Increasing Hamstring Flexibility Decreases Lower Extremity Overuse Injuries

A recent study found that regular hamstring stretching helps to significantly decrease the number of overuse injuries that occur with physical training.(1)  Two different companies of military infantrymen going through a 13 week basic training program were used.  One group went through the normal basic training course, which included stretching before physical training in the morning, including hamstring stretching.  The other group added three hamstring stretching sessions per day.  The number of lower extremity overuse injuries was significantly lower in the stretching group (25 injuries compared to 43 injuries in the non-stretching, control group).  Both groups had approximately 150 men.

The hamstring stretch used involved having a partner help.  The trainees face each other and the heel of the leg to be stretched was held so that the hip was at 90 degrees of flexion.  The subject then bent his body forwards while maintaining an anterior tilt of the pelvis, keeping the back straight, until a stretch was felt in the hamstring muscle.  Each stretch was held for 30 seconds and repeated five times in each stretching session.  Stretching was done three times per day, in addition to the stretching included in the morning workout. The group that did the additional hamstring stretching increased their hamstring flexibility an average of 7 degrees compared to an increase of 3 degrees in the other group.

While it is often accepted that stretching can help reduce injuries, there has been little data to back this up. This study found that stretching the hamstrings four times per day resulted in a significant increase in hamstring flexibility and a significant decrease in lower extremity injuries.  Thus, stretching can help to prevent injuries, but only if it is done properly and frequently throughout the day.



1. Hartig DE, Henderson JM. Increasing hamstring flexibility decreases lower extremity overuse injuries in military basic trainees. The Am J of Sp Med. 1999; 27: 173-176.