Video gaming has become a popular recreational pastime of many people around the world. In addition to the prevalence of child participation in gaming, as much as 45% of the adult population in the USA also plays video games with some evidence suggesting that greater participation is associated with poorer mental and physical health in this population (13). A recent trend has been to develop new video games that incorporate physical activity into gaming, rather than relying on traditional sedentary gaming activity. This trend is an effort to counter the negative effects of sedentary gaming and theoretically would allow game manufacturers to capitalize on the potential positive effects of gaming on physical fitness and health.
Products such as Nintendo's Wii Fit™ are advertised as a new way to work out from the comfort of your own home. In addition to children, data suggest that adults are also involved in using this new mode of gaming to improve and maintain physical fitness (5). Some data suggest that active video games significantly increase total body movement and energy expenditure compared to sedentary gaming (1-5,10). Although some accurate energy expenditure data exist regarding caloric expenditure in children (12) and young male college students (11) playing a video dance game, Dance, Dance Revolution™, to our knowledge, only 1 study has used an accurate method of measuring oxygen consumption (O2) and energy expenditure to determine the effectiveness of the Wii Fit™ in adults (8). Moreover, we are not aware of any studies that have accurately determined the percentage of maximal oxygen uptake elicited by these active video games in individual participants nor are we aware of any studies that have determined the effect of game level (intensity) on O2.
Accurate determination of O2 and energy expenditure in different video games and game intensity levels, which has not previously been done, is critical in establishing the viability of this form of active gaming to improve health status. Understanding the O2 and caloric cost of different video games and game levels would allow game users to accurately determine the time required to meet aerobic exercise intensity recommendations and to change the game or game level to meet a specific caloric expenditure requirement. Adjusting the game level or game time to achieve known metabolic rates and caloric costs would enable the user to meet goals for physical fitness and overall health.
This study was conducted to precisely determine the effect of 2 of the more popular Wii Fit™ aerobic fitness games and game levels on O2, energy expenditure, and percentage of O2max. We hypothesized that the O2 and energy expenditure from the step and hula games at the intermediate game level would be comparable to moderate to brisk walking and would elicit an oxygen cost equivalent to approximately 30% O2max. In addition, we hypothesized that the game level would significantly affect O2 and caloric expenditure and that higher game levels would be better for meeting recommended energy expenditure requirements for improved health.
Experimental Approach to the Problem
Subjects performed 2 exercise sessions employing a within-subject study design. The sessions consisted of a preliminary trial for basic cardiorespiratory fitness assessment and 2 subsequent sessions, 2 days apart, in a counterbalanced fashion in which they performed different video games, step and hula, at different game levels, beginner and intermediate. The O2, percent O2max, caloric expenditure, respiratory exchange ratio (RER), and rating of perceived exertion (RPE) were assessed and compared between the 2 trials. Measuring O2 and percent O2max allowed for accurate determination and comparison of the oxygen cost and the induced cardiorespiratory stress between the step and hula games in response to the beginning and intermediate game stages. Measuring RER allowed for accurate determination and comparison of carbohydrate as well as fat use and (combined with O2 data) kcals expended per minute between the step and hula games at the beginning and intermediate game levels. Measuring RPE allowed for determination of effort perception. Collectively, these variables were analyzed to determine whether oxygen and caloric cost of these 2 games along with substrate use and effort perception at an intermediate stage were greater than that elicited by a beginning stage and equal to values found from walking at 3.5 mph. These data could be used subsequently to establish the viability of the Wii Fit™ hula and step games for health improvement.
Volunteers were recruited from a university student population. The experimental procedures of the study were approved by the Southeastern Louisiana University Institutional Review Board. Eight apparently healthy female college students (mean ± SD age, height, weight, and O2max = 21.88 ± 2.20 years, 170.25 ± 7.29 cm, 71.31 ± 11.13 kg, and 33.11 ± 2.33 ml·kg−1·min−1, respectively) completed a medical history questionnaire and gave written informed consent to participate in the study. None of the subjects was a college athlete engaged in a strenuous aerobic training regimen. Exclusion criteria for participation in the study included (a) history of any cardiovascular disease, (b) presence of metabolic diseases that could affect metabolic responses, for example, diabetes, (c) taking prescription medications that could affect metabolic or cardiorespiratory measures, and (d) inability to complete 30 minutes of Wii Fit activity™. Each subject participated in 3 separate sessions.
