Getting maximum benefit from low intensity training

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.

22 Responses to “Getting maximum benefit from low intensity training”

  1. Pepe Says:

    Very interesting, as usual.
    In your opinion, how long is an adecuate base-training phase to prepare a marathon for a well trained popular runner?
    And what’s your opinion in strengh-training during this phase

    • canute1 Says:

      Thanks for your comment. The required duration of both the base-building and the race-specific phase almost certainly depends on the past experience and individual strengths of the athlete. For an athlete who can run at an easy pace for about 60 minutes at the beginning of base-building, I think base-building should be at least 10 weeks, allowing the athlete to achieve multiple 2 hours easy runs each week without exhaustion. Then I would suggest making one of the long runs into a progressive run, aiming to build up to achieve at least half of the distance of the long run at MP. I suspect this can typically be achieved after another 10 weeks. This should allow a ‘good’ marathon but maybe not the best possible for that athlete. However, I would anticipate that the following year, the multiple long runs might be extended beyond 2 hours in the base-building phase, and the program is likely to produce a better performance. On the other hand, for a very experienced athlete with a well-established ‘base’ it might be best to focus largely on the race-specific phase, with emphasis on long runs including a substantial amount of MP.

      I think some strength training is essential. I myself do free weight sessions (focussed on squats and deadlifts), though hill sessions might be an adequate alternative.

  2. Ewen Says:

    Thanks Canute. Firstly, I’m very pleased that your own version of ‘Whitlock training’ is going well. Are you planning on doing any tests to compare how your overall fitness is to years past?

    “First, the long run itself might leave the runner tired and aching, limiting the quality of training on subsequent days” – I think this is a key point. My own experience as an older runner is that the traditional Sunday long run I ran in my youth, as an older runner, tended to leave me in ‘recovery mode’ for 2 or 3 days. I think not having substantially different days is a good basis for a training plan (Hosaka being extreme in this regard). Whitlock is similar in not having substancially different days apart from the small amount of high intensity running.

    Malek’s study on mice (3 x 10 mins = to 1 x 30) backs up the training that many Kenyan runners do. Paul Tergat for instance, training twice a day (once Saturday and Sunday) at 6AM and 10AM. Interestingly, Tergat’s longest run by time was about 80 minutes (14 miles at 5:40 per mile). His Sunday run was 12 miles at 6 minutes per mile, so a relatively easy recovery day of 72 minutes duration.

    • canute1 Says:

      Thanks for your comment.
      At the moment the only formal tests I am doing are the sub-maximal tests that I developed a year ago. However, over the next few months the biggest question is whether I can build up volume to include 4 moderately long runs each week without cumulative exhaustion. With regard to racing as a test, although I am not focussing on the marathon, for which I have no recent comparison, I will probably do a half marathon at some stage to allow comparison with the last few years – I am intrigued to see if I can arrest the marked decline that became very prominent last year.

      Thanks for the details about Paul Tergat. If the Whitlock-style program does not turn out to suit me I will probably switch to doing doubles 4 days per week – but this is less time-efficient

      • Ewen Says:

        Canute, perhaps after a few months you could schedule a Parkrun 5k as a comparative test? I recall you racing a Parkrun some years ago.

        On a side issue, there was an interesting article in Runner’s World about heart health, showing ‘competitive’ runners when they reached the average age of 70 as having healthier hearts. No mention of what distances they competed at though.

    • canute1 Says:

      Yes I will do some Parkruns in the not too distant future, though not until after I complete the current phase of building up the duration of the 4 longish runs each week. Finding time for 4 two hour runs in a working week demands that I do two of these runs on the weekend – and adding a maximum effort 5K on Saturday morning would be a bit risky. However, once I have confirmed that I can cope with 4 two hour runs, I will occasionally adjust the weekly schedule to include 3x2hour runs together with Parkrun and a couple of easy short sessions.

      Thanks for the link to the recent study of heart health in elderly athletes. In fact I had seen the original article:
      This is encouraging as it indicates that competitive Masters athletes who do 6 or 7 sessions a week have more flexible left ventricles in comparison not only with sedentary elderly men and also in comparison with committed exercisers who train up to 4 or 5 times per week.

