Predicting energy expenditure with loads while standing or walking very slowly.

Abstract : Six men each carried loads of 32, 40 and 50 kg while walking at 1.0, 0.8, 0.6, 0.4 and 0.2 m/s, to extend the range of speed down to the standstill level. Metabolic cost of standing with 0, 10, 30 or 50 kg backpacks was also investigated in 10 men to evaluate the energy expenditure of load carriage while standing. Energy expenditure increased with external load, both standing and walking. No increased inefficiency occurred with very slow walking; M decreased smoothly as speed approached zero. The revised predictive formula, empirically derived, which now covers standing and the whole range of walking speeds, is presented where: M = metabolic rate, watt; W = subject weight, kg; L = load carried, kg; V = speed of walking, m/s; G = grade, %; N = terrain factor (N = 1. 0 for treadmill). The new formula not only extends the range of application but also allows an adjustment for load as a function of body weight and permits easier calculation of energy expenditure.