Archive for January, 2009

Downhill running, eccentric contractions and torn hamstrings

January 31, 2009

A week or two ago, Ewen’s comment about down-hill running led me to pose the question about the balance of risks and benefits of fast downhill running – and more generally, the risks of long term muscle damage from forms of training that focus on eccentric contraction. I am still looking into the scientific evidence on this question – but it is a tricky subject because the type of long term damage that I am concerned about might not emerge for years and it is virtually impossible to conduct rigorous comparative studies over that time scale. There is little doubt that at least some people who do a lot of very demanding training do eventually suffer long term damage (see Grobler et al, Br J Sports Med, 38,697-703). This seems to be a greater problem for runners than cyclists, but whether this is due to eccentric loads, is not easy to establish.

Even more important for the average runner, is whether a minor, but nonetheless appreciable degree of long-term damage occurs in the majority of runners, but this is even harder to establish. In a fairly recent review Brancaccio and colleagues point out that downhill running is associated with increased release of the muscle protein creatine kinase into the blood-stream and that this might be associated with significant damage of muscles. They conclude that in individuals with evidence of muscle damage, intense prolonged exercise may produce negative effects, as it does not induce the physiological muscle adaptations to physical training given the continuous loss of muscle proteins. (Br Med Bull. 2007;81-82:209-30). I am still working on assembling as good a collection of evidence as possible.

Meanwhile I have been grateful to receive interesting comments from several people based on their experiences. Thomas, who is preparing for Boston this year, commented on a friend who had injured himself with down hill running in preparation for Boston, with its notorious down-hills.   Jason pointed out that he has experienced a gradual reduction in the DOMS produced by downhill running after a  moderate amount of down hill running at speed incorporated within his overall training plan. I think that taken together, these comments confirm that downhill running at speed has some risk, but a period of moderate amounts of fast downhill training leads to adaptive changes so that it is no longer as damaging. This of course is the training effect that is the goal of most training programs, and makes sense. It suggests that someone preparing for Boston might benefit from a moderate amount of down hill running.

It still leaves open the question of very long term consequences – but even if very long term adverse consequences are possible, this is merely a specific example of the risk that we take with any demanding training – and it is probable that gradual adaptation is less damaging than a single major stressful event without adequate preparation. So on balance, if I were preparing for Boston, I think I would incorporate a moderate amount of downhill running at marathon pace or slightly faster, into my program. However, a least until I have a better understanding of the situation I am trying to minimize the amount of high demand eccentric work in my program, and in particular, I do only a very small amount of light plyometrics.

However, my experience last week when I went all-out to hold off a challenge in a 100 metres sprint late in the afternoon with inadequate warm-up despite rapidly dropping air temperature, an hour or so after a mile race, illustrated the fact that subjecting ones muscles to large eccentric loads without adequate preparation is almost certainly more damaging than a gradual build up of eccentric loading in a sensible training program. However, as I remarked last week, sometimes life is more fun when you throw caution to the winds and I do not regret the choice I made, despite the fact that my wings have been clipped for the time being.

In fact my injury is not too bad; my hamstring complains a bit if I inadvertently stretch it when bending down, but it feels OK when jogging a few metres. Tomorrow I will probably go for a short, slow paced run.

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Throwing caution to the winds

January 24, 2009

After a frustrating few weeks in which my lingering breathing problems torpedoed any serious attempt at interval training, I was ambivalent about turning out the for Fetch west-midlands mile today. It was clear that a serious attempt at 6:00 was out of the question, though maybe 6:13 (my M60 PB) was within reach. Last night I was a bit wheezy but the wheezes settled after a puff of my inhaler and this morning there was no trace of a wheeze, so I decided I would run. The event is a sociable get-together of Fetchies as well as being a chance to race over a mile – a distance that still retains a certain magic aura.

The divisions were based on predicted time, so I lined up with the second division (predicted time range 6:00 – 7:30). My expectation for my own time was in the range 6:10 to 6:20 but in light of my lack of opportunity to develop a good sense of pace in that range, I decided I would run a purely tactical race with the goal of finishing within in the first three, and let time look after itself.

Biking Badger led off at a fair lick and I slipped into third place, feeling fairly comfortable but aware that the pace was faster than I could maintain. My time for the first lap (plus the extra 9 metres) was 89 seconds. Biking Badger kept going at his initial pace but almost everyone else slowed a bit. Coming into the home straight for the second time Ronners went past strongly into second place and I tried to follow him but realised that he too was headed for a time well under 6 minutes, so I would have to settle for a contest for third place. I covered the second lap in 93 seconds. As a result of my initial attempt to keep up with Ronners I had opened up a small gap separating me from rest of the field. As far as I could judge from the spectators’ calls of encouragement to the runners behind me, I was about 20 metres clear of the following pack as we entered the third lap. I was still feeling quite comfortable, and decided that my strategy should be to hold onto a moderate lead over the ‘pack’ for as long as possible without pushing myself too hard, so that I would be fresh enough to hold off any challenge in the final lap. My time for the third lap was a leisurely 99 sec. I continued down the back straight in the final lap maintaining a comfortable pace listening for the challenge from behind. But no challenge came, so I picked up speed in the final 200 metres and finished quite strongly, covering the final lap in 93 seconds, for a total time of 6:17.

In retrospect I think that perhaps I could have made a stronger effort for an M60 PB. If I hadn’t taken it easy in the third lap, I might well have achieved a time around 6:12, but in view of the uncertainties about my breathing, I think I made the right decision to run a tactical race. There is no doubt that I was right to let Biking Badger and Ronners go – their finishing times were 5:48 and 5:49 respectively, and there was no possibility that I could have matched those times. So I am quite happy with my third place, even though the next time I run a mile I will be aiming for a faster time.

