To study the effect of prediction induced by prior and different instructions about an abrupt change of workload on the cardiorespiratory responses to the ensuing exercise, fifteen healthy volunteers performed the same bicycling exercise under three conditions in which the instructions about the load change were no, true, or false. The workload of the bicycling exercise in all three conditions was stepwisely increased from 40 % to 50% of maximal oxygen uptake level at 5 min after the start of exercise. Before the change of workload, both true and false conditions elicited the same magnitude of anticipatory increase in minute ventilation, heart rate, and mean arterial blood pressure (MAP), whereas the no condition had no effects. After the increase of workload, three conditions produced different responses in the hemoglobin oxygenation (oxy-Hb) and the index of muscle blood flow (MBF) in the exercising thigh muscles measured by near-infrared spectroscopy. The magnitude of the reduced oxy-Hb in response to the abrupt increase of workload was lower in the true condition than other conditions. Concurrently, the MBF in true condition was significantly increased more than other conditions. The less reduction of oxy-HB and the higher MBF in the true condition resulted in the lowest increase of MAP. These results suggest that the predictive and voluntary control resulting from the prior and different instructions about load change can modify the cardiorespiratory adjustment to the ensuing exercise.

DESCENTE SPORTS SCIENCE Vol.21/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE