Technology can boost physical activity promotion  

Accelerometers record body acceleration minute to minute, providing detailed information about the frequency, duration, intensity, and patterns of movement. Counts from accelerometers are used to estimate energy expenditure. Accelerometers have been used to provide an objective measure of compliance with physical activity recommendations for the U.S. population (Troiano et al. 2008). Accelerometer data indicated that less than 5% of adults in the United States engaged in 30 min/day of moderate exercise, 5 to 7 days/wk. This is substantially lower than the self-reported value (49%) from national surveys. Also, only 8% of adolescents reached the goal of exercising 60 min/day, 5 to 7 days/wk, based on accelerometer data. The relatively higher cost of accelerometers (about $300 U.S. per unit) compared to pedometers ($10 - $30 U.S. per unit) limits their use in large-scale, physical activity interventions. In the future, lower-cost units may be developed and more widely used in national surveys and community-based interventions. Heil, Brage, and Rothney (2012) offer a 7-step, 3-phase algorithm built on best practices for gathering, manipulating, and conveying accelerometry-based physical activity data.

 

Accelerometer technology is now finding its way into newer classes of waist-mounted pedometers and smartphones. The piezoelectric mechanism is sensitive to the vertical acceleration at the hip (Tudor-Locke, Bassett, et al. 2011). Data storage capabilities of these new piezoelectric pedometers range from 1-day periods over 7 days to 1 min periods over 60 days and hour-long periods over 200 days. Stored data are transferable to a computer via a USB cable. Nike has designed a piezoelectric pedometer that fits into a customized indentation in the midsole of the shoe; it uses the ground contact time to derive speed of motion, total distance covered, and energy expended. These data are transmitted by radio waves to an intermediary device (i.e., Apple iPod nano) for display, storage, or eventual download to a computer.

 

Heart rate monitors are used primarily to assess and monitor exercise intensity. These devices are especially useful for monitoring exercise intensity of individuals in cardiac rehabilitation programs and highly trained, competitive athletes. Because heart rate is linearly related to oxygen uptake, it can be used to estimate the individual's exercise energy expenditure. However, estimates of energy expenditure from heart rate may be affected by factors such as temperature, humidity, hydration, and emotional stress.

 

The prediction of energy expenditure during physical activity is improved by 20% when data from heart rate monitors are used in conjunction with accelerometer measures of physical activity (Strath, Brage, and Ekelund 2005). Devices that simultaneously monitor heart rate and body motion provide valid and reliable measures of physical activity of children, adolescents, and adults in free-living conditions (Barreira et al. 2009; Crouter, Churilla, and Bassett 2008; Zakeri et al. 2008). For a thorough discussion regarding the future directions of multisensor data synchronization and data fusion, see the article by Intille and colleagues (2012).

 

Textiles are being explored in terms of their ability to interface between the human body and physiological variables; these smart fabrics hold promise for combining electrical and computing properties with nonintrusive monitoring (Paradiso and Pacelli 2011). Such wearable monitoring systems integrate clothing with sensors capable of remotely monitoring physiological responses during daily activities and sleep (Paradiso, Faetti, and Werner 2011). Baek and colleagues (2012) used a biometric chair to successfully and unobtrusively measure beat-to-beat ECG heart rate and blood pressure without skin-to-sensor contact and while their participants were wearing casual clothes.

 

In addition to being misstated in self-reports, body mass can vary dramatically within any given time period; treating it as a constant introduces error into the energy expenditure equations. Sazonova, Browning, and Sazonov (2011) presented a novel integration of insole pressure sensors with a 3D accelerometer mounted on the heel of tennis shoes. The results of their study led them to conclude that this combination of accelerometry (e.g., motion velocity) and pressure sensor (e.g., body mass) technology is feasible for the indirect estimation of energy expenditure.

 

Wireless body area networks (WBANs) are cutting-edge technological concepts for evaluating physiological responses as individuals undergo their daily activities. WBANs utilize medical-grade sensors (e.g., brain wave, oxygen saturation, motor unit recruitment, blood pressure, temperature, inertia, and location) that are placed on or near the surface of the skin. These various sensors transmit physiological data to a small, unobtrusive coordinator node worn on the body. The coordinator node is responsible for data fusion and integration. These integrated data can then be transmitted either wirelessly via a mobile device (e.g., smartphone with Bluetooth technology) or existing Internet technology to a central data repository (Felisberto et al. 2012; Marinkovic and Popovici 2012). Although WBAN applications have evolved through the need to continuously monitor healthcare patients remotely, this technology may prove to be useful in exercise science research studies.

