Comparison of uphill and downhill walking and concentric and eccentric cycling

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Abstract
Seven male subjects (20 years, 176cm. 70kg, 16% body fat) walked on a treadmill at various grades (— 15 to + 30%) and speeds (up to 1 -56 m s−1) carrying loads up to 30 kg. They also performed concentric and eccentric cycling at exercise intensities (EI) ranging from 0 to-260 W (∼ 1600kpmmin7minus;1). Exercise bouts lasted 20min. At the same oxygen consumption, eccentric cycling elicited the highest heart rate, followed by downhill walking, uphill walking and concentric cycling. Only the regression line for eccentric cycling had a significantly higher slope than the other three regression lines (p<0-05). Average gross exercise efficiencies for uphill walking and concentric cycling were similar (13-5 and 14-5%), and were significantly different from those for downhill walking ( — 33-5%) and eccentric cycling ( — 60-6%). For each type of exercise, absolute efficiency was greater with increasing EI. Actual energy expenditures for walking uphill and on the level were then compared to predicted values using the formula of Pandolf et al. (1977). The formula was found to be accurate for all uphill conditions at 112ms-1. For walking uphill at 0-56ms"’, the formula predicted slightly low (5-16%) while the formula underestimated energy expenditure for level walking by 14-33%. These findings would imply further modifications to this formula are necessary, particularly to include the observations for downhill walking.