LE3 .A278 2014

2014

Landry, Scott

Acadia University

Bachelor of Science

Honours

Biology

Biology

Females have a 3-9 times greater risk of sustaining a non-contact ACL injury in sport, compared to males after puberty. The increased occurrence of ACL injuries in females may be influenced by muscle activation patterns that are not yet fully understood. This study set out to identify if gender and leg dominance differences existed in male and female soccer players, under the age of 12 years. Muscle activation patterns during the stance phase of 45o side-cut maneuvers were analyzed under unanticipated conditions to closely emulate a true game-like scenario where non-contact ACL injuries most likely occur. Nine male and nine female youth soccer players had muscle activity measured for the following muscles: lateral and medial gastrocnemii, lateral and medial hamstrings, and vastus lateralis and medialis. Mean muscle activation waveforms during the stance phase of the cutting stride were amplitude normalized to a series of maximal voluntary isometric contractions. Principal component analysis was performed on the individual mean waveforms of each athlete, capturing differences in overall magnitudes and phase shifts. A two-way mixed model ANOVA was used to test for the presence of gender, leg, or interaction effects. Significant findings (p < 0.05) included: i) males and females displaying greater activation magnitudes in the medial gastrocnemius of their non-dominant leg and ii) males displaying greater activation magnitudes in the vastus medialis. Generally, it has been reported that female collegiate athletes display greater activation magnitudes in the vastii muscles, potentially putting them at greater risk of sustaining an ACL injury. In the younger population of athletes tested in this study, this finding was not supported, and therefore, suggesting that different muscle activation strategies may be occurring prior to the onset of puberty. Further investigations analyzing gender and leg dominance differences could provide more of an insight into the mechanisms behind non-contact ACL injuries and could help in the prevention of these devastating injuries.

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https://scholar.acadiau.ca/islandora/object/theses:1134