Hamstring injuries account for a larger percentage of lost time than any other muscle-tendon injury. Once injured your hamstring is susceptible to have another. The hamstrings: four muscle bellies originate on the pelvis and insert on the lower leg. Functionally, the hamstrings can produce and control a multitude of lower-extremity motions. With the leg in a non-weight bearing position (such as during the swing phase of running), the hamstrings can shorten concentrically to extend the hip or flex the knee, and lengthen eccentrically to control hip flexion or knee extension. Hamstrings also move the pelvis relative to the femur. They can produce a posterior rotation of the pelvis such as when straightening up from a bent over position or control an anterior rotation of the pelvis such as when flexing forward.
Predisposing Injury Factors to an injury include inadequate hamstring strength, reduced flexibility, strength imbalances between the hamstrings and the quadriceps, excessive anterior rotation of the pelvis (which may place excessive eccentric stress on the hamstrings).
The traditional approach to preventing and treating hamstring injuries has been to focus on isolated stretching and isolated concentric strengthening. Traditional hamstring strengthening exercises usually emphasize the function of the hamstrings at the knee such as hamstring curls.
Functional approaches to training focuses on the use of weight-bearing exercises that challenge the hamstrings concentrically and eccentrically. The emphasize is on eccentric exercise. To replicate the function of the hamstrings, and mimic the mechanism of their injury, strengthen them in the position of greatest tension: the hip in forward flexion and the knee in extension.
Pelvic tilt issues need to be addressed. Tightness of the quadriceps and hip flexors contribute to increased anterior pelvic tilt, which places tension on the hamstrings even before the hip begins to flex during walking and running. Hamstrings function predominantly with an eccentric action (control forward hip flexion) which added tension places additional stretch on the hamstrings.
Pelvic tilt is also affected by and contributes to other muscle imbalances: tight latissimus, back extensors, quadratus lumborum, weak abdominals
Exercise Recommendations: Stretching for hip flexors, quadriceps, back extensors to help reduce pelvic rotation and minimize the tension in the hamstrings. Stretch hamstrings only if they are short and tight not long and taut. For reconditioning and rehabilitation include eccentric exercises with hip in flexion and concentric exercises with hip in extension.
These exercises all require the hamstrings to control hip flexion and produce hip extension in weight bearing
Deadlifts: emphasize the hamstrings function of controlling the movement of the pelvis on the femur. Train the muscles to control the anterior rotating pelvis during the lowering phase of the exercise (eccentric) and to create posterior rotating pelvis during the raising phase of the exercise (concentric)
Forward and/or diagonal lunges require hamstrings to control hip flexion and produce hip extension in weight bearing
Two-leg and one-leg squats require hamstrings to control hip extension and produce hip extension in weight bearing. Hamstring curls on a Swiss ball strengthen the knee flexion action in both concentric and eccentric phases. Another method to produce eccentric hamstring retraining is with a cable or band. Attach elastic tubing to a secure point on a wall at hip level, then attach the other end to your ankle, facing the wall in a lunge stance, standing far enough away to place maximum tension on the tubing. Controls the tubing to pull the leg forward, off the ground, into hip flexion and knee extension, using the hamstring muscles to control this action.
Focus retraining on both eccentric and concentric actions of the hamstrings. Add additional load as able to tolerate. Address pelvic rotations and stretch when appropriate.