      At this stage my own tentative overview on running and heart health is that a large amount of running is likely to increase heart health, subject to two caveats: 1) doing stressful sessions without adequate recovery is likely to promote chronic inflammation that might increase risk of coronary heart disease; 2) very large training volumes increase the risk of rhythm disturbances such as atrial fibrillation. In other words, the risks are small and are likely to be outweighed by the benefits if one trains in a way that minimises stressful training. As Arthur Lydiard advised: train but don’t strain. One approach is polarised training in which one builds up volume of the easy sessions and also the volume of the hard sessions in a gradual manner so that the body is well adapted to the stresses imposed upon it. I am continuing to record cardiac R-R intervals during most of my training sessions, in order to monitor frequency of ectopic heart beats. These appear to be less frequent now than a few years ago, but I still think it is sensible to monitor the situation.

  3. Robert Osfeidl Says:

    It’s great to hear that your training is progressing well, and your body is coping with the increase in time on your feet each week.

    The approach of doing several (2 or 3) longish runs (1:40 to 2:20) each week rather than one long run each week was the foundation of my preperation of doing the West Highland Way Race this year. In between these longer runs I did plenty of 1hr runs. This worked really well for me – building up my resilience, aerobic fitness and crucicially fat burning capacity. I amazed myself just how much I could build up my weekly training and not get injured.

    Since changing my training to build towards faster shorter races I’ve replaced many of the longer runs with faster sessions. Initially I say fitness gains but in the last month I think injuries have started to creep in, interrupting my training which has finally taken a toll in my overall fitness.

    It may be that I re-introduced the faster sessions and racing too quickly and my body didn’t have a chance to adapt, or it could be that the balance between low intensity and high intensity was wrong. Or perhaps just other things in life also affecting how rapidly my body was healing after training.

    Getting this balance right is hard, especially when you are sailing close to the over training line. For me lots of slow runs of moderate length seemed to work well, basically low stress running day in day out. If I had the time I’d certainly do doubles and get a 1hr nap after lunch to add a little more rebuilding time in between.

    Long runs (i.e 3hrs+), faster sessions and racing are stressful on the body, they are the dangerous ones for acute injuries and over stepping the mark into general over training. I for sure will be more careful going forward adding too many of these in too short space of time.

    • canute1 Says:

      Thanks for your comment. Your great run in the WHWR appears to be an endorsement for the strategy of several longish runs each week. I am sorry to hear that you are having more injury niggles since returning to some more intense running. As you say, getting the balance right when you are near the edge of over-training is a major challenge.

      I am continuing with one intense session each week, but while I am building up the total volume I am keeping the proportion of intense work quite low – typically less than 5% of total training time. I suspect I could build aerobic capacity more quickly if I did a somewhat higher proportion of high intensity work, but I think it is better to build a high level of resilience before gradually adding more high intensity running.

      • Robert Osfeidl Says:

        This morning it occurred to me that perhaps my recent struggles with getting the right balance of high intensity and low intensity right might be down to lack of periodization.

        The training I have done is based around the races that I’ve entered, with four key races each three weeks apart. The race sequence has been road 10k, trail 41 mile ultra, road half marathon with a 38m hilly trail ultra to come at the end of October. I also added in a trail 10k two weeks after the 41 miler/one week before the last weekend half marathon.

        Within these three blocks I have to recover from a race, train for the next, and then taper. There really isn’t much time for full recovery, providing the appropriate training stimulus and then giving time for the required adaptations to take effect.

        It’s a sequence that goes Fast short, Slow long, Fast short, Slow long, so there isn’t the continuity of each event building upon the last.

        To complicate things I’ve had a serious of minor injuries that have required either full rest like last week, or lots of east runs when I hadn’t planned them.

        In the last weeks taper before last weekend’s half it really felt like my muscles were beginning to rewire themselves, but not neccesserily for the better. It’s almost like I’ve given my body too many different stimulus and it bascially didn’t know which way to turn.

        In hindsight I probably should have stuck to a series of fast races or a series of long race and not tried to mix and match.

