Journal of Applied Physiology, Vol 44, Issue 6 952-955, Copyright © 1978 by American Physiological Society
Optimal rate of work for mountaineers
P. K. Nag, R. N. Sen and U. S. Ray
The physiological responses of seven young male highlanders were recorded
at high altitude while they were carrying loads (0, 25, 35, 45, and 55 kg)
on snow at different speeds, supporting the loads on their backs by
circular straps around the forehead. The rates of work calculated from the
gross weight (body weight plus actual load in kg) multiplied by the speed
of walking, m.min-1, ranged from 4,460 to 8,440 kg.m.min-1. The
relationship between the rate of work and energy expenditure was
rectilinear within the present range of values. The oxygen consumption
(51.6 and 59.7 ml.min-1.kg-1 BW) for 55-kg load (at 4.09 and 4.64 km.h-1)
possibly reached maximal aerobic capacity. At higher energy output at high
altitude the subjects were exhausted after a short period of work. The
proportion of increase of oxygen consumption per kg gross weight carried or
per kg.m was almost constant up to a 55-kg experimental load. It is
suggested that for day-to-day operations work should not be undertaken at
more than 30-40% of maximal work capacity; a rate of work around 4,000
kg.m.min-1 (25-30 kg actual load at 3.0 to 3.5 km.h-1) may be considered as
optimal for highlanders and porters at high altitude.
