Background: Wireless accelerometers provide a method of performing running assessments in sports-specific environments. The purpose of this study was to investigate differences in running movement using centre of mass acceleration-derived variables between runners of varying skill levels and examine fatigue-related changes during a long distance over ground run. Methods: Ninety-two runners performed a self-selected paced long distance over ground run, with a tri-axial accelerometer attached to their low back. Runners were divided into four groups (elite, advanced, intermediate and slow) based on their finishing run time. Spatiotemporal (contact time, flight time, step frequency), dynamic postural stability (ratio of root mean square of accelerations), dynamic loading (peak impact and braking accelerations) and variability (step and stride regularity), were derived from acceleration data. Speed and acceleration-derived variables were used to investigate between group differences and within group fatigue-related changes. Results: Faster runners (elite and advanced groups) exhibited significantly shorter contact times and higher step frequencies than the slow group. Fatigue-related changes throughout the run were only observed amongst the slower runners (intermediate and slow groups). The main changes in the intermediate group were an increase in ratio of root mean square in mediolateral acceleration, and a decrease in speed in the slow group. Conclusion: The shorter contact times and higher step frequencies and no fatigue-related changes exhibited by the faster runners indicate an efficient running movement pattern. Fatigue-related changes in the slower runners were a decrease in postural dynamic stability in mediolateral direction in the intermediate group and a decrease in speed in the slow group which impacted on performance. These runners would benefit from exercise interventions and pacing strategies to reduce these fatigue-related changes and improve performance.
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