Leg curls are the most common, and effective, hamstring exercise. Leg curl machines isolate, and develop, the hamstring and gluteal muscles. When done properly, this strength training exercise can show results in as little as two weeks. There are three types of leg curl exercises: lever lying, seated and standing.
Lever lying leg curl, or prone, exercise machines are found in most gyms, and consist of a decline bench with weights attached. To perform leg curls on this type of machine, the user lies face down on the bench and grasps the hand grips. The user lines his knees up with the rotating cam on the machine and presses his ankles against the pads. Keeping his hips pressed against the bench, he curls his legs upward, pauses, then lowers his legs back down to the starting position. Using momentum to swing the weight upwards won't produce results and may cause lower back injury.
Seated leg curls are recommended for people with lower back problems. Before performing this exercise, the user must adjust the machine to fit his height. This is done by pulling the lever and moving the back of seat until his knees are lined up with the bottom of the chair pad. He then places his legs on the ankle pad and engages his abs, bringing his heels towards his hips. To complete the leg curl, he extends his legs slowly until he reaches his starting position.
Standing leg curls are performed on a machine that isolates the individual legs, allowing for even development of the hamstring muscles. The user must first adjust the weights to be lifted, then he stands on the non-slip platform and places the leg to be lifted on the underside of the lifting bar. Gripping the upper handles, the user exhales and lifts the bar toward his buttocks with the chosen leg. Upon completion of the leg curl, the user slowly returns the leg to the starting position.
Leg curl exercises are only beneficial to the user when done correctly. If the strength training exercise can't be performed without hyper-extending the back, lessen the amount of weight being lifted. Before performing the leg curl exercise, warm up your muscles with, at least, twenty minutes of cardio exercise. Possible injuries of this exercise include muscle strains, muscle tears, hip and knee injuries and joint pain. Before beginning any weight training exercise, it is recommended to seek the assistance of a personal trainer.