When young guys who don't normally lift weights push their muscles to the max during workouts and eat enough protein, they build bigger muscles no matter how heavy or how much they lift, with their thigh muscles growing 3-7% bigger in about 10 weeks.

If guys who already lift weights drink a 20g protein shake after working out for 9 weeks, they’ll gain more muscle and get stronger—even if the protein is a mix of fast- and slow-digesting types.

When young male athletes push themselves as hard as they can in weight training, whether using heavy or light weights, their muscles grow about the same amount after 8 weeks.

Lifting weights until you can't do any more reps, whether with light or heavy weights, makes muscles grow bigger in fit young men after 8 weeks. It shows that pushing to your limit is what really matters for growth, not how heavy the weights are.

If you're someone who already lifts weights regularly, pushing your muscles until they can't do another rep might help you grow slightly bigger muscles than if you stop before reaching failure.

If you're already experienced with weightlifting, pushing your muscles to failure might help them grow bigger—but if you're new to lifting, doing the same thing doesn't seem to give you the same benefit. Your experience level changes how effective this technique is.