Abstract
BackgroundThe present study was designed to evaluate load carriage performance at extremely high altitudes with different loads and walking speeds in terms of physiological evaluation. The degree of maximum oxygen consumption changes at high altitudes was also examined.MethodsTwelve Indian Army soldiers were acclimatized at altitudes of 3,505 m and 4,300 m. They walked for 10 minutes on a motorized treadmill at 2.5 km/h and 3.5 km/h speeds during carrying no loads and three magnitudes of load (10.7 kg, 21.4kg, 30 kg) at both altitudes. Physiological parameters such as oxygen consumption, energy expenditure, heart rate, and ventilation were recorded for each breath using a gas analyzer. The rating of perceived exertion was also noted after each load carriage session. Maximal oxygen consumption (VO2max) was measured at sea level and the two high altitudes, and respective relative workloads (% of VO2max) were calculated from oxygen consumption. Repeated measure ANOVA was applied to reveal the significant effects of the independent variables.ResultsThe participants had significant reductions in VO2max with rising altitude. Marked increases in almost all physiological parameters were observed with increasing load, altitude, and speed. The soldiers expressed heavy perceived exertion levels with higher loads at 3.5 km/h at the two high altitudes.ConclusionsConsidering the physiological responses, expressions of perceived exertion and changes in relative work load at both of the high altitudes Indian soldiers are advised to walk slowly with adequate rest in between their schedules and to carry not more than 32% of their body weight.
Highlights
The present study was designed to evaluate load carriage performance at extremely high altitudes with different loads and walking speeds in terms of physiological evaluation
As per rules of the Indian Army, once a soldier completes his posting at High altitude (HA), a gap of at least one year is provided before re-induction
One way repeated measure ANOVA revealed that the changes are significantly different [F (2, 22) =100.8, P < 0.5]
Summary
The present study was designed to evaluate load carriage performance at extremely high altitudes with different loads and walking speeds in terms of physiological evaluation. Manual load carrying by Indian soldiers is often necessary in the remote countryside and mountainous areas, as these regions are mostly inaccessible to vehicles. Indian infantry soldiers carry loads on the waist, back, shoulders and hands for marching orders [8] They carry loads ranging from 10 to 30 kg over different terrain and in extreme environmental conditions. Pal et al [10, 11] established standards of optimum load carriage at varying speeds and gradients for Indian Army soldiers on plains based on the energy cost, oxygen requirement and relative workload of the specific task. A linear regression equation was applied to calculate the optimum load for each gradient and speed
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