HAMSTRING INJURIES IN TEAM SPORTS
A stretch or tear of one of the three large muscles of the back of the thigh comprising the hamstring muscle group (biceps, semimembranosus, and semitendinosus) typically occurs when these muscles are contracting forcefully during the sprinting or jumping action. Some studies indicate the injury is also more likely to occur in sprinters and other athletes as they run the curves on a 400-meter track.
Athletes experience a burning or popping sensation followed by pain when walking, jogging, bending or strengthening the leg. Bruising may also be noticeable below the injured site in 2-3 days. Hamstring injuries generally occur at the proximal myotendinous junction. In the biceps femoris muscle, this junction extends over most of its entire length. Injury rarely occurs within the tendon itself.
• Grade 1 is a mild strain, with few muscle fibers being torn.
• Grade 2 is a moderate strain, with a definite loss in strength.
• Grade 3 is a complete tear of the hamstrings.
An avulsion strain is rare, but much more serious and occurs when the tendon tears pulling a small part of the bone away with it. This is more common in younger athletes (14-18 year olds) who may have had a history of chronic hamstring tendinitis. If a young athlete complains of severe hamstring pain at the point of origin, avulsion strain should be suspected until it is ruled out by an X-ray or bone scan. Treatment of a severe case will require surgery.
In young athletes in the developmental stage, risk factors include inadequate warm-up, failure to use proper techniques of dynamic stretching immediately after the general warm-up period, muscle tightness, muscle imbalance (low hamstring to quadriceps ratio), incorrect muscle timing (muscle groups firing in the wrong order), muscle fatigue, and over training. Studies also show that the flexibility of the hamstrings and the eccentric and concentric muscle torque in the hamstrings and quadriceps muscles at different angular velocities are a factor. Sprinters who suffered a previous hamstring injury have significantly tighter hamstrings than uninjured sprinters. Uninjured sprinters had significantly higher eccentric hamstring torques at all angular velocities and higher concentric quadriceps and hamstring torques at 30 deg/sec but not at higher velocities. Sprinters with a history of hamstring injury have been found to be weaker in eccentric contractions and in concentric contractions at low velocities.
The exact cause of hamstring strains is still unknown and cannot be attributed to any single factor. One area of concern in team sports has been the belief that the common strength disparity between hip extensor and hip flexor muscles may play a role. Some coaches have even recommended a 1:1 ratio between the hamstrings and quadriceps although most have their athletes strive for hamstrings strength development to approximately 75-80 per cent of the quadriceps. Injuries are more likely a result of a multi factorial group of risk factors. Sprinting is a complicated, demanding skill that places supra-maximal loads on the hamstring muscle group. In fact studies show that the hamstrings may be the most active muscles during the sprinting gait cycle. During the forward leg swing phase, the hamstring activity increases. Once the terminal stage of the forward swing phase is complete, muscle activity continues to remain high as the hamstrings concentrically contract to extend the hip and flex the knee. Greater speeds of running have been found to be associated with longer periods of hamstring activity during the support phase. Researchers believe that this further validates the role of the hamstrings as hip extensors during the stance phase of running and sprinting.
Proper treatment calls for 2-3 days of ice packs for 20-30 minutes every 3-4 hours, elevating the leg with a pillow when resting, use of compression by wrapping the thigh with an elastic bandage, use of anti-inflammatory medication prescribed by a physician, and use of crutches until you can walk pain free.
Athletes return to their sport and workouts after full range of motion and full strength returns without pain, linear jogging and sprinting occur without pain, 45 degree cuts can be completed without pain, and jumping on the injured leg can take place without pain.
Rehabilitation exercises used both during the recovery and as preventive movements following recovery recommended by Pierre Rouzier, MD (The Sports Medicine Patient Advisor, ©2004) include the following:
Prone Leg Bends–Lie on your stomach with legs flat on the floor. Bend your knee and bring the heel toward your buttocks, then back down to the starting position. Complete 2-3 sets of 10 repetitions.
Standing Hamstring Stretch–From a standing position, place the heel of the injured leg on a chair approximately 15” high. Bend at the hips and lean forward to produce an easy stretch at the back of the thigh. Hold the stretch for 30-60 seconds, repeat 3 times.
Hamstring Stretch on the Wall–Lie on your back with the buttocks near a doorway and legs extended through the doorway. Raise the injured leg and rest the heel against the door frame. Hold the stretch you feel in the back of your thigh for 30-60 seconds, repeat 3 times.
Standing Calf Stretch–Place both hands on a wall at chest level. Place the injured leg 12-18” behind the front leg. Keep the injured leg straight and the heel flat on the floor as you lean into the wall. Bend the front knee until you feel an mild stretch in the back of the calf muscle of the injured leg. Hold for 30-60 seconds, repeat 3 sets.
Prevention involves use of a 15-25 minute general warm-up followed by dynamic stretching before each workout. Static stretching of the hamstring muscle group occurs at the close of each workout or practice session to increase range of motion.