Effects of load carriage, load position, and walking speed on energy cost of walking

Purpose: The purpose of this study was to examine the effects of load, load position, and walking speed on the energy cost of walking per unit distance (C-w: ml/kg/m). Methods: Eight young male subjects walked on a treadmill at various speeds with and without load in the hands, oil the back, and on the legs. The C-w values were determined from the ratio of 2-min steady-state oxygen consumption (V-O2) above resting value (net V-O2) to the walking speed (v): C-w = net V-O2/v. Results: An energy-saving phenomenon was observed when the load was carried on the back at slower speeds. This phenomenon diminished at faster speeds, particularly when walking faster than 90 m/min. It was also observed when the load was carried in the hands at slower speeds. Conclusions: These findings partly supported our hypothesis that an energy-saving phenomenon would be observed due to an interaction between rotative torque around the center of body mass and excessive burden on the lower muscles as a function of speed. (C) 2004 Elsevier Ltd. All rights reserved.