Grounded Running Reduces Musculoskeletal Loading

Purpose Recent observations demonstrate that a sizeable proportion of the recreational running population runs at rather slow speeds and does not always show a clear flight phase. This study determined the key biomechanical and physiological characteristics of this running pattern, i.e. grounded running (GR), and compared these characteristics with slow aerial running (SAR) and reference data on walking at the same slow running speed. Methods Thirty male subjects performed instructed GR and SAR at 2.10 m·s-1 on a treadmill. Ground reaction forces, tibial accelerations and metabolic rate were measured to estimate general musculoskeletal loading (external power and maximal vertical ground reaction force), impact intensity (vertical instantaneous loading rate and tibial acceleration) and energy expenditure. More explicit measures of muscular loading (muscle stresses and peak eccentric power) were calculated based on a representative subsample, in which detailed kinematics and kinetics were recorded. We hypothesized that all measures would be lower for the GR condition. Results Subjects successfully altered their running pattern upon a simple instruction towards a GR pattern by increasing their duty factor from 41.5% to 51.2%. As hypothesized, impact intensity, general measures for musculoskeletal and the more explicit measures for muscular loading decreased by up to 35.0%, 20.3% and 34.0% respectively compared to SAR. Contrary to our hypothesis, metabolic rate showed an increase of 4.8%. Conclusion Changing running style from SAR to GR reduces musculoskeletal loading without lowering the metabolic energy requirements. As such, GR might be beneficial for most runners as it has the potential to reduce the risk of running related injuries while remaining a moderate-to-vigorous form of physical activity, contributing to fulfillment of the recommendations concerning physical activity and public health. Corresponding author: Dirk De Clercq; Watersportlaan 2, 9000 Gent, Belgium; +32 9 264 63 22; dirk.declercq@UGent.be Mizuno Corporation provided financial and product support for this study. All authors declare no conflict of interest. The results of the study are presented clearly, honestly and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by ACSM. Accepted for Publication: 18 October 2018. © 2018 American College of Sports Medicine

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