If older women who aren't used to working out do 12 weeks of strength training—using 8 exercises and doing 10 to 15 reps each time—they’ll get noticeably stronger in both arms and legs, gain muscle, and improve key health markers, whether they do one or three sets per exercise.

Older adults, even those over 85, can gain just as much leg strength as younger seniors from 12 weeks of regular weight training — and some even gain a bit more!

If you've never worked out before, lifting weights for 10 weeks can make your muscles stronger and bigger — especially in your legs and arms — while people who don’t train see almost no changes.

For older women who don’t usually lift weights, doing one set of each exercise is just as good as doing three sets for getting stronger and building muscle over 12 weeks — more sets don’t seem to help extra at this stage.

Whether you use machines that change resistance as you lift or keep the same weight all the way through, after 20 weeks of training, healthy men gain about the same strength and muscle size either way.

Older women who started out weaker in their legs got stronger in their legs more than the stronger ones after doing leg exercises for 12 weeks, but everyone gained about the same amount of muscle and upper-body strength.