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Open AccessArticle

Duty Factor Is a Viable Measure to Classify Spontaneous Running Forms

Research and Development Department, Volodalen Swiss SportLab, 1860 Aigle, Switzerland
Research and Development Department, Volodalen, 39134 Chavéria, France
Research Unit EA3920 Prognostic Markers and Regulatory Factors of Cardiovascular Diseases and Exercise Performance, Health, Innovation platform, University of Fanche-Comté, 25000 Besançon, France
Division for Physical Education, Tomsk Polytechnic University, 634050 Tomsk, Russia
Adams Centre for High Performance, Division of Health, Engineering, Computing and Science, Te Huataki Waiora School of Health, University of Waikato, Tauranga 3116, New Zealand
Author to whom correspondence should be addressed.
Sports 2019, 7(11), 233; (registering DOI)
Received: 23 October 2019 / Revised: 7 November 2019 / Accepted: 8 November 2019 / Published: 10 November 2019
Runners were classified using two different methods based on their spontaneous running form: (1) subjectively using the V®score from the Volodalen® scale, leading to terrestrial and aerial groups; and (2) objectively using the duty factor (DF), leading to high (DFhigh) and low (DFlow) DF groups. This study aimed to compare these two classification schemes. Eighty-nine runners were divided in two groups using the V®score (VOL groups) and were also ranked according to their DF. They ran on a treadmill at 12 km·h−1 with simultaneous recording of running kinematics, using a three-dimensional motion capture system. DF was computed from data as the ratio of ground contact time to stride time. The agreement (95% confidence interval) between VOL and DF groups was 79.8% (69.9%, 87.6%), with relatively high sensitivity (81.6% (68.0%, 91.2%)) and specificity (77.5% (61.6%, 89.2%)). Our results suggest that the DF and V®score reflect similar constructs and lead to similar subgroupings of spontaneous running form (aerial runners if DF < 27.6% and terrestrial runners if DF > 28.8% at 12 km·h−1). These results suggest that DF could be a useful objective measure to monitor real-time changes in spontaneous running form using wearable technology. As a forward-looking statement, spontaneous changes in running form during racing or training could assist in identifying fatigue or changes in environmental conditions, allowing for a better understanding of runners. View Full-Text
Keywords: running; biomechanics; running form running; biomechanics; running form
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Patoz, A.; Gindre, C.; Thouvenot, A.; Mourot, L.; Hébert-Losier, K.; Lussiana, T. Duty Factor Is a Viable Measure to Classify Spontaneous Running Forms. Sports 2019, 7, 233.

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