This exercise isolates and adds mass to your hamstring muscles.
Hamstring muscles are used in this exercise. When using either the seated or lying leg curl machine, the muscles on the back of the thigh will contract to bend your knee. The hamstrings are made of three muscles – the biceps femoris, the semimembranosus, and the semitendinosus. The largest of the three is the biceps femoris.
Your hamstring muscles are built to work with your glutes to create movement. Seated or prone leg curl machines, however, ignore your glutes, which increases your risk of hamstring pulls and knee injuries. By isolating the hamstrings alone, they become tight and overactive over time.
Lie face down on a leg-curl machine and hook your heels under the roller pad.Your legs should be stretched out straight so that the pads rest on the back of your ankles.Grasp the handles under the bench for support.
Remaining flat on the bench, curl your legs up until your hamstrings are fully contracted.Release and lower the weight slowly back to the starting position.Concentrate on using a full range of motion.
TIP: try pointing your toes to intensify the burn in your hamstrings.
If you are doing the lying leg curl, your legs are relatively straight in relation to your torso. This body position causes the biceps femoris (outer hamstring muscle) to get more emphasis.
In seated leg curls your legs are bent at the hips about 90 degrees in relation to your torso. This bend stretches the semitendinosus and semimembranosus – the inner hamstring – with better success, so they get worked harder in this position.
The best practice for you is to do both seated leg curls and lying leg curls in your routines from week to week. If your inner hamstring muscles are having trouble growing, we suggest you use the seat leg curl more often.