Journal of Applied Physiology, Vol 77, Issue 1 245-251, Copyright © 1994 by American Physiological Society
Effect of step length optimization on the aerobic demand of running
D. Morgan, P. Martin, M. Craib, C. Caruso, R. Clifton and R. Hopewell
Department of Exercise and Sport Science, University of North Carolina at Greensboro 27412.
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.
