If you're a guy who's already lifting weights, doing 4 workouts a week for 8 weeks will noticeably grow your thigh muscles — and it doesn’t matter whether you stick to the same routine or mix it up every time.

This study only looked at the front and side of the thigh—so we don’t know if doing more sets helps your front thigh or hamstrings grow more.

After 10 weeks of lifting weights, whether you rest 20 seconds or 2 minutes between sets, your thigh muscle gets about 15% bigger and you can lift about 40% more weight.

If you lift weights twice a week for 8 weeks and do the same total amount of work, your upper and middle thighs will get thicker — no matter what fancy technique you use.

If you're already fit and lift weights, doing anywhere from 5 to 20 sets per muscle group each week will make you stronger and build more muscle — and it doesn't matter much which number you pick within that range.

If you're already fit and lift weights, doing 5 to 10 sets per muscle group each week will make you stronger—but doing more than that (like 15 to 20 sets) won't make you any stronger, no matter how hard you push.