Some more great research I just came across. They are looking into two types of fatigue that occurr during training, peripheral and central fatigue.
Here’s how it was described at Conditioning Research
What I thought was neat about the study was the distinction between “peripheral” and “central” fatigue: the former is the reduced ability of your muscle itself to contract, and the latter is a reduction in the signal from your brain to your muscle demanding contraction. If you pick up a heavy (above critical torque) dumbbell and lift it until you can’t anymore, the limiting factor appears to be peripheral fatigue. Your muscles are simply no longer capable of contracting powerfully enough to lift the weight.In contrast, if you lift a lighter (below critical torque) dumbbell to failure, your muscles themselves fatigue to a much lesser extent, suggesting that fatigue somewhere in your brain or central nervous system is the problem.
AH HAH! As I’ve said before, and I will say again, lifting heavy weights at a handfull of reps, is the best and fastest way to make progress. It allows us to fatigue the muscle itself, “peripheral” fatigue, which triggers an adaptive change, forcing muscle growth.
If you don’t fatigue the muscle to the max in a short enough time, you aren’t actually hitting the “wall” of your strength. You aren’t actually hitting the physical limit of your muscle’s ability to lift that weight.
High reps causes the “central” fatigue, that of the CNS and the brain. Your muscles can’t lift the weight any more, not because you have hit the physical limit of the muscle’s strength, but because your brain is stopping it from contracting. This does not cause the same “stressor” or adaptation as “peripheral” fatigue, therefore, once you have healed and try the lift next week, your threshold to lift a heavier weight is diminished.
This has been my experience in real life too. Max muscle damage, by reaching actual limits of the muscle’s strength, causes larger adaptations.