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.

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One Response to “Sloppy snow and reactive oxygen”

  1. Ewen Says:

    Glad you were able to run to and from work. Funny about it being the most efficient form of transport!

    Regarding the ‘damage’ caused to muscles by excessive aerobic metabolism… do you think this is good evidence for a training program (for older athletes) that limits aerobic running and promotes higher quality running? When I say “limits”, I’m thinking a runner who might have run 80k per week in their youth, now runs 50-60k, but with higher quality.

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