Sloppy snow and reactive oxygen

In the past eight years, snow in the east midlands has never remained on the ground for more than 24 hours, but this week we have had lingering snow for five days. It snowed again last night and continued in the morning. Unlike the initial flurries of crisp polar snow on Sunday, today’s precipitation was typical sloppy English snow, created as a result of a weakening stream of cool sub-arctic air from the east meeting warm moist maritime air from the southwest. When I set out for work the slope down the escarpment to the river was treacherous, so I decided to run to work rather than cycle. The riverside path was delightful as the fresh snow was largely undisturbed, but elsewhere was mush. Apart from free flowing traffic on the few major roads that had been gritted, the roads were in chaos. I am sure that running was preferable to any other form of transport today. The round journey to and from work is about 15 Km. I was pleased that there was no trace of discomfort in my hamstring

This week, in my continuing attempt to assemble the evidence about possible long term muscle damage from forms of training such as downhill running; plyometrics or simple long runs, that entail large amounts of eccentric muscle contraction, I have been looking into the mechanism of damage at the cellular level. There is very strong evidence, which I will review in greater detail in a later post, that sudden increases in amount of strenuous exercise cause damage to muscle via the generation of re-active forms of oxygen – various atomic and molecular forms of oxygen with an extra electron attached. These are generated by aerobic metabolism and cause damage within the muscle fibres. Furthermore, the generation of these reactive forms of oxygen is much greater in the elderly. At first sight, this appears to provide clear-cut support for the value of supplementary antioxidants such as vitamin C.

However, as with almost all processes in the human body, there are natural compensation processes. Training helps build up chemical processes that neutralise the reactive forms of oxygen. Inappropriate supplementation with anti-oxidants might at least in principle diminish this natural intrinsic protective process. On the other hand, in the elderly, the development of natural ability to counteract over-reactive forms of oxygen is more sluggish. So far, I have not managed to identify evidence establishing whether eccentric and concentric muscle contractions differ in their ability to promote protection.

So what can we conclude. As is often the case, the evidence is not adequate to allow definitive conclusions, but several guidelines appear sensible.

1) this evidence confirms that sudden increases in training load are more likely to result in long term damage, even when there is no overt injury.

2) slow build up of training load is likely to help build up of the ability to counteract oxidative damage.

3) plentiful natural anti-oxidants in the diet (eg vitamin C from citrus fruits etc) are likely to be beneficial. As an ‘oldie’, I am veering towards adding supplements, but want to look further into the possible danger of suppression of intrinsic defence mechanisms before consuming an amount in excess of that in the diet that humans have adapted to over our evolutionary history.

Polar snow

Ewen, as you imply, De Castella’s demanding 10 mile sessions including fairly fast down-hill running at Stromlo almost certainly contributed to his good performance in Boston, but it is intriguing to speculate that they might also have contributed to the fact that he is now ‘well and truly retired’ at 51. Of course there are many possible reasons why a former world record holder might choose to take it easy as middle age approaches.

However, it is disconcerting that some evidence indicates that elite athletes who stop training tend to deteriorate faster in middle age than sedentary individuals.   In a comparison of 64 sedentary men with 89 endurance-trained men, Pimentel and colleagues (Journal of Applied Physiology, volume 94, pp 2406-2413) found a more rapid decline in maximum oxygen uptake (VO2max) after age 50 in the endurance trained men. Not surprisingly the accelerated deterioration was associated with reduced training volume, though the causal mechanism was not established. In a 30 year follow-up study of men who had participated in the 1966 Dallas bed rest study in their youth, McGuire and colleagues (Circulation, 104, 1350-1357, 2001) found that the cardiovascular deterioration due to 3 decades of aging was less than that due to 3 weeks of bed-rest at age 20. Of special note with regard to the mechanism of deterioration, they found that the decrease in VO2max could be attributed mainly to decreased ability of muscle to extract oxygen from blood. In other words, the deterioration with age was largely due to deterioration within the muscles, though whether this deterioration was merely a loss of aerobic enzymes, or to the loss of fibres, and/or capillaries is unknown.

In the 4^th edition of his book ‘Lore of Running’, Tim Noakes proposes that the springiness of muscles is significantly compromised by large numbers of runs over 21k, and he advocates that runners seeking a sustained quality running career should minimise eccentric muscular damage. So, I will continue to be cautious about forms of training that focus on eccentric contraction. Maybe the most important thing is allowing adequate recovery, especially when the legs start to show signs of cumulative fatigue over several consecutive days.

