Upper Trunk-Pelvis Coordination During Running Using the Continuous Relative Fourier Phase Method

The upper trunk-pelvic coordination patterns used in running are not well understood. The purposes of this study are to (1) test the running speed effect on the upper trunk-pelvis axial rotation coordination and (2) present a step-by-step guide of the relative Fourier phase algorithm, as well as some further issues to consider. A total of 20 healthy young adults were tested under 3 treadmill running speeds using a 3-dimensional motion capture system. The upper trunk and pelvic segmental angles in axial rotation were calculated, and the coordination was quantified using the relative Fourier phase method. Results of multilevel modeling indicated that running speed did not significantly contribute to the changes in coordination in a linear pattern. A qualitative template analysis suggested that participants displayed different change patterns of coordination as running speed increased. Participants did not significantly change the upper trunk and pelvis coordination mode in a linear pattern at higher running speeds, possibly because they employed different motion strategies to achieve higher running speeds and thus displayed large interparticipant variations. For most of our runners, running at a speed deviated from the preferred speed could alter the upper trunk-pelvis coordination. Future studies are still needed to better understand the influence of altered coordination on running performance and injuries.