Publication Date

8-2009

Type of Culminating Activity

Dissertation

Degree Title

Doctor of Education in Curriculum and Instruction

Department

Curriculum, Instruction, and Foundational Studies

Major Advisor

Ron Pfeiffer

Second Advisor

Jonathan Brendefur

Abstract

Context: Females are two to eight times more likely to sustain an ACL injury than males participating in the same sport. The primary mechanism reported for noncontact ACL injury involves landing from a jump, unanticipated change of direction, and/or deceleration activities.

Objective: The purpose of this study was to determine if adolescent female athletes perform athletic activities with decreased hip and knee flexion angles, and decreased EMG activity of the gluteus medius relative to their male counterparts.

Design: Cohort study from local club basketball teams.

Setting: University Laboratory.

Participants: Ten healthy adolescent basketball athletes (5 females, 5 males).

Interventions: Each participant was instructed to jump over a barrier, land with each foot on a floor-mounted force plate, and cut in a specific direction. Participants made a side cut either to the right or left, or stepped forward into a straight run. Each subject performed fifteen (15) randomized jump, land, and unanticipated cutting maneuvers.

Main outcome measures: The peak electromyography (EMG) and ground reaction force (GRF) [normalized with body weight] data were analyzed during the landing for the three cutting directions. Kinematic variables include joint angles for the ankle, knee and hip at landing and push off.

Analysis: Independent samples t-tests examined differences between the genders for dependent variables.

Results: No differences were noted for the left or right EMG amplitudes or muscle onsets. The joint angle in the left ankle (p = 0.019) during peak knee flexion of the left cut demonstrated the females performed tasks with greater dorsiflexion angles than males. However, during the peak GRF of the center cut in the right ankle (p = 0.012) males had greater dorsiflexion. The male participants sustained greater anterior forces in the left leg during the peak knee flexion angle (p = 0.022) and push off (p = 0.040) during the left cut. The male participants sustained lateral forces and female participants sustained medial forces (p = 0.010) during the center cut. The female participants sustained greater anterior forces in the right leg than the males (p = 0.041) during the peak knee flexion angles, and that females sustained anterior forces, while the male’s sustained posterior forces (p = 0.009) in the right leg during peak GRF. The male participants sustained greater medial forces during the peak knee flexion angles (p = 0.031) compared to the female participants.

Clinical relevance: This study may advance our understanding of potential forces and muscle activation strategies about the ankle, knee, and hip during sport specific activities as our findings suggest women might sustain different forces during landing and cutting. Even though we did not find statistical differences in the muscle activation strategies when comparing gender, further analysis could reveal muscular imbalances or muscle training issues between the genders. The females in this population were athletically trained and participated in training outside of their sport, which could decrease the gender effects seen in other studies. Additionally, this study could provide support for the screening of hip strength during the pre-participation physical examination and the education and creation of targeted exercise intervention programs designed to reduce the risk of non-contact ACL injuries.

Keywords: anterior cruciate ligament; kinematics; kinetics; knee; basketball athletes; gender-differences; hip

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