Q: I increased the weights I use so that instead of being able to do 15-20 (or sometimes more) reps/set, I can only do 6-10. But now I don't get that muscle ache that you get when your muscle starts getting fatigued. Instead the muscle just gives out, but I don't feel a burn or an ache or anything. Just complete weakness to where I can't finish another rep. Is that ok?

A: That's perfectly fine. The burn you were feeling before is not an indicator of progress either in strength or in muscle growth. With your new rep range you hit failure before the burn sets in, but in this range you'll make much quicker progress in building muscle and getting stronger.

Same thing is true for 'the pump' which many people like to exercise for. There's nothing wrong with having 'the pump' (just like there's nothing wrong with the burn), but you do not need the pump to make progress and, conversely, achieving the pump is no guarantee of progress.