mid-stance is directed forwards and upwards. Dr Romanov’s mantra of ‘pose, fall, pull’ does not correspond to what happens. As a result, Dr Romanov seriously underestimates the crucial role of a well-timed push upwards and forwards off stance.

Five years later, I still regard this as the cardinal flaw of the Pose technique. The fact that my post continues to be widely read five years later indicates that the running community is still curious about Pose, but as far as I aware, serious discussion about running technique is now more focussed on how to achieve a well- timed and directed push after mid-stance.  My own opinion is that the most effective strategy is to rely on the cue provided by a brisk downward swing of the arm contralateral to the leg on stance.

Forces acting on a runner after mid-stance.

Forces acting on a runner after mid-stance.

Lydiard v Maffetone

The other ‘historical’ post among the five most viewed in 2014 was my comparison of Lydiard v Maffetone, posted in 2009. I have a great respect for both Lydiard and Maffetone, particularly on account of the emphasis they place on the importance of base-building in the annual training cycle. The purpose of my post was to compare their recommendations for paces during base-building. Lydiard was less precise in his prescription than Maffetone, but as far as can be estimated, both made very similar recommendation for long run pace. However, Maffetone is much more adamant in recommending avoidance of training in the upper aerobic zone during base building. In my post I discussed several of the plausible physiological mechanisms by which running in the upper aerobic zone might be counter-productive, but I concluded that none of the mechanisms was likely to impair aerobic development provided the majority of sessions were lower aerobic sessions. I therefore came down favouring of Lydiard over Maffetone

I still adhere to the main principles that I advocated in that post, though my opinion about optimum paces has changed over the past 5 years. As discussed in my recent post on the virtues of high intensity v high volume training I now favour a somewhat more polarised approach during base-building (and also during race specific preparation) than either Lydiard or Maffetone would have recommended. I think that it is more constructive to replace some of the ½ effort and ¾ effort runs recommended by Lydiard with short high intensity sessions, as I consider that the cost/ benefit ratio of high intensity sessions is greater than that of upper aerobic sessions. However I do not regard this issue as settled beyond doubt.

Candy for Running Nerds

Of all the comments I have received on my blog over the years, the one that most tickled my fancy was Eternal Fury’s remark a few years ago that my blog is a candy shop for running nerds. I assume that the candy to which EF referred was the detailed technical examination of the physics and physiology of running. Indeed I do enjoy looking into the biomechanics and physiology of running.

I believe that the best foundation for making sensible decisions about training and racing is a synthesis of practical observation of what works for others and one’s own experiences, interpreted in the light of what we know about how the body works. So I hope that the candy is both interesting entertainment for running nerds and informative for runners who simply aim to run as ‘fast and injury free’ as possible.

I was therefore very pleased two days ago when Steven Brewer posted a series of questions on my 2012 post ‘Is there a magic running cadence’. It was interesting to review the evidence that I had  presented in 2012, and to note that the evidence that has emerged since then has largely consolidated the picture from 2012. However as the discussion started to become even more arcane, Steven remarked ironically ‘The more I learn, the more I am discovering that running is an extremely complicated process. This makes me appreciate the simplicity of calculating the energy levels of an electron trapped in an infinitely deep well! ‘ At that point, Laurent Therond interjected ‘IMHO, running form is mostly innate, and what your body has come up with is likely to be what works best for you.’

In fact I agree strongly with Laurent. Running is largely innate and therefore we should largely trust our body to run in the manner that comes naturally. However, many runners suffer injury, and when this happens repeatedly we need to ask why.

So is it possible to distil the science of running into a few clear principles?    The short answer is no. Running involves every system of the body, ranging from the brain (and mind) to the toes, so it would be fat too simplistic to try to condense the essentials into a few principles. However, when I started this blog, one of my main pre-occupations was how to run ‘injury free’.   I believe that it is possible to distil the science of running injury free into a small number of basic principles – though as Einstein once remarked, we should seek explanations that are as simple as possible, but no more simple. So here is my response to Steven in which I have tried to distil the science of running injury free, in a manner that is as simple as possible but not too simple.

The distilled science of running ‘injury free’

In the past decade I think there has been an over-emphasis on   faults of style as the major cause of injury. I believe that subjecting the body to greater stress than it can cope with is the major causal factor in in many instances. Therefore one of the main strategies for avoiding injury is building up training load gradually, and at all times recognising when the body is near the limit of coping. This is not easy, though a variety of signs covering both overall well-being (mood; heart rate variables) and focal signs such as accumulating aches in connective tissues or local muscle spasm provide useful clues.

However, in some instances faulty technique plays a role. But there is a great deal of misleading information in circulation, due to over-simplistic analysis. The human body is very complex. Nonetheless, it does obey several well established principles, based on both Newtonian mechanics, and the principles governing the behaviour of biological tissues.

Newtonian mechanics

The first things to consider are the laws of Newtonian mechanics. We need to meet two goals: minimising energy expenditure and minimising stress on body tissues. Minimising energy expenditure requires the optimum adjustment of the three major energy costs: getting airborne; overcoming braking and the cyclical repositioning the limbs relative to the torso. Simplistic focus on just one of these leads to over-emphasis on a single requirement. For example, we can minimise the cost of getting airborne by reducing vertical oscillation, but that inevitably increases the cost of overcoming braking, at a given cadence.   We can minimise both braking costs and cost of getting airborne by increasing cadence, but that increases limb positioning costs.   Conversely, if cadence is too slow there is a strong temptation to increase stride length by reaching out with the swinging leg, thereby incurring braking costs that are inefficient and potentially damaging.

The need to balance the three main costs leads to 2 important conclusions: first, simplistic rules such as avoid vertical oscillation without considering other costs are misleading and potentially dangerous. In general, it is best to let the non-conscious brain do the calculation required to optimise the three energy costs, because the brain is usually very good at finding the most efficient solution.

However, as discussed in most post on running cadence, there appears to be one exception: most recreational runners select a cadence which appears to be slower than optimal for fast running. Maybe this is because we are naturally adapted for slow running over rough terrain where maintaining balance is a high priority; alternatively it might be that a sedentary lifestyle encourages our brains to be too cautious. So if there is one simple issue we should address consciously, it is making sure that cadence is not too slow (eg at least 180 steps/minute at 4 m/sec).

The second general conclusion arising from the need to balance the three costs, is that large forces will necessarily be exerted. A quite strong push against the ground is inevitable. Running is a dance with the devil – gravity. We therefore must build up the strength to cope with this, by gradual increase in training volume. Specific exercises, both plyometrics and resistance exercises, can help.

