A biomechanical analysis of sex and age's effect on the squat and lunge exercises
LE3 .A278 2023
Bachelor of Kinesiology
With the growing base of research concerning mechanisms of anterior cruciate ligament (ACL) and knee injuries in post-pubertal female athletes, little research has investigated the suitability of common therapeutic exercises. Many injury-causing exercises are performed at a high intensity or velocity, a frequently cited mechanism within these is the valgus collapse or dynamic knee valgus (DKV). Rehabilitative or preventative programs employ lower-intensity movements to re-train or prevent this risk-inducing maneuver, with the squat and lunge being staple exercises in these programs. It was hypothesized that females would demonstrate higher degrees of hip adduction and range of motion (ROM) and higher hip abduction maximum and mean internal moments, as well as knee maximum and mean internal adduction moments throughout both the lunge and squat. Age was hypothesized to have the same effect as sex, where older groups would exhibit the same proposed risk-inducing traits of females. A group of 90 participants from a longitudinal ACL injury research study were tracked performing both the squat and lunge using motion capture and force plate data. Frontal and sagittal plane joint angles and internal moments of the hip and knee joints were tracked and analyzed. Where the sex and age of an athlete are seen to impact knee injury rates, a two-way analysis of variance model was used, comparing sex (male and female) and age (young and old). Two notable sex effects were found, being the decrease in hip joint ROM (p=.014) and the increase in abduction internal moment (p=.015) experienced by females during the squat. Numerous age effects were found, causing an increase in frontal plane hip joint angle ROM in the squat (p=.032), but a decrease in the lunge (p<.001) for the old group. Age effects in internal joint moments showed increases in maximum abduction (p=.014) and mean (p=.046) hip joint frontal plane moment in the lunge in both older groups. An interaction effect was found for both with maximum knee extension and mean knee extension internal moments during the lunge, with younger males demonstrating a smaller maximum (p<.001) and mean (p<.001) moment than their older counterparts. Though some significance reflects the hypothesized increase of proposed injury-inducing traits of females and older individuals as seen in high-intensity movements, primarily only age effects were present. Though the significance of the results is largely inconclusive, the present effect of age increasing lower limb biomechanics leading to DKV is a consideration to be taken in the prescription and administration of the squat and lunge.
The author grants permission to the University Librarian at Acadia University to reproduce, loan or distribute copies of my thesis in microform, paper or electronic formats on a non-profit basis. The author retains the copyright of the thesis.