Profiling exercise intensity during the exergame Hollywood Workout on XBOX 360 Kinect®

Introduction

Physical inactivity is associated with an increase in the risk of a variety of chronic diseases (such as diabetes mellitus and arterial hypertension) and consequently, premature deaths (Ding et al., 2016). Although well documented, a large part of the population remains sedentary (Fox, 2012). In this context, adults who are not engaged in traditional exercise methods with a minimum intensity corresponding to 55% of maximal heart rate (HRmax) require a strategy to achieve and maintain sufficient physical activity for health benefits (Garber et al., 2011).

Exergames, or active videogames, may motivate some adults to engage in physical activity and may be an attractive and fun alternative of physical activity for increasing the motivation of people to engage in an exercise programme (Street, Lacey & Langdon, 2017).

Exergames can be defined as electronic games that allow players to physically interact with images on screen (Foley & Maddison, 2010). Traditionally, exergames are characterized as physical activities including games that simulate walking, running, stair climbing, cycling, rowing, and swimming (Graves et al., 2010; Wu, Wu & Chu, 2015). Furthermore, there are games that require mixed activity that simulate jumping, throwing, and kicking (Bird et al., 2015).

Most studies involving exergames investigated the acute and chronic effects on caloric expenditure (Barkman et al., 2016), motor aspects (Collado-Mateo et al., 2017), and cognitive function (Garcia et al., 2016; Stanmore et al., 2017) in different healthy and clinical populations (Dos Santos Mendes et al., 2012; Collado-Mateo et al., 2017). However, less is known about the physiological responses during an exergame session, especially regarding oxygen uptake (${\dot{\text{V}}\text{O}}_{\text{2}}$) and heart rate (HR). These physiological variables are a common form for gathering information about exercise intensity. Moreover, these physiological variables are useful tools to monitor responses and adaptations to exercise. In this regard, it has previously been shown that an increase in one metabolic equivalent in exercise capacity decreases mortality rate by 12% (Myers et al., 2002; Kodama et al., 2009).

Neves et al. (2015) investigated the acute cardiovascular responses during a session of the game Zumba Fitness Core® performed with XBOX 360 and observed a significant increase of HR immediately after the session. Graves et al. (2010) compared the physiological cost among adolescents, young, and older adults during a game with a joystick, Wii® Fit activities (yoga, muscle conditioning, balance, and aerobics), and brisk treadmill walking and jogging and found that energy expenditure and HR of Wii® Fit activities were greater than joystick games, but lower than treadmill exercise and that the Wii® elicited moderate intensity activity. Rodrigues et al. (2015) evaluated the acute metabolic and cardiovascular responses of healthy men during exergames with the Nintendo Wii® (obstacle course, hula hoop, free run, soccer heading, penguin slide, and table tilt) and found that the Wii® exercises are considered to be of light and moderate intensity. Wu, Wu & Chu (2015) examined and compared the energy expenditure and intensity of XBOX 360 Kinect® exergames (boxing, soccer, track and field, ping pong, beach volleyball, and bowling) in healthy young adults and observed that boxing and soccer exergames provided the greater exercise intensity. It is important to note that none of these studies determined exercise intensity based on metabolic thresholds obtained in a continuous laboratory treadmill test, such as maximal graded exercise testing (GXT) (De Lira et al., 2013).

Thus, despite the increasing popularity of exergame practice (Sween et al., 2014) and its promising benefits in counteracting physical inactivity, limited research has been performed to document the physiological responses during an exergame session, which makes it difficult to characterize the physiological responses and brings uncertainty regarding its potential benefits in increasing physical fitness. Therefore, the aims of this study were to investigate physiological parameters of young men, to describe HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ responses during the exergame Hollywood Workout on XBOX 360 Kinect session, and to compare with responses in a joystick game. Also, the study compared HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ responses during exergame with those HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ associated with first and second ventilatory thresholds (VT1 and VT2, respectively) attained during a maximal graded exercise test.

The exergame Hollywood Workout on XBOX 360 Kinect was chosen with the intention of maintaining ‘ecological validity,’ as this game simulates some exercises, such as, push-ups, skater lunges, and bicycle crunches that are performed in exercise facilities.

