How Much Weight Should You Train to Fatigue?

With any amount of weight, you can build muscle, as long as you train to muscular failure. Weight and raps doesn't really matter if you fatigue the muscle ten does it really need to be failure? It's very likely that your study is too small. The sex hypothesis are almost impossible to show in a study. So i don't think we'll have any clear evidence abat about what's truly optimal. But i do think we have pretty good guid lines within which rules we have to play.