Bio-mechanical differences between adolescent male and female soccer players result in greater risk of serious knee injury.

Studies show girls who play soccer are anywhere from 2 to 8 times more likely than boys to suffer a non-contact tear to their Anterior Cruciate Ligament (ACL) while participating in their sport¹.  The injuries usually occur when the athletes make a sudden change in direction or while landing after jumping².  The greater risk-factors can, in great part, be attributed to the way hip and knee flexion, internal knee rotation and activation levels of the quadriceps and hamstring muscles interact in girls vs. boys.

A study conducted at Dalhousie University and published in the American Journal of Sports Medicine tested 42 healthy adolescent soccer players for bio-mechanical differences.  The participants were asked to perform a series of sports maneuvers including:  A straight run, a side cut following a straight run, and a cut across the body after a straight run. 

The results of the tests demonstrate bio-mechanical differences do exist between young male and female athletes.  Female athletes have greater muscle activation magnitudes in their gastrocnemius (upper calf muscle) and Rectus Femoris (one of the

quadricep’s muscles) muscles and a reduced hip flexion angle during cutting movements compared to their male counter parts.  However, hamstring activation magnitudes were shown to be about the same. The study also found differences in the joint movements including hip adduction, hip internal rotation, knee adduction, and ankle eversion during the first 20% of the cutting movement, the time when most ACL injuries occur².

Because of these differences, special care should be taken when designing strength training programs for young female athletes to avoid further increasing the magnitude of muscle activation in girls' quadriceps. Steps also should be taken to increase the magnitude of the hamstring muscles to help narrow the ratio between the two.  Attention should also be paid to lateral stability of the hip, knee and ankle to lessen the impact of hip rotation, knee inversion/eversion, and ankle flexion.  Finally, it is important to teach proper landing and cutting techniques to girls as they relate to their sports.  By paying attention to these details, based on the data in this study, you may be able to help reduce the risk of serious knee injuries in your young female soccer players.

Tom Dueber is the founding partner and a strength and conditioning coach specializing in programs for adolescent athletes at Canyon Performance Training.

Scott C. Landry, Kelly A. McKean,et al. Neuromuscular and Lower Limb Biomechanical Differences Exist Between Male and Female Elite Adolescent Soccer Players During an Unanticipated Side-cut Maneuver: Am J Sports Med. 2007; 35

1. Agel J, Arendt EA, Bershadsky B. Anterior cruciate ligament injury in national collegiate athletic association basketball and soccer: a 13-

year review. Am J Sports Med. 2005;33:524-530.

2. Boden BP, Dean GS, Feagin JA Jr, Garrett WE Jr. Mechanisms of anterior cruciate ligament injury. Orthopedics. 2000;23:573-578.