Collections > Electronic Theses and Dissertations > Changes in lower extremity movement patterns following exercise-induced fatigue and verbal feedback

The present study investigated how exercise-induced fatigue and verbal feedback altered lower extremity coordination, variability, and kinetic variables in male and female athletes. Sixty-one healthy, club level athletes were divided into two groups: one that received a verbal feedback intervention post-fatigue, and one that did not. All subjects performed an unanticipated side-step cut, agility task, and vertical jump pre-fatigue, then completed an intense, intermittent, multi-directional fatigue protocol. Subjects in the feedback group received a quick verbal feedback intervention, focusing on landing technique. All subjects then repeated the pre-fatigue testing. The results indicated that fatigue caused subjects in the non-feedback group to change their coordination pattern in the sagittal plane, while subjects in the feedback group maintained their pre-fatigue pattern in all but one segment pairing (thigh-trunk frontal plane decreased post-fatigue in the feedback group). Fatigue caused all subjects to decrease their variability in the foot-shank and shank-thigh pairings in both the frontal and sagittal plane. Subjects in the non-feedback group also increased their anterior tibial shear force and vertical ground reaction force (VGRF), while the feedback group decreased their VGRF and knee extension moment. Fatigue also decreased vertical jump, and increased the score in the agility task, in both groups post-fatigue. These results suggest that an intermittent, multi-directional fatigue protocol causes a more in-phase, stiffer, less variable movement pattern, but that a simple verbal feedback intervention can prevent many of these changes from occurring. While the implications of these results on actual injury risk are unknown, these changes do suggest that verbal feedback may be an effective method for acutely altering some proposed risk factors for lower extremity injury, particularly anterior cruciate ligament injury. These results also suggest that muscular fatigue may be an important factor to consider when addressing potential injury risk in athletes.