The purpose of this study was to characterize the heart rate response to 30 minutes of Nintendo Wii Sports boxing to determine if this active video game provides a cardiorespiratory training stimulus and contributes to the daily exercise requirements for healthy young adults. Our hypothesis that participants would achieve a HR response that would provide cardiorespiratory benefits was supported by the finding that 18 of 20 participants had a mean HR response in the moderate-intensity or vigorous-intensity range. Furthermore, this HR response occurred across a range of fitness levels, as evidenced by the wide range of fitness levels among participants and the lack of correlation between fitness level and HR response to the boxing session. Overall, the results of this study indicate that for healthy young adults of varying levels of fitness Wii Sports boxing can serve as a light-intensity to very high-intensity form of aerobic exercise, based on the ACSM guidelines for achieving cardiorespiratory fitness.3
The current investigation expands on the findings of other recent investigations that measured HR and metabolic responses in adults when playing several active video games in a 30-minute session.17,18
Siegel et al17
studied a similar age group to ours and found that exercise HR was adequate for a training response and energy expenditure was sufficient to meet ACSM recommendations for daily physical activity. These investigators tested a small number of subjects using 3 different active games in an arcade setting, but playing video games at home is a more convenient and likely means of engaging in active video game play. While the mean HR for the 3 arcade games was higher than the mean HR for the current study, 2 of the 3 arcade games primarily involved the lower extremities during play, and participants actively moved from one game to another during the session, making a comparison of HR response in these two settings difficult.17
Our lower mean HR response, while still considered vigorous,3
probably engaged the lower extremities to a lesser extent than the arcade games. However, an active video game like Wii boxing that engages both upper and lower extremities may still have the potential to elicit a maximal HR response similar to what one might achieve with a lower-extremity dominant activity such as running.21
Graves et al18
also reported different HR responses to active video games than what we report here, but unlike our findings with Wii Sports boxing, their reported HR response to Wii Fit aerobics was below recommended levels for maintaining cardiorespiratory fitness for adolescents and younger and older adults. The researchers compared the metabolic and HR response in these age groups to inactive video games, Wii Fit games, and treadmill jogging. They found that in spite of the inadequate HR response energy expenditure during Wii Fit aerobics was of moderate intensity, but this intensity was only measured for 10 minutes.18
We were interested in engaging our participants in a sustained bout of a single active game to assess its effectiveness in producing a cardiorespiratory response similar to a typical bout of conventional aerobic activity. Unfortunately, a direct comparison between HR response and metabolic cost for individuals cannot be made because these two parameters are not linearly related.22,23,24
Therefore, we measured HR response because this measure provided a more direct representation of the cardiorespiratory response during Wii Sports boxing, but we did not measure energy expenditure. Miyachi et al16
also measured the metabolic cost of interactive Wii games (both Wii Sports and Wii Fit games) in adults and, similar to Siegel et al17
and Graves et al,18
they concluded that the increased energy expenditure contributes to the 30 minutes of physical activity that adults are recommended to participate in at least 5 days per week. However, based on 8 minutes of metabolic measurements, Miyachi et al16
concluded that these activities could be considered at most a moderate-intensity activity, depending on the game, but not a vigorous-intensity activity. The relationship between metabolic cost and HR response to an exercise bout is complicated,24
but this metabolic finding is not consistent with the mean HR intensity, which was in the vigorous or very hard intensity range for our participants for 58% of the 30-minute boxing session. Eight minutes of play may not be sufficient time to interpret whether active video games provide cardiorespiratory benefits and contribute to daily physical activity requirements. There is a benefit in playing these games for a longer period as our participants did, not only because longer play would increase energy expenditure but because it would provide the chance for more challenging levels of play, which could contribute to a greater cardiorespiratory (HR) response.
In contrast to our findings and those of other studies for adults playing active video games, Graves et al14
compared the caloric expenditure in 13- to 15-year-old adolescents playing active and sedentary video games. As expected, the authors found that playing active video games used significantly more energy than sedentary video games and that the mean energy expenditure during Wii Sports boxing produced the greatest metabolic response of all Wii Sports games, using 730 kJ/h compared to 450 kJ/h for a more sedentary video game. However, the authors concluded that the energy expenditure from playing Wii Sports games was not high enough to contribute to the 60-minute recommended daily amount of exercise for children. Since adults and children have different daily exercise recommendations,3
the use of active video games to meet daily activity recommendations may be appropriate for adults but not for children.
