Date of Paper/Work


Type of Paper/Work

Research Project

Degree Name

Doctor of Physical Therapy (DPT)


Physical Therapy

First Advisor

Jaynie Bjornaraa


BACKGROUND AND PURPOSE: Injuries to the anterior cruciate ligament (ACL) are common among athletes, particularly females. This research aims to reconcile the anticipated and unanticipated movement pattern of jumping and cutting with fatigue for both genders. The research will compare lower extremity biomechanics of a jump-cut after a sports specific fatigue protocol, intending to examine movement patterns which may predispose the subject to ACL injury. METHODS: Twenty healthy subjects were studied (24.9±3.3yrs), including 10 females. A 3D electromagnetic system measured knee kinematics and kinetics during jump-cut tasks. The jump-cut task included anticipated (A) and unanticipated (UA) trials to both directions. For the UA trials, the subject was unaware of the cutting direction until initiation of the task. The fatigue protocol consisted of jumping, sprinting, step-ups, and agility. Subjects completed the jump-cut task again in a fatigued state. A repeated measures ANOVA was used to analyze peak and mean angles, moments and ground reaction forces (GRF), with post-hoc Tukey tests for significant findings between factors (gender, pre/post-fatigue, A/UA). RESULTS: Significant main effects were found for gender and IR/ER and ADD/ABD peak and/or mean angles, and ADD/ABD moments; pre and post-fatigue and IR/ER, EXT/FLEX, and ADD/ABD peak and/or mean angles, and ADD/ABD moments; A/UA conditions and IR/ER and ADD/ABD peak and/or mean angles. Significant interactions existed for gender and A/UA for EXT moment and for pre/post-fatigue and A/UA for EXT moment, IR moment and IR/ER angles.

CONCLUSION: Subjects demonstrated significant changes in knee kinematics and kinetics. Fatigue and A/UA states influenced knee movement patterns in variable ways, which may indicate an attempt to safely land and cut. Additionally, females demonstrated biomechanics that may increase their risk for ACL injury relative to males. Gender, fatigue, and A/UA conditions had an impact on one another and should be considered when designing sports training programs to reduce risky movement patterns.