growuprunner wrote:
why someone say that from 17 to 21 year old a runner can improve drastically with same mileage?is it because the physical components like heart and lungs are still growing larger?
Not sure what you are asking here, maybe missing a word or two in that sentence?
If you are talking about the same 17-21 year old that continues to train during that 4 year span, of course the 21 year old will probably be faster because of the cumulative effect of the training.
But say you take un-trained 17 year old, train them for 6 months see what they can do, and then they don't run for 3 years. And train them for 6 months at age 21. As long as they hadn't gained a lot of weight, I'd think the 21 year old would do somewhat better because they'd have more muscle development. However, males might do better than females in the follow up, because females would have had more hip development, etc. at 21.