For older adults between 59 and 76 years old, doing gentle strength training twice a week for 12 weeks makes them stronger but doesn't build much muscle size.

If you're over 60 and lifting weights, doing it more than twice a week probably won't make you any stronger or give you bigger muscles than doing it just twice a week.

If older people who didn’t get stronger from doing just one set of weight exercises start doing four sets instead, they’ll likely grow bigger muscles in their thighs after 10 weeks of working out twice a week.

When older men get stronger quickly at the start of weight training, it’s often just because they’re learning how to lift better—not because their muscles are growing or getting stronger for real. So, early gains don’t mean they’ll keep getting stronger over time.

For people over 60, adding one extra day of weight training each week might help them get a little stronger, but it won’t make their muscles noticeably bigger.

If older men in their early 70s lift heavy weights three times a week for four months, they’ll get noticeably stronger and their big muscle fibers will grow bigger.