Lifting weights (3 sets of 8 reps at 80% of your max) three times a week for six weeks can increase the thickness of thigh muscles in young men who haven't trained before by about 2.9%.

In men new to weight training, a program that includes two weeks of lighter training still leads to the same increase in thigh muscle size as a program with consistently heavy training, even though the total amount of lifting is 18% lower.

If young guys who’ve never lifted weights before do regular strength training twice a week for two months using moderate weights, their thigh muscles get bigger and stronger—whether or not they use special bands to restrict blood flow.

If a guy does leg workouts with just one leg, three times a week for two months using heavy weights, that one leg gets noticeably bigger in muscle size—especially the fast-twitch fibers—while the other leg stays the same.

Lifting weights just twice a week for two months is enough to make the upper and middle parts of your thighs bigger—even if you change how you do the sets, as long as you do the same total work.

If you lift weights the same total amount each week, it doesn’t matter if you do it in one big session or split into three smaller ones—you’ll get just as strong and build just as much muscle.