Optimal back-pack load for short distance hiking

20 Young men marched 6 and 12 km with a well-fitted back-pack load of 30 or 35 kg. Each subject served as his own control. No significant increase in mean heart rate, rectal temperature, or decrease in mean VO ₂ max and serum levels of glucose and muscle enzymes were recorded in the groups marching 6 km with 30 and 35 kg. Significant differences in the increases in mean heart rate, the decreases in VO ₂ max and the changes in blood glucose were noted between the 2 groups carrying 30 and 35 kg for 12 km. These significant differences were also supported by the subjective feelings of the volunteers. The present study shows the optimal back-pack load for healthy young men, marching at 6 km/hr on a paved road, road to be 30 kg for 12 km and 35 kg for 6 km without considering the task too difficult and with no significant decrease in VO ₂ max. The results are relevant to hiking, rescue assignments, and military missions.