Ross Tucker wrote:
I didn't comment on the mechanism for the pacing - there's a lot more to it than the aerobic-anaerobic dichotomy.
Can you tell us what you know about ammonia as a factor in fatigue?
The PAIN of the 800 meters explained by an exercise physiologist
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Can you tell us what you know about ammonia as a factor in fatigue? -
jcreardon@wisc.edu wrote:
Dear Pariah,
Yes, I am looking for a metabolite to blame for the limitations to performance in 400m and 800m races.
One has to be careful with the word "fatigue" because there are many types of fatigue, and different writers may use the word in different senses.
I agree the glycogen depletion is intimately related to the sense of exhaustion one feels at the end of a marathon, and is likewise intimately related to the limitations of performance in the marathon.
One argument against glycogen depletion as being the cause of performance limitation in the 400m and 800m (which I sometimes refer to as "butt-lock") is that if you are reasonably well-trained you can run an all-out 400m (to the point of butt-lock), rest for an hour, and then do it again, and hope to achieve very nearly the same time. However, the time-scale for recovering muscle glycogen stores is much longer than one hour.
Also I cannot think of any way that such a short period of exercise as 2 minutes, no matter how intense, would deplete the glycogen stores of a significant number of muscle fibers.
So you are looking for a metabolite to blame. Stop doing that. That's not good science.
You are missing the point about glycogen depletioon. It's a depletion of the most powerful fibers. Yes we can use them again after a rest, this is because accumulated lactate can be reconverted to liver and muscle glycogen, a process known as gluconeogeneis. There are many gluconeogenic pathways.
Your basic hypothesis seems to me to be that no-one has a hypothesis. I'm sure that if Ross Tucker had the time, he would be polite, but you aren't giving him anything really profound are you? Just a load of Newtonian physics equations and a suggestion that if we can't blame 'lactic acid' we must find another culprit. How many other half baked hypotheses do you think he gets asked to read? -
"Surely glycogen depletion of the most powerful fibers ..." sounds like another half baked hypothesis.
Forming hypotheses, even wrong ones, is not bad science.
Looking for evidence, even for wrong hypotheses, is not bad science. -
The Glycogen depletion of the most powerful fibers hypothesis relating to the very fast starts and extended high speed endurance of 400 and 800 meter races, has been around a long time. It's common sense. Hypothesizing that there must be some unknown metabolite which causes fatigue?..... Not so much.
