The effect of body mass on physiological indicators in the performance of forestry workers

The paper presents the results of research into the effects of body mass (BM) on basic physiological indicators of work capability among forestry workers. The indicators included the maximum theoretical heart rate, the maximum heart rate in exertion tests, and the basal energy expenditure. The effects of the deviation of the actual from the ideal BM values were analysed on a sample of 8 workers. The variables included age, body height and mass. These were used to determine the maximum theoretical heart rate. The maximum heart rate was determined in an ergonomic laboratory in a programmed exertion test on a treadmill. Using standard formulae in work physiology, values of work capability indicators were calculated for the actual and ideal BM of each worker. The results, embracing individual and summary values and their absolute and relative ratios, showed that workers exceeded their ideal BM by an average of 9.9 kg. In all workers, the maximum theoretical heart rate was higher than that achieved in the exertion test. It was also found that even significant deviations of the ideal from the actual BM (the actual BM was more than 20% higher than the ideal BM) did not have any considerable effects on the maximum theoretical heart rate. The analysis of oxygen consumption showed that in relation to physical capability of the ideal BM and the maximal theoretical heart rate, physical capability of each worker was lower by an average of 11.5%. The highest reduction of physical capability was found in those workers with the least favourable ratio between the theoretical and the maximal tested heart rate. It was concluded that on average, the basal energy expenditure in each worker was higher by 7.45% due to the deviation of the actual from the ideal BM. At constant values of other factors, this means an equivalently lower capacity for daily physical performance.