With regard to the recovery from my recent hamstring injury, my easy 7 Km run today went well despite the rather stripey weather. Fitful sunshine alternated with brief flurries of snow. Although the flurries were brief, the flakes were small and compact, typical of polar snow borne by a north-easterly airstream. Nonetheless it was good to be out of doors. After a gentle warm up, I gradually increased pace up to 5:30 min per Km for the 6^th Km and was not aware of any discomfort in my hamstring. So I hope that after a week or two of gentle running I will be able to return to moderately intense efforts by mid February.

Downhill running, eccentric contractions and torn hamstrings

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.

Dancing with the devil in 2008

Despite lingering constriction of the throat and sore ears, I decided it was time to recommence moderate intensity running today with three 1Km repeats at 5K pace (around 4:20 min/Km ). I did the first two repetitions in 4:20 and 4:21 at mean heart rate 142 and 143. Then during the third, the cold air upset my airways and I started to develop an asthma attack. I completed that repetition in 4:32 at HR 144, and jogged home. I had taken one puff of my long-acting inhaler early in the morning, but it appears that in this weather I should increase the dose. Nonetheless I was quite pleased that despite my recent bout of flu, my pace and heart rate in the first two repetitions were similar to the recordings in a 6×1Km session on 6^th December.

This a picture of the Trent beside the path where I do 1Km repeats, taken in May of this year. Ignore the incorrect date setting on my camera.

I had started this year with the intention of developing a running style that minimised risk of injury, especially the risk of further damage to my right knee which has been ravaged by intermittent attacks of inflammatory arthritis since childhood. I have read fairly widely and been influenced by an number of authors, especially Gordon Pirie, and to a lesser extent by Nicholas Romanov, the inventor of the Pose technique. Some of the principles of Pose appear to violate the laws of physics, especially the laws of conservation of energy and momentum, but despite its shaky theoretical foundation, the experimental evidence confirms that Pose places less stress on the knee. The study by Arendse and colleagues from Tim Noakes laboratory in Cape Town demonstrated a 50% reduction in work done at the knee joint when running Pose style compared with heel striking. So I attempted to work out a rational basis for a running style including what I regarded as the good features advocated by Pirie and by Romanov, but with a rational foundation based on the laws of physics. The details are described in the articles in the side bar entitled ‘A dance with the devil’

Unfortunately I have had a somewhat disappointing year, mainly due to respiratory problems, and it is difficult to judge whether my running style has been a success. The good news is that my knee is coping fine. It has caused far less trouble this year than it did in my mid-fifties before I recommenced running; and also, less trouble than last year, when I had remained injury free for most of the year, but suffered a flare up of arthritis in late summer that caused me to descend stairs on all fours for a week or so. That was the final impetus to develop a safer running style.

While my knee has been virtually trouble free this year, I have suffered two minor injuries. In neither case was running style the main cause, though in each case, I think that my new style did exacerbate the problem.

One of the crucial features that I learned from Pirie and Romanov is the principle of lifting the foot from stance as quickly as possible. This ensures that much of the energy stored in the muscles, tendons and ligaments at footfall is recovered via elastic recoil. Because muscle and tendon is viscoelastic, recovery of energy is greatest when recoil is rapid. The time on stance should be around 100 milliseconds or less. If cadence is around 180 steps per minute, which experience indicates provides optimum efficiency, the duration of each stride is 333 milliseconds. Therefore, when time on stance is less than 100 milliseconds, the major part of the stride is spent airborne. The vertical ground reaction force that must balance the downwards impulse of gravity acts only for a minor fraction of the gait cycle, and hence this ground reaction force will be several times body weight. For cadence180 steps per minute and time on stance of 100 milliseconds, the average vertical ground reaction force will be three times body weight, and for shorter times on stance, it will be even greater.

Another, more controversial feature borrowed from Pirie and Romanov is that it is most efficient to land on the forefoot. If vertical reaction force is over three times body weight, this places a substantial load on the ball of the foot. In addition, a substantial tension develops in the Achilles tendon. If the knee is slightly flexed at the time, a large portion of this strain is taken by soleus, the deeper of the two calf muscles. Unlike the larger gastrocnemius muscle, soleus does not cross the knee. Hence when the knee is flexed, tension in gastrocnemius is low and soleus bears the main burden.

So how did the principles I borrowed from Pirie and Romanov contribute to my injuries? The main culprit for the first injury was a stone on the path. I landed with the stone beneath the head of my second metatarsal, and a force greater than three times my body weight was transmitted directly onto the metatararsal head and adjacent metatarso-phalangeal joint. Ouch! This part of my foot has always been vulnerable and I was hobbling for several weeks afterwards.