Associated with the large forces required to get airborne is the fact that the geometry of our hips knees and ankles results in quite large rotational effects around two, or sometimes all three axes, at these joints. Some of these effects are not easily envisaged, so there are certain injuries that do require a careful biomechanical analysis. Nonetheless I consider that gradual build-up of training load and trusting your non-conscious brain is the most effective way of minimising the risk of such problems. If you do decide that you need to adjust style consciously, it is safest to focus on a compact, brisk but relaxed arm action.   This tends to promote a compact efficient leg action as a consequence of the way the brain codes movement.

The physiology of injury

With regard to the physiological properties of body tissues there are several principles that are worth considering. The first is that running mobilises the catabolic hormones (adrenaline, cortisol) necessary to promote energy metabolism. Catabolic processes break down tissues that must subsequently be prepared by anabolic processes. The art of training is largely about balancing catabolism and anabolism – the most important requirement is ensure that recovery is adequate.

The second valuable principle is that repair of damage tissues involves an inflammatory process that often involves laying down of collagen fibres in a randomly ordered manner. However, the relevant muscle or tendon functions best when the fibres are aligned in the direction of the usual forces, so once the initial inflammation has settled, gentle active recovery helps re-model the tissues in the optimum manner.

Overall, the science of running is complex. Some problems are indeed more challenging than applying quantum mechanics to calculate the energy levels of an electron trapped in an infinitely deep well, but a few simple principles provide most of the guidance a runner needs to maximise the chance of running injury-free.

Reminiscences of 2014: Modifying the marathon training of Ed Whitlock

December 30, 2014

Memories of times past

When I had run marathons in the 1960’s it was an event for wiry young men. Typically a few dozen of us lined up across the roadway at the start. We expected to finish in a time somewhere between 2:15 and 2:45 although we were not fixated on time. In that era the IAAF did not recognise world records for the marathon because courses were not considered comparable. Boston was point-to-point and down hill. Similarly the Polytech Marathon in the UK was a point to point from Windsor to Chiswick.   But despite the fact that the marathon community was a small fraternity of wiry young men who trained fairly hard with little expectation of public recognition, the romance of the marathon was beginning to grow.

At the beginning of the decade, Abebe Bikila had won gold running barefoot in Rome. Four years later in Tokyo, he again won gold in a time more than three minutes faster than his time in Rome. At that time we did not appreciate the significance of Bikila’s Ethiopian origins, but we were inspired by his charisma.

The other charismatic figure of the 1960’s was Arthur Lydiard.   The success of Peter Snell, Murray Halberg and Barry Magee in the Rome Olympics imbued Lydiard’s training method with a magical aura.   Although few of us had read his first book, Run to the Top, that appeared in the early sixties, the key principle of building a base by running 100 miles a week at a good aerobic pace had thoroughly permeated the distance running world via word of mouth. Lydiard had not defined ‘a good aerobic pace’ in precise detail, and most of us probably ran it a little too fast. I usually ran at about 6 minutes/mile which was only about 30 sec /mile slower than my marathon pace. Nonetheless, this pace felt easy. After Percy Cerutty’s daunting Spartan approach with its killer sand-hill runs, Lydiard’s advice ‘to train. not strain’ seemed almost too soft, but the evidence from Rome was proof that it worked.

By 1968, the foundation of the modern marathon had been well laid and the event was about to emerge from the status of a challenging but obscure historic relic reserved for hardy young men. In the preceding December Derek Clayton had run under 2:10 in Fukuoka. Two years later, when I lined up for the start of the Australian marathon championship in Melbourne, I was a little disappointed that Clayton, winner of that event in both 1968 and 1971, was not there.   Not that I would have had any expectation of keeping him in sight for long, but if he had been there it would have nourished the almost-credible but fading illusion of belonging to a small but select fraternity. That same year Frank Lebow and Vince Chiapetta organised the first New York Marathon. Initially it was a small event confined to laps of Central Park, but when the event moved onto the streets of the five boroughs with over 2000 entrants in 1976, the era of the big city marathon had begun.   However, by that stage, I was no longer running marathons. My running had been displaced, initially by mountaineering, and then, after I married, by hill walking.

When I took up running again in my late fifties, the elite event was not all that different. It was a little faster and the Kenyans and Ethiopians were beginning to assert their dominance. The truly amazing transformation had been blossoming of the marathon as a massive community phenomenon. Thousands of runners, tens of thousands in the larger city marathons, started with expectations of finishing times ranging from 2:15 to 6 hours or more.

Out of curiosity I decided to run the Robin Hood Marathon a decade ago.  It was over thirty years since my last marathon, the ill-starred 1972 Polytechnic marathon in which we ran an extra three miles or so, after the lead car broke down and we went off course. More than three decades later, after a brief preparation, I found myself at the start of another marathon, engulfed in a vast ocean of variegated humanity   I spent far too much energy struggling to find some space in the melee, but eventually settled in comfortably     I reached half-way in 93 minutes but not surprisingly, I slowed badly after 20 miles, finishing in 3:27. At that time I considered that it would be a fairly straightforward matter to achieve 3:15 or even perhaps sub-3 hours if I trained systematically.

Little did I realise that I was on the edge of a seemingly inexorable descent into old age.   During my sixties, the various minor health problems that had dogged me for years started to loom larger in my life.   By early this year it was clear that if I wanted again to race a marathon I should not wait too long before embarking on systematic preparation.

Training in spring, 2014

Training this year has been an intriguing adventure. In the spring I began gradually increasing the length of the weekly long run and by early May, I was running up to 34 Km on Sunday morning – very slowly.   I was a little disconcerted by the lingering tiredness and aching connective tissues.  After the long runs I immersed myself waist deep in cold water in a wheelie bin, which provided some relief.  However in June I was knocked sideways by a bout of flu, and then in July, tore my gluteus maximus when leaping full length to catch a ball during a game of rounders – a team building exercise after a long day of project planning with my research team. It was a freak injury with an identifiable immediate cause, but I think that being over-tired makes a significant contribution to most muscle injuries.   Consistent with this interpretation, it took me a while to get going again.

Medical students are encouraged to heed Occam’s Razor: ‘Plurality of causes must never be posited without necessity’. However, in my experience, focusing on a single cause for an event often leads to failure to identify effective future prevention strategies. Summer flu followed by a torn muscle suggested it was time to reconsider my strategy.

Modifying Ed Whitlock’s approach

Rather than exhausting myself in a weekly long run, I decided to try Ed Whitlock’s approach of multiple easy longish runs each week, initially aiming to build gradually to 4 two hour runs per week by mid-December. Ed modestly states that his method works for him, but he is reluctant to recommend it to others. However, even accepting that Ed is endowed with an exceptional natural talent for marathoning and a predisposition to age well, his phenomenal performances suggest that his training can’t be holding him back.   Is there an understandable explanation for the success of his training strategy?

