THE EFFECT OF AMBIENT TEMPERATURE ON HUMAN STRENGTH

Impact of environmental conditions like temperature is usually not considered in the measurement of work content analysis. However, to ensure healthy work conditions, it is imperative that studies on the effects of heat and cold stress on workers' capacity are carried out and existing guidelines on working capacity be suitably modified. In this study, the effect of heat stress on the physical strength of subjects measured in terms of average push/ pull/ pedal/ grip force applied over 30 seconds was recorded. In dry bulb temperature studies, it was found that subjects showed a maximum strength at 20oC or 25oC and a 30% and 35 % drop in strength was observed at 5oC and 40oC respectively. In case of wet bulb globe temperature (WBGT), the maximum strength was recorded between 13oC to 21oC and a 31% and 41% drop in strength was observed in the range 3oC to 5oC and 37oC to 39oC respectively. Statistical analysis of strength at ambient temperatures between 5oC to 40oC dry bulb values gave a second order "inverted-U" relationship between strength and temperature and, a second order "U-shaped" relationship between the drop in strength and temperature