The event is a sociable, light-hearted event and in addition to the mile, the program also includes some 100m races, which gives the non-sprinters a chance to remind themselves why they took up distance running. However, when Slickster crossed the line in the first division race in 11.20, I was glad that I opted for the third division. Although it had been a brilliantly sunny winter day, by the time I stripped off for the third division race the air temperature had dropped, and I was aware that my muscles had stiffened after the mile. I did a short warm-up that got the blood circulating a bit more briskly, but as we lined up I was still rather stiff. However as I have never actually run a 100m race before, it was too good an opportunity to miss. No-one in our division was a specialist sprinter so I hoped I could make a reasonable race of it, without pushing myself too hard.

I concentrated on running as relaxed and as fast as possible, and at 60 metres was pleased to find myself in the lead, but I was aware that a runner a few lanes to the left of me was closing the gap. The competitive instinct took over and I threw caution to the winds. In the next few strides I opened up the gap again, but at 75 metres I felt my right hamstring tear. My experience last November when I had completed a 1K repetition during an interval training session after a minor tear of my soleus and had subsequently been scarcely able to train for several weeks, should have reinforced the lesson that one should stop immediately when muscle fibres start to give way. However at this point I was only about 20 metres from the line, leading in what was my first, and perhaps life-time only, 100m race. So I simply focussed on relaxing as much as possible without losing too much pace, and crossed the line in first place in 15.8.

So now I have an M60 PB for the 100m. In fact it probably could be described as a life-time PB, but despite not having kept records of the races in my youth, I am fairly sure that in my heyday I often covered the final 200m of a 5K at around that pace or faster, so I would be reluctant to record it as a life-time PB.

Afterwards we assembled at the home of el-Bee and Velociraptor for a cake-fest. El-Bee had organized the races, and between them they provided a wonderfully hospitable day. It was great to meet other Fetchies. As Fetch is an internet community, it is especially good to have an opportunity to get together socially from time to time. So overall a very satisfying day: a satisfying tactical race for third place in the second division mile; a victory (albeit over other non-sprinters) in my only attempt at 100m and an M60 PB for that distance; and a great cake-fest. I hope the torn hamstring does not prove too much of a problem, but on balance, am prepared to accept that life is more fun if you are not too prudent all the time.

Two big questions

January 21, 2009

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Two of Ewen’s comments in recent times raise the two major issues that I face in planning my training. Two days ago he raised the issue of the possible advantages of running down hill. Running down hill at speed provides a large eccentric load on the extensor muscles, such as quads. Developing leg muscle that are strong and efficient during eccentric contraction is crucial for running, but it is also damaging in the short term. Indeed the short term damage is probably essential for achieving the desired training effect. The same issues apply to plyometric exercises designed to induce eccentric contraction. But does down hill running (or plyometrics) do permanent damage? Until we have a clear answer to this question, the response to the question abut down hill running is that it offers short term gains, but its long term risks are inadequately understood and hence, I personally am very circumspect about down hill running at speed and about plyometrics. In the near future, I intend to examine carefully all the evidence I can find about the long term risks of large eccentric loading of muscles, and will present the evidence I uncover here on my blog.

The other question is the issue of whether or not it is desirable to include some speed work in the training program throughout the year. This is contrary to the recommendations of Hadd who emphasizes that during base building it is important to avoid the training zone around lactate threshold and above. As far as I understand Hadd’s reasoning, it is based at least in part on the way he interprets the findings of Dudley’s study of rats. Dudley reported that in rats who ran at easy paces, the development of mitochondria in slow twitch fibres was greater than in those running a faster paces. This indicates that slow running has benefits. However it does not prove that some faster running will obliterate those benefits. I think that Dudley’s findings do not support the conclusions drawn by Hadd, and I am at present, inclined to disagree with Hadd’s recommendation about avoiding lactate threshold during base building. I am a strong believer in the beneficial effects of running in the lower regions of the aerobic range for the purposes of base building, but I do not think that the inclusion of some lactate threshold work during that phase is counter-productive. However the overall evidence on this issue is also complex, so that is another question that I want to review in some detail in future weeks.

I would certainly value other peoples opinions and experiences regarding these two issues.

Back-to-back sessions

January 18, 2009

I have just got back for a 16K run which included 12 K of moderate intensity fartlek done in the hope of getting a little bit of speed back into my legs. It was a wonderful blue-sky day with a brisk breeze creating choppy patterns on surface of the river, and I felt quite energized. During the ‘speed’ phases of the fartlek I was fairly fluent, though there was a slight residual heaviness in the legs after yesterday’s interval session. I am persisting with my plan of doing moderately intense back-to-back sessions once per week, followed by a rest day and an easy day. Because of my recent respiratory problems the sessions have been a bit less intense than originally intended (eg 4x1Km rather than 6x1Km on the first day) and it is still too early to judge how successful this strategy will be be in improving my fitness. Nonetheless, so far I am pleased to find that I am able to achieve a substantial cumulative training load over the two day period without subjecting myself to intense stress, and hope this training load will provide a good stimulus to anabolic processes during the subsequent recovery period.

Cross training

January 18, 2009

The past few days have not been kind to my lungs. My peak expiratory flow has fluctuated between 500 litres/min (fairly good) and 240 litres/min (a level at which even mild exercise causes me to wheeze). I am not sure why the situation has deteriorated, as the weather has been milder this week with air temperatures well above zero degrees C. Today I did 4x1Km aiming for mean heart rate 142. I found it more effortful than last week. I managed to keep the mean HR at 142.5, but my average time per Km was 4:24, compared with 4:21 last week, and 4:20 in early December before my current episode of respiratory problems began.

