lets say i use a free to work out my bicepts, such as a barbell. But its a reallly light wieght. So i do as many reps as it takes for me to finally feel the burn. Will i still gain muscle this way even though its a light weight, and im feeling the burn... ???
no you wont.
to gain muscle, you need to be fatiguing the muscle within 6-12 reps, resting only about 1 to 2 minutes befire you do it again, and again, and again, and again.