    • canute1 Says:


      You raise an interesting point. I think it is very likely that rapid changes from low intensity training to a schedule with a substantial amount of high intensity training without adequate opportunity for adapting, carries substantial risk of injury.

      However Ed Whitlock demonstrates that at least in his case, it is possible to do short races and marathons in close proximity. He regards the combination of successful build- up of volume to include 3 or 4 easy long runs per week and a recent fast 10K are the two criteria that indicate that he is in top marathon form.

      I am inclined to advocate slightly more marked periodization of training than Ed Whitlock, but nonetheless think that if a small proportion of high intensity training is included at all phases of the training program, the neuromuscular coordination and resilience required for 10K races can be sustained even during marathon preparation.

      Maintaining a small proportion of high intensity training during preparation for an ultra might present a greater challenge. I do not think that the small amount of high intensity training would undermine fitness for an ultra, but for a recreational athlete with a job and family responsibilities, simply finding enough time to fit any high intensity sessions into the schedule might be a problem.

      So I agree you probably set yourself a race schedule that demanded too much change in the content of training within a short period.

  4. Ewen Says:

    Sorry, I forgot the link to that heart-health story:

  5. Seth Leon Says:

    Thanks for another fine post!

    I just completed my third marathon. I do mostly easy/comfortable running as doubles on weekdays, a long run on Saturday often with a decent fraction of the run close to marathon pace, and an easy recovery run on Sunday averaging 70 miles a week for the last 8 weeks of the cycle. I understand this program lacks speed work and is not ideal, but it fits my lifestyle well and allows me to run with a group on Saturdays which I like socially.

    Anyway I mysteriously acquired a hamstring issue on a very easy taper run leading into this marathon after getting sick in the taper period before my prior marathon. I was able to complete the marathon with a pr (3:39) despite having the hamstring pain from the outset. I believe the hamstring issue caused me to alter my stride somewhat and I also lowered my pace goal from the outset. My cadence was about 4 steps per minute faster than usual at the same pace. I was happy with my race execution and the level at which I was able to maintain my HR throughout the race (averaging 153 BPM or 89% of max, rising into the low 160’s toward the finish).

    My HR however was higher than expected ( and higher than normal) given the pace I ran at. Given your knowledge and experience I am wondering if this may have been due to the shortened stride i used to protect the injury, or if you think it was more likely the excitement of the event? I am trying to gauge whether or not my result was a true indication of my fitness or if I may have raced faster if the injury had not occurred. I didn’t have much left aerobically at the end of the race.

    Your insights are always appreciated, many thanks 🙂

    • canute1 Says:


      Congratulations on your marathon pr.

      It was a shame about the hamstring injury. It seems to me that you made very sensible decisions, both cutting back your target pace from the beginning and shortening your stride. Shortening stride is the most effective way to reduce the magnitude of forces that must be exerted by the leg muscles. However an unaccustomed stride would almost certainly have been a bit less efficient and probably accounts at least in part for you elevated HR. Muscle become less efficient as they become exhausted, so it is usual for HR to rise in the later stages of a marathon even in the absence of injury. If you were running with an unaccustomed stride, this would have almost certainly added to the exhaustion. So it is very likely you could have run faster without the injury.

      Maintaining a HR at 89% for most of the race indicates that your endurance was good and also suggest to me that you were fairly well adapted to using fat as fuel from the start, thereby minimising lactate production.

      So I think your prospects for an even better marathon in future are good. Avoiding illness or injury in the final few weeks is a challenge. I think one important thing is avoiding cramming too much training into the final 5 weeks

      • Seth Leon Says:

        Many thanks, I’m always grateful for your input.

        ” Muscle become less efficient as they become exhausted, so it is usual for HR to rise in the later stages of a marathon even in the absence of injury”

        I interpreted my increased HR towards the end of the race as positive indication of a race fairly well paced. In my prior marathon back in May I was only able to average 150 bpm for the race (3 less), and in the last 7 miles could not get my HR over 147 compared to the lows 160’s in the last few miles of my recent race. My goal was to run with a HR at 87-88 % of max for the first 20 miles and then maintain pace expecting HR to increase towards the if the pacing was appropriate for my fitness.

