A b st r a ctThe purpose of this study was to develop a virtual cycling system and examine the in uence of virtual reality (VR) on test performance during clinical exercise testing. We aimed to compare the physiological responses of the cardiovascular and ventilatory systems during incremental exercise testing with or without VR, and to measure VR effects on the ratings of perceived exertion (RPE) and cycling duration throughout the test.Twelve healthy senior citizens (ten men and two women) with a mean age of 74.5 6 4.7 years participated in the study. The codes of behavior for this study included a maximum graded exercise tolerance test, a submaximal endurance VR exercise, and a submaximal endurance non-VR exercise. A friction-braked cycle ergometer was used to conduct the exercise tests. For the subject's movement speed to create an appropriate environment ow on the display screen, the bike was connected to a personal computer. The cardiorespiratory and hemodynamic parameters were evaluated at both peak and submaximal exertion.The results show that the VR versus non-VR programs did not differ on submaximal and peak exercise responses during the cycling test. However, signi cant differences were observed between the mean values for cycling duration, distance, and energy consumption. The difference between RPE curves for VR and non-VR protocols revealed promising results within 45 min. of cycling (Breslow test, p 5 .06); however, no statistical signi cance was achieved at the test termination (log rank test, p 5 .17).