The key factor that has been ignored in this study is the difference between muscle fiber types... there are four however the three that are most often discussed are:
Type 1 ( slow twitch ) These fibers are aerobic meaning they use oxygen to generate ATP. Athletes who have a predominance of these fiber types do well in sports such as long distance running and activities that require endurance. These muscle fibers respond well to lower weight, higher repetition weight training.
Type IIa : (fast twitch, fatigue resistant ) These are aerobic fibers which can split ATP at a very rapid rate yet fatigue much more quickly than Type 1 fibers. Athletes who have a predominance of these fiber types do well in sports such as middle distance running, olympic swimming etc. These muscle fibers respond well to both low weight / high rep training as well as high weight / low rep training.
TypeIIb ( fast twitch fatigue-able ) These are Anaerobic muscle fibers that are are characterized by an absence of myoglobin and a reliance on glycolytic enzymes. These fibers are perfect for short bursts of speed and power and use both oxidative metabolism and anaerobic metabolism ( the burning of carbohydrates primarily ) to generate ATP. Athletes who have a predominance of these fiber types do well in sports such as powerlifting, short distance track, football linebackers, lineman etc. These muscle fibers respond well to high weight / low rep training.
Every person has all of the muscle fiber types but we each have them in varying percentages. And these percentages can vary widely between individuals.
So if you are someone with predominantly Type I muscle fibers .. low weight / high rep will serve you well .. in general.
But
If you are predominantly Type II a low weight / high rep routine is counter productive if your goal is to gain mass.
Sorry for the geek speak on the subject.. but this is what I did my dissertation on. Fiber typing and the Krebs Cycle.... and people wonder why I jumped into adult