I have contemplated stopping training for a while, but I doubt that would help, as my respiratory problems usually tend to persist for months following a cold or flu. During my short-lived return to running in my late 50’s, I developed a cold and stopped running. I still had symptom three months later, and had lost most of my fitness. The current symptoms are mainly due to excessive reactivity of my airways to any irritation rather than persistent infection. Unless I develop clear signs of bronchitis, I will persist with light to moderate intensity training. At this stage I am undecided about the mile race next week. If there is no further deterioration I might run, but an M60 PB is unlikely.

Cross-training

Since the onset of my breathing problems I have been doing a moderate amount of indoor training on the elliptical cross-trainer to minimize exposure to the cold air that irritates my bronchioles. In a recent comment Ewen raised the question of whether or not low intensity running might be as beneficial as cross-training. As with most questions to do with the optimal way to train, the issue is debateable. Some of the relevant ‘facts’ are:

1) A previously fit runner who changes to a program of cross-training alone, will suffer a substantial deterioration in running performance.

2) A previously fit runner who adds cross-training to his/her current training program can achieve a worthwhile improvement in running performance.

3) High volume running produces short term damage to muscles which can promote improved performance after recovery.

4) High volume running can result in muscle damage which is more persistent than that due merely to over-training, and may be permanent, in at least some individuals.

Each of these ‘facts’ is supported by a substantial amount of scientific and anecdotal evidence, but I do not have time to address all of these issues today. Maybe in future posts I will look at the evidence for each of these statements in some detail. Today I want to address several speculative issues that are relevant to Ewen’s comment:

1) In races run at paces in the vicinity of lactate threshold pace (10K to marathon) the ability to remove lactate from the blood stream is as important as the minimization of lactate production.

2) Elliptical cross training (and cycling) might be more effective than low intensity running in engaging fast twitch fibres (which tend to work anaerobically and therefore produce more lactate) but does less damage to muscle than is typical of high intensity running. Therefore, elliptical cross-training might be a safer way to develop the capacity to remove lactate from the blood stream.

Increased removal v reduced production of lactate

A study by Tim Noakes and colleagues from Cape Town demonstrated that lower blood lactate values during exercise after training were due to diminished lactate production at low work rates but in contrast, were due to elevated removal of lactate higher work rates, (McRae et al, Effects of training on lactate production and removal during progressive exercise in humans, Journal of Applied Physiology, Vol 72, 1649-1656, 1992). Thus, when running at paces near or above lactate threshold, the ability to remove lactate appears at least as important as the ability to minimize production of lactate.

Engagement of fast twitch fibres during concentric contraction

Resistance training typically engages fast twitch fibres resulting in muscle hypertrophy, whereas high volume low intensity running engages slow twitch fibres resulting in improved endurance, but minimal hypertrophy. This is dramatically illustrated by the identical twins, Otto and Ewert, described by Mike Rennie in the GL Brown Prize Lecture on Physiology in 2005 (Rennie, M., Exp. Physiol vol 90 pp 427-436). Otto trained for endurance events and developed a lithe, endurance runner’s physique, Ewert trained for field events and developed the ‘walnuts in a stocking’ look that Arnold Schwarzenegger subsequently emulated. Depending on taste you might find Otto a little puny. (See http://www.arthurdevany.com/webstuff/images/Twins.tiff)

In examining the effects of resistance training on different muscle fibre types, it is important to take account of the differences between concentric contraction, in which the muscle shortens as it develops tension, and eccentric contraction, in which the muscle is required to develop tension while it is being stretched.  A study of the effects of a resistance training program involving eccentric and concentric muscle contractions compared with concentric contraction alone, conducted in Gary Dudley’s lab, demonstrated that the combined eccentric/concentric program produced hypertrophy of both fast twitch and slow twitch fibres, whereas the program that included only concentric contraction (but similar total workload) produced mainly hypertrophy of fast twitch fibres. (Hather et al, Acta Physiologica Scandinavica, Vol 143 , Pp 177 – 185, 1991). Thus, for maximal development of muscles fibres during resistance training, it is necessary to combine eccentric with concentric contraction.

It is also of interest to note that concentric training produced an increase in capillaries per fibre area for both fast and slow twitch fibres and that the increases in capillaries were maintained 4 weeks after discontinuation of training.

Differences between running and elliptical training

It is necessary to be cautious in applying any conclusions from a study of resistance training to either running or elliptical training. Nonetheless, it is noteworthy that running and elliptical training differ in the relative amounts of eccentric and concentric contraction. Running involves relatively more eccentric contraction. In the quadriceps, the majority of the work while running is eccentric contraction performed as the muscle is stretched at footfall. In contrast, elliptical cross-training involves a more sustained concentric push by quadriceps. Thus elliptical training would be expected to engage fast twitch fibres to a greater extent. This is consistent the observation that ventilatory threshold (and therefore, the lactate threshold) occurs at a lower heart rate and lower level of energy consumption on the elliptical. This implies a higher proportion of anaerobic contraction, which is characteristic of fast twitch fibres.

So elliptical training (and also cycling) apparently differs from running by relatively greater engagement of fast twitch fibres and greater lactate production at a given level of energy consumption. Elliptical training might therefore be useful for developing the ability to metabolise lactate. Is this likely to be a beneficial form of training for a runner? At first sight it appears to be a waste of time for a distance runner to miss an opportunity to employ eccentric muscle contractions which might be used to develop both slow and fast twitch fibres. It should be noted that, contrary to the teachings of Hadd, even at running paces that engage predominantly fast twitch fibres there is also at least some development of slow twitch fibres – (see Dudley et al. Influence of Exercise Intensity and Duration on Biochemical Adaptations in Skeletal Muscle,’ Journal of Applied Physiology, vol. 53, pp. 844-850, 1982). But running at paces fast enough to induce the enzymes that metabolize lactate is where the issue of muscle damage enters the equation.

