i just did 72 reps of dumbell curls with 5kg db's, is this good or bad for my muscles cause my hands are like hanging in mid air and the pump is so enormous man, its difficult to keep my hand straight down or stop it from shaking
I like you, keep posting. Repped.You'd simply be depleting muscle glycogen at a faster rate. Depending goals, like said above, the effects can be acute. In simple terms, you will only be improving endurance within the musculature, opposed to progressive overload.
It could also react as a way of anaerobic cardio for the muscle fibers. I wouldn't do this on a regular basis.