One possibility is that a training load that is spread fairy uniformly across the week is less likely to produce marked transient exhaustion than a traditional marathon program dominated by the weekly long run – even if length of the long run has been increased gradually. Each training session contributes to both fatigue and eventual fitness. In the short term the rise in fatigue is more prominent, but fatigue fades fairly rapidly. The gain in fitness is less immediately apparent, but takes longer to fade away.   At any point during a training program, the ability to resist injury and also the ability to race well, is determined by the difference between accumulated fitness and accumulated fatigue.

Because fatigue fades more rapidly, after an arduous training program, performance is usually enhanced by a taper during which fatigue disappears more rapidly than fitness. Conversely, during arduous training, risk of injury or illness is likely to be minimised by avoiding abrupt increases in fatigue that eat into the margin of reserve between fitness and fatigue.

Following a suggestion from Laurent Therond, I use a fairy simple mathematical model based on plausible values for the rate of decay of fatigue and of fitness to estimate my reserve of fitness during training. (I will post the details of the calculation on my calculation page soon).   The units are arbitrary and the precise numbers should not be taken too seriously, but the principles emerge fairly clearly. In May, following several months of cautious increase in training volume, my fitness reserve typically rose to around 500 units by Saturday, but fell dramatically after Sunday’s long run. For example, after a 34 Km long run in May, my estimated fitness reserve fell from 591 on Saturday to 368 after the long run on Sunday.

More recently, after several months of Whitlock-style training, my fitness reserve remained stable in the range 500 to 600 units throughout the week. Furthermore, my total training load was over 20% greater than it had been in May. However, by the beginning of December, I was just a little disconcerted. My training load was substantially greater than at any time in the past 40 years and I was aware of a mild accumulation of fatigue in some of the long runs. On two occasions I had felt a few fibres in my hamstrings give way when I bounded up a flight of steps to surmount the River Trent flood defences. On each occasion shortening stride alleviated the discomfort, but it indicated that I was not far from my safe limit.

In any case I intended to introduce some progressive runs into my schedule early in the New Year as a part of specific training for spring marathon. I therefore decided in the third week of December that I would cut back to 2 easy two-hour runs per week, and introduce some progressive runs to see how comfortably I could maintain a pace near marathon pace. After a short recovery session on Monday, my reserve fitness score was at an all-time high of 680.   On Tuesday morning, heart rate and heart-rate variability confirmed that I was in a relaxed state, so I set off for a 10K progressive run. After an easy start, I gradually increased the pace and by the end was feeling very fluent. It was a wonderful sensation to be running freely.   Retrospective analysis revealed that my pace in the final stage was 5 min/Km and heart rate at 83% HRR.   In my youth 5 min/Km would have scarcely been a jog, but on Tuesday it was exhilarating. Of course, it is virtually impossible that I could maintain HRR at 83% for a full marathon, so there is no reason to adjust my target marathon time downwards, but the wonderful thing was that I felt more like a runner once again.

On Wednesday I did a short high intensity interval session that I do frequently without overt evidence of exhaustion. I was little disconcerted to find in retrospect that my heart rate was higher than usual. The reason became clear that night. I was kept awake by a rising fever and a horrible cough that sent lancing jabs of pain through my head. The fever lasted for five days, and even since it has settled I have had a rather irritating cough.

A pause for recovery

Our family spent Christmas at my wife’s brother house in the Lake District. My wife’s brother is a former mountain guide and is currently Safety Advisor for a company that provides leadership training in various formats including outdoor adventure. Christmas at his house usually includes an adventure or two. This year it was mountain biking on Christmas Day and caving in the Yorkshire Dales on Boxing Day. It seemed to me that getting a bit of fresh air in my lungs would be more likely to help my recovery than harm it. Though I was the oldest member of the party, I was able to hold my own with the youngsters fairly well on both days. However, when I had to hoist myself onto a rock ledge while my feet dangled freely in the air below, to exit one of the caves, what would normally have been a simple manoeuvre had me struggling to find the required strength and brought home to me that I have not yet fully recovered.

Cycling on Christmas Day

Cycling on Christmas Day

Pause for the group photo. I am fourth from rigth (with dark glasses)

Pause for the group photo. I am fourth from rigth (with dark glasses)

Caving on Boxing Day

Caving on Boxing Day

Exit from Thistle Main

Wriggling out of Runscar Cave



So what is the conclusion? In the final few months of the year, I had achieved a larger volume of training than in any other 12 week period over the past 40 years. At the end of the 12 weeks I was running more fluently than at any time in recent years, though there were a few hints that I was on the edge of over-training. As I began to cut back the volume in mid-December, I was laid low yet again by a viral infection. Occam’s admonition against seeking unnecessary ‘plurality of causes’ would encourage me to look no further than the fact that many of my work colleagues and students had been suffering from upper respiratory infections at the time. The immediate cause of my illness was no doubt exposure to a sea of nasty viral particles. But I suspect that least in my case, training added a little to the vulnerability.

Nonetheless, I consider that on balance, in 2014 I have laid of solid base. Whitlock-style training is a viable proposition. It facilitates the building of a large training volume while avoiding sporadic peaks of stress. But like any training program that pushes the limits of ones reserves, for a cronky old-timer the best laid plans cannot eliminate the element of unpredictability.

The immediate challenge is to throw off the vestiges of my recent upper respiratory tract infection, without losing too much fitness. My experience in recent years is that for an elderly person, fitness dissolves very rapidly during complete rest, so I will aim for an active recovery in which I build up training volume gradually over a few weeks. Once I am back into full training, I will persist with the Whitlock principle of multiple longish runs at an easy pace each week. However if I am to be ready to race a marathon in the spring, I need to sharpen-up a little. Ed relied largely on short races for sharpening, but the demands of my present work schedule make it necessary for me to fit in two of the easy-paced long runs on the week-end, making racing impractical.   On the other hand, progressive runs that reach marathon pace in the later stages provide race-specific experience without sustained stress, and seem to me the form of sharpening that best suits my present circumstances. So my key sessions will include a progressive run along with several longish runs at an easy pace, each week.

Happy New-Year

Running Efficiency

December 2, 2014

Most endurance athletes focus their training on attempting to increase their aerobic capacity (VO2max) and their endurance. Training increases aerobic capacity by increasing the ability to deliver oxygen to muscle fibres and by increasing the capacity of mitochondrial enzymes to generate energy by oxidation of fuel. However our maximum capacity to generate energy by oxidation of fuel appears to be limited by our genes and/or early development.

The traditional approach to improving endurance is the long run. This increases resilience of muscles, tendons and ligaments, and enhances the ability to metabolise fats.   Once we have trained our aerobic capacity to our limit, and we have developed sufficient endurance to sustain us for the duration of our target event, what scope is there for further improvement in performance? The remaining option is increasing efficiency: that is the effectiveness with which we can use energy to produce speed.


