Body Temperature and Capacity for Work

Summary. It is a well established fact that the body temperature increases during muscular exercise, and that the increase is regulated (NIELSEN, 1938). It was the purpose of this paper to study the effect of the increased body temperature on the performance of maximum work, viz. a work performance of short duration (12 to 15 seconds) and a work performance lasting 4 to 5 minutes. The effect on a peak effort (a “push” or a “pull”) was also studied. The experiments showed: A given amount of work could be performed better – i. e. in a shorter time – when the organism was warmed up by a preliminary work. Also a greater muscular tension could be developed when “warmed up” than when not. A passive warming up – e. g. by means of radio diathermy or by hot baths – also increased the capacity for work. Massage had no beneficial effect on the performance. The harder the preliminary work was, the higher rose the temperature and the better was the performance (only demonstrated in the work of shorter duration (12 to 15 sec.)). The increased ability to perform hard work is closely correlated to the temperature of the working muscles. The maximum oxygen uptake is slightly higher when the organism is warmed up than when this is not the case, but the oxygen necessary for a certain amount of work is reduced. From these results it is concluded that a higher temperature in the muscles benefits the ability to perform work by accelerating the chemical processes in the muscles, probably also by decreasing the intramuscular viscous resistance. The accurately regulated higher rectal temperature in work (NIELSEN) allows the muscles to obtain a higher temperature during work than would otherwise be possible.