The energy cost of walking and running with and without a backpack load.

The effect of backpack load (20 kg) on oxygen consumption while walking and running at different speeds was investigated. Fifteen males walked an ran (with and without load) up a 5% sloped treadmill at 6.4, 7.2, 8.0, 9.6, and 11.2 km/h (4, 4.5, 5, 6, and 7 mph). While walking VO2 rose at a rate of 0.6 (l/min)/(km/h) and while running 0.3 (l/min)/(km/h). The mean oxygen consumption at the various speeds was 28.65, 33.78, 40.64, 46.84, 54.48 ml O2/kg BW/min, respectively, for the whole group without load and 26.52, 32.26, 38.28, 44.26, 48.16, respectively, with load. The breaking point between walking and running was at about 8.2 km/h. Carrying the load increased VO2 at a constant rate, and induced a breaking point between walking and running at a significantly lower speed for the smaller subjects than for the more robust ones. The results indicate that for certain tasks involving endurance and heavy load carriage, people should be selected according to criteria which integrate aerobic capacity and anthropometrical features.