        I saw a study of fit recreational runners (in the 3:30 marathon range ) that measured their average percent of max HR at 87% for the marathon. In this study the HR for the runners actually tended to decrease in the late miles (like mine in my May marathon). I wanted to avoid that this time and was pleased to succeed on that account. My pace did back off some in the last mile even with the increased effort so I think I paced my effort pretty well. Maybe a slightly too fast in the first half.

        Thanks again 🙂

      • Seth Leon Says:

        If you are interested this is the study I was referring to:

        Cardiac Output and Performance during a Marathon Race in Middle-Aged Recreational Runners
        Véronique L. Billat, 1 ,* Hélène Petot, 1 Morgan Landrain, 1 Renaud Meilland, 1 Jean Pierre Koralsztein, 2 and Laurence Mille-Hamard

      • canute1 Says:

        Thanks for the link to the Billat study.

        I intended my statement about HR rising in the latter stages of a marathon to apply to runners who do not slow down appreciably, in whom the rise in HR is at least in part a compensation for muscle exhaustion (especially skeletal muscle exhaustion but cardiac muscle exhaustion is also possible). Several studies have reported that HR also rises in those who slow down.

        The runners studied by Billat exhibited marked slowing for an average of 12.5Km/Hr down to 10.7Km/hr with the rate of slowing being greater in the second half. Average HR was 160 at the start, remained near or above 160 until 29Km, dropped to 155 at 32 Km and rose to 163 at the end. This suggests that HR did fall as the runners failed to make an adequate cardiac response to compensate for muscle exhaustion around 30-32 Km. They apparently did increase effort again at the end. It is note-worthy that heart beats / metre rose throughout the race, consistent with expectation that as skeletal muscle becomes exhausted, efficiency decreases and both heart beat/metre and cardiac output/metre must rise.

        I think that it is a mostly good sign if HR (and cardiac output) rise to compensate for the loss of efficiency due to skeletal muscle exhaustion, though ideally, a well-trained runner would exhibit only a small loss of muscle efficiency and the rise in HR would be small.

        So overall, I think it is a good sign that your heart rate did not fall, but actually rose in the later stages; this was probably a compensation for exhaustion of skeletal muscles, which in your cases was almost certainly exacerbated by the need to maintain higher cadence and shorter stride than normal to protect your hamstring.

        [Note also that HR will rise if body temperature rises and also if the proportion of fat in the fuel mix increases, though a well-trained runner should use a high proportion of fat right from the start. However possible temperature rise and also increase proportion of fat in the fuel mix might have contributed to your HR].

  6. Pete Says:

    Hi Canute,

    Thank you for the insightful and enjoyable blogs!

    Regarding periodization: If an athlete sets his goal to a marathon race two years from now, how many cycles of base building and race-specific training should he optimally do?

    It seems to me that the only reason to periodize the training at all (except for the final 8-12 weeks leading to the race) would be to gauge oneself’s fitness in realistic conditions and to assess the progress. Perhaps no training-phase heart rate parameters (e.g. beats/km) can reliably tell how much you can squeeze out from the engine in the race situation. And, of course, some runners just love the racing in and of itself.

    Otherwise, I would think that the intermittent race training phases would only slow down the gradual development of the base fitness. Not to mention the increased risk of overtraining and injuries.

    What’s your take on this?

    • canute1 Says:

      You raise an interesting question that I intend to discuss in detail in a future post, though I have several other topics to deal with before that, so I will outline some of my thoughts now.

      It is widely accepted that the body requires continual challenge to stimulate improvement. The mechanism of the training effect includes the action of catabolic hormones, anabolic hormones and the various substances (such as cytokines) that mediate inflammation. However if increases in catabolic hormones and/or mediators of inflammation are excessive, there is a risk of sustained damage. Therefore, I consider that in general it is best to encourage gradual adaptation via a long series of small challenges. Therefore, most training objectives require a long term approach. Furthermore, there is little evidence that high intensity sessions undermine the benefits of low intensity sessions and vice versa, so both can proceed in parallel provided the total demand is not excessive. Thus I do not think that it is necessary employ marked periodization with major differences between phases.

