Thread: HIIT Cardio Theory - Recent Observations

any type of endurance training, is going to have the greatest impact on red muscle fiber, you may retain muscle, but no way could you gain or even mantain the same amount of LBM as someone that was strictly training anaerobically.

Much would have to do with what they do in the off season too.

I agree, that swimmers typically have well developed backs and shoulders, and cyclists often have well developed quads, but I have never seen a long distance runner with large legs, it's contradictive.

My theory is that since much of their training is above the anaerobic threshold (in terms of heart rate) they manage to maintain much of their muscle mass while doing this sort of long distance training.

And I do not understand what you mean by this...please explain further.

Sprinters have large legs, not marathoners.

300 pounds and endurance are two terms that dont go together, how does the body get endurance? Besides cardiological fitness, staying light and lean is going to help allow the person to last longer.

Originally posted by Prince
any type of endurance training, is going to have the greatest impact on red muscle fiber, you may retain muscle, but no way could you gain or even mantain the same amount of LBM as someone that was strictly training anaerobically.

Much would have to do with what they do in the off season too.

I agree, that swimmers typically have well developed backs and shoulders, and cyclists often have well developed quads, but I have never seen a long distance runner with large legs, it's contradictive.



And I do not understand what you mean by this...please explain further.

Much of the training that I am experiencing thus far is sprint training (distances where effort is only expended for 1-2 hours instead of the 4-8 of marathons and Ironman triathlons). Most of the training is done at a very high heart rate threshold (80-90% of max HR) which causes you to go past your aerobic system and into your anerobic one for extended periods of time.

Now that I think about it, most marathoners and long distance runners are very thin, especially in the legs. What makes me wonder is that many of the triathletes (not marathoners) I see have quite large legs (relative to normal size...definitely not BB size but still big), and I was thinking (just curious) that it might be due to training so high in the heart rate threshold (80-90% of HRR) as opposed to traditional cardio (60-80% of HRR). Would this type of training stimulate fiber growth, even if it was the red fibers?

Difference being most marathoners probably train and race within that 60-80% HRR threshold, while triathletes at least over short distances manage to maintain a much higher HR over a shorter period of time.

To me a sprint is 100 yards, not 1-2 hours, but its not like I know anything about this stuff. One of the le mans type bikers claimed he had large legs but they didn't look large to me, and he was on anabolics (fina and so on).

Red fiber is an endurance muscle fiber, it does not have the characteristic of "size".

Anaerobic exercise involves short bursts of exertion followed by periods of rest. So, what they're doing is not anaerobic.

No, this would not cause growth in white fiber, it would cause an increase in red fiber, and ultimately a loss of white fiber, and inevitably a loss of muscle size and strength and an increase in muscle endurance.