The effect of stride length variation on oxygen uptake during distance running

Abstract
Ten recreational runners (mean .ovrhdot.VO2 max [maximum O2 uptake] 64.7 ml .cntdot. kg-1 .cntdot. min-1) underwent a 5 day acclimation period to treadmill running at a 7 min .cntdot. mile-1 pace (3.83 m .cntdot. s-1) for 30 min each day. During these runs their freely chosen stride lengths were determined and expressed as a percentage of leg length (%LL). On 2 subsequent testing days stride length was systematically varied over a range of .+-. 20% LL about the freely chosen value. .ovrhdot.VO2 was determined by the Douglas Bag method. All subjects exhibited a stride length at which .ovrhdot.VO2 was minimized, although the individual profiles varied considerably. The mean increases in .ovrhdot.VO2 were 2.6 and 3.4 ml .cntdot. kg-1 .cntdot. min-1 at the short- and long-stride length extremes, respectively. During unrestricted running deviations from optimal stride length caused a mean increase in .ovrhdot.VO2 of 0.2 ml .cntdot. kg-1 .cntdot. min-1. The relatively efficient running patterns used by the subjects during unrestricted running indicate an adaption to the chosen stride length through training or a successful process of energy optimization.