Figure 1 shows speed (in metres/min plotted) against rate of energy production (VO2 measured in ml/min/Kg) for three hypothetical athletes. The slope of each line represents the efficiency of each athlete.   The line with medium slope represents the average runner in the sample used by Jack Daniels to derive the VDOT charts in his book ‘Daniels Running Formula’. The steeper line represents an athlete 10% more efficient than average. The less steep line represents an athlete 10% less efficient than average. Greater efficiency indicates a greater speed for a given rate of energy production. Note that the lines are almost straight, indicating that efficiency is nearly constant across a wide range of paces, though there is a minor degree of flattening of each line at higher paces, indicating a somewhat lesser increase in pace for each additional unit of oxygen consumed.

Figure 1: The relationship between pace and aerobic energy production.  These lines are derived from the data used by Jack Daniels to derive his VDOT tables. The middle line (brown) is the data for an athlete who had the average efficiency from the sample studied by Daniels. The upper (blue) line represents an athlete who is 10% more efficient than average.  The lower represents an athlete who is 10% less efficient than average.

Figure 1: The relationship between pace and aerobic energy production. These lines are derived from the data used by Jack Daniels to derive his VDOT tables. The middle line (brown) is the data for an athlete who had the average efficiency from the sample studied by Daniels. The upper (blue) line represents an athlete who is 10% more efficient than average. The lower represents an athlete who is 10% less efficient than average.

If each of the three hypothetical athletes had a VO2mx of 72 ml/min/Kg (typical of an elite distance runner) the athlete with average efficiency would achieve a pace of 350 metres/min at VO2 max while the athlete who was 10% more efficient would achieve a pace of 385 m//min. At 80% of VO2 max (57.5 ml/min/Kg), the athlete with average efficiency would be expected to achieve a pace of 293 m/min while the athlete who was 10% more efficient would achieve 322 m/min. It should be noted that for an athlete with a lower VO2max, the pace at VO2 max and at any given percentage of VO2max will be less, but the relative gain in pace from an increase in efficiency will be similar. In other words, for two athletes with the same VO2max, a 10% improvement in efficiency would result in 10% faster times in races run at any given proportion of VO2max.

Might training produce an increase in efficiency of 10% or more?   The measurements of Paula Radcliffe performed by Andrew Jones for more than a decade provide clear evidence that the answer is yes. In fact, the data shows that Paula achieved a 15% increase in efficiency over the decade from 1993 to 2003*. Her VO2max remained virtually constant at around 70 ml/min/Kg over this period. Thus, a major factor in Paula’s phenomenal marathon record of 2:15:25 recorded in 2003 appears to be the remarkable improvement in efficiency. How might an athlete improve efficiency?  There are two possibilities: increasing biomechanical efficiency and increasing metabolic efficiency.

Biomechanical efficiency

There are three major energy costs of running:

  • overcoming the braking that occurs while on stance;
  • getting airborne;
  • swinging the leg forwards after lift-off from stance.

There is also the cost of unnecessary tension or movements of other body parts, but as is well illustrated by Emil Zatopek and Paula Radcliffe, who both achieved phenomenal performance despite unnecessary upper body movements, the cost of such movements is relatively small, and there is unlikely to be more than a slight gain from reducing them.

Minimizing the sum of the three major costs requires a balance between conflicting effects. At a given cadence (steps/min) braking cost increases as the cost of getting airborne decreases because less time in the air inevitably results in a larger proportion of time on the ground. Although braking only occurs when the point of support is in front of the centre of gravity, braking cost cannot be reduced merely by attempting to land with the foot under the body, because at constant speed the forward-directed impulse generated after mid-stance and the backward directed impulse generated by braking before mid-stance must be equal (after allowing for overcoming wind resistance).  For a give cadence, the cost of braking can only be reduced by spending more time airborne.

During a marathon, many runners spend an increasing proportion of the time on stance as the race progresses. This is likely to result in greater braking and reduced efficiency. It is noteworthy that the well-known picture of Paula Radcliffe at mile 14 on her way to victory in the 2007 New York marathon shows her getting well-airborne. This demonstrates that she had adequately developed reserves of the leg muscle power required to get airborne. Andrew Jones’ measurements demonstrated that her vertical jump performance increased from 29cm in 1996 to 38cm in 2003.

Paula Radcliffe airborne at mile 14 in the New York marathon, 2007.  Photo by Ed Costello, Brooklyn, NY,US

Paula Radcliffe airborne at mile 14 in the New York marathon, 2007. Photo by Ed Costello, Brooklyn, NY,US

The cost of getting airborne can be reduced by increasing cadence, because the body falls a lesser distance during a series so short hops than during a longer hops covering the same distance, simply because a freely falling body accelerates, thereby gaining greater speed the longer it is airborne. The optimum cadence increases with increasing speed, because if cadence does not increase with increasing speed, stride length would necessarily have to increase disproportionately, resulting in heavy costs of getting airborne and also braking. However, there is a limit to the gains that can be achieved by increasing cadence, because the cost of moving the swing leg forwards increases in proportion to cadence (as shown on the my calculations page).

Nonetheless, many recreational athletes have scope for increasing efficiency by increasing cadence. The study by Heiderscheit and colleagues indicates that a typical recreational runner might improve efficiency by decreasing both airborne costs and braking costs by increasing the self-selected cadence by up to 10% . This increase in cadence also reduces stress at the joints by virtue of the reduction in forces required to get airborne and overcome braking.   Heiderscheit reported that a 10% increase in step rate from a self-selected mean step rate of 172.6 ± 8.8 steps/min at a pace of 2.9 ± 0.5 m/s led to an almost 20% reduction in energy absorbed at hip, knee and ankle joints.

It is probable that Paul Radcliffe achieved optimum balance between the cost of getting airborne, braking and advancing the swing leg largely by virtue of fairly intense running, together with hopping drills and weight lifting.   While training near to race pace might optimise neuromuscular coordination, I suspect that the major requirement for optimising mechanical efficiency is adequate muscle power. Although I do not have direct evidence to prove it, I think it is plausible that a small amount of high intensity training will achieve as much gain in mechanical efficiency with less total wear and tear on the body compared with a larger volume of threshold training, simply because training near to maximal effort is more effective for improving muscle strength and power.

Metabolic efficiency

Metabolic efficiency of oxygen consumption is a measure of the amount of mechanical work (and hence speed) that can be achieved from the consumption of a given amount of oxygen. Several factors influence this. The most important is the fact that the efficiency of conversion of metabolic energy to mechanical energy during contraction of a muscle fibre is greatest when the speed of contraction is near the middle of the range of contraction speed that can be achieved by that fibre. When a fibre contracts too slowly it consumes energy developing tension that does little work. Fast twitch fibres have an optimum speed of contraction that several times faster than that of slow twitch fibres. But the speed of fibre shortening during distance running (and also cycling) is better matched to the optimum contraction speed of slow twitch fibres.

