Originally Posted by infantrycak
I am not arguing with your general description. However I think this is still a somewhat undeveloped field of medicine and even the terminology of power gets hinky. As a simple example Tour de France cyclists. Both considering very short term max efforts (say the same half a kilometer) the sprinters will blow the doors off the climbers on a flat but put them on a mountain and in that same half K the climbers will blow the doors off the sprinters. Both are power situations.
Back when I was involved more with the science of lifting, they'd only identified the type I, IIa, and IIb. The IIx is, afaik, a relatively new discovery. So, you're absolutely right about this still being worked out. AND I might not understand it correctly because I was just an amateur at the science part of this.
Very few people's muscles all have the same composition. So while I might have fast twitch in my pecs, my triceps might be more toward the slow twitch. So when I bench, my triceps will be my limiting muscle group and I'll need to train them to be more fast twitch. But I can only go so far because there will be a genetic limitation to just how fast twitch I can make them.
Some muscle groups are normally more slow twitch than others. Calves have a tendency to be slow twitch.
But to your example, I think it depends on the composition of the muscles being used and how they're trained. I would imagine, and I could be wrong, that going up vs. sprinting flat, you actually use a somewhat different set of muscles. So the rider with muscles better adapted to a particular type of ride would do better at that type of ride. The more you train for mountain riding, the fibers will begin to shift over to the white in those muscles while they start to shift back to the red in the others that are more for sprinting.