Sex differences in trunk, pelvis, hip and knee kinematics and eccentric hip torque in adolescents

• Sex differences exist in the kinematics of the single-leg squat task in adolescents.
• Adolescent males perform this task using greater trunk flexion than females.
• Adolescent females squat with greater hip adduction and lateral rotation than males.
• Adolescent females also have greater knee abduction during this task than males.
• Lastly adolescent females have impaired hip eccentric torque when compared to males.

BackgroundAdolescents have a high incidence of knee joint dysfunctions, with up to 28% of adolescents reporting knee pain. Although adolescent females have a greater incidence of knee injuries in comparison to males, few studies conducted biomechanical evaluations in this population aiming to identify sex differences. If trunk and/or lower limb biomechanical impairments are identified in female adolescents, the implementation of early interventions for injury prevention will be better justified. The purpose of this study was to compare the trunk, pelvis, hip and knee kinematics during a single-leg squat task, as well as the isokinetic eccentric hip torque, between male and female healthy adolescents.MethodsForty-four healthy adolescents were divided into two groups, group of males (n = 22) and group of females (n = 22). Kinematics during single-leg squat were assessed using a electromagnetic tracking system. For the evaluation of eccentric hip torque in the three planes an isokinetic dynamometer was used. Group differences were assessed using a one-way multivariate analysis of variance.FindingsResults showed that adolescent females presented greater hip adduction, hip external rotation and knee abduction, as well as smaller trunk flexion during single-leg squat in comparison to males. Additionally, adolescent females showed smaller isokinetic eccentric hip torque normalized by body mass in all planes in comparison to males.InterpretationThese sex differences in terms of trunk/lower limb kinematics and eccentric hip torque generation might play an important role in the greater incidence of overuse knee injuries observed in adolescent females.