If you lift light weights super slowly and hold the tension, your thighs get stronger and bigger after 12 weeks—but if you lift the same light weights at a normal pace, you won’t see much change.

Doing slow, low-effort weight training three times a week for 12 weeks can make your thigh muscles bigger and stronger, just as much as doing fast, high-effort weight training.

Slow, low-effort weight training keeps your muscles working hard and starves them of oxygen more than fast, heavy lifting, which might help build muscle and strength just as well by stressing the muscles in a different way.

Doing slow, controlled weight lifts with light weights can make your muscles use up more oxygen during the workout than doing the same lifts fast or lifting heavy weights—even if the heavy lifting feels harder.

Doing slow, low-intensity weight training twice a week for about three months can build muscle and strength almost as well as fast, heavy lifting in young men who don't normally exercise.

Doing gentle weight training slowly twice a week for 13 weeks makes young men's muscles about 7% bigger and 33% stronger, almost as much as regular heavy lifting, which made muscles 9% bigger and 41% stronger.