Technique
- Stand in front of a standing leg curl machine. Grasp the machine handgrips or upright supports and place your chest (or hips and thigh, depending on the machine) against the stationary support pads.
- Adjust the resistance lever to fit your leg length and place the back of your ankle against the padded resistance roller.
- Rest the front of your thigh against the front support pad to stabilize the upper leg but keep your knee free to bend. Hold the support leg straight but not locked in the knee and your support foot in full contact with the floor. Keep the foot of the exercise leg extended and relaxed.
- Inhale slightly more than usual and hold your breath as you bend the knee to raise your foot against the resistance roller until the shin is above horizontal.
- Hold the up position momentarily and then exhale and lower the shin to the initial position. Pause for a moment and then repeat.
- Keep your torso erect or inclined forward against the support pad throughout execution.
- When you complete the necessary number of repetitions with one leg, switch legs and repeat. Performance
- Do not use an excessive amount of weight as it may force you to jerk the beginning movement in order to overcome resting inertia. In so doing, you may pull or injure your hip or lower back muscles or tendons.
- Be sure to raise the resistance lever so that your shin is above level. Going much beyond a level position is not needed as the effective resistance decreases as the foot approaches the buttocks.
- Depending upon the machine and size of the resistance roller, it is important that you start with the roller in a position where it will not roll off (or in some cases roll up) the shin when you reach the end position. This often occurs when the axis of rotation of the machine does not line up with your knee joint or the thigh is free to move.
- Maintain a stable body position as you execute the movement. Pulling with the grips ensures that your upper body remains in place or in a strong position while you execute the knee bend.
- For maximum tension on the hamstrings, point your toes as you do the curling movement. If you keep the ankle flexed so that the toes remain up, you will make the gastrocnemius taut so that it becomes more strongly involved in flexing the knee.
To increase the effectiveness of the exercise, lean the trunk forward from the hips as much as the machine will allow. Doing this makes the upper hamstrings more taut (places them on stretch) allowing for a stronger contraction at the knee joint. Do not start the movement with a powerful action. When your weight is on one leg your pelvic girdle is displaced slightly and the normal curvature of the spine is somewhat skewed. Because of this the hips and lower back become more prone to injury if there is any strong, quick movement that overstresses your abilities.
PRIMARY MUSCLES INVOLVED
The hamstrings, a group of three muscles, which attach to the pelvic girdle at the upper end and the shinbones at the lower end. Of the three muscles, the biceps femoris is the largest; it has two heads and the most muscle mass. It is located on the outer side of the posterior thigh. The other two muscles, the semitendinosus and semimembranosus are relatively long and thin and are located on the inner side of the posterior thigh. Their muscle mass is relatively high on the thigh. In the standing leg curl, all three muscles are involved, but the major role is played by the biceps femoris. The gastrocnemius (calf) muscle assists the hamstrings specifically when the resistance is great and the foot is dorsoflexed.
MUSCLE/JOINT ACTIONS
The hamstrings and to a limited extent the gastrocnemius muscle, perform knee joint flexion. In this action, the back of the lower leg (shin) moves toward the posterior thigh, which remains stationary.
SPORTS USES
In fitness, the standing leg curl is important for increasing muscle mass of the posterior thigh. One of the greatest values of the leg curl is strengthening and stabilizing the knee joint. The hamstrings provide lateral stability to the knee and help balance the strength of the quadriceps muscle located on the front of the thigh that acts in knee joint extension. The strength of the quadriceps however is always greater than that of the hamstrings by a three or four to one ratio. In sports this exercise is important for athletes who are involved in running and kicking. But, because the standing leg-curl exercise does not strengthen the upper hamstring muscle-tendon junction as in the good morning or deadlift, it plays a relatively minor role in most sports that require hip joint extension. The hamstrings play a role in knee joint flexion as needed in back kicks in soccer, in various wrestling movements and in execution of different stunts on the high bar and unevens in gymnastics. Acrobats use knee flexion when hanging from their knees on the trapeze or horizontal bar.