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Women Roll and Glide with the Noncontact Punches

Doctors, sports trainers, and physical therapists are scratching their heads about something. Women are up to eight times more likely to injure the anterior cruciate ligament (ACL) of the knee in the same athletic activities as men.

Even more puzzling is the fact that these injuries are more likely to occur without contact with any other player. Researchers have found some possible risk factors. They include hormones, knee angle, and joint laxity. Muscle strength, knee stiffness, and type of sports may also make a difference.

Physical therapists are teaming up to explain this problem. This study looks at differences in knee joint rolling and gliding between men and women. Rolling occurs when both sides of the joint move against each other. Gliding occurs when only one side of the joint moves on the surface of the other.

These researchers also measured muscle activity and compared women to men. The quadriceps muscle along the front of the thigh and the hamstrings muscle at the back of the thigh were the two key muscles studied.

The authors report a difference in rolling and gliding between men and women. Men tend to roll at the very end of extension (straightening the knee). Women roll and glide throughout the motion. The amount of rolling and gliding is the same whether the foot is planted firmly on the ground or lifted off the ground. Greater rolling and gliding means more joint surface is involved. With more joint surface motion comes more strain on the ACL. This increases the risk of injury.

Differences in muscle activity between men and women weren't noticeable. Men tended to use the hamstrings more when extending the knee. The authors conclude that the way the joint moves with increased joint surface gliding may put greater strain on the ACL in women. Less hamstring activity at the same time may add to the risk of noncontact injury.

References: John H. Hollman, PhD, PT, et al. Gender Differences in Surface Rolling and Gliding Kinematics of the Knee. In Clinical Orthopaedics and Related Research. August 2003. Vol. 413. Pp. 208-221.

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