Physiological responses to intensive snow shoveling performed by volunteers in heavy snowfall area

The purpose of this study was to examine the physiological responses to intensive snow shoveling. The subjects were six males (25-71, 50 +/- 8 years) who participated in a snow removal volunteer tour. Prior to the tour, each subject engaged in a cycle ergometer test (Test 1) and a multistage shoveling test (Test 2) to evaluate the relationship between volume of oxygen consumption ((V)over dotO(2)) and heart rate. Field measurements were performed in Miruto of Iwamizawa City, Hokkaido, Japan on February 2, 2014. Average air temperatures of that day were -6.3 degrees C in the morning and -1.4 degrees C in the afternoon. The snow layer at the work site had various grain shapes and snow density linearly increased with snow depth. While snow hardness increased exponentially with increase in snow depth. Mean heart rate during working time in the afternoon (142 +/- 9 beats min(-1)) was significantly (p<0.01) higher than that in the morning (131 +/- 9 beats min(-1)). These heart rates correspond 84 % and 77 % of the predicted maximum heart rate (HRmax), respectively. Ratings of perceived exertion were not different in the morning (12.9 +/- 0.4) and afternoon (12.4 +/- 0.3). The mean values of (V)over dotO(2) in the total work period ( 111 +/- 3 min) was estimated to be 22.2 +/- 1.2 ml kg(-1) min(-1) (Metabolic equivalent; 6.4 +/- 0.3 METs). Estimated energy expenditure averaged 782 +/- 46 kcal. It is conceivable that increase in snow hardness and snow density caused an increase in work intensity.