The first session consisted of preliminary height and weight measurements and a graded exercise test to determine O2max. The O2max was assessed on a treadmill by measuring respiratory gases with an automated system (ParvoMedics, TrueOne 2400, Sandy, UT, USA). Before each O2max determination, gas analyzers were calibrated with gases of known composition. Subjects began the graded exercise test at 2.5 mph and 4% grade. Every 2 minutes, the treadmill speed was increased 1 mph and 4% grade remained constant (Kraemer Protocol). Subjects reached O2max with achievement of either the primary criterion of a plateau in O2 with increased workload or with 2 of 3 secondary criteria: (a) attained predicted maximal HR, (b) RER > 1.1, or (c) an RPE (15-point Borg scale) of 19 or 20. After the O2max test, the subjects were familiarized with both the Wii Fit™ step and hula games.
Sessions 2 and 3
During the next 2 sessions, the subjects played the Wii Fit™ aerobic step and hula games. Sessions 2 and 3 were scheduled at least 2 days apart, and exercise was restricted for 24 hours before each trial. Subjects began the testing sessions in a 2-4 hours postprandial state. Subjects had varying experience levels with the Wii Fit™. To control as much as possible for experience level, we allowed each subject to become familiar with the game for several minutes after O2max testing in the preliminary trial, and we allowed subjects to adjust to the game for 7 minutes at each stage before measuring O2.
Before subjects began the games, resting HR and blood pressure (BP) were recorded. Subjects then performed the game for 1 minute as a warm-up followed by 10 minutes at the game level. Subjects completed 3, 10-minute game stages with 5-minute rest between stages allowing time to measure and record HR, BP, and RPE (6-20, Borg scale) of the subject. The games were counterbalanced for each subject. The first and second 10-minute stages consisted of beginning or intermediate step or hula. The third 10-minute stage was used to monitor subjects' responses to both advanced step and boxing; however, several subjects did not meet the proper step sequence, which resulted in data from the third 10-minute period not being viable for steady-state O2 determination; therefore, only data from the first and second 10-minute stages were analyzed. The subject's O2 and RER were measured continuously while playing each game using the same metabolic cart used in session 1. From the O2 data, energy expenditure (kcal·min−1) and RER were determined.
The stages (beginning and intermediate) included multiple game sessions so that they added up to 10 minutes each stage, that is, the beginning hula game session only lasted approximately 2 minutes, so the game was restarted multiple times encompassing 10 minutes of play. The reason why we chose 10-minute stages was because of the nature of the video games. We wanted each subject to reach and maintain a steady-state O2. Steady-state O2 is typically reached within 2-3 minutes in aerobic activity. In the case that the subject was frustrated by the game because of differences in experience or skill, the 10-minute time period allowed them to respond to the game and adjust their movements so that after 7 minutes, the O2 was expected to be stable and could be measured as steady-state O2 during the last 3 minutes of the 10-minute game stage. Data reviewed from the subjects across the 10-minute stage indicated that indeed this was the case. In addition, we viewed 10 minutes as a duration representing typical time players spend at a game level before becoming bored and changing games or game levels.
The O2 during the last 3 minutes of each 10-minute stage for beginner and intermediate hula and step was used for analysis. O2 (L·min−1) was converted to %O2max for each subject. %O2max, RER, caloric expenditure (kcal·min−1), and RPE were analyzed using dependent t-tests. Differences were considered significant at an alpha level of p ≤ 0.05. Energy expenditure from carbohydrate and fat use during the last 3 minutes of each game phase was determined by multiplying the average O2 in liters per minute for each minute by the caloric equivalent of the corresponding RER using standard thermal equivalents of oxygen utilization based on nonprotein RER. In a few cases in which RER slightly exceeded 1.0, an energy equivalent of 5.047 was used.