Materials and Methods

Experimental procedures

Maximal graded exercise testing

Graded exercise testing was administrated to determine VT₁, VT₂, and maximal oxygen uptake (${\dot{\text{V}}\text{O}}_{\text{2}}\max$), as well as their associated running velocities, HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$. Prior to performing the GXT, participants were given a standardized set of instructions explaining the test. On completion of these preliminary procedures, each participant underwent an incremental maximal exercise test on a motorized treadmill (ATL, Inbramed, Porto Alegre, Brazil) with 0% slope. The schedule of this test consisted of a 5-min warm-up period at seven km.h⁻¹, and then the initial speed was progressively increased by one km.h⁻¹ every minute until exhaustion (De Lira et al., 2013). During the exercise testing, participants were verbally encouraged to exercise for as long as possible. Respiratory gas samples were measured continuously using a metabolic system (VO2000; MedGraphics, Saint Paul, USA). Prior to testing, the metabolic system was calibrated according to the manufacturer’s instructions. HR was recorded using a HR-monitor (RS800CX; Polar Electro, Espoo, Kempele, Finland). Figure 1 shows a participant during the GXT.

The following data (averaged over 10 s) were obtained: ${\dot{\text{V}}\text{O}}_{\text{2}}$ (mL.kg⁻¹.min⁻¹) at standard temperature (0 °C) and barometric pressure at sea level, carbon dioxide production (${\dot{\text{V}}\text{CO}}_{\text{2}}$) (mL.kg⁻¹.min⁻¹) at standard temperature (0 °C) and barometric pressure at sea level, respiratory exchange ratio (RER), minute ventilation (${\dot{\text{V}}}_E$) (L.min⁻¹) at body temperature and saturation pressure, respiratory rate (breaths per minute (bpm)), ventilatory equivalents for O₂ and CO₂ (${\dot{\text{V}}}_E$/${\dot{\text{V}}\text{O}}_{\text{2}}$ and ${\dot{\text{V}}}_E$/${\dot{\text{V}}\text{CO}}_{\text{2}}$, respectively), expired fractions of O₂ and CO₂ (%) and HR (beats per minute (bpm)). Peak treadmill speed was defined as the last achieved running speed sustained for at least 30 s. ${\dot{\text{V}}\text{O}}_{\text{2}}\max$ was defined as the highest 10-s averaged ${\dot{\text{V}}\text{O}}_{\text{2}}$ value with inclusion criteria consistent with conventional guidelines for ${\dot{\text{V}}\text{O}}_{\text{2}}\max$ (e.g. an inability to sustain the workload, relative HR > 95% predicted for their age, RER at maximal exercise ≥ 1.1, and ${\dot{\text{V}}\text{O}}_{\text{2}}$ plateau [the point at which ${\dot{\text{V}}\text{O}}_{\text{2}}$ increases less than 150 mL.min⁻¹ for a given increase in workload]) (Howley, 2007). VT₁ and VT₂ were assessed using established criteria (Wasserman et al., 2005). Briefly, VT₁ corresponds to the break point in the plot of ${\dot{\text{V}}\text{CO}}_{\text{2}}$ as a function of ${\dot{\text{V}}\text{O}}_{\text{2}}$. At that point, ${\dot{\text{V}}}_E$/${\dot{\text{V}}\text{O}}_{\text{2}}$ increases without an increase in ${\dot{\text{V}}}_E$/${\dot{\text{V}}\text{CO}}_{\text{2}}$. VT₂ was located between VT₁ and ${\dot{\text{V}}\text{O}}_{\text{2}}\max$, when ${\dot{\text{V}}}_E$/${\dot{\text{V}}\text{CO}}_{\text{2}}$ starts to increase and ${\dot{\text{V}}}_E$/${\dot{\text{V}}\text{O}}_{\text{2}}$ continues to increase. VT₁ and VT₂ were determined independently by two experienced investigators. If agreement between the investigators was not achieved, VT₁ and VT₂ were determined by consensus. To determine the ${\dot{\text{V}}\text{O}}_{\text{2}}$ and ${\dot{\text{V}}}_E$ at VT₁ and VT₂, the average of the last 10 s of each corresponding level was used. In practical terms, ventilatory thresholds represent points that can be used to classify the intensity of aerobic exercise.

Exergame session

The exergame session was conducted in a room (10 × 6 m) and was accompanied by a certified trainer that was experienced in exergames. For the purposes of the present study, the exergame Hollywood Workout (Majesco Entertainment, Edison, Hazlet, NJ, USA) was used with the intention of maintaining ‘ecological validity,’ as this game simulates some exercises usually performed in exercise facilities. Indeed, this exergame has several pre-established training protocols consisting of standardized exercises. Due to the feasibility of performing the exercises by coupling the participant to the metabolic system, the training protocol used in the present study was the Sports Athlete.

