Effect of active warming-up on thermoregulatory, circulatory, and metabolic responses to incremental exercise in endurance-trained athletes.

The influence of 10 min warming-up at 40% VO2 max on thermal, circulatory, and metabolic responses to an incremental exercise to exhaustion as well as on the anaerobic threshold at the blood lactate level of 4 mmol.l-1 (AT) and the individual anaerobic threshold (IAT) was investigated in eight cross-country skiers. During exercise preceded by warming-up, the mean skin temperature (T sk) and external auditory canal temperature (Tac) did not change significantly in contrast to exercise without warming-up, producing a rise in both T sk and Tac (by approx. 1.2 degrees C and 1.1 degrees C, respectively). Warming-up did not alter the course of the rectal temperature changes during exercise. With warming-up skin humidity rose immediately after the beginning of exercise, whereas the onset of sweating without warming-up appeared much later at higher work intensities. Warming-up did not change the circulatory and ventilatory responses to incremental exercise and the oxygen uptake (VO2) either at submaximal or maximal work loads. With warming-up a significant increase was found in the threshold work load both at the AT and the IAT. The data demonstrated that warming-up has an advantageous effect on the efficiency of thermoregulation in endurance-trained athletes producing an early sweating response to the incremental exercise that results in attenuation of hyperthermia. An increase in the anaerobic threshold during incremental exercise preceded by warming-up may indicate an enhancement of the endurance capacity subsequent to warming-up.