Three-dimensional kinematics of the thorax during over-ground running

Background: Given the size and mass of the thoracic segment, understanding its neuromotor control demand during over ground running at different speeds is important in the rehabilitation and research setting. This study describes key kinematics characteristics as proxy measures for thoracic neuromotor control. We hypothesized that thoracic kinematics would differ significantly when running at different running speeds and that speed related thoracic kinematic changes would not differ between gender. Methods: Three-dimensional thoracic kinematics of 19 healthy runners were recorded using an optical 3D motion capture system. We compared peak kinematic angles and range of motion of the thorax in each anatomical plane, in three running speeds during the stance phase. The Wilcoxon Signed Rank Test was used to analyse thoracic kinematics differences across different speeds. Results: There was increased group peak kinematic angles and total range of motion during slower and faster than self-selected pace compared to self-selected pace in all three planes. There were gender differences in the changes in kinematic measures at different running speeds. Conclusion: Our findings suggest that the differences in thoracic kinematics as a result of non-self-selected running speed may be due either to the increased neuromotor demands inherent to that running speed or due to the individual's adjustment to running at an unfamiliar speed. Further investigation is required to determine whether protocols that require participants to run at speeds other than self-selected pace confound the results. We therefore recommend normative data set protocols that avoid potential confounding by employing only self-selected pace. Our findings further suggest kinematic changes due to speed differed across gender, most notably in the transverse plane. Thus, we propose that gender specific normative data sets may be required.