It is noteworthy that many of the large muscles that act at hip and knee cross both joints, flexing one while extending the other or vice versa. However during running hip and knee flex simultaneously or extend simultaneously. Consequently, the rate of change in length in these muscle during running is small. Thus type 1 fibres which are well suited to the isometric contractions required to maintain upright posture are also well suited to distance running during which contraction rate is slow.

In the case of cycling, there is direct evidence that efficiency of metabolic to mechanical conversion is greater in individuals who have a higher proportion of type 1 fibres. Although I do not know of any similar measurements in runners, it is very likely that runners with more highly developed type 1 fibres will be more efficient.

The most effective way to develop type 1 fibres is likely to be consistent high-volume training over a sustained period. It is likely that a major part of Paula Radcliffe’s improvement in efficiency was consistent training, with a gradual increase in training volume over a period of a decade. As discussed in my previous post, Paula did a lot of her training at a moderate or high intensity. It remains a matter of speculation as to whether she could have achieved similar phenomenal marathon performances with less damage to her body by a more polarised approach, in which a modest amount of high intensity running was accompanied by a larger proportion of low intensity running. Perhaps she could have achieved similar improvement in metabolic efficiency with a larger proportion of low intensity training over a longer period of time. My own view, based on Skoluda’s evidence that many distance runners have evidence of sustained high levels of the potentially harmful catabolic hormone, cortisol, is that for many athletes a polarised approach offers the best prospect of gradual improvement in metabolic efficiency and hence, the prospect of year-on-year improvement over many years.


Paula Radcliffe’s spectacular 15% increase in efficiency over a period of about a decade, despite an approximately constant VO2max, provides compelling evidence that a worthwhile enhancement of efficiency is possible. It is likely that a combination of high intensity training, hopping drills and weight lifting honed her biomechanical efficiency.  For many recreational athletes, biomechanical efficiency might also be improved by increasing their self-selected cadence by as much as 10%.  It should be noted that optimum cadence increases with speed.

It is also likely that a gradual improvement in metabolic efficiency over a period of more than a decade was also a major contributor to Paula’s improved efficiency.  It is likely that she achieved this by consistent training, with a gradual increase in volume over the years.  Whether or not she might have achieved a similar enhancement of efficiency with a less damaging, more polarised approach to training remains a matter for speculation. Nonetheless, in my opinion, for many athletes, a polarised approach is likely to offer the best prospect of gradual improvement in metabolic efficiency over a period of many years.


*A minor point to note is that Andrew Jones estimated speed at VO2max by assuming a linear increase in pace with increased VO2. This is likely to produce a small over-estimate of actual pace at VO2max, because in reality the curve flattens a little at high values of VO2. Nonetheless, provided all the measurements are made at a similar region of the curve, the error in estimate will be consistent across different measurements. It is pace at around 80% of VO2max that matters most to a distance runner.

Getting maximum benefit from low intensity training

October 3, 2014

In my recent posts I have discussed the evidence suggesting that if one’s goal is year-on-year improvement in marathon performance, the best approach is a polarised program including a large volume of low intensity training and a small volume of high intensity training. Since at least 80% of the training time during a polarised program is devoted to low intensity runs, it is worth considering how to derive the greatest benefit for these sessions.

First, I should make it clear that I believe in a periodized approach that includes a base-building phase and a race-specific phase. Both phases should be polarised, each embracing both low intensity and high intensity training. In the base-building phase, the goal is to build all of the basic physiological capacities required for marathoning. In this phase, the low intensity sessions play a crucial role in developing several of these capacities, but high intensity sessions also play a key role. In the race-specific phase a small proportion of the sessions are devoted explicitly to developing the mental and physical strength required for racing. This post will deal mainly with the base-building phase. Nonetheless, even in the race-specific phase it is crucial to maintain the capacities developed during base-building, so many of the principles apply to planning training in both phases. I will address the specific requirements of race-specific phase in greater detail in a future post.

In my post of 20th September I listed the five physiological capacities that need to be trained in preparation for a good marathon:

  • VO2max – this measures the maximum rate at which oxygen can be delivered to tissues and hence the maximum rate at which muscles can generate energy.
  • Speed at VO2max.
  • Pace at lactate threshold as a proportion of pace at VO2max. For a well-trained marathoner, race pace is near to lactate threshold.
  • Ability to conserve glycogen so that glucose supply is not exhausted before 26.2 miles.
  • Resilience of leg muscles to sustain pounding for the duration of the marathon with only minimal loss of power.

Each of these five capacities can be enhanced by several different types of training stimulus, so full development each of the variables requires a complementary mix of low and high intensity training. The low intensity session play an especially important part in increasing three of the five capacities: VO2max; conservation of glycogen; and developing resilience of leg muscles, so we should consider each of these in turn.

Enhancing VO2max

The two major ways in which low intensity training enhances VO2 max are by increasing the aerobic enzymes in mitochondria; and by enhancing the capillaries that deliver blood to muscle fibres. These physiological processes can be examined in muscle biopsies from athletes, but more detailed information can be obtained from the study of animals. Despite the large scale anatomical differences between the human and rodent musculo-skeletal systems, at the level of individual fibres the structure and functional of muscles are similar across the species so studies of the ways rodent muscle fibres respond to training are likely to be informative about the ways in which human fibres respond.

One of the major questions in planning a training schedule is whether it matters whether the training is done in multiple short session or fewer long sessions. The long slow run has been regarded as a core feature of marathon training for years, though the data for study of animals suggest that with regard to enhancing aerobic enzymes and capillaries, multiple short runs might be just as beneficial.

In a recent study. Malek and colleagues trained mice on a treadmill on 5 days a week for 8 weeks. One group of mice trained for 30 minutes continuously on each training day, while another group of mice trained for 3 periods of 10 minutes separated by a 2 hour rest. The intensity of training was equal.  The animals started at the rather slow pace of 7.5 metres per minute, and over the 8 weeks, increased the rate of working up to 60% of maximum power output. A control group of mice were placed on the treadmill but did no training. Compared to the untrained controls, both groups of trained mice exhibited similar major improvements in both speed and distance covered during an incremental treadmill tests administered at the beginning and end of the training period. The untrained controls exhibited a 1% increase in the distance covered in the incremental test after 8 weeks, while the group who trained continuously for 30 minutes exhibited an increase of 107% and the group who trained for 3×10 minutes exhibited an increase of 117%. . Furthermore, after training, the capillary density and the number of capillaries per muscle fibre in quadriceps muscle were approximately twice as great in the two training groups compared with the untrained controls. Similarly the amount of the aerobic enzyme, citrate synthase, in the plantaris muscle in both of the trained groups was about twice as great as in the controls. Thus, running performance, muscle capillary density and aerobic enzymes showed large, but similar, increases in both trained groups. This suggests that with regard to improving VO2max , three 10 minute training sessions produce very similar enhancement to one 30 minute training session.

