Regular physical activity is essential for maintaining health, yet many adults remain inactive - often due to low motivation or lack of access to engaging training formats. Exergames, which combine physical movement with interactive gameplay, offer a promising solution. However, many existing systems fail to reach sufficient intensity to produce measurable physiological benefits. This study evaluates SkyRide, an adaptive exergame integrated into the immersive ExerCube system, which merges virtual environments with ergometer-based endurance training. Twenty-one healthy adults participated in a comparative assessment involving both a conventional cycle ergometer session and a SkyRide session. Key physiological parameters - maximum heart rate (HRmax) and maximal oxygen uptake (VO2max) - were continuously recorded. Findings indicate that SkyRide can elicit cardiovascular responses comparable to traditional ergometer training in the overall sample. However, subgroup analyses revealed differing patterns of exertion: female and lower-fit participants showed signs of overexertion, while male and high-fit participants experienced an appropriate level of exertion to slight underload. Subjective feedback was largely positive, with many participants describing SkyRide as motivating, varied, and physically engaging. Overall, SkyRide demonstrates potential as a health-oriented training modality capable of delivering effective cardiorespiratory stimulation in an enjoyable format. Enhancing the system’s ability to adjust intensity based on individual fitness levels is recommended to improve training balance across user groups.