I can do elliptical sessions including about 30 minutes at the ventilatory threshold on four consecutive days without noticeable muscle stiffness or pain, whereas two consecutive days of running at ventilatory threshold pace for 30 minutes leave me a bit stiff and sore – yet I have spent far more hours running than training on the elliptical and would therefore expect to be relatively better adapted to running.

In conclusion, the elliptical appears to offer the prospect of inducing production of the enzymes that metabolize lactate with minimal wear and tear on the muscles. This is a tentative conclusion based on a slender evidence base, and I will not be convinced that it will lead to more effective training until I have more experience of putting it into practice. Nonetheless, I think the evidence is good enough to justify a trial of mixing running and elliptical sessions.

So for the time being, I will continue with both running and elliptical sessions. The running will include low intensity sessions and a small number of moderate intensity sessions. The low intensity running sessions are designed to increase mitochondria in slow twitch fibres thereby decreasing lactate production, while also increasing ability to metabolise fat and strengthening connective tissues. The moderate intensity running sessions are designed to increase mitochondria in both slow and fast twitch fibres producing not only a decreased rate of lactate production but also increasing the ability to metabolise lactate. The elliptical sessions will be mainly of moderate to high intensity, with the goal of increasing the ability to metabolise lactate and also increasing capillaries per fibre, but with minimal risk of muscle damage. Thus each type of session has its own major goals. There is of course the risk that mixing the various types of sessions will be counter-productive, but that is another complex issue that will have to be deferred to another day.

The benefits of different aspects of aerobic training

January 13, 2009

In his comments on my post on 10th Jan, Ewen has raised two interesting points. First, is running at the lower aerobic zone more useful for runners than use of the elliptical cross-trainer, and secondly, are runs of differing intensity in the aerobic zone of similar value if they involve a similar amount of total work. In his words: ‘If the total number of heart-beats in the session above ’standing HR’ are the same, then the runs have the same value. In other words, a run of 60 minutes @ AHR 80% might be equivalent to a slow run of 75 minutes @ AHR 70%?’

I think the answer to the question about the merits of elliptical cross training depends on the answer to the second question about the merits of differing intensities of aerobic training, so for now I will offer my thoughts about the second question and return to the issue of the elliptical later in the week.

It seems clear that cardiovascular fitness (i.e. the ability to run at a given speed in the aerobic range at the lowest possible heart rate) improves whenever there is a challenge to the relevant physiological mechanism, and for most runners, either a lot of running at the lower end of the aerobic range or a lesser amount of running nearer the upper end of the aerobic range will result in improvement, provided it does not result in injury. However, the question of which will be of greater benefit to a particular runner at a particular time in his/her training program probably depends on which physiological mechanism is most in need of improvement at that time.

Ewen’s question explicitly addresses the equivalence of runs within the middle of the aerobic range, but as I understand it, there is a gradual transition in the nature of the training benefits across the entire aerobic range, so I think that is best to approach his question by considering the benefits of training in each part of the aerobic spectrum.

As far as I understand from my understanding of physiology, the aim of aerobic training is to produce in improvement in the following mechanisms or systems:

1) Increase in the number or diameter of capillaries that deliver blood to muscle. More capillary capacity will allow extraction of a higher proportion of the oxygen and glucose from blood and hence will allow a lower heart rate for a given speed. I suspect that any training that demands increased blood supply to muscle will lead to increased capillary capacity. Hence any aerobic training is probably beneficial in this regard, with the amount of benefit proportional to the total requirement (i.e twice a much time to achieve comparable benefit at half the heart rate). However, in general there is a lower risk of injury at lower speeds. This type of anatomical adaptation is likely to develop relatively slowly and the benefits might also be sustained over a long period.

2) Increased ability to utilize fats and spare glucose. The relative proportion of consumption of fats to glucose is higher at the lower end of the aerobic range and hence, running at the lower end of the range will be expected to induce the activity of the enzymes that metabolise fats. As far as I understand it, these enzymes get switched off as the lactate threshold is approached, so ability to burn fat will not be developed and might perhaps deteriorate if too much of the training load is near (or above) the lactate threshold.

3) Increased number of mitochondria (the organelles in which glucose is oxidized producing carbon dioxide and water and generating energy) within muscle fibres, thereby resulting in more effective aerobic glucose metabolism. A study by Dudley (‘Influence of Exercise Intensity and Duration on Biochemical Adaptations in Skeletal Muscle,’ Journal of Applied Physiology, vol. 53, pp. 844-850, 1982) demonstrated, in rats, that running at relatively low speed increased mitochondria in the slow twitch fibres while running at faster speeds resulted in an increase in mitochondria in fast twitch fibres. However, running fast produced a worthwhile increase in mitochondria even in the slow fibres, so overall, fast running is beneficial for both fast and slow twitch fibres. Possibly the most effective way to increase mitochondria across the range of fibre types is sustained running at highest level that can be maintained comfortably for long periods. This is likely to be at the border between mid and upper aerobic zones

4) Increased ability to metabolise lactate (either in the muscles themselves or in other tissues). Even in the mid-aerobic range, some lactate is produced. Increased ability to use this lactate as fuel will improve efficiency. Lactate production rises rapidly towards the upper end of the aerobic range, so running at the upper end of the range is likely to be most effective at inducing the enzymes that metabolise lactate.

Overall, these considerations suggest that both lower aerobic and upper aerobic running are beneficial but there are some differences in the types of improvement they produce In general, an effective training program will include both.

