The concurrent effects of strike pattern and ground-contact time on running economy

• Published in: Journal of science and medicine in sport 2014-07, Vol.17 (4), p.414-418
• Main Authors: Di Michele, Rocco, Merni, Franco
• Format: Article
• Language: English
• Subjects: Adult; Athletic performance; Biomechanical Phenomena; Biomechanics; Cross-Sectional Studies; Distance running; Exercise Test; Foot - physiology; Humans; Linear Models; Male; Oxygen consumption; Oxygen Consumption - physiology; Physical endurance; Physical Medicine and Rehabilitation; Running; Running - physiology; Sports Medicine; Strikes; Studies; Time Factors; Track & field; Young Adult
• ISSN: 1440-2440; 1878-1861
• DOI: 10.1016/j.jsams.2013.05.012

Abstract Objectives Running economy is a key determinant of endurance performance, and understanding the biomechanical factors that affect it is of great theoretical and applied interest. This study aimed to analyse how the ground-contact time and strike pattern used by competitive runners concurrently affect running economy. Design Cross-sectional. Methods Fourteen sub-elite male competitive distance runners completed a 6-min submaximal running trial at 14 km h−1 on an outdoor track using their habitual strike pattern ( n = 7 rearfoot strikers: average age, 25.3 years old (SD = 2.4); average weight, 64.7 kg (SD = 5.6); average height, 175.3 cm (SD = 5.2); n = 7 midfoot strikers: average age, 25.0 years old (SD = 2.8); average weight, 69.6 kg (SD = 4.0); average height, 180.1 cm (SD = 5.1). During the run, the oxygen uptake and ground-contact time were measured. Results Midfoot strikers showed a significantly shorter ( p = 0.015) mean contact time (0.228 s (SD = 0.009)) compared with rearfoot strikers (0.242 s (SD = 0.010)). Conversely, there was no significant difference ( p > 0.05) between the groups with respect to mean oxygen uptake (midfoot strikers: 48.4 ml min−1 kg−1 (SD = 5.3); rearfoot strikers: 49.8 ml min−1 kg−1 (SD = 6.4)). Linear modelling analysis showed that the effect of contact time on running economy was very similar in the two groups, with a 1 ms longer contact time involving an approximately 0.51 ml min−1 kg−1 lower oxygen uptake. In contrast, when controlling for contact time, midfoot striking involved an approximately 8.7 ml min−1 kg−1 lower oxygen uptake compared with rearfoot striking. Conclusions When adjusting the foot–ground contact biomechanics of a runner with the aim of maximising running economy, a trade-off between a midfoot strike and a long contact time must be pursued.