title: Energy expenditure and cardiorespiratory responses at the transition between walking and running.
abstract: We investigated whether the spontaneous transition between walking and running during moving with increasing speed corresponds to the speed at which walking becomes less economical than running. Seven active male subjects [mean age, 23.7 (SEM 0.7) years, mean maximal oxygen uptake (VO2max), 57.5 (SEM 3.3) ml.kg-1.min-1, mean ventilatory threshold (VTh), 37.5 (SEM3) ml.kg-1.min-1] participated in this study. Each subject performed four exercise tests separated by 1-week intervals: test 1, VO2max and VTh were determined; test 2, the speed at which the transition between walking and running spontaneously occurs (ST) during increasing speed (increases of 0.5 km.h-1 every 4 min from 5 km.h-1) was determined; test 3, the subjects were constrained to walk for 4 min at ST, at ST +/- 0.5 km.h-1 and at ST +/- 1 km.h-1; and test 4, the subjects were constrained to run for 4 min at ST, at ST +/- 0.5 km.h-1 and at ST +/- 1 km.h-1. During exercise oxygen uptake (VO2), heart rate (HR), ventilation (VE), ventilatory equivalents for oxygen and carbon dioxide (VE/VO2, VE/VCO2), respiratory exchange ratio (R), stride length (SL), and stride frequency (SF) were measured.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Laboratoire de Physiologie des Interactions, Hôpital Arnaud de Villeneuve, Montpellier, France.
authors.forename: J
authors.initials: J
authors.lastname: Mercier
authors.forename: D
authors.initials: D
authors.lastname: Le Gallais
authors.forename: M
authors.initials: M
authors.lastname: Durand
authors.forename: C
authors.initials: C
authors.lastname: Goudal
authors.forename: J P
authors.initials: JP
authors.lastname: Micallef
authors.forename: C
authors.initials: C
authors.lastname: Préfaut
mesh_terms: D000328:Adult; D001784:Blood Gas Analysis; D001794:Blood Pressure; D002320:Cardiovascular Physiological Phenomena; D004734:Energy Metabolism / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D012119:Respiration / Q000502:physiology*; D012129:Respiratory Function Tests; D012420:Running / Q000502:physiology*; D016138:Walking / Q000502:physiology*