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.

If older people don’t get stronger from doing just one set of weight exercises, doing four sets instead might help them build more strength after training twice a week for 10 weeks.

If women who already work out do too many sets each week, they might gain less muscle and strength than if they did fewer sets.

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.

If women who already lift weights increase their workout volume every couple of weeks, they’ll get stronger on the leg press faster than if they stick to the same number of sets the whole time.

If you're already fit and lift weights, doing way more sets (15–20 per muscle group per week) doesn't make you stronger faster—in fact, you might even gain less strength than if you stick to just 5–10 sets.