Sympathovagal modulation during immersion in a virtual environment is an important influence on human performance of a task. The aim of this study is to investigate sympathovagal modulation using heart rate variability and perceived exertion during exercise in a virtual reality (VR) environment. Sixteen young healthy volunteers were tested while using a stationary bicycle and maintained at an anaerobic threshold intensity for exercise sessions of approximately 10 min duration. Four randomized viewing alternatives were provided including desktop monitor, projector, head mounted device (HMD), and no simulation display. The “no simulation display” served as the control group. A quick ramp exercise test was conducted and maintained at an anaerobic threshold intensity for each session to evaluate power spectral density and rating of perceived exertion (RPE). The sampled heart rate data were rearranged by cubic spline interpolation into power spectrums spanning the ultra-low frequency (ULF) to high frequency (HF) range. A significant difference was found between the no-display and projector groups for total power (TP) and very low frequency (VLF) components. In particular, there was a significant difference when comparing HMD and no-display exercise RPE curves within 6 min of cycling and at the termination of the exercise. A significant difference was also achieved in projector vs. control group comparison at the termination of the exercise. Our results indicate that the use of HMD and the projected VR during cycling can reduce the TP and VLF power spectral density through a proposed decrease in the renin-angiotensin system, with the implication that this humoral effect may enable anaerobic exercise for longer durations through a reduction in sympathetic tone and subsequent increased blood flow to the muscles.

The purpose of this study was to develop a virtual cycling system and examine the influence 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 74.5-4.7 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 flow 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, significant 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 = .06); however, no statistical significance was achieved at the test termination (log rank test, p =.17). In conclusion, this study found that the maintenance of endurance, the increase in target intensity, and total energy consumption in exercise programs may be assisted by introducing VR technology. In addition, the activities taking place in virtual environments can be performed in complete safety.