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.

When people who’ve never lifted weights before do leg exercises with either 20-second or 2-minute breaks between sets—while doing the same total amount of work—their thigh muscles grow about the same amount.

If new guys do leg exercises to failure using medium weights, slowing down the movement doesn’t make their muscles grow more than doing faster reps — both ways work about the same.

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.

If you want to make the front part of your thigh (rectus femoris) bigger, leg extensions work better than leg presses — after 12 weeks, leg extensions made it grow 12% more than leg presses did.

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.