Washington:The significant differences in the knee alignment and muscle activation that exist between men and women also translate into the way they play soccer, says a new study. Data reveals that males activate certain hip and leg muscles more than females during
the motion of the instep and side-foot kicks - the most common soccer kicks -
which may help explain why female players are more than twice as likely as males
to sustain an Anterior Cruciate Ligament (ACL) injury. "By analyzing the detailed
motion of a soccer kick in progress, our goal was to home in on some of the differences
between the sexes and how they may relate to injury risk," said orthopaedic surgeon
Robert H. Brophy. "This study offers more information to help us better understand
the differences between male and female athletes, particularly soccer players,"
he added. Using eight to 10 video cameras, 21 retroreflective markers and 16 electrodes
simultaneously, researchers measured the activation of seven muscles (iliacus,
gluteus maximus, gluteus medius, vastus lateralis, vastus medialis, hamstrings
and gastrocnemius) in both the kicking and supporting legs; as well as two additional
muscles (hip adductors and tibialis anterior) in the kicking leg only. Male players
activate the hip flexors (inside of the hip) in their kicking leg and the hip
abductors (outside of the hip) in their supporting leg more than females. In the
kicking leg, men generated almost four times as much hip flexor activation as
females. "Activation of the hip abductors may help protect players against ACL
injury," said Brophy. "Since females have less activation of the hip abductors,
their hips tend to collapse into adduction during the kick, which can increase
the load on the knee joint in the supporting leg, and potentially put it at greater
risk for injury," he said. Brophy said that although the study does not establish
a direct cause-and-effect relationship between muscle activation and knee alignment
and ACL injuries, the data "moves us toward better understanding of what may contribute
to differences in injury risk between the sexes and what steps we might take to
offset this increased risk in females." The study is published this month in the
Journal of Bone and Joint Surgery.