As a non-specific preparation for training for any distance, it is probably useful to have spent several years training regularly at an easy pace to enhance capillary development in a non-stressful way. It is probable that this adaptation will be maintained whatever training is routine is adopted subsequently, provided the amount of training is adequate.

Whether or not you are training for a marathon or 1500m, it is important to develop mitochondrial density. On the basis of Dudley’s studies of the effects of different work–rates on different types of fibres in rats, I suspect that the greatest overall increase in numbers of mitochondria can be achieved by sustained running around the border between mid and upper aerobic zones. Therefore, in the pre-season, I think that quite a lot of running should be done at this speed. In my own experience, I have found that this is helpful.

A marathon runner also needs to develop the ability to metabolise fats, and long runs at a relatively slow pace are probably the best way to do this. However, when racing, a competitive marathon runner maintains a pace in the upper part of the aerobic zone, where appreciable lactate is generated, so it is also crucial to be able to utilize lactate. The ability to do this can probably be best achieved by also including a substantial amount of training at lactate threshold. Although the goals of developing the ability to metabolise fats and also the ability to metabolise lactate require different strategies, I am not aware of clear evidence that one goal seriously interferes with the other, so a balance of the two types of training is required. Certainly I have mingled both strategies in the past, though whether or not I might have done better to separate them, I do not know.

If you are training for 1500m, as the racing season approaches it is essential to maximise the ability to handle lactate, as well as enhancing the anaerobic metabolism and developing the neuromuscular coordination required to run fast, so the emphasis in training will clearly shift to higher intensity running. Furthermore, there is some evidence that inclusion of too much low intensity work at this time might actually have the harmful effect of developing slow twitch fibres at the expense of fast twitch fibres

So I think this all adds up to the conclusion that in general a training program should include both lower and upper aerobic sessions, as these two types of training do not have identical benefits even after adjusting for total workload. However a degree of periodization of effort is required depending on the target race distance.

The doctrine of training specificity has only limited validity. I think that Emil Zatopek’s rhetorical question: ‘why should I train slowly if I want to run fast?’ is misleading. Training only at fast speeds is likely to result of too much damage to muscle fibres and in the release of too many stress hormones such as cortisol, which ultimately damages body tissues. Maybe Zatopek had a unique capacity to cope with training stress, but is it interesting to speculate whether or not he would have been even more successful if he had adopted a more flexible approach to training. His PB for the marathon was 2 hours 23 minutes– that was good enough to win the Olympic gold in Helsinki in 1952, and to set a new world record. However, in the preparation for the Melbourne Olympics in 1956 he suffered a serious groin strain and despite subsequent heroic effort, finished sixth in the marathon behind Alain Mimoun.

These thoughts go somewhat beyond the scope of Ewen’s specific question about the middle part of the aerobic range. If we set aside the issue of the specific benefits of lower aerobic sessions for developing fat utilization and upper aerobic sessions for developing the ability to utilize lactate, and consider only the other two major goals: increasing capillary capacity and increasing mitochondria; I think that it probably is fairly true to say that ‘If the total number of heart-beats in the session above ’standing HR’ are the same, then the runs have the same value’.

Thinking about racing again

January 11, 2009

I have re-instated my plan of doing back-to-back moderate intensity sessions once per week, though after yesterday’s 4x1Km interval session, I took a rather soft option for today’s session, which was 20Km focusing on running form. I didn’t take either a watch or heart rate monitor, so I am being rather lenient in regarding it as a moderate intensity session, but at least it could count as a long run.

The good news is that my peak expiratory flow today was 530 litre/min and yesterday was 510 litre/min. From the beginning of December, when I suffered a bad cold, maybe a flu virus, until last week, my peak flow readings have been in the range 250-310 litre/min. Last summer my peak recording was 615 litre/min, so the past two day’s recordings suggest that I am really on the way to recovery.

If I continue to improve I will run the West Midlands Fetch Mile Challenge race in two weeks time. What time should I set as my target? I am not a miler, though ironically I think I have probably won as many races of one mile as of any other distance over the years, so I will use my past fleeting moments of glory to set the target for two weeks time.

The first victory I remember was in the South Australian schoolboy mile championships in the early 1960’s. In those days there was no dedicated running track in Adelaide, apart from a delightful old cinder track belonging to Adelaide Harriers but that was only about 250 yards per lap, so the state championships were held on a grass track in the west parklands. On the day of the schoolboy championships that year, there had been heavy rain overnight and the track was flooded. In addition, a south-westerly gale was howling up the home straight. So conditions were far from ideal, but that suited me because I used to be fairly good at using mental robustness to compensate for lack of natural talent. Nonetheless, I didn’t think I had much chance of being among the medal winners, and I was amazed to find myself in the lead, battling down the water-logged home straight into the teeth of a gale to win in what must have been the all-time record slowest winning time in a schoolboy state championship. I think it was about 4:45.

The other mile victory I remember was a year ago, in the East Midlands Fetch Mile. The organisers put on a second division race for the slow-coaches, and again to my amazement, I won. On that occasion, my time was 6:13, and that being my only mile race since I recommenced running, stands as my M60 PB.

As the age grading tables suggest that a time of 4:45 is equivalent to 6:00 at my present age, I will set my gold standard target as 6:00 and my silver target as 6:12. The silver target would be an M60 PB and is the pace that I will aim for in the first two laps. That will mean 93 second laps, which sounds a bit ambitious in my present condition. In view of my recent ill-health I will also allow myself a softer bronze target of 6:24. But all of this planning depends on my lungs remaining is reasonable condition for the next two weeks.

