A comparative study of physiological strain of underground coal miners in India.

Ninety-eight healthy underground coal miners aged between 23-58 years were studied during their activity period. Physiological strain of different category of miners in terms of heart rate was monitored continuously with heart rate monitor that revealed the tasks as heavy to very heavy for them. Oxygen consumption was measured directly by using oxylog-2 machine that corresponded to metabolic costs for different activities ranging from 4.96 kcal/min to 5.47 kcal/min. The mean relative aerobic strain varied from 47.4%-56.8%--depicting acceptable level of physical strain was well encroached by the miners who irrespective of ages and categories showed poor recovery responses. This entails that miners are exerting themselves beyond their capacities where inevitably older workforce face the maximum burden.