The aims of this study were to investigate the user acceptance of exercise using the IREX™ Interactive Rehabilitation and Exercise system (a video-capture gaming environment) in comparison with exercise in a gym-based environment; and to compare users' flow experience - absorption in the activity - using the two exercise environments. A convenience sample of 18 healthy men and 20 healthy women, mean age 34 (1SD 12.8) years, with sedentary lifestyles were recruited from university staff and students. Participants were randomised into two groups - IREX™ (n = 19) or gym-based exercise (n=19). Both groups took part in three exercise sessions over two weeks. Apart from a greater Performance Expectancy with IREX, there were no significant differences in user acceptance and flow experience between the two environments. These results show IREX™ to be an acceptable alternative to gym-based exercise.