On the other hand, Dudley’s well known studies, in which he trained rats at several different speeds for varying lengths of time per day showed that very long sessions did not produce greater enhancement of aerobic session that medium length sessions. The greatest gain in cytochrome C (a complex of aerobic enzymes) occurred in rats trained at a pace of 30 metres/min. Thirty metres/min is a medium pace for a rat; typically a rat can maintain 60 metres/min for about 10-15 minutes whereas it can sustain 30 metres/min for an hour or so with little difficulty. The rats that trained at 30 m/min showed a steady increase in enhancement of cytochrome C in red soleus muscle with increasing daily run time up to 60 minutes, but the there was only a slight further training effect in the group who trained for 90 minutes, suggesting no benefit with regard to aerobic enzymes beyond 90 minutes..

It is important to note that Dudley’s rats did not have much opportunity to adapt to the training load.   After an initial five day introductory period of running 5-10 minutes daily at approximately 30 m/min, they were allocated to the designated training and the training load was ramped up at the rate of 12 additional minutes each day, ensuring that the animals allocated to train for 90 minutes per day were training at full load by the end of the second week. It is possible that the rats allocated to 90 minutes per day at a pace of 30 m/min were not given adequate time to adapt to the training load. Inadequate adaption to the load would be expected to result in excessive release of cortisol which has a damaging catabolic effect on muscle.

Taken together, the findings from Malek’s study of mice and Dudley’s study of rats, indicate that there is little difference in the training benefit derived from a single continuous session of 30 minutes compared with three session of 10 minutes, while the benefits of increasing the length of sessions beyond 60 minutes are small in the absence of an adequate period to adapt to the training load. It is speculative, but I consider quite plausible that provided long run duration is built up gradually, that additional benefit will accrue beyond 90 minutes. Nonetheless, with regard to enhancing erobic capacity, the evidence suggests that multiple short runs are likely to be at least as effective as a similar total duration of long runs. This would suggest that for VO2max development, doubles might be at least as effective, and perhaps more effective in terms of time spent and stress sustained than single daily sessions. However, enhancing VO2max is not the only goal of training.

Enhancing conservation of glycogen.

Endurance training produces an increase in the proportion of energy derived from fat, across a wide range of intensity of exercise. Although it is well established that in both trained and untrained individuals, the proportion of energy derived for fat is less at paces above lactate threshold than at paces below threshold, nonetheless, even above threshold, trained athletes derive a larger proportion of total energy from fat than untrained individuals. [See the opinion piece by Coggan.]

While many studies have demonstrated that trained individuals derive a greater proportion of the energy required during exercise from fat, compared with untrained individuals, there have been only a few longitudinal studies that have demonstrated the efficacy of a specific endurance training schedule for enhancing fat metabolism. One particularly informative study was done by Henriksson. He subjected 6 cyclists to a training program in which only one leg was trained for 45 min/day at 70% of VO2max (estimated for one leg) for an average of three days per week for a period of 8 weeks.

Before and after the training period, a muscle biopsy was taken from quadriceps for determination the activity of the aerobic enzyme, succinate dehydrogenase. The subjects were also tested on different submaximal and maximal one-legged and two-legged workloads. Catheters were inserted into the femoral arteries and veins at the groin in both legs to allow measurement of blood oxygen and carbon dioxide levels. In the submaximal test, participants performed two-legged exercise for 1 hour at 67% of VO2 max.  In the trained leg, there was a substantial greater capacity of muscle to extract oxygen from blood, demonstrated by increased arterio-venous difference. The respiratory exchange ratio (RER) was 0.91 throughout the 1 hour in the trained leg. Respiratory exchange ratio is the ratio of the amount of CO2 produced to O2 consumed. It has a value of 1 when carbohydrate is the sole fuel and a value less than 1 if fat is included in the fuel mixture. Thus the value of 0.91 indicates that a substantial proportion of energy was obtained from fat. In contrast, in the untrained leg, RER after 10 minutes was 0.96 indicating that the majority of the energy was obtained from carbohydrate metabolism and even after 50 minutes, the RER in the untrained leg was 0.94. Thus the proportion of energy derived from fat had increased as might be expected if glycogen stores were being exhausted, but nonetheless even after 50 minutes the proportion of energy derived from fat in the untrained leg was less than in the trained leg.

Henriksson estimated that in the trained leg, 42% of energy was obtained from glycogen while in the untrained leg, 62% of energy was derived from glycogen. Thus, the increased utilization of fat in the trained leg resulted in appreciable conservation of glycogen. Furthermore, rate of lactate release in the untrained leg was between 2.5 and 3 mmol/min in the period from 10 to 30 minutes yet remained below 0.5 mmol/min in the trained leg, confirming the expectation arising from the fact the fat metabolism does not generate lactate.

It was also of interest to note that measurement of free fatty acids in the blood demonstrated that the increase fat metabolism came largely for increased consumption of triglycerides stored within muscle. The mechanism of this increase was not clear. The activity of aerobic enzyme succinate dehydrogenase increased in the trained leg. This increase in aerobic enzymes would lead to faster fat metabolism. However it is probable that an increase in enzymes involved directly in fat metabolism and also an increase in ability to transport fats into mitochondria played a part

In summary, the study by Henriksson established that moderate intensity exercise (70% VO2max) for 45 minutes 3 days per week produced a substantial enhancement of fat metabolism, thereby conserving glycogen and reducing the production of lactate.   He did not address the question of whether or not a greater benefit would have been obtained from longer duration of exercise. However the observation that even in the untrained leg the proportion of energy derived from fat increased appreciably by 50 minutes confirms the expectation that a long duration low intensity session would be more effective for enhancing fat metabolism than multiple short duration sessions.

Thus, it is likely that long runs lasting an hour or more are the most effective for increasing fat metabolism, but it is necessary to bear in mind that unless long run duration is increased gradually, there is a risk of increased release of cortisol. Similarly, training in a fasted stated would be expected to produce greater enhancement of fat metabolism but care should be taken to avoid excessive stress. As I suggested in my previous discussion of training in the fasted state, I suspect that the inconsistent results reported by different studies of training in the fasted state reflect differences in the degree to which there was adequate adaptation to training in a fasted state.

Resilience of leg muscles

Eccentric contraction at foot strike causes microscopic tearing of muscle fibres. This is likely to be the major factor in the production of Delayed Onset Muscle Soreness (DOMS). However, as virtually every athlete knows from direct experience, after DOMS, the muscle adapts rapidly to prevent subsequent damage if the same exercise is repeated.

Although many recreational athletes preparing for a marathon experience some DOMS early in the program, they quickly develop sufficient resilience to prevent serious DOMS in subsequent weeks. However, the observation that many experience a recurrence of severe DOMS in the aftermath of the race itself, indicates that they failed to develop adequate resilience to cope with the sustained pounding of the marathon.   While a few days of DOMS after the event might be of little consequence, the effect of microscopic damage during the event is potentially of much greater importance. Muscle damage during the marathon appears to be one of the major causes of slowing down in the second half of the race. Therefore, development of adequate resilience is a high priority.