One consideration in the use of active video games as exercise for both children and adults is that exergaming may not provide the same stimulus as performing the actual activity. Graves et al14
noted that energy expenditure measured during individual Wii Sports games in their adolescent population was much less than calculated values of energy expenditure during those actual activities. Similarly, Wii Fit aerobics was determined to elicit less energy expenditure than treadmill walking or jogging for adults.18
Kravitz et al25
studied the cardiorespiratory response to punching tempo in young adults (mean [SD] age, 22 [2.8] years). During 2-minute shadow boxing trials, participant heart rates were between 167 and 182 bpm, or 85% to 93% of HRmax
, suggesting that shadow boxing to an upbeat tempo has cardiovascular benefits. The mean HR response of our participants to Wii boxing was lower than the Kravitz et al25
results, with individual responses ranging from 57% to 90% of HRmax
, but our exercise session was sustained for a much longer time. Hence, while some forms of exergaming may not produce the same physiological response and benefits as would occur with a real sport, an active video game such as Wii boxing does elicit a physiological response that is consistent with cardiorespiratory benefits. Thus, the current findings suggest that active video games provide an alternative to standard cardiorespiratory training activities, which may be appealing for some people.
An interesting finding in our study was that participants with less experience playing Wii Sports boxing spent more time in vigorous to very hard intensities of activity, while those with previous experience spent more time in light, moderate, and vigorous intensities, but no time in very hard intensity. White et al26
assessed the influence of experience on energy expenditure during active video game play in boys and concluded that experience did not affect energy expenditure during play. However, Sell et al27
measured significantly higher energy expenditure and mean HR among college-age males who used the interactive Dance Dance Revolution
(DDR; Sony Computer Entertainment of America, Foster City, CA). In spite of the trends observed in our study, only one experienced participant had a markedly lower HR response to Wii boxing than the others (mean response 56.7% of HRmax
) and was the only participant who subjectively reported himself to be an expert in Wii boxing. During the boxing session, this participant was observed using much less upper extremity, trunk, and lower extremity movements than other participants. Such observations were not measured in this study, so they cannot be compared quantitatively among the participants. The lower HR response in this expert player could reflect the participant's playing style, or it might indicate that refined Wii boxing skills reduce the cardiorespiratory response due to greater efficiency of movements. This particular participant was in the 75th percentile for aerobic power and reported engaging in daily exercise that included resistance and aerobic conditioning, but other participants had higher aerobic power and reported similar exercise regimens. Furthermore, one other participant who had a mean HR response in the light intensity range had a similar level of fitness, but reported no experience with Wii boxing. Considering the stratification trends that occurred in this study, Wii boxing may elicit a higher aerobic response among those with more limited Wii boxing experience. Alternatively, an optimal cardiorespiratory response may be obtained through enthusiastic play and intentional use of the whole body during a session, regardless of experience. This type of play could be encouraged in those who play the game for cardiorespiratory fitness and should be further investigated among individuals of varying levels of expertise with the game. However, the finding of a higher HR response among less experienced players also raises the caution that some individuals, particularly elderly or medically-compromised people, should be monitored carefully during play as Wii boxing could elevate their HR beyond recommended training intensities.
An added benefit of playing active video games is that a player might exercise intensely without perceiving the activity as difficult. In spite of the moderate to vigorous HR response among our participants, the mean RPE rating was “somewhat hard” and did not differ by experience. The perception of exertion could be related to being engaged in an enjoyable exercise. Obese adults have reported walking for pleasure as “light” intensity in terms of perceived exertion, in spite of working at 70% of HRmax
The current study had several limitations that should be acknowledged. First, this study included healthy young adults and only HR response and perceived exertion were measured while they played Wii Sports boxing, an upper extremity dominant active video game. Our results should not be extrapolated to other populations or other active video games. Second, HR responses were measured while subjects played Wii boxing during a single session. The HR response to multiple sessions may differ from the response to a single session, and the potential training effects cannot be determined based on the current study. Finally, delayed-onset muscle soreness or other effects of the session were not monitored during the days following the boxing session, and these effects may need to be taken into consideration if an older or compromised population were to play Wii boxing.
In spite of the acknowledged limitations, the results from the current study support the use of an active video game for cardiorespiratory benefits and provide a useful foundation for future studies. For instance, the longitudinal training effects of Wii Sports boxing should be measured, and the effects of Wii boxing in other populations, particularly those with cardiorespiratory or neurological impairments, should be investigated. Those individuals tend to have much lower aerobic capacity than their healthy counterparts and would benefit from a cardiorespiratory exercise that engages the whole body. Considering the clinical applications of this research, the HR responses from the current study could be compared to HR responses from playing other Nintendo Wii Sports and Wii Fit games, as well as other active video games. Comparing these data could aid clinicians, such as physical therapists and cardiac rehabilitation specialists, in selecting the most appropriate active video games for their patients, and it could be used as the basis for developing and progressing patient treatment plans.