The hamstring muscles are three large muscles at the back of the thigh. They are important in bending the knee and also serve to rotate the leg from side to side.

They are attached to the tibia by certain tendons, called hamstrings, which can be felt near the back of the knee.

Lying Leg Curls directly stress the hamstrings in relative isolation from the remainder of the body. Lie face-down on a leg curl machine with your knees on the pad edge closest to the lever arm of the machine. Hook your heels under the upper set of roller pads and fully straighten your legs. Grasp either the handles provided or the edges of the machine bench to steady your body. Don't allow your hips to come off the padded surface as you perform the exercise. Slowly bend your legs as completely as possible, holding the top position of the movement for a moment to achieve a peak contraction in your hamstrings. Return to the start point.

Place your right foot on a  block positioned next a standing leg curl machine.  The block should be close enough to the machine to provide stability, but not so close as to get in your way. Put your left ankle in front of the roller at the bottom of the machine; your left knee should be just below the support pad on the apparatus. Contract your hamstring muscles by curling your left leg as far as possible, then return to the starting position. Don't use momentum to lift the weight; your lower leg is the only part of the body that should move during this exercise. If you want to work more on the leg biceps peak, point your toes way out behind you and come up all the way to the top. This causes a strong contraction on those hammers; however you'll probably have to decrease the weight because of the purity of the motion. Switch sides; repeat with your other leg.

Stand holding a dumbbell in each each hand. Bring the dumbbells down along the sides of your legs. Bend the knees slightly to reduce the strain on your lower back. Descend until you cannot bend any more without rounding your back. At the bottom, your back must be flat and dumbbells should be just above floor level. Stretch the glutes at the bottom, extend back up, and contract the glutes at the top.

In the classic sumo wrestling stance, i.e. with your feet about 24 or more inches apart, you perform the standard squat exercise. Make it a point to go past parallel during the downward stroke. The exercise is great for adding mass.

The Squat uniquely builds the frontal and rear thigh muscles simultaneously. During the descent, the torso inclines forwards, resulting in a high degree of flexion of the hip joints. On rising the hips must be extended — one of the muscle groups responsible for this is the hamstrings.

• Biceps
• Triceps
• Chest
• Deltoids
• Forearms
• Calves
• Quadriceps
• Glutes
• Lower Back
  
• Abs
• Lats
• Trapezius
• Obliques
• Serratus