      On the other hand, a wide range of different training stimuli are required to maximise development. Furthermore, the body tends to adapt to challenges in a manner that neutralises them, so it makes sense to have some variation through the year. For most competitive athletes this will fit with the varying demands of the race calendar, but even for a runner with one major long term goal, I think that ringing the changes from time to time stops the body from neutralising the challenge. On the other hand the success of both Ed Whitlock and Yoshihisa Hosaka, who employ little day by day variation in their training does suggest that consistency might be more important that variability.

  7. Laurent Therond Says:

    Fascinating, as always.
    I am also going to change my training regimen drastically in 2015.

    I am going to periodize more. Both training and nutrition.
    I am going to keep track of time instead of miles.
    I am going to polarize my training dramatically.
    I am going to include more low-aerobic cross-training activities, which will have no impact force. (cycling and rowing)

    Enough changes for a fresh start, after experimenting and tinkering with exercise physiology concepts for the past 10 years.

    If you would like to contact me to share your training plan, please send me a note at:

    This is a temporary email address I created for this purpose only, I will deactivate it in a month or so.

    • canute1 Says:


      That is very interesting. As you will know from the content of my blogs, I am in the process of implementing many of those features in my own training. At this stage, I am experimenting with a Whitlock-style program in which the cardinal feature is multiple long duration easy runs each week. I am also doing a small amount of high intensity training, some easy elliptical cross-training sessions and some strength sessions. I have now almost achieved the first step: So far I have coped well with four longish duration easy runs of gradually increasing duration, each week. This coming week I aim to do four easy 2 hour runs. Provided I confirm that I can cope with these sessions without accumulating fatigue, I will then focus my attention again on the content of the high intensity sessions.

      I would be very happy to discuss my program with you in greater detail, and to hear more about your proposed program. I am quite busy for the next few days but will nonetheless start the ball rolling by sending you a brief summary of last week’s training, to the email address you specified.

  8. Robert Osfield Says:

    Been hoping for an update post to see how training is progressing. Hope all is well and fitness is progressing along nicely.

    My own racing and training has continues to go well. With 12 months of solid training/racing behind me I’ve been able to do some analysis of how my fitness has progressed and what appears to affect it most. What I found is that running more often each month looks to be far stronger stimulus than running for more time each month.

    I suspect running more often with a short individual run length doesn’t over stress the body the same way doing a small number of longer runs, even if the total time/distance is similar.

    I’ve progressed my own running so that I can now do a run every day pretty comfortably. Adding more runs would require running doubles which is rather intrusive time wise so increasing time of each run looks to be my next avenue for improvement.

    W.r.t intensity I haven’t found an particular correlation with adding tempo or high intensity sessions with general improvments of aerobic fitness – these sessions seem to tune me up for race pace but my beats per mile/calories per mile figures don’t appear to improve like they do with doing easy runs every day.

    What seems to go wrong is the high intensity work several times resulted in injuries and with it enforced days off. Loosing these days training set me back so possible benefits are lost.

    Over the next 12 months I’ll try to add small amounts of high intensity training but keep the volume really modest, I’ll back off if it looks like injury risk increases so to avoid missing any days.

    • canute1 Says:


      You have certainly had an impressive year. Your conclusion that number of training sessions rather than intensity has been the major factor in improvement confirms that consistency is the greatest of the three ‘graces’ of training: consistency, volume and intensity. All three can bestow benefit but the greatest gift is bestowed by consistency.

      I am continuing with my attempt to test a program based on Ed Whitlock’s approach in which the key feature is multiple easy paced long runs each week, together with a small amount of intense running. I typically do 4 easy-paced longish runs each week. In the period from August to mid-September I built up the duration of these gradually from 70 minutes to 120 minutes each over a period of eight weeks and since early October I have done 3 or 4 easy 2 hour runs each week. There have been a definite gain in my capacity to metabolise fats and also in leg muscle resilience, though the improvement on aerobic capacity has been slight.

      It is too early to judge whether or not this program has been successful for me. It should be noted that Ed built up long run duration over a period of about 5 years. I had initially planned to do an initial assessment of progress after 4 months. I will post a review of the program in mid-December.

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