The Sports Athlete protocol consists of three phases: warm-up, main, and cool-down, with a total exercise time of 19 min and 28 s and total time in transitions between exercises of 8 min and 32 s, totalling a session of 28 min. However, total session time could vary according to the ability of the participant in the transitions between exercises. At the end of the Sports Athlete protocol, a numerical total score was provided. Table 1 provides the exercises used in Sports Athlete protocol.

Table 1:

Sports athlete protocol of the exergame Hollywood Workout.

Phases	Exercises	Sets	Time (seconds)	Repetitions*
Warm-up	Jog	1	71	25
	Trunk crosses	1	62	20
	Jumping jacks	1	68	40
	Ice skaters	1	59	12
Main	Push-ups	1	59	12
	Skater lunges	1	69	16
	Bicycle crunches	1	74	25
	Push-ups	1	73	15
	Skater lunges	1	82	24
	Bicycle crunches	1	74	25
	Push-ups	1	74	15
	Skater lunges	1	81	24
	Bicycle crunches	1	74	25
Cool-down	Punches	1	61	25
	Jump rope	1	56	40
	Side shuffles	1	68	20
	Mountain climbers	1	63	25

DOI: 10.7717/peerj.5574/table-1

Note:

* Repetitions proposed by the exergame. However, the participant was instructed to perform as many repetitions as possible.

Heart rate and ${\dot{\text{V}}\text{O}}_{\text{2}}$ were recorded before and during (including rest periods between sets) the Sports Athlete protocol. HR (5 s average HR value) and ${\dot{\text{V}}\text{O}}_{\text{2}}$ (10 s average ${\dot{\text{V}}\text{O}}_{\text{2}}$ value) registers were monitored by a HR-monitor (RS800CX; Polar Electronics, Finland) and metabolic system (VO2000; MedGraphics, USA), respectively. HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ recorded during the Sports Athlete protocol were compared with HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ corresponding to VT₁ and VT₂ obtained in GXT Fig. 2 shows participants performing the Sports Athlete protocol.

Joystick session

The participants also underwent a 25-min joystick game session (traditional sedentary video gaming) (Fig. 3). To reduce the effect of playing ability among participants was chosen the joystick-game Injustice: Gods among us, ultimate edition. This game is easy to play and allow the participants restart the fight easily and faster. We tried other joystick-games (fight games) but the participants dispended a lot of time between one fight and other. Indeed, we did not find a joystick-game similar with the exergame Hollywood Workout, since it is an exergame which simulates traditional physical exercises. HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ values were recorded during all time sessions and compared with the HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ corresponding to VT₁ and VT₂ obtained in GXT.

Results

Discussion

The main aims of the present study were to investigate the responses of HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ in young men during an exergame session (Hollywood Workout on XBOX 360 Kinect®) and compare with HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ measured during joystick session. We also aimed to compare HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ during the exergame session in relation to VT₁ and VT₂. As expected, physiological response values during the joystick session were lower than those evaluated during the exergame session. In addition, we found that the average intensity of the Sports Athlete protocol was ‘light to moderate,’ as an appreciable percentage (∼86% [HR] and ∼92% [${\dot{\text{V}}\text{O}}_{\text{2}}$]) of the exercise bout occurred at an intensity lower than HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ in VT₁ levels (Stangier et al., 2016). Confirming this finding, the average percentage HRmax and percentage ${\dot{\text{V}}\text{O}}_{\text{2}}\max$ during the Sports Athlete protocol were 70.7% and 41.6%, respectively.

