Fourteen subjects (22#xA0;yr, 175#xA0;cm, 72#xA0;kg) walked for 20#xA0;min on a treadmill at 3-2, 4-8, or 64#xA0;km h-1carrying 35, 40, 45, or 50#xA0;kg; during a second phase, ten additional subjects (22#xA0;yr, 178#xA0;cm, 75#xA0;kg) attempted to walk for 45#xA0;min at the same speeds carrying 60, 65. or 70#xA0;kg Energy expenditure when expressed as cm3oxygen per minute per kilogramme of total weight (man + clothing + load) agreed, for the no load condition, with literature values. After deducting the individual's no load cost, the resulting net energy expenditure for carrying the loads, when expressed as cm3kg-1min-1was generally constant at each speed; i.e. loads from 35 to 70#xA0;kg showed no statistical differences in energy expenditure per kilogramme at 3 2 and 4 8#xA0;km h-1. At 6-4#xA0;km h-1carrying 70#xA0;kg, the average measured cost per kg was statistically different (p 005) than carrying 35#xA0;kg at this speed; subjects were working at greater than 90 of their maximal Vdot02levels carrying 70#xA0;kg. However. similar comparison of the measured cost per kg between loads of 40 and 65#xA0;kg was statistically the same at 6 4#xA0;km h-1. The general constancy of measured energy expenditure per kg for loads even up to 70#xA0;kg, probably depends on the condition that the load is well balanced and close to the centre of the body. As reported earlier, higher costs are associated with loads in unbalanced positions. Thus, the limitations commonly encountered in load carrying capacity may arise from poor positioning of the load rather than from the weight of the load per
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