 

Global positioning system (GPS) technology uses 24 satellites and ground stations as reference points to calculate geographic locations and accurately track a specific activity. For example, a portable GPS unit provides information about altitude, distance, time, and average velocity while hiking. A graph depicting the uphill and downhill portions of the terrain is also provided. GPS can be used in conjunction with accelerometers to assess and monitor physical activity (Maddison et al. 2010; Rodriguez, Brown, and Troped 2005; Schutz and Herren 2000; Troped et al. 2008). Some models can compute calories expended (Maddison et al. 2010). Due to the need of GPS units to detect satellite signals through direct line of sight, they fail to record indoor positions (Cho, Rodrigues, and Evenson 2011). GPS receivers that can be worn on the wrist or upper arm or at the waist are now available. These units are being investigated in terms of their utility in accurately tracking bouts of outdoor walking lasting a minimum of 3 min (Cho, Rodriguez, and Evenson 2011). In a proof-of-principle study, smartphone GPS with accelerometry technology and Bluetooth transmitters were found to be a cost-effective method of noninvasively monitoring temporal and spatial patterns of day-to-day movements both indoors and out (Schenk et al. 2011). As the technology develops, GPS in combination with the global telecommunications networks may become more widely used to assess and to promote physical activity. However, inter- and intra-unit validity and reliability should be established as part of any future research project incorporating GPS technology (Abraham et al. 2012).

 

The geographic information system (GIS) is a computer system that stores information about location and the surrounding environment. Using GIS, the influence of the environment (i.e., its form and design) on physical activity can be assessed (Zhu 2008). Detailed information about using GIS to assess environmental supports for physical activity is available (Porter et al. 2004). GIS was instrumental in an investigation of how the built environment (e.g., sidewalks, open spaces, bike paths, nighttime lighting, and population density per block) influences physical activity and the walkability index in a Houston, Texas neighborhood (Oluyomi et al. 2012). Combining data regarding environmental features with census data will provide developers and city planners with the opportunity to design neighborhoods that are more conducive to walking, biking, and active play.

 

Another use of GIS technology was evident in a study of physical activity patterns in teenagers living in New Zealand (Maddison et al. 2010). GPS and accelerometry data were synchronized and combined based on date and time. Subsequently, this merged file was overlaid with GIS coordinates identifying roads, buildings, land use, and home addresses. This combination of technology was successful in identifying that the teens exceeded the recommended 60 min of moderate- to vigorous-intensity physical activity per day; however, there was no ability to identify the types of activity in which the teens were engaged. Differences in their locations and free-living physical activity intensity were also evident based on the day of the week. The fact that most of the moderate- to vigorous-intensity activity occurred near home and school suggests the benefit of utilizing those environments for future health behavior interventions (Maddison et al. 2010).

 

Although interactive video games, like Dance Dance Revolution (DDR), Wii Sports, Wii Fit, Sony Play Station, Xavix, and EyeToy games were designed to create a more engaging game play, studies show that these games increase energy expenditure and may produce positive health benefits (Bailey and McInnis 2011; Chamberlin and Gallagher 2008; Graves et al. 2007; Maddison et al. 2011; Murphy et al. 2009; Zhu 2008). Many fitness centers, schools, and senior centers are now offering interactive games to promote physical activity of children, adolescents, and older adults. These interactive games are well suited for playing alone or with others, and they require little training or skill, provide an alternative to exercising in bad weather, and may serve as a transition to actually participating in sports and physical activities (Chamberlin and Gallagher 2008). Acute bouts of interactive gaming have also improved children's cognitive processes (Best 2011). Warburton and colleagues (2009) reported that interactive video game cycling significantly increased steady-state HR and energy expenditure compared to traditional cycling at constant, submaximal workloads; both forms of cycling (traditional and interactive video game cycling) resulted in similar ratings of perceived exertion. Energy expended playing interactive video games is significantly higher for games primarily played with lower body movements compared to upper body movements (Biddiss and Irwin 2010; Jordan, Donne, and Fletcher 2011). An extensive study of interactive video games monitoring children's energy expenditure with indirect calorimetry highlights the influence of gender, intensity, and active mass on the overall energy cost of the games (Foley and Maddison 2010).

 

Exergaming is the term given to interactive digital games in which the player actively moves. Bailey and McInnis (2011) evaluated the enjoyment and 10 min energy demand of six different exergaming systems and treadmill walking for children of normal and above-normal BMIs. The associated MET levels were in the moderate- to vigorous-intensity ranges; Wii boxing and treadmill walking at 3 mph produced the lowest MET levels, while Sportwall and Xavix produced the highest. The children reported high levels of enjoyment. Interestingly, the children in the highest BMI percentiles reported more enjoyment with the exergames and treadmill walking; they also expended significantly more energy per kg of lean tissue during exergaming compared to their lower-BMI counterparts. Although not many randomized controlled trials have investigated the effects of exergaming, a reduction in weight gain, waist circumference, and blood pressure have been reported for overweight children who participate in exergaming (Maddison et al. 2011, Murphy et al. 2009).

