Intramuscular, Rectal and Oesophageal Temperature During Exercise

Temperature recordings were made from the vastus lateralis of the m. quadriceps femoris, from the m. biceps brachii, from oesophagus and from rectum, before, during, and after exercise on a bicycle ergometer, using the loads of 900, 1,200 and 1,500 kpm/min. Three adult males served as subjects. The temperature of the vastus lateralis at rest was 33.5–35d̀ C. The beginning of the work was followed by a rise which levelled after about 15 min. The final temperatures were 37.8–39.7d̀ C, corresponding to the load. The changes from the temperature of the resting biceps brachii, 34.5–36.0d̀ C, were slight, less than 0.5d̀ C. The oesophageal temperature showed an initial fall of 0.1–0.4d̀ C during the first minutes, followed by a rise; the temperature levelled within 15 min to 37.8—39.0d̀ C, corresponding to the work load. The rectal temperature failed to show an initial fall, rose steadily throughout the 30 min exercise period. After exercise, the oesophageal temperature returned to resting values in half an hour, while the rectal temperature showed a steady fall over an hour. During the first minutes of exercise, the active muscles gain heat from the rest of the body.