The aim of this investigation was to determine if gait manipulation influences running economy. Following 30 minutes of accommodation to level treadmill running at 3.35 m·s^-1 and determination of VO_2peak, nine female distance runners (age = 23.3 ± 4.2 years; body mass = 57.5 ± 5.2 kg; height = 1.64 ± 0.10 m; body fat = 11.4 ± 2.4 %; VO_2peak = 54.9 ± 4.1 ml·kg^-1·min^-1) completed two treadmill running sessions. In each session, standing VO₂ was measured and subjects ran for 6 minutes at 3.35 m·s^-1 under 4 randomly-selected conditions: a) normal running (NL), b) hands behind back (BK), c) hands on head (HD), and d) running with exaggerated vertical oscillation (VOSC). During the last 2 minutes of each running bout, samples of expired air were analyzed to determine oxygen uptake (VO₂). Data obtained by averaging gross VO₂ values across sessions indicated that VOSC (51.0 ± 2.5 ml·kg^-1·min^-1) and HD (46.1 ± 2.0 ml·kg^-1·min^-1) resulted in significantly (p < 0.05) elevated VO₂ values compared to BK (43.9 ± 2.4 ml·kg^-1·min^-1) and NL (43.4 2.6 ml·kg^-1·min^-1). VO₂ measured during VOSC was also higher compared to HD. Viewed in concert, these results suggest that specific gait manipulations can produce marked decrements in running economy among trained female distance runners.

• This investigation demonstrates that specific biomechanical manipulations can produce substantive increases in the oxygen cost (VO) of submaximal running in female distance runners.

• The magnitude of increases in VO reported in this study raises the intriguing possibility that meaningful improvements in running economy might be achieved by manipulating the gait of distance runners who exhibit specific aspects of running style that deviate markedly from the optimum.