Interesting Book I Read Yesterday

So yesterday as I was in borders trying to learn my stats so I can do the homework tomorrow, I read this book called The Lore of Running. It was very cool; a biochemical/ physiological guide to almost everything having to do with running, including real statistics, etc. I mean, it was like a 600 pp. book, so I didn't read the whole thing, but one part that was very interesting to me was the muscle recovery part.

What was fascinating was that the book said that statistics have determined the optimal time for recovery for a run is 24 hours. This was based on repletion of muscle glycogen stores and overall improvement of VO 2 max over an extended period of training. It showed that up to two days (48 hours) between training sessions had no ill effects on the runner in terms of loss of VO 2 max capacity. However, it then discussed deconditioning effect. This was fascinating. Most deconditioning from a fit state occurs between days 2 and 5 off, with greater than 50% deconditioning occuring during this period. After 10 days the body is 75% deconditioned, and it is fully deconditioned after 21 days. The study was done on (I think) semi-elite or elite half-marathon runners, which is a good category of runners to look at (in my non scientific opinion) because half-marathon training is much more "reasonable" than marathon training (no extremely long long-runs +20 miles required, which means that strange effects for glycogen repletion would not occur) and much more steady than 5k or 10k training (where speed training might cause spikes in the VO2 max capacity increases).

I really found this quite fascinating. Also, interestingly, it showed that in the first 10-20 minutes of training, the body uses almost 70% of energy from carbohydrate stores and 25 % from fat stores (5% from protein); up to 1.5 hours of training it is pretty much a 50-50 split (with 5% from protein being fairly consistent), and after 1.5 hours, the glycogen stores have reached their "we're almost out" stage, in which case the fat usage increases. The body stores, apparently, about 1800 kcals of energy in the glycogen. I would imagine smaller people would have less glycogen stores (smaller muscles) and larger people would have more (bigger muscles), but that ultimately the times would be about the same, since smaller people burn less calories (less to move around) and bigger people burn more (more to move around). It has also been shown that the process of carbohydrate loading in the four days preceding a a race can actually increase the capacity of these stores, although I would argue that this will also make you feel bloated, and you'll probably run slower due to bloat annoyance (non scientific opinion FTW).

This, I suppose, is why marathoners almost always take a gel at mile 18... that would be the final use of the glycogen stores (as I would assume most marathoners are more efficient and lighter than standard runners).. and they clearly do not have much fat to back them up, and that would be about 1.5 hours into a race (for the REALLY FAST ONES). Fascinating.

I really am in awe of the deconditioning statistics. Only 2-5 days to lose significant amount of the fitness? Wow. Oh, I should note; when the runners were reconditioned (the study was done over a three month period, I think the author commented "they must have gone insane!"), they reconditioned more quickly than average, so they were fully "decontioned" but "reconditioning" didn't take as long as for someone who had never had past conditioning-- clearly muscle memory or adaptivity was at work somewhere beneath the VO2 max / glygocen access-- so the term "deconditioning" here refers to aerobic capacity and not muscle fitness-- wow, very cool stuff.