Intervals again, and some thoughts about cross-training

January 10, 2009

Today I resumed moderate intensity running sessions after a period of lower intensity training due to a respiratory infection and its aftermath. I did a 4x1Km interval session on the riverside path, aiming for mean HR 142 (around 90% of HR maximum for an old-timer like me). On the first repetition, the breeze was behind me and I went too fast (4:13 per Km, with mean HR 145) but then settled down well to achieve mean HR 142 on the subsequent three repetitions, giving an overall mean HR of 143 and mean pace of 4:20 /Km. This is similar to my performance a week before I was smitten with a respiratory tract infection in early December, when I achieved a mean pace of 4:21 /Km at mean HR 142 in a 6x1Km session. Today’s session felt a little harder – probably because I had started too fast – but overall, I am pleased that I have not suffered any appreciable loss of fitness during my period of illness and convalescence. In fact I hope that my aerobic base fitness might actually have improved a little as a result of the relatively large volume slow running over the holiday season.

During my convalescence I have also done an increased amount of cross training on the elliptical cross trainer. The elliptical cross trainer is probably an excellent mode of exercise for non-athletes who wish to maintain a moderate level of aerobic fitness with minimal risk of injury. However, it is not clear how useful it is for runners. The available evidence is sparse. One study from the Human Performance Lab at Appalachian State University indicates that performance in a 3Km time trial deteriorated by 48 seconds during 5 weeks of elliptical training that included one lactate threshold interval session, one sprint session and 3 or 4 easier sessions per week, but no actual running. A comparison group who did ‘off season’ running training during the 5 weeks actually improved their 3K run time by a small amount (9 seconds – not a statistically significant improvement, but certainly not a deterioration). So it is unlikely that the elliptical alone is much use for preparing for a race (Honea and Dumke, http://www.osr.appstate.edu/present/documents/Honea-student_research_poster.ppt).

However, my own preliminary observations led me to wonder whether or not the elliptical might have a useful role. I found that I reached ventilatory threshold at a lower heart rate (and greater perceived effort) on the elliptical compared with running. My first impression was that this merely confirms that elliptical cross-training is a less enjoyable way of getting out of breath. This conflicts with the claims of the manufacturers who emphasize that perceived effort is less on the elliptical, but I think those claims mainly apply to non-runners working at a level well below lactate threshold, where the smoothness of the ‘ride’ is indeed quite relaxing.

But I was intrigued to understand why the ventilatory threshold appears to occur at a lower heart rate. This suggests that more lactate is produced at a given heart rate, implying that anaerobic metabolism of glucose kicks in at a lower heart rate.

To investigate this further I searched the sport medicine literature and found a recent study by Garlatz and colleagues from Western Washington University (The FASEB Journal. 2008;22:1175.2). In a group of trained distance runners they found that at 90% of Working Heart Rate Range, perceived effort was higher but oxygen consumption lower on the elliptical cross-trainer compared with the treadmill. This confirms my own observation, and strongly supports the hypothesis that there is a higher proportion of anaerobic glucose metabolism at this heart rate on the elliptical.

In retrospect this is easy to understand. The action of the elliptical involves a strong push, especially by quadriceps which are active though most of the gait cycle, whereas the quads are only active for a small part of the gait cycle when running.  However when running the quads suffer a lot of stress because they work hardest when being stretched at footfall – and this generates the micro-tears that might cause DOMS the next day. In other words, on the elliptical, the quads do more work but it is different in nature and potentially less damaging in comparison with running. It is likely that the additional work recruits a higher proportion of fast twitch fibres which tend to metabolise glucose anaerobically. Thus elliptical cross training might be a very good way to improve the body’s capacity to handle lactate with relative little damage to muscles.

If you want to run a fast 3K, you really need to train your muscles to cope with large eccentric loading. The elliptical is probably not much use for this but may nonetheless have a useful role to play in improving the capacity to metabolise lactate with minimal damage to muscles.

Dancing with the Devil: More about the mind of the dancer

January 4, 2009

Many of us accept in an abstract manner that the mind controls the body, but in everyday life, we do not usually act as if we believe it. We aim to get fit by stressing our bodies. We focus on miles or kilometres run; or on repetition times recorded on the stop watch. In September I described evidence from a study of hotel cleaners who were advised about the health benefits of their daily work. In comparison with their colleagues who did similar work without information about its health benefits, they showed significant improvements in physiological variables such as blood pressure. Mental approach to physical activity influences the physiological benefits derived. Today I found myself wondering about the interaction between psychological and physiological processes for a different reason.

In the past 10 days, as I have attempted to throw off the lingering symptoms of a bout of flu, I have been unable to train even at moderate intensity because my airways have become excessively sensitive to any stresses. Deeply breathing air at temperatures near to zero brings on an asthma attack. So I have increased the volume of my training but kept the intensity low. In fact, I have run more kilometres in the past 10 days than in any consecutive 10 days in almost forty years. Mostly I have really enjoyed being outside in the fine but bracing weather. I have listened carefully to my body to make sure that I was not overdoing things. Today, I set out for an easy 10 K run, but my muscles felt tired. There was no sign of any focal musculo-skeletal problem, so there was no reason to abandon my run, but I faced the challenge of how to make the most of my run on very tired legs.

A digression

I will start with a brief(ish) digression about tired legs. Before taking up running again in my sixties, I had made one previous ‘come-back’ to running. In my late 50’s I ran one race, a marathon. I had done 16 weeks of training that had been fairly consistent, but the weekly volume was less than half of that more typical of my younger days. I started the race with little idea what pace I should set. According to the age grading tables of the World Masters Athletics Association, the performances of my heyday suggested that as a 58 year old, I might be capable of around 2 hours 50 minutes if fully fit, but I was far from fully fit. So I set myself a choice of three goals: a gold standard of 3 hours, but I realised this was little more than a dream; a silver standard of 3:15 – I considered that this was possible but I would nonetheless have been extremely pleased to have achieved it; and a bronze standard of 3:30, which I was fairly confident was within my reach.