The other injury occurred when I made a fairly rapid increase in the intensity of my training. After several months of low intensity training, I did two speed sessions within a week. In the second session, while running fairly fast uphill over irregular ground, I suffered a minor tear of soleus. Undoubtedly the main culprit was increasing intensity too quickly. I had not conditioned soleus adequately for the task, so I do not think that I should lay too much blame on my change of running style. However, this injury emphasises the importance of conditioning soleus well before increasing training intensity. It also suggests that when running longer distances, it is best to allow the heel to touch the ground in mid stance to avoid the risk that repeated micro-tears will combine to produce a full-blown tear of the muscle.

Despite the occasional tribulations, I am still greatly enjoying running and looking forward to an even better year, next year.

Happy New Year and good running in 2009.

Running in the twilight

In the past few days a northerly air-stream has brought the temperature down, and the dawn light this morning revealed a slight dusting of snow in the roof tops – a rare occurrence in the English Midlands in recent years. The ground temperature was still too high to allow the snow to settle. Midmorning, there was another flurry of soggy snow flakes but then sun came out and the temperature rose a degree or two. I was busy doing various odd and ends about the house, and daylight was fading rapidly by the time I got ready to go for a run. I decided that it would be best to follow the fairly open path beside the River Trent to make the most of the last glimmer of sunset reflected off light cloud above and the water beside me, rather than risk tripping over tree roots in the evening gloom on my more usual woodland route.

The open river bank path exposed me to the wind which had swung to the west and strengthened. Any gain in temperature due to the replacement of Arctic air from the north with Atlantic air from the west was negated by the increased wind chill factor. I was wearing light-weight shorts but also a long sleeve top and gloves, so with the wind at my left shoulder on the long reach of the river as it flows northeast from Clifton village to Wilford, I felt comfortable but invigorated. It was tempting to increase the pace, but bearing in mind my recent muscle problems, I restrained myself to a gently fluctuating pace ranging from about 6min per Km to 5 min per Km (for a 100 metre or so at a time). There was no trace of discomfort from my right calf.

As I passed a clump of trees just before reaching the point where Fairham Brook joins the Trent, I was subjected to scrutiny by a predatory owl. He swooped down silently from behind me, but clearly recognized I was far too big a morsel for supper, and wheeled away over the river. At Fairham Brook I turned for home. Now the chilly wind was on my right cheek and I realised that I was starting to wheeze. I have not yet adopted the habit of using my salbutamol inhaler regularly when I run, but it was the exacerbation of my asthma by cold air last winter that led to the need for anti-asthma medication for the first time in my life. So today’s run was a valuable reminder that this winter I should use my inhaler before running whenever the temperature is low.

My distance today was only a little over 6Km and peak pace was no faster than my estimate of my current marathon pace, but it was a good session. There was no trace of pain in my calf; I learned a little more about managing my asthma. I celebrate the fact that as I approach the twilight years of late middle age, I can still enjoy running in the countryside. But I have a wistful awareness that the carefree days when I could run, play football or climb mountains without concern for my body are now well behind me. In those long-gone days I had many mild problems – congenitally twisted toes; inflammatory arthritis; mild asthma – but those problems were a trivial nuisance that never amounted to anything disabling. I am certainly glad that I never let concern for these minor infirmities become a reason to wrap myself in cotton wool. Even now I think that I am likely to remain healthiest by maintaining a fairly demanding training schedule. I just need to learn the difference between the incidental twinges that are part of growing old and a significant muscle tear such as I suffered a few weeks ago.

Running again

It was great to go for an easy paced 5 Km run today. Though a wintery sun struggled to penetrate the clouds and fine droplets of rain hung in the air, a variegated pattern of russet, brown and gold carpeted the woodland floor. In places the vivid brown of beech leaves dominated, elsewhere it was the dull brown of oak or the brilliant gold of maple. Under the stand of larch, a shower of fresh yellow needles added to the deep pile that has accumulated over the years creating my favourite running surface.

In light of my recent calf troubles, I ran with small steps, focusing on lifting my foot from the ground rather than actively pushing off to initiate each airborne phase. There was a scarcely perceptible ache in my right calf, concentrated in the vicinity of the muscle tissue damaged by the vicious nocturnal cramp I had suffered recently, in the week following a mild tear of my right soleus muscle arising for an injudicious increase training intensity a month ago. It appears that my lingering troubles are more closely related to the nocturnal cramp than the original injury. It is difficult to know whether the two events were even related. The primary precipitant for the nocturnal cramp was apparently dehydration, and the cramp affected both legs simultaneously. However, it is possible that irritability of the previously injured muscle contributed to greater damage on the right. Whatever the cause, it is clear that I must take things easily in the next few weeks, but I am happy to be running again.

