Neue Ergebnisse über die Arbeitshyperthermie des Menschen

Abstract

Nielsen (1938) demonstrated that hypothermia during exercise is independent of room temperature within a range from 5° to 32° C. Subsequently, other investigators confirmed this observation. From these results,Asmussen &Nielsen (1947) concluded that a resetting of the thermoregulatory centre brought about by impulses reaching the brain from the working muscles or from the motor centres takes place. In order to find out whether impulses from motor centres really affect the thermoregulatory centres, we tried, by administration of curare in human beings, to increase the frequency of impulses necessary to bring about a certain amount of mechanical work. However, in 2 series of experiments at room temperatures of 23° and 34° C respectively and at a constant work output of 3 mkp/sec, no significant differences in body temperature (measured in the lower esophagus) before and during curare infusion could be detected. In the resting conditions, curare exerts no influence on body temperature. In normal subjects performing low work (3 mkp/sec) the body temperature decreases at a room temperature of 23° C but increases at a room temperature of 32° C. In conclusion, the hyperthermia during exercise cannot be due to a resetting of thermoregulatory centres. It works rather like a proportional closed loop control system. The relative independence of the hyperthermia from the environmental temperature suggests a considerable influence of the latter parameter via the thermoreceptors of the skin on the thermoregulation during work.

Zusammenfassung

• 1. Die Klimaunabhängigkeit der Arbeitshyperthermie führte zu der Annahme einer Sollwertverstellung thermoregulatorischer Schaltstellen durch irradiierende motorische Impulse oder proprioceptive Rückmeldungen.

• 2. Folgende Befunde sprechen gegen diese Annahmen: (a) Unter der Einwirkung von Curare ändert sich die Arbeitshyperthermie trotz vermehrter efferenter Impulse nicht. (b) Bei kleiner Leistung (3 mkp/sec) ist schon bei 23°C Außentemperatur ein Abfall der Kerntemperatur nachweisbar.

• 3. Es wird versucht, die Arbeitshyperthermie als bleibende Abweichung in einem P-Regelsystem, die Klimaunabhängigkeit als Folge der Störgrößenaufschaltung an den Thermoreceptoren der Haut zu erklären.