After doing strength training for 8 weeks, older women got stronger and their muscles worked better—but their muscles didn’t get bigger. This suggests their brains and bodies got better at using the muscles they already had, not at making new muscle.

When older women lift weights for 8 weeks, their muscles don’t get much bigger, but they do get stronger and walk faster—so it seems like something other than bigger muscles is helping them move better.

After 12 weeks of lifting weights, both strong and weak older women gained about the same amount of muscle—starting strength didn’t affect how much muscle they built.

When older women do strength training for 8 weeks, they tend to walk faster if their leg muscles get stronger or work better—but not if they just gain muscle mass or lose fat.

Older women who lift weights—even just one arm or leg at a time—gain muscle and fight off the natural muscle loss that comes with aging.

After doing strength training for 12 weeks, older women—whether they started strong or weak—gained about the same amount of strength in their arms and the same amount of muscle, no matter how strong they were at the start.