 

Dance Dance Revolution (DDR) is a video game with a floor pad controller that has a grid of arrow panels. Because dancing is a good aerobic activity, DDR has been used to promote physical activity and weight loss in obese children and adults (Epstein et al. 2007; Zhu 2008). As predicted by Zhu (2008), more than 1500 schools in the United States use DDR in physical education classes, with the state of West Virginia initially taking the lead. Sell and colleagues (2008) reported that energy expenditure while playing the DDR video game depends on the participant's experience. Although for inexperienced participants, DDR was equivalent to light-intensity exercise (18% V\od\O₂R and 4.8 kcal·min^-1), on average, DDR was classified as a moderate-intensity activity (47% V\od\O₂R and 10.5 kcal·min^-1). DDR produced an average energy expenditure of 5.4 ± 1.8 METs among children of various BMI values; girls reported a higher level of enjoyment of DDR than did boys (Bailey and McInnis 2011).

 

Wii Sports is a home video game that uses a wireless, handheld remote controller to detect movement in multiple dimensions while mimicking sport activities. The games include tennis, golf, bowling, and boxing. Although playing Wii Sports will not burn as many calories as actually playing the sport, Wii bowling, tennis, golf, and boxing games increased energy expenditure by 2% compared to sedentary computer games (Graves et al. 2007). Also, energy expenditure and heart rate were significantly greater in Wii boxing (3.2 METs), bowling (2.2 METs), and tennis (2.4 METs) compared to sedentary (1.4 METs) gaming (Graves, Ridgers, and Stratton 2008). Boys report enjoying Wii boxing (level 3) more than do girls as performed at 4.2 METs (Bailey and McInnis 2011). Wii tennis and boxing played in a standing position during a single 15 min session provided moderate-intensity physical activity (3.7 and 4.1 METs, respectively) for a small convenience sample of chronic (>6 mo) stroke patients (Hurkmans et al. 2011).

 

In 2008, Wii Fit was launched by Nintendo. This interactive video game offers more than 40 training activities categorized into four areas: aerobics (e.g., hula hoops and running), strength training (e.g., lunges and leg extensions), yoga, and balance training. This exercise game uses the handheld Wii remote controller and a balance board peripheral for some of these activities (e.g., running in place and yoga poses). In light of the positive response Wii Sport and Wii Fit have received, many fitness centers, senior centers, hospitals, and physical therapy centers are now incorporating this interactive technology into their exercise and rehabilitation programs (Zhu 2008).

 

While a great majority of the exergaming focus has been on children, it also holds promise for promoting functional independence, improving balance, preventing falls, reducing premature disability, and maintaining health by increasing the physical activity levels of adults and seniors (deJong 2010). Balance confidence, mental health, and timed walking along a narrow path improved for the seniors who completed a 3 mo video dancing intervention (30 min per session, twice weekly) (Studenski et al. 2010). Older (>65 yr) community-dwelling adults of normal ability and with no previous experience with exergaming played 9 active video games in 5 min bouts (Taylor et al. 2012). The boxing and bowling games were played in both the seated and standing positions. The energy expended, on average, ranged from 1.5 to 3 METs and did not differ for comparisons of seated versus standing gaming positions. Consequently, such activities may be beneficial in helping seniors reap the benefits of physical activity regardless of their ability to stand and walk.

 

Virtual reality, or simulation technology, is an exciting advancement of the human-computer interface with potential for penetration into the interactive healthy behaviors domain. Immersive virtual reality utilizes head-mounted displays, body-motion sensors, real-time graphics, and advanced interface devices (e.g., specialized helmets) to offer user-specific experiences in a simulated environment (Rizzo et al. 2011). Nonimmersive virtual reality utilizes current flat-screen (e.g., television or computer screens) and traditional interface devices, such as keyboards, game pads, and joysticks. Some high-end fitness centers have embraced the interface between traditional exercise equipment and virtual reality technology to offer more diverse exercise experiences. Optical motion tracking of human motion is made possible by commercially available web cameras and light-emitting diodes or strategically placed reflective markers. Although this technology is still evolving, the Xbox Kinect system uses a depth-sensing camera to capture full-body movement. Since the human body is the interface device, the player can move more naturally. With further interdisciplinary research and development, this style of interactive exergaming may offer full body - interaction gaming that further promotes physically active lifestyles (Rizzo et al. 2011).