title: Are gait characteristics and ground reaction forces related to energy cost of running in elite Kenyan runners?
abstract: The aim of this study was to determine whether gait cycle characteristics are associated with running economy in elite Kenyan runners. Fifteen elite Kenyan male runners completed two constant-speed running sets on a treadmill (12 km ·h-1and 20 km ·h-1). VO2and respiratory exchange ratio values were measured to calculate steady-state oxygen and energy cost of running. Gait cycle characteristics and ground contact forces were measured at each speed. Oxygen cost of running at different velocities was 192.2 ± 14.7 ml· kg-1· km-1at 12 km· h-1and 184.8 ± 9.9 ml· kg-1· km-1at 20 km· h-1, which corresponded to a caloric cost of running of 0.94 ± 0.07 kcal ·kg-1·km-1and 0.93 ± 0.07 kcal· kg-1· km-1. We found no significant correlations between oxygen and energy cost of running and biomechanical variables and ground reaction forces at either 12 or 20 km· h-1. However, ground contact times were ~10.0% shorter (very large effect) than in previously published literature in elite runners at similar speeds, alongside an 8.9% lower oxygen cost (very large effect). These results provide evidence to hypothesise that the short ground contact times may contribute to the exceptional running economy of Kenyan runners.
authors.affiliation: a Department of Physical Education and Sport , University of the Basque Country UPV/EHU , Vitoria-Gasteiz , Spain.|b Division for Exercise Science and Sports Medicine, Department of Human Biology , University of Cape Town , Cape Town , South Africa.
authors.forename: J
authors.initials: J
authors.lastname: Santos-Concejero
authors.affiliation: b Division for Exercise Science and Sports Medicine, Department of Human Biology , University of Cape Town , Cape Town , South Africa.
authors.forename: N
authors.initials: N
authors.lastname: Tam
authors.affiliation: b Division for Exercise Science and Sports Medicine, Department of Human Biology , University of Cape Town , Cape Town , South Africa.
authors.forename: D R
authors.initials: DR
authors.lastname: Coetzee
authors.affiliation: c Department of Physiology , European University of Madrid , Madrid , Spain.
authors.forename: J
authors.initials: J
authors.lastname: Oliván
authors.affiliation: b Division for Exercise Science and Sports Medicine, Department of Human Biology , University of Cape Town , Cape Town , South Africa.
authors.forename: T D
authors.initials: TD
authors.lastname: Noakes
authors.affiliation: b Division for Exercise Science and Sports Medicine, Department of Human Biology , University of Cape Town , Cape Town , South Africa.|d School of Medicine , University of the Free State , Bloemfontein , South Africa.
authors.forename: R
authors.initials: R
authors.lastname: Tucker
mesh_terms: D001696:Biomechanical Phenomena; D004734:Energy Metabolism / Q000502:physiology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D007630:Kenya; D008297:Male; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D012420:Running / Q000502:physiology*; D055815:Young Adult
keywords: African runners; Energy cost of running; ground contact; stride frequency; stride length