Even though leg extensions only move one joint, they might work your front thigh muscles better than squats or leg presses because they really target one specific muscle in the quad.

If you're a guy new to lifting and want your front thigh muscle to grow as much as possible, doing leg extensions with your hip more bent (40°) is probably better than keeping it straighter (90°).

Doing leg extensions (kicking your leg out while sitting) makes the front thigh muscle right above your knee grow more than doing leg presses (pushing a heavy platform with both legs).

For people who don't usually work out, using a knee extension machine grows the front thigh muscle much more than using a leg press machine.

Doing leg extensions might grow your front thigh muscle more than leg presses, even though both workouts work the other big thigh muscles just as hard.

Different leg exercises make different parts of your thigh muscles bigger — leg extensions grow the front part, squats grow the lower outer part.