These values are similar to data from other studies with exergames (Tan et al., 2002; Unnithan, Houser & Fernhall, 2006; Jordan, Donne & Fletcher, 2011) and contrary to other (Neves et al., 2015). Jordan, Donne & Fletcher (2011) reported that 15 healthy men (age 29 ± 4 years, body mass 81 ± 12 kg, height 1.77 ± 0.05 m, body mass index 25.9 ± 3.8 kg.m⁻², ${\dot{\text{V}}\text{O}}_{\text{2}}\text{peak}$ 44.8 ± 5.5 ml.kg⁻¹.min⁻¹) attained ∼66% and ∼72% of HRmax and ∼41% and ∼56% of ${\dot{\text{V}}\text{O}}_{\text{2}}\max$ during Wii® boxing and an exergame controlled only with movements of the lower limbs through the PlayStation® 2, respectively. Tan et al. (2002) reported that 40 young individuals (21 men and 19 women, age 17.5 ± 0.7 years) attained an average HR of 137 bpm (70% of HRmax), average ${\dot{\text{V}}\text{O}}_{\text{2}}$ of 24.6 mL.kg⁻¹.min⁻¹ (44% of ${\dot{\text{V}}\text{O}}_{\text{2}}\max$) during the exergame Dance Dance Revolution 3rd Mix^™ Konami®. Unnithan, Houser & Fernhall (2006) reported that children and adolescents (11–17 years) attained ∼65% of HRmax during the exergame Dance Dance Revolution^™ Konami®. On the other hand, average ${\dot{\text{V}}\text{O}}_{\text{2}}$ (∼35% of ${\dot{\text{V}}\text{O}}_{\text{2}}\text{peak}$) did not reach the minimum values for development and maintenance of cardiorespiratory fitness (>46% of ${\dot{\text{V}}\text{O}}_{\text{2}}\max$) proposed by the American College of Sports Medicine (ACSM) (Garber et al., 2011), similar to the results of the present study. Mills et al. (2013) and Lau et al. (2015) found similar results to the present study regarding percentage of HRmax in children during a high-intensity exergame (Kinect Sports–200 m Hurdles) and the exergame I-Dong running, respectively; however, the percentage of ${\dot{\text{V}}\text{O}}_{\text{2}}\max$ reported by Mills et al. (2013) and Lau et al. (2015) was, respectively, lower (40.3%) and higher (61.4%) than that found in the present study. In general, despite previous studies investigating different populations and exercises, our results are in line with the literature. However, it is important to emphasize that the presented data should be extrapolated with caution.

According to the ACSM criteria, the intensity of the Sports Athlete protocol of the exergame Hollywood Workout can be classified as moderate, since it elicited average HR values corresponding to 70.7% of HRmax, framed in the range of 64–76% of HRmax proposed by the ACSM (Garber et al., 2011). The moderate intensity of the Sports Athlete protocol can be justified by fact that the evaluated participants presented high cardiorespiratory fitness, demanding a lower HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ for the same workload when compared to sedentary individuals (DeMaria et al., 1978). In addition, the ACSM suggests that exercise must have a minimum intensity corresponding to 55% of HRmax to evoke the benefits of aerobic training (Garber et al., 2011). Therefore, the Sports Athlete protocol of the exergame Hollywood Workout can be a useful tool for improving cardiorespiratory fitness as well as being an alternative tool to traditional exercise protocols. However, it should be noted that for this purpose, the weekly exercise volume of at least 150 min (which would correspond to five exercise sessions, considering that each Sports Athlete protocol lasts approximately 30 min) must be met. An important advantage of the Sports Athlete protocol compared to classic aerobic activities (e.g. running, cycling) is that this protocol has exercises for both lower and upper limbs, thus being a training protocol for the whole body, which can increase ${\dot{\text{V}}}_E$, HR, and ${\dot{\text{V}}\text{O}}_{\text{2}}$ values to exercise through a greater amount of muscle mass involved (Jensen-Urstad, Svedenhag & Sahlin, 1994).

When evaluating the protocol in phases, significant differences were found between average HR of the ‘warm-up’ and the ‘main phase.’ As desired, the intensity of the ‘warm-up’ period was lower than the intensity of the ‘main phase,’ which follows the recommendations for exercise prescription (Powers & Howley, 2017). This is a very important aspect, since the ‘warm-up’ may be related to the reduction of the probability of muscular injuries due to stretches or dislocations (Woods, Bishop & Jones, 2007) in addition to influencing subsequent physical (Fradkin, Zazryn & Smoliga, 2010) and muscular performance (Mascarin et al., 2015). On the other hand, a significant increase of the HR and ${\dot{\text{V}}\text{O}}_{\text{2}}$ occurred at the end of the ‘cool-down.’ This is contrary to the recommendations for exercise prescription (Pescatello et al., 2014; Powers & Howley, 2017), since the ‘cool-down’ should provide a gradual decrease of the HR (Powers & Howley, 2017). A possible explanation for the ‘cool-down’ intensity remaining high may be related to the Mountain Climbers exercise present in the ‘cool-down’ period, since the participants arrived very close to the ‘maximum effort’ (reported by participants), reflecting the amount of repetitions performed both in this exercise as in the others that constituted the ‘cool-down.’

Conclusions

From the present data, it appears that the exergames used in the present study can be classified as light to moderate physical exercise for the participants evaluated. Indeed, during the exergames trial, ${\dot{\text{V}}\text{O}}_{\text{2}}$ and HR remained predominantly below the VT₁ level previously assessed during the GXT. Confirming this finding, the average ${\dot{\text{V}}\text{O}}_{\text{2}}$ and HR during the exergames were according to ACSM’s recommendations. Thus, exergames could be an interesting alternative to traditional forms of exercise as a tool for increasing physical fitness.

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