Investigating the Relative Exercise Intensity of Exergames in Prepubertal Children

Objective: The literature remains equivocal as to whether exergames elicit energy expenditure (EE) commensurate with physical activity guidelines. Such discrepancies may be attributable to a reliance on absolute exercise intensities, which fail to account for differences in cardiorespiratory fitness levels. Materials and Methods: Thirty-four prepubertal children (20 boys, 14 girls; 10.8 +/- 1.0 years old) completed a 30-minute exergame (two 15-minute games from "Kinect Adventures! Xbox 360" [Microsoft, Redmond, WA]) and an incremental treadmill test to determine peak oxygen uptake ( [GRAPHICS] ) throughout which breath-by-breath gas exchange was measured. Results: Both games elicited moderate-intensity physical activity (5.7 +/- 1.5 and 5.5 +/- 1.4 metabolic equivalents [METs]), with 36 percent demonstrating a mean EE in excess of 6.0 METs, commensurate with vigorous intensity. Furthermore, boys demonstrated higher EE during both games (boys versus girls: Game 1, 6.0 +/- 1.7 versus 5.2 +/- 1.0 METs; Game 2, 6.0 +/- 1.4 versus girls, 4.9 +/- 1.2 METs; P < 0.05). Hierarchical linear regression revealed sex, maturity, and fitness to be significant predictors of EE, accounting for 24 percent of the variance: relative exergame [GRAPHICS] = 24.53 + (2.12 x Sex) - (0.42 x Maturity offset) - (0.16 x Relative peak [GRAPHICS] ). There was no correlation between absolute [GRAPHICS] during the exergames and peak [GRAPHICS] , but [GRAPHICS] expressed as a percentage of peak [GRAPHICS] was correlated with peak [GRAPHICS] during both Game 1 (r = -0.62, P < 0.01) and Game 2 (r = -0.59, P < 0.01). Conclusions: The present findings provide further evidence that exergames can elicit EE values commensurate with national physical activity guidelines and extend our understanding of the mediators of EE. Specifically, cardiorespiratory fitness and sex must both be considered in the design and implementation of future interventions seeking to use exergames to enhance physical activity levels and/or cardiorespiratory fitness.