I lined up with thousands of others; a strange and unsettling experience compared with the races of my youth when even a major international marathon field was rarely larger than a few hundred. The start was complete bedlam. In an attempt to break clear of the melee I ran far too fast, and covered the first three miles in a little over 20 minutes, which was somewhat faster than my ‘dream’ gold standard pace and definitely not sustainable. I reached the halfway mark in about 93 minutes. My legs were starting to feel a little tired but my silver target appeared still to be within reach.

On the basis of my marathon running practice from several decades previously, I did not replenish glucose supplies along the way. Nor had I pre-loaded with carbohydrate the day before. In the 1960’s we didn’t entertain such notions. Maybe this old dog should have tried to learn some new tricks. By 20 miles, I was in serious trouble. My running action degenerated to a shuffle. My pace slowed to somewhere around 6 min/Km or even slower, but my mind was too fuzzy to read my watch and calculate times properly.

At the 23 mile marker, I was able to read my watch well enough to see that I had been running for three hours, and my befuddled brain was able to work out that I needed to maintain a pace a little faster than 10 minutes per mile to achieve my bronze target. I could hear a runner behind slowly closing the gap between us, and I realised that perhaps my only chance to achieve my target was to tuck myself in behind him and let him pace me to my 3:30 deadline. However, he went past and I simply could not lift my speed by the small margin required. My legs just would not obey the command. I was flabbergasted, but nonetheless was able to keep putting one foot in front of the other, and I plodded on. More runners passed me, and within the final kilometre a young man, perhaps about 30 years my junior, went by but I simply could not increase my speed.

When I turned into the home straight with about 100 metres to go I could make out most of the numbers on the huge digital clock over the finish line. It read 3 hours twenty something. I did not take in the minutes exactly, but my brain registered that there was still a chance of achieving the bronze standard. Suddenly I was sprinting. It wasn’t merely a delusion created in a glucose-deficient brain. I was gaining on the young man who was now about 40 metres ahead. At that point even time didn’t matter; it was a race to the finish. The spectators in the grand stand were shouting encouragement and it was only their shouts (or perhaps my gasping breath) that alerted my quarry. With a few metres to go he looked over his shoulder and scampered across the line just in front of me. My finishing time was 3:27:35. A few years later I met an acquaintance who told me he had been there that day and remarked on what a spectacular finish it had been.

For me the memory is vivid though the observation is commonplace: with an appropriate trigger, we can mobilise reserves that are ordinarily inaccessible. It is worth pondering several issues. At 20 miles I was conscious of the fact that I could no longer maintain the pace of the first twenty miles. At that point I was not capable of computing the pace required for my bronze target, but my unconscious brain selected a pace for me. I doubt that it was based on a non-conscious calculation of the requirement for the bronze target; more likely it was simply an estimate of the output my muscles could sustain without some metabolic catastrophe, perhaps a serious fall in blood glucose. At 23 miles, when I attempted to increase the pace marginally, I simply could not do so despite my conscious judgment that I would be unlikely to achieve even my bronze target unless I could tuck in behind a suitable pace-setter. Nonetheless, in the final 100 metres, I was able to muster a sprint that had the spectators in the grand stand buzzing. My brain was quite prepared to let me build up a small deficit of oxygen and burn up an extra few grams of glucose, now the end was in sight.

The central governor

So my experience confirms Tim Noakes proposal that the final arbiter of performance is a central governor in the brain. Is it worth exploring the possibility that we might train our brains to re-set the central governor? Mat Fitzgerald has recently published a book on Brain Training for Runners that makes suggestions for how we might do this. But is it a sensible thing to do?

I suspect that the central governor is not merely whimsical, but makes its decisions on the basis of data about the metabolic status of the body. There are many possible messengers that the brain should heed. Microscopic damage of skeletal muscles or of heart muscle releases enzymes into the blood stream. Maybe the brain might detect these and order a shut-down before serious damage is done. Maybe the kidney signals when electrolyte imbalance is developing, or pressure receptors in the large blood vessels might signal a fall in blood volume due to dehydration. The temperature regulator in the hypothalamus might order a shut down when body temperature increases too far beyond 40 degrees C (Nybo & Neilson, (Hyperthermia and central fatigue during prolonged exercise in humans. J Appl Physiol. 2001;91(3):1055-60). It s likely that the brain itself would take action to prevent a fall in glucose which is essential to the brain’s own continued function. Clearly, if we decide to reset the criteria by which the central governor reacts to such messages, we are tinkering at our peril.

However, it is probable that the criteria set by the central governor are cautious criteria and it is likely that among elite endurance athletes it is those with less cautious central governors that win gold medals. The image of Jim Peters staggering into the arena and collapsing from heat stroke 200 metres before the end of the Commonwealth and Empire Games marathon in Vancouver in 1954 suggests that one of the factors that made him the pre-eminent marathon runner of his era was the ability to tolerate a high body temperature. Maybe some training to produce small adjustments of the central governor’s physiological criteria is sensible, but it is difficult to know where to draw the line.

Mental influence on the Governor

It is also likely that there are there are largely psychological mechanisms that activate the central governor. One of these is our perception of how much longer we are required to sustain a stressful effort. When doing 8x1Km repetitions in training it is often possible to squeeze out a little more speed on the 7th and 8th repetition than would have seemed possible on the 6th. Machiavelian coaches sometimes announce after the 7th repetition that ‘today we will do 10’ just to build up the mental toughness necessary to cope with an unexpected challenge in the final stages of a race.