Patience on the road to recovery

In a comment on my most recent blog Jason suggested that my current goal should not be described as ‘speeding recovery’ but ‘ensuring proper recovery’. His choice of words implies the importance of the crucial but daunting virtue of patience.

Mostly I have been patient, but every so often I am tempted to test the limits. It is now a little over three weeks since I suffered a minor tear of my calf muscle. The injury was almost certainly a consequence of increasing intensity of training too quickly. I had introduced some interval training after a period of base building. The first two sessions went well, but then in the third session, in which I planned 6×1km at my estimated 5K pace, I pushed myself a little faster the target pace that I had set myself and had suffered a tear of soleus on the 4^th repetition.

After icing for two days and a further day of rest, I had very gradually introduced light exercise, starting with body-weight calf raises while bearing weight equally on two legs; then moving onto calf raises while standing on one leg and gradually building up the number. Apart from a mild setback when I suffered nocturnal cramp after getting dehydrated during a very long flight from Shanghai to London, things progressed well. After two and a half weeks, I had progressed to 3×20 ‘one leg’ calf raises with no trace of discomfort. I then re-introduced running technique sessions that involved running with very short strides covering only a few metres at a time, concentrating on technique. The calf felt good and I was itching to increase the distance a bit. So today, as it was now over three weeks since the injury, I set out to jog a few Km in the local woods.

The day had dawned with a blue sky and brilliant sunlight on the autumn leaves. The dark clouds started to roll in as I set out from home, but it was still an inspiring morning to be out and about. After jogging about 2 Km there was no trace of discomfort in the calf, so I decided to increase pace a little up to what I would estimate is my current marathon pace – around 5 minutes per Km. After a Km, I slowed to a jog for another Km, and as my calf still felt fine, I increased pace up to estimated marathon pace again. However this was a mistake – as I negotiated a boggy patch of woodland I felt a slight but ominous jab in the calf – a few inches about the site of the initial injury but in the vicinity of the site which had been most painful following the ferocious nocturnal cramp I had suffered two weeks ago. I stopped immediately and walked home. Fortunately I had decided to stick to the one Km loop path near to home so I only had to walk a short distance. Now, a few hours later, there is a definite persisting pain at the site damaged by the nocturnal cramp. So my calf is still very vulnerable and I need to remind myself that patience continues to be the prime virtue.

How can I speed the recovery of my calf muscle?

As far as I can see, after a few days of RICE, the best way to recover from a muscle injury is to engage the injured muscle in light exercise to ensure that the healing process lays down fibrous tissue predominantly along the direction of muscle contraction, rather than producing a higgledy-piggledy tangle of fibrous tissue, which might require subsequent pruning to allow efficient muscle contraction. The challenge is adjusting the level of exercise so as to promote the desired formation of aligned fibrous tissue without repeatedly tearing the muscle at its point of weakness.

I have not run since tearing my right soleus muscle two weeks ago. Most days I have done either a core strength workout (various forms of crunch, press-ups, dips etc) or light leg strengthening exercises. In the past, in my occasional leg strengthening sessions I have focussed mainly on body-weight exercises while standing on one leg (squats, calf-raises, hip swings etc) but since injuring my right soleus I have mainly done the corresponding exercises while standing on both legs, wherever possible. This places only a light load on the injured leg. Until a few days ago, things appeared to be going well.

At the beginning of this week, I traveled to Shanghai for a meeting. The return flight to London on Wednesday involved one hour of sitting in my seat before take-off, and then twelve and a half hours in the air, followed by a train journey back to Nottingham. Despite drinking only two small glasses of red wine and fairly large amounts of water and orange juice during the flight, I think I became quite dehydrated during the journey.

In the early hours of Thursday morning I awoke with excruciating cramp in my right calf, and a less severe cramp in the left peroneus longus – the muscle that runs down the side of the lower leg. Attempts to massage the cramp away were futile – the mild degree of stretching of muscle fibres during massage only encouraged an even fiercer cramping, so there was nothing I could do except passively planar flex my ankle to lower the tension in the calf and hopefully minimise tearing of muscle fibres, while waiting for the contraction to subside spontaneously. The next morning I had quite noticeable pain in my right calf – mainly in gastrocnemius, but also some discomfort in soleus. Three days later the discomfort persists, so I am not sure when I will get back to running again.