Hamstring injuries are common among runners. The hamstring muscles run down the back of the leg from the pelvis to the lower leg bones, and an injury can range from minor strains to total rupture of the muscle. The three muscles that make up the hamstrings are the biceps femoris, semitendinosus and semimembranosus. A hamstring injury is recognized by a sudden, sharp pain in the back of the thigh that may stop you mid-stride. After such an injury, the knee may not extend more than 30 to 40 degrees short of straight without intense pain.

Sprains and strains are caused by excessive stretching (tearing) of muscle fibers soft tissues. Hamstring strains are classified as 1st (mild), 2nd(moderate), or 3rd (severe) degree strains depending on the severity.

Common Causes of Hamstring Injuries

Some of the more common reasons for hamstring injuries are:

    * Doing too much, too soon or pushing beyond your limits.
    * Poor flexibility.
    * Poor muscle strength.
    * Muscle imbalance between the quadriceps and hamstring muscle groups.
    * Muscle fatigue that leads to over exertion
    * Leg Length Differences. A shorter leg may have tighter hamstrings which are more likely to pull.
    * Improper or no warm-up.
    * History of hamstring injury.

Treatment

Treatment may depend upon the severity of the injury, with third degree strains requiring a doctor's evaluation. In general the following tips are used for most muscle strains.

    * After an injury it's important to rest the injured muscle, sometimes for up to two or three weeks.
    * RICE - Rest, apply Ice and Compression. Elevate the leg if possible.
    * An anti-inflammatory can be helpful to reduce pain and inflammation.
    * A stretching program can be started as soon as the pain and swelling subsides.
    * A strengthening program should be used to rebuild the strength of the injured muscle in order to prevent
       re-injury. Make sure you increase this gradually.
    * A thigh wrap can be applied to provide support as the muscle heals.

Prevention

    * Warm up thoroughly. This is probably the most important muscle to warm-up and stretch before a
       workout.
    * Stretching after the workout may be helpful.
    * Try adding a couple sessions per week of retro-running or backward running which has been should
       decrease knee pain and hamstring injuries.
    * Follow the "Ten Percent Rule" and limit training increases in volume or distance to no more than ten
       percent per week.
    * Other ways to prevent injury are to avoid doing too much, too soon, avoid drastic increases in intensity
       or duration, and take it easy if you are fatigued.