Leg extensions and leg curls are two opposing movements that should be worked together. Leg extensions focus on working the quadriceps and knee extension. Whereas, leg curls focus on working the hamstrings and knee flexion. Both the quadriceps and hamstrings need to be balanced to reduce the risk of knee injuries.

So, what is the difference between the leg extension and the leg curl? The leg extension isolates the muscles in the front of the leg (quads), while the leg curl targets the muscles in the back of the leg (hamstrings). Leg extensions can improve your squat, while leg curls can be used to improve your deadlifts.

Leg extensions move a weight while extending the knee, while leg curls flex the knee. Knee extension will help movements such as kicking and cycling, whereas knee flexion helps with movements such as walking and running.