Although active gaming is popular and can increase energy expenditure in young adults, its efficacy as a prescriptive exercise tool is not well understood. This study aimed to: (1) compare the activity intensities experienced by young adults while playing active tennis gaming with conventional sedentary gaming, tennis game-play and current activity recommendations for health, and (2) identify changes in activity intensities across playing time. Following habitualization, ten active young adults (age: 20.2 +/- 0.4 years; stature: 1.74 +/- 0.03 m; body mass: 67.7 +/- 3.3 kg) completed three experimental trials (sedentary gaming, active tennis gaming and tennis game-play) on separate days in a randomized order. Heart rate (HR) and metabolic equivalents (METs) were averaged across 5-min and 10-min intervals, and the entire 20-min bout within each condition. Active gaming produced greater intensities across 5-10, 10-15 and 15-20 min time intervals compared with sedentary gaming (p < 0.01). Tennis game-play elicited greater HR (67 +/- 5%HRmax) and MET (5.0 +/- 0.2) responses than both sedentary (40 +/- 2%HRmax, 1.1 +/- 0.1 METs) and active gaming (45 +/- 2%HRmax, 1.4 +/- 0.1 METs) (p < 0.001). Only tennis game-play produced activity intensities meeting current recommendations for health benefit. Lower HR intensities were reached across 0-5 min than during later time intervals during active gaming (6%) and tennis game-play (9%) (p < 0.01). Activity intensities elicited by active gaming were greater than sedentary gaming, but less than tennis game-play and insufficient to contribute towards promoting and maintaining good health in young adults. These data suggest that active tennis gaming should not be recommended by exercise professionals as a substitute for actual sports participation in young adults.