@article{ref1,
title="Why do we transition from walking to running? Energy cost and lower leg muscle activity before and after gait transition under body weight support",
journal="PeerJ",
year="2019",
author="Abe, Daijiro and Fukuoka, Yoshiyuki and Horiuchi, Masahiro",
volume="7",
number="",
pages="e8290-e8290",
abstract="BACKGROUND: Minimization of the energetic cost of transport (CoT) has been suggested for the walk-run transition in human locomotion. More recent literature argues that lower leg muscle activities are the potential triggers of the walk-run transition. We examined both metabolic and muscular aspects for explaining walk-run transition under body weight support (BWS; supported 30% of body weight) and normal walking (NW), because the BWS can reduce both leg muscle activity and metabolic rate. <br><br>METHODS: Thirteen healthy young males participated in this study. The energetically optimal transition speed (EOTS) was determined as the intersection between linear CoT and speed relationship in running and quadratic CoT-speed relationship in walking under BWS and NW conditions. Preferred transition speed (PTS) was determined during constant acceleration protocol (velocity ramp protocol at 0.00463 m·s<sup>-2</sup> = 1 km·h<sup>-1</sup> per min) starting from 1.11 m·s<sup>-1</sup>. Muscle activities and mean power frequency (MPF) were measured using electromyography of the primary ankle dorsiflexor (<i>tibialis anterior</i>; TA) and synergetic plantar flexors (calf muscles including <i>soleus</i>) before and after the walk-run transition. <br><br>RESULTS: The EOTS was significantly faster than the PTS under both conditions, and both were faster under BWS than in NW. In both conditions, MPF decreased after the walk-run transition in the dorsiflexor and the combined plantar flexor activities, especially the <i>soleus</i>. <br><br>DISCUSSION: The walk-run transition is not triggered solely by the minimization of whole-body energy expenditure. Walk-run transition is associated with reduced TA and <i>soleus</i> activities with evidence of greater slow twitch fiber recruitment, perhaps to avoid early onset of localized muscle fatigue.<br><br>© 2019 Abe et al.<p /> <p>Language: en</p>",
language="en",
issn="2167-8359",
doi="10.7717/peerj.8290",
url="http://dx.doi.org/10.7717/peerj.8290"
}