During the race itself it is the combination of the duration of the stress and the intensity of stress that does the damage. It is therefore likely that a multi-facetted approach, involving both long duration sessions and some more intense running is required to build the required resilience. An approach that relies too heavily on extending the duration of intense exercise would be risky. Although complete recovery from DOMS is usual provided there is adequate subsequent opportunity for recovery, if there inadequate opportunity for recovery, the muscle might eventually lose its capacity to recover. It appears likely that the relatively rare Fatigued Athlete Myopathic Syndrome (FAMS) is the end stage of repeated microscopic muscle trauma without adequate opportunity for recovery. In cases of FAMS the athlete exhibits marked disruptions of muscle microstructure and suffers loss of the ability to tolerate further training.  On the other hand, repeated exposure to a small stress can protect against future larger stresses, so long slow runs are the safest way to establish the foundation for the resilience required to withstand the repeated pounding at marathon pace


The evidence provides very strong grounds for arguing that a substantial volume of low intensity training is an effective complement to a small volume of more intense training during marathon preparation. In particular, the low intensity training is a safe way of enhancing VO2 max; promoting the ability to conserve glycogen (and incidentally reducing the production of lactic acid); and lays the foundation for the muscle resilience required to avoid slowing in the later stages of the race.

This evidence also provides guidance regarding how best to schedule this training. The first point to note is that multiple short session are likely to effective in enhancing VO2max in a safe manner. However, at least some longer duration sessions are also required to optimise the ability to conserve glycogen via utilization of fat, and to develop the required resilience.

The traditional answer to these requirements is to incorporate a weekly long run of gradually increasing length in the training schedule. This traditional answer certainly has merit. However, it is possible that this strategy relies too heavily on the weekly long run. For example, building up the long run length from less than 10 miles to more than 20 miles within the course of a 12-16 week program might not provide adequate opportunity to adapt adequately to the demands of the long run. This has two consequences. First, the long run itself might leave the runner tired and aching, limiting the quality of training on subsequent days. Secondly, there is a substantial risk that one long run per week will prove inadequate for developing the resilience required to maintain pace for the full 26.2 miles.

An alternative to placing so much of the emphasis on a single weekly long run is to add small increments to the duration of several runs each week, thereby creating a more uniform build-up of training load throughout the week and avoiding the disruptive influence of a single long run. This is the approach pioneered with great success by Ed Whitlock. He gradually built the capacity to cope with three or four 3 hour slow runs each week, in preparation for his phenomenal 2:54:48 in the Toronto Waterfront marathon at age 73. Ed acknowledges that although this worked so well for him, such an approach might not work so well for others. However, in my view the evidence we have considered in this post provides reasonable grounds for expecting that Ed’s approach might work well for others.   The evidence that capillaries and aerobic enzymes can be developed effectively in multiple relatively short sessions and that appreciable improvement in fat metabolism can be achieved with session of 45 minutes duration, while on the other hand, long sessions without adequate foundation create risk of excessive release of damaging catabolic hormones, suggests that gradual build-up of the duration of multiple longish runs each week might be effective.

It is important to note that the two crucial features of Ed’s approach are the multiplicity of long runs each week and the gradual increase in length of these long runs. While it is true that by age 73 most of his long runs were of 3 hours duration, he had built up to that duration over 6 years. When he first set a single age world record for the marathon at age 68, the majority of his long runs were only two hours in duration. He did not measure the distance of these runs, but as far as I can estimate from his own description of these easy long runs, it is unlikely that in 2 hours he ran more than 14 miles. I think that the evidence we have considered above suggests that the important feature is the consistency throughout the week rather that the focus on a single very long run each week.

There is one respect in which I am inclined to recommend a difference from Ed’s approach. His high intensity sessions took the form of frequent races over shorter distances, and occasional fartlek sessions, but no specific preparation for maintaining marathon pace throughout the race. I think that in the final 12-16 weeks of preparation for a marathon, one of the weekly long runs should be replaced by a race-specific training session aimed at developing the required mental and physical strength for racing. However I will defer detailed discussion of ways of implementing this to a future post.

I am at present working on gradually increasing the duration of four runs each week.   I started with four 65 minute easy runs in the first week of this program, and after 6 weeks have increased the duration of these four longish runs to 105 minutes each. I am also doing at least one high intensity session per week and one or two other short sessions. I am carefully monitoring the rate of increase in duration of these four runs to ensure that there is no cumulative tiredness. It is still far too early to deliver judgment on this strategy. However I have now built up to a weekly volume that is almost as high as the highest I have achieved at any time in the past few years. Last year and also the year before, I had found that after a few weeks at this volume of training I was showing signs of accumulating exhaustion and therefore was obliged to cut back the volume of training. If I continue to make small advances in run duration without accumulation of tiredness over the next few weeks I will have the first indications that this strategy is working.

What is the best way to increase lactate threshold?

September 20, 2014

There are five physiological variables that need to be trained in preparation for a good marathon:

  • VO2max – this measures the maximum rate at which oxygen can be delivered to tissues and hence the maximum rate at which muscles can generate energy.
  • Speed at VO2max.
  • Pace at lactate threshold as a proportion of pace at VO2max. For a well-trained marathoner, race pace is near to lactate threshold.
  • Ability to conserve glycogen so that glucose supply is not exhausted before 26.2 miles.
  • Resilience of leg muscles to sustain pounding for the duration of the marathon with only minimal loss of power.

These five variables are all trainable to at least some extent, though the first two are largely determined by genetic factors. These two variables set the ultimate limit on performance. The other three can be trained to the level where they no longer impose the limit. But nonetheless, the way in which any of them is trained is likely to affect the others, and hence the choice of training schedule must take account of all of the requirements.

As discussed in my previous post about the physiology of Paula Radcliffe, once you have dealt with any remediable defects of strength or form that impede your speed, if you want to push to the very edge of the limitations that your genes and/or the aging process have placed on VO2max and speed at VO2 max, the main focus of training should be on increasing pace at lactate threshold. Therefore in this post, I will address the question of how best to increase pace at lactate threshold, while minimising risk of injury and taking into account the need to ensure that none of the other four requirements are undermined.

Threshold training

The most obvious way to increase pace at lactate threshold is to do a lot of running near lactate threshold. This will encourage the development of the mechanism for transporting lactate out of muscles and for metabolising lactate in other tissues such as liver and heart, thereby not only conserving fuel but also minimising the accumulation of acidity. Thus lactate threshold will be pushed upwards to a faster pace. This is the approach that was employed by Paula Radcliffe, with striking success. I think it is highly likely that this is the approach can work well for many runners, at least in the short term, but there are dangers in this approach that limit its value.