Analyses revealed that %O2max was significantly higher for the intermediate step than for the beginning step game level (Figure 1). Although mean values were higher for the intermediate hula game level than for the intermediate step game level, %O2max was not significantly different between games at the intermediate level. Percent O2max ranged from 30.6% for the beginning step to 39.4% for intermediate hula. As expected, caloric expenditure followed the same pattern as %O2max with significantly higher kcal·min−1 for the intermediate step and hula than beginning step and hula, significantly greater kcal·min−1 for intermediate hula than for the beginning step, but similar values at the intermediate level for both games (Figure 2).
Respiratory exchange ratio was not significantly different between the intermediate and beginner game levels (Figure 3). Respiratory exchange ratio values ranged from 0.91 to 0.96. The RPE was lowest in the beginning step and highest in intermediate hula with perceptions of effort significantly affected by game level and intermediate hula being significantly greater than in the beginning step (Figure 4).
One of the ways in which the physiological responses to active gaming can be determined to be effective is to compare the responses to those of other modes of exercise. We compared the O2 and energy expenditure rates for beginning and intermediate hula and step to that of grade walking. Using standard equations that predict O2 from walking speed (14), we determined that the lowest O2 value (10.13 ml·kg−1·min−1) was equivalent to a walking speed of 4.02 km·h−1 (2.5 miles·h−1) and the highest O2 (13.14 ml·kg−1·min−1) was equivalent to walking 5.79 km·h−1 (3.6 miles·h−1).
Data from the study substantiated the hypotheses that the video games would elicit a %O2max of approximately 30% and that game level would affect oxygen and caloric cost of the physical activity. This study revealed that the metabolic responses to the Wii Fit™ games of step and hula elicited greater %O2max and energy expenditure values at higher vs. lower game levels of the same game and that greater values were produced by the intermediate hula compared with the beginning step game. This is the first investigation to determine the precise O2, %O2max and caloric expenditure in response to Wii Fit™ active gaming at different game levels in adults. The data presented in this study suggest that this form of active gaming can be used to generate important health benefits generally produced by aerobic exercise in adults, especially at higher game levels.
Playing short intervals of Wii Fit™ aerobic games has been compared to light to moderate intensity activities, such as walking or jogging (6), but there are few studies that have accurately measured oxygen cost and caloric expenditure of these games. In this study, the highest RER (0.96), highest % O2max (39.8%), and the highest caloric expenditure (4.70 kcal·min−1) values were found during intermediate hula. This could be attributed to the fact that the hula involves more total body movement exercise than step and uses more muscle groups. The lowest of these values was found during the beginning step game. This could be attributed to the fact that the step game at this lower intensity level involves mostly lower limb work without additional upper body muscle contractions, with a constant step up and step down on the board compared to the constant swivel motion of the whole body.
Research has been conducted with children playing the Dance Dance Revolution game (1,11,12) and with adults playing 2 other games, XaviX J-mat and XaviX bowling (7). These investigations have reported increases in HR and caloric expenditure in subjects playing these games. Another study investigated the effects of the Wii Fit™ to improve balance, strength, and aerobic power in women (30-58 years) over 10 weeks. They found no significant improvements in aerobic power based on a 6-minute walk test (9). This study did not use open circuit spirometry as we did to measure the subject's aerobic power. A recent and very thorough study by Miyachi et al. (8) compared the caloric costs of a number of Wii Fit™ games using a metabolic chamber. The caloric expenditure values that were presented for hula and step were within a range similar to those presented in this study, but the investigators did not differentiate between stage levels, nor did they measure the subjects O2max to determine the percentage of O2max the active video games represented.
Thus, this study clearly demonstrates that the Nintendo Wii Fit™ hula game produces greater metabolic stress and energy expenditure than does the step game with an equivalent effect of a walking speed >3.5 mph (American College of Sports Medicine Metabolic Equations). Moreover, increases in game level significantly increase oxygen consumption and caloric expenditure in these games. Future studies should consider the effects of age and gender on caloric cost and metabolic responses to the wide variety of Wii Fit™ games to develop recommendations for optimal benefit by the general population.
Data from this study suggest that this form of active video gaming (step and hula) can be used as an effective mode of physical activity to improve health in adult women, but that users should strive to participate at higher (intermediate) game levels for fitness improvement.
We wish to thank the subjects for participation in the study. We also wish to thank Michelle Francois for her work in the laboratory. There is no disclosure of funding to report for this study.
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