With the exception of the short biceps femoris muscles in all muscle groups are responsible for bending the knee. The hamstrings are often underdeveloped relative to its opposing muscle group – the quadriceps. The result of muscle imbalance often seen when you run a sprint race of 100 meters. When a voltage, the athlete clutch back and hamstrings. The injury is a consequence of hamstring underdeveloped not withstand the power generated by the quadriceps. You must train the hamstrings directly to prevent these imbalances. It is best done by squatting and movements of hip extension.

Video:

Instruction:

1. Lie on your stomach, knees slightly put off the bench. The stuffing should be placed just above the ankle.
2. Exhale, keep your feet and legs had to curl the bottom at a controlled rate. Pointing reduces stretching of the calf and makes it less effective in helping to bending the knee. This will help isolate the hamstrings.
3. Inhale and slowly lower to a stop just below the extension of the leg. It is important to control his weight and does not allow weight plates touch. If the plates are in contact, are exempt from hamstring strength and control of the game will be less effective.
4. Repeat until you complete the desired number of repetitions.

Variation:
Stressing the toes towards the knees build additional recruitment of calves which helps make movement easier. This can actually be used in two ways.

1. Once the failure is reached with the peak position of the anchor may be changed and additional recruitment of the calf will help to get more reps.
2. The muscles are naturally stronger during the eccentric phase of contraction. The eccentric phase refers to the stage at which the muscle is stretched. Example: the descending phase of a bicep curl. An advanced student can adapt the principle of variable resistance, alternating the standing position. This can be obtained by selecting a slightly heavier weight and do the curling motion with the fingers pointing toward your knees and down to the toes.