The greatest of these dangers is undue accumulation of stress. This is likely to lead to sustained high levels of cortisol that damage tissues. Such damage not only decreases the ability to generate the power essential for achieving optimum speed at VO2max,but also decreases the resilience of muscles and increases risk of injury.   Furthermore, the impact forces at foot strike increase greatly with speed, so the direct physical trauma imposed on the legs is substantially greater during threshold training than low intensity training.  As shown in figure 1 (showing data reported by Peter Weyand and colleagues) the impulse transmitted through the leg (the product of average force  x time on stance) rises very rapidly as speed increases from low speed reaching a peak at typical tempo speeds and then actually decreases a little a higher speed due to decreased time on stance.  Since energy is consumed while force is sustained and muscle failure will occur when the required force can no longer be sustained, I suspect that impulse might be a better predictor of likelihood of damage than the magnitude of the force.  If so, tempo speeds are likely to be especially damaging.

Figure 1. Upper panel: the average vertical force (expressed relative to body weight) during stance as a function of running speed.  Lower panel: the vertical impulse (average force x duration of stance) transmitted through the leg during stance as a function of running speed.

Figure 1. Upper panel: the average vertical force (expressed relative to body weight) during stance as a function of running speed. Lower panel: the vertical impulse (average force x duration of stance) transmitted through the leg during stance as a function of running speed.

I believe that Paula Radcilffe achieved her phenomenal marathon record of 2:15:25 in 2003 not only because she did a lot of training at a pace near lactate threshold but also because she employed a strengthening program that minimised loss of power and provided some protection against injury. However, I also think that it is likely that in Paula’s case, her strategy did ultimately lead to injury that frustrated her hopes of Olympic gold. The question of whether or not she could have achieved her phenomenal run in London in 2003 without putting herself at risk of injury in the longer term remains unanswered and perhaps will remain unanswered until someone else breaks her record via a less stressful training program.

Low intensity training.

The alterative to relying on highly developed enzymes for metabolising lactate is minimising production of lactate. Lactate is produced when glucose is metabolised in the absence of a copious supply of oxygen. Fat metabolism generates energy via aerobic metabolism and hence is not able to meet needs when oxygen supply is seriously limited. However, provided there is some oxygen available, fat metabolism generates energy without the production of lactic acid because the pathway of fat metabolism leads directly into the Krebs cycle (as illustrated in my post of 5th Dec 2013). The rate at which energy is produced by fat metabolism is relatively slow, and therefore, for most athletes, fat metabolism is inadequate to meet the requirements in the upper aerobic zone. However, the capacity to generate energy by fat metabolism can be increased. Such an increase will not only help conserve glucose, but also minimise production of lactic acid when running in the upper aerobic zone.   Thus, increased ability to metabolise fat would be expected to raise lactate threshold such that a faster pace can be achieved at threshold. One way to promote the capacity to metabolise fat is to do a lot of running at slow speeds. This mobilises slow twitch fibres that preferentially utilise fat.

A large amount of slow running will also help develop the muscle resilience to cope with a long duration of running, though perhaps not the resilience required to maintain marathon pace for a long period. A schedule that consists entirely of slow running is unlikely to develop the neuromuscular coordination required to achieve a high speed at VO2 max, nor the coordination required to protect the muscles against damage at marathon pace. Furthermore, merely minimising the generation of lactate is not adequate for optimum performance, since once pace increases to the level where lactate does begin to accumulate, the accumulation will be rapid unless the ability to metabolise lactate is also well developed.. In addition, a large amount of slow running would also be expected to lead to sustained high cortisol levels unless the body is well adapted to long slow runs. So low intensity training alone is unlikely to be the answer.

Polarised training

We are faced with several competing demands: the need to raise lactate threshold without undue accumulation of stress, while also maintaining the neuromuscular coordination and power required to run fast. This suggests that some higher intensity training is required. The key question is whether it is possible to combine low intensity and high intensity training in a manner that achieves the advantages of both without each damaging the benefits produced by the other.

High intensity training (above lactate threshold) does actually enhance fat metabolism while increasing aerobic enzymes. Therefore, in itself high intensity training, at least in moderation, would not be expected to harm the benefits derived from low intensity training. High intensity training also enhances ability to metabolise lactate. In addition, high intensity training promotes release of anabolic hormones. However, the risk is rapid accumulation of stress. The greater impact forces at higher speeds increase the risk of physical trauma to muscles. Thus, high intensity training is potentially dangerous unless done judiciously.

On the other hand, excessive low intensity training might harm neuromuscular coordination required for faster running, but the contrast between the pictures of Ed Whitlock training in the Evergreen Cemetery and racing suggests that only a small proportion of higher intensity running is required to maintain the required neuromuscular coordination.

Thus, there is little reason for believing that a judicious combination low and high intensity training will be mutually antagonistic. The major issue to be addressed is avoidance of accumulated stress from both types of training. The accumulation of stress is probably best dealt with by gradual build up.

The question of how much high intensity training is required to develop adequate ability to metabolise lactate, or alternatively, whether at least some threshold training is required remains unanswered. The evidence from the training of elite athletes suggests that at least some threshold training should be included in the mix.

Cruise intervals

There is an alternative strategy for enhancing capacity to metabolise lactate: cruise intervals in which periods of running at or perhaps a little faster than lactate threshold pace alternate with recovery periods during which the lactate is cleared from the system. Jack Daniels advocated moderately long periods at tempo pace with short recovery to enable tempo pace to be maintained longer. It is likely that Zatopek’s legendary interval sessions were a variant of cruise intervals with the faster epochs appreciably faster than lactate threshold pace, as Ewen pointed out in his comments on my post about Zatopek in 2009. I find that I recover well from cruise intervals with moderately short effort epochs (e.g 6 minutes) a little above lactate threshold.


On balance, the evidence indicates that polarised training is best if one wants to achieve year on year development, or to slow the deterioration with age. But it remains unclear whether a strategy that produces year on year development will ultimately lead to one’s best possible performance. Alternatively, if one’s goal is to produce one’s best possible marathon without concern for longevity, might a large amount of threshold training be best? Is it better to flash with the brilliance of Paula Radcliffe in 2003 but burn like a meteorite, or is it best to glow with the unassuming brightness of Ed Whitlock, like Sirius in the night sky?

Perhaps Yoshihisa Hosaka will break Ed’s M70-75 record in a few years’ time providing evidence suggesting that Whitlock might have done better with more intense training. Perhaps some yet unknown female marathoner will eclipse Paula Radcliffe’s record after less stressful training. The future will answer these questions. But at least for the time being, my own evaluation of the evidence favours the polarised approach: a large amount of low intensity running to enhance fat metabolism thereby minimising the production of lactate in the upper aerobic zone, together with a small proportion of high intensity training and a similar proportion of threshold training, perhaps in the form of cruise intervals, to enhance lactate metabolism.


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