Seeing the end in sight mobilises reserves; it is probable that awareness of just how much further there is to go at the twenty mile mark in marathon has the opposite effect, via a mechanism that has more to do with mental perceptions than it has to do with physiological danger signals from the body. How can we prevent these self-defeating perceptions from causing premature shut-down?

Paula Radcliffe reports that she does it by distraction. She counts to 100, or as in the New York in 2007, in her first marathon after the birth of baby Isla, she recites ‘I love you Isla’

However, for a generation whose bible was Robert Pirsig’s ‘Zen and the Art of Motorcycle Maintenance’ there is another approach. Live wholly in the present and banish any temptation to create self-defeating perceptions of the length of the road ahead. Focus on every breath; on every step. Maintain a brisk cadence in the range 170-180 steps per minute. Lift the foot from stance with a short and sweet pull that directs it smartly up and forwards, but not too far forwards. Tip the rim of pelvis up at the front to facilitate a well coordinated swing and footfall. The goal is to achieve that zone of all encompassing bodily awareness where effort becomes effortless.

As I set out on my 10K run today I switched on my heat rate monitor, but apart from checking that it had started recording (it has a wonky switch), I didn’t look at it again until the end. I was aiming for pace in the mid-aerobic zone, a zone sometimes disparaging described as ‘junk miles’ by runners familiar with the excellent physiological principles of Daniels, because it is not fast enough to place a heavy demand on the biochemical pathways that deal with lactate, but too fast to be described as recovery. However, I think that point of view under-estimates the valuable role of that pace for developing a sense of effortless efficient running. In my youth, my most frequent training run was a distance of 15-20 Km at a pace around 3:20-3:30 per Km. That was pace that I felt I could maintain for ever, or at least for as long as I ever wanted to run. In those days it was slightly slower than my marathon racing pace. Allowing for the extra adrenaline of race day, it felt similar to racing a marathon, so it was no doubt a good mental preparation for a marathon runner. However that mental preparation for effortless running also stood me in good stead over shorter distances. I only ever ran one 10K race and I have no record of my time, but that race sticks in my mind for two reasons: it felt effortless and I won it (quite a memorable feature because I rarely ever won races on the track).

This morning, I easily found the same zone, though of course at a much slower pace than 40 years ago. My breathing was just audible at a rate between 40 and 45 breaths per minute. I felt I was being stretched without strain. In the language of materials science where stretch is synonymous with strain and both are proportional to stress, being stretched without strain is nonsense, but for me the concept evokes the right mental image. I think it is similar to what Sebastian Coe describes as the pace of a therapeutic run.

Holme Pit in May 2008

Holme Pit in May 2008

I focused on brisk cadence and lifting my foot from stance with a short sweet pull. I was not wearing gloves and at first I was aware of tingling fingers, which was scarcely surprising as Holme Pit was frozen. However, after a short while the tingling faded into the background. Visually I focused on the next bend in the path though I imagined that beyond the bend was an endless series of twists and turns stretching to infinity. When I got home I checked my heart rate monitor. The recorded mean heart rate was 136, which for me is about 85% of maximum, and somewhat lower than I would expect to maintain in a marathon. I didn’t measure the distance exactly, but my pace was around 5 min per Km. It was my most enjoyable run of the week, apart perhaps from my unplanned ‘race’ with the family of cyclists on New Years Day

I do not intend to test this mental approach in the final miles a marathon in the near future. In the next few weeks I have a more mundane goal. Because I do not think I will be able to push myself into the upper reaches of the aerobic zone outdoors until the air temperature increases a bit on account of my asthma, it would be good to develop a mental strategy to make upper aerobic workouts on the Elliptical cross trainer seem effortless.

Push or pull?

January 2, 2009

Yesterday Ewen raised the issue of getting the foot off the ground quickly to minimise time on stance. I certainly agree that getting the foot off the ground quickly is an essential strategy. The main debate is how is it done. Does it require a push or a pull?.

The Pose school emphasizes a pull, via hamstring contraction – however an isolated hamstring pull might bring the foot nearer to the buttock (or buttock nearer to foot) – but cannot lift the centre of gravity (COG) any more than you can lift yourself off the ground by pulling on your own bootstraps – so lifting the COG must involve a push.

Lifting the COG is an inescapable necessity because once airborne, the body must inevitably fall. In part, the energy to lift the COG in the next step can be provided by capturing the energy of the fall and recovering it via elastic recoil, but unless the capture and recovery of the energy of the falling body at the end of the airborne phase is 100% efficient, there must be some additional push.

Some elite runners (such as Sebastian Coe) consciously focussed on this push. Maybe if you want to run really fast, it is useful to focus on pushing, but I am more inclined to focus on the pull and let the push look after itself. This is because a conscious push might easily result in a tendency to contract the quadriceps, and this would be counter-productive because in early swing the knee needs to flex to allow the foot to be carried through reasonably high to minimise the length of the swinging leg. So the conscious emphasis should be on lifting the foot smartly from the ground, and letting elastic recoil, aided by little bit of automatic push by the calf muscles lift the body .

The next question is how to execute the pull. A pure hamstring contraction is inadequate because that would not only bring the heel towards the buttock, but also extend the leg backwards at a time when it is crucial to get the leg swinging forwards rapidly. So it is essential to activate hip flexors at the same time – I suspect that iliopsoas is the most useful muscle for this. However, I do not find it helpful to try to micromanage each muscle; it is better to imagine the required direction of travel of the foot. So I simply focus on rapidly lifting the foot and bringing it smartly forwards – but the forward propulsion of the leg relative to torso must be short and sweet, or there will be a risk of over-striding.