Effect of step length optimization on the aerobic demand of running.

Abstract

To assess whether distance runners displaying uneconomical freely chosen step lengths (FCSL) could be trained to shift FCSL toward a more optimal setting, six males and three females who exhibited uneconomical FCSL [mean optimal step length (OSL) = -9.81% of leg length from FCSL; mean change in oxygen uptake (VO2) (FCSL - OSL) = 1.46 ml.kg-1.min-1] comprised an experimental group that completed 15 treadmill sessions (30 min/day, 5 days/wk, 3 wk) of OSL training at individually determined running velocities (2.87-3.74 m/s). Training sessions featured alternating 5-min periods of combined audio and visual feedback matching OSL and no feedback. A control group of three subjects with uneconomical FCSL (2 males, 1 female) performed 3 wk of treadmill running without feedback. The extent of step length optimization was evaluated by comparing pre- and posttraining differences between FCSL and OSL and between pre- and posttraining VO2. Compared with the control group, the experimental group demonstrated a significantly (P < or = 0.05) greater relative shift in FCSL toward OSL and a marked reduction in FCSL VO2. Taken together, these results suggest that short-term audiovisual feedback training can be effective in optimizing step length and producing a decrease in aerobic demand among distance runners exhibiting uneconomical FCSL.