When older men who are healthy lift heavy weights for 16 weeks, most of them—82%—get much stronger and build more muscle, while barely 5% don’t improve much, so it’s rare for someone to not benefit at all.

When older men do heavy weight training, some get much stronger and build more muscle than others—even when they do the same workout—and those differences are bigger than any mistakes we might make when measuring them.

For older people, lifting weights once or four times a week might not make much difference in how much stronger they get—but it could make a big difference in how much their muscles grow.

For older adults doing light weight training, pushing muscles to complete exhaustion doesn't give extra benefits like more strength or muscle growth compared to stopping before exhaustion, since both ways work about the same after 12 weeks.

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.

Older adults doing light weight lifting twice a week for 12 weeks can get about 20% stronger, even if they don't push themselves to their absolute limit every time.