LE3 .A278 2016

2016

Landry, Scott

Acadia University

Bachelor of Kinesiology

Honours

Kinesiology

Kinesiology

Anterior cruciate ligament (ACL) injuries are one of the most common knee injuries sustained in sport. The ACL functions to passively resist anterior tibial translation on the femur and to stabilize the knee during internal/external and varus/vagus moments. The quadriceps, hamstrings and gastrocnemii actively support the knee joint during movement. Non-contact ACL injuries, classified as injuries that are not sustained by a direct blow to the knee, account for upwards of 70% of all ACL injuries. Moreover, females are 2-8 times more likely to sustain a non-contact ACL injury compared to males after the onset of puberty. Identification of risk factors that contribute to non-contact ACL injuries are imperative to mitigate the devastating effects of this injury through effective injury prevention and rehabilitation programs. The purpose of this study was to examine the effect of sex (male versus female) and age (early versus post-pubescence) on gluteus medius activation patterns and hip joint biomechanics during double leg drop jump landings , a maneuver that puts athletes at risk of ACL injury. A comprehensive protocol has been developed within the John MacIntyre motion Laboratory of Applied Biomechanics (mLAB), enabling longitudinal data to be collected for the purpose of identifying non-contact ACL injury risk factors. Biomechanical and muscle activation patterns proximal to the knee joint influence kinematics and kinetics directly at the knee joint due to the kinetic-chain nature of the lower extremities. Specifically, hip internal rotation and adduction (primary movements controlled by the gluteus medius) contribute to knee valgus, found to be a risk factor for ACL injuries. Elite level court and field athletes (males n=10, females n=10) participated in the present study and they were recruited from Acadia University varsity programs and local youth sport organizations. Of the males, 5 were categorized as early pubescent (young) (age=11.6 yr ±0.9, height=154.1 cm ±12.3, weight = 42.5 kg ±7.2) and 5 categorized as post-pubescent (old) (age = 20.8 yr ±1.5, height = 179.4 cm ±7.4, weight = 78.2kg ±8.4). Similarly, 5 females were categorized as early pubescent (young) (age = 10.8yr ± 0.8, height = 150.7cm ±5.5, weight = 38.3 kg ±6.1) and post-pubescent (old) (age = 19.6yr± 2.3, height = 169.2cm ±6.0, weight = 63.8 kg ±6.8). A double leg drop jump protocol was used to analyze gluteus medius activation patterns, hip joint angles and hip joint moments using 16 wireless electromyography electrodes, a 12-camera motion capture system and 3 force platforms. A 2-way between subjects ANOVA was used to test for age (early pubescent versus post-pubescent) and sex (male versus female) effects. Multiple Bonferroni corrected pairwise comparisons were performed on the data when an interaction effect was identified for a particular measure. The findings were that female athletes, particularly post-pubescent females, demonstrated enhanced gluteus medius activation levels in combination with altered hip joint biomechanics that might put this particularly small group of females at reduced risk of injury compared to their male counterparts. This preliminary study was successful in developing a comprehensive testing and data analysis protocol that will continue to be used within Acadia’s John MacIntyre mLAB for a long term follow-up study focused on investigating the mechanisms or risk factors of non-contact ACL injuries in athletes.

The author retains copyright in this thesis. Any substantial copying or any other actions that exceed fair dealing or other exceptions in the Copyright Act require the permission of the author.

https://scholar.acadiau.ca/islandora/object/theses:1451