For young women lifting weights until they can't anymore, it doesn't matter if they use light or heavy weights—they'll build the same amount of muscle and strength after 6 weeks.

When young women push themselves as hard as they can during weight training, it seems that how much weight they lift doesn't matter for building muscle size or strength—both light and heavy weights give similar results after 6 weeks.

When young women lift weights until they can't anymore, using lighter weights (30% of max) gives about the same strength gains as heavier weights (80% of max) over 6 weeks, with arms and legs getting stronger by similar amounts.

When young women do strength exercises until they can't do any more, their arm and leg muscles get stronger by about 15-27% after 6 weeks. It doesn't matter if they lift heavy or light weights—both ways work just as well for building strength.

When young women lift weights until they can't anymore, using lighter weights or heavier weights doesn't make a big difference in how much stronger they get. Their arm and leg strength both go up about the same amount after six weeks.

When young women lift weights until they can't anymore, they build similar muscle size and strength whether using light or heavy weights. This suggests that pushing to muscle failure fully activates muscles no matter the weight.