Two 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.