J. F. Morrison

The influence of boot weight on the energy expenditure of men walking on a treadmill and climbing steps

SummaryTwo subjects either walked on a motor-driven treadmill at 3 m.p.h. or stepped on and off a one foot high wooden block at 12 and 24 steps/min while wearing boots weighing either 4.08, 4.41, 5.62 or 6.50 1b per pair. The energy cost of each task was determined by measuring and analysing the expired air and calculating the amount of oxygen taken up in the lungs. Heart rates were also recorded during the stepping tests and all the data were statistically analysed.When subjects walked at 3 m.p.h. or climbed steps at a rate of 12 steps/min no significant increase in oxygen intake was observed when boot weight was increased. Even the additional weight of leg guards had no marked influence on the energy expenditure at these two work intensities. Significant differences in oxygen intake did occur when the subjects stepped up and down at 24 steps/min, but the highest oxygen intake did not occur when the heaviest boots were worn by either subject. Provided that the weight of mine boots is kept within the limits of 4 to 6 lb per pair, there is no question of any loss in efficiency due to fatigue caused by boot weight.

The metabolic cost of marching at 3 m.p.h. over firm and sandy surfaces

SummaryThe study was designed to determine the energy cost of walking over sandy and firm surfaces, and to compare the physiological responses of recruits recorded while walking over these surfaces.The average oxygen intake of 11 young men walking over loose sand at 3 m.p.h. and carrying loads of about 50 lbs each (inclusive of clothes) was 1.973 litre/min. as compared with 1.101 litre/min. for walking on a firm surface, an increase of 80 per cent. The average pulse rate and rectal temperature were significantly higher during the march over sand (150 beats/min. and 101.5 °F respectively) than while walking over firm surfaces (127 beats/min. and 100.5 °F). The increased physiological strain was obvious. Most of the men were working at more than 50 per cent of their estimated maximum oxygen intakes while walking on sand, as a result of which their heart rates and rectal temperatures would have increased progressively with time.