Exergaming Characteristics in Interventions Addressing Physical Activity and Nutrition: A Systematic Literature Review

INTRODUCTION: The increasing popularity of exergames to promote the adoption of physical activity and healthy nutrition among different population groups is well established. However, due to the use of various types of exergames, their effectiveness in addressing specific behaviours varies. OBJECTIVES: This systematic review aims to identify, classify exergaming elements, and examine their efficacy in enhancing physical activity levels, improve nutrition habits, or a combination of both, across various populations. METHODS: A systematic search was conducted to identify relevant publications. Data on study characteristics pertaining to types of exergames, purpose, focus, target population, technologies used, and the theoretical framework were extracted. A classification scheme of exergaming components and characteristics has been developed to facilitate this systematic review. RESULTS: A total of 34 studies were included and n=21 of them were experimental. Most studies (n=31) were focused on Physical Activity using exergames, whereas n=9 studies addressed both Physical Activity and Nutrition simultaneously. CONCLUSION: All of the studies reported positive behavioural outcomes, although, prolonged and sustained engagement with exergames were not consistently reported.


Introduction
Exergames, which is a sub-category of Serious Games (SGs), have emerged as promising technological solutions to reduce sedentary behaviours and promote healthy habits, such as Physical Activity and Nutrition (PAN), among different populations [1]- [3]. While SGs deal with aspects of physical, mental and social well-being, Exergames are more focused on incorporating physical activities and healthy eating habits into gameplay. They require players to engage in body movements and record their intake of healthy food as game

Study selection and inclusion criteria
Studies were considered for this review and included if they met the following criteria: (1) a specific exergame, through a mobile application, a video-game console or specialised equipment, or a combination, was used in an intervention to bring about changes in at least one of the targeted behaviours -physical activity and/or nutrition; (2) targeted children and/or adolescents and/or adults (which also included the senior population); (3) attention given to prevention and/or treatment and/or management of diseases; (4) focused on rehabilitation purposes after strokes or physical injuries. Other outcomes deemed relevant to have an influence on health behaviours and have the potential for behavioural changes, such as BMI, general health and wellness relating to improved quality of life, were also included. Studies were also accepted despite the variation in reporting measurement types (calorie counts, step counts, energy expenditure, METminutes etc). Studies were excluded from this review if they were not (1) experimental (2) peer-reviewed; (3) published in the English language; (4) Used exergaming only for cognitive training.

Data extraction
Data extraction was conducted using a shareable Google spreadsheet template developed for this review, adapted from the one used in [8]. For all included studies, data were extracted for author, year, country, exergame title, study design, population/sample size, Focus (PA/Nutrition/Both), duration, theoretical perspectives, social components, strengths and limitations and the main findings. The primary outcome measures were physical activity and healthy eating habits. Other relevant outcome measures were behaviours related to fitness, sedentary behaviour and quality of life. For each study included in this review, two independent reviewers (BSE and RE) extracted data simultaneously to maximise inter-rater reliability. Both reviewers agreed on the data extraction in over 70% of the studies. Discrepancies were then resolved through discussion between the reviewers.

Quality assessment and risk of bias
The quality of included studies were assessed using the fundamental mechanisms of the AMSTAR checklist [9]. Some adaptations were made since the original checklist is mainly used for critically appraising systematic reviews of RCTs while our selection also included published experimental studies. For the purpose of this review, bespoke categories were added and included: use of existing exergame apps or exergame equipment or custom-developed exergames; inclusion of social components and use of wearable devices amongst others. The items used for rating are presented in an additional file. The series of questions resulted in an overall rating of high, moderate or low quality. The reviewers (BSE and RE) compared their assessments and any mismatch between the ratings for the included studies was resolved through consensus. Only reviews that had a high rating (≥7) were included. Studies that were rated (≤6) (low/moderate quality) were excluded to avoid unreliable conclusions. The adapted-AMSTAR checklist and the corresponding rating of the included articles are presented in Appendix A.2.

Study selection and study characteristics
The study selection process is presented in Figure 1.  Study design n=21 studies were experimental, n=4 of them were userstudies, n=2 studies consisted of field trials, and n=7 studies did not report on their research design, or not applicable.

Duration
The duration of experiments ranged from 1 to 27 weeks and the majority (n=18) did not adequately report on the exact duration of their experiments.

Target population
Nineteen studies targeted adults, n=8 of them involved children and adolescents, n=2 studies included both adults and children in terms of parent-child relationships; and n=9 studies did not report on the target population. The total number of participants across studies was 447 adults and 249 children. The majority of studies reported more male participants in exergames (n=139) compared to female participants (n=82).

Target activities
Most studies did not address nutrition and physical activities simultaneously, except for n=3 included studies, where they promoted healthy eating through earning points for the consumption of seasonal fruits, vegetables and water, while encouraging physical activity among participants. Thirty-one out of n=34 included studies focused solely on physical activity. Out of the n=34 selected studies, n=16 focused on walking, n=10 studies considered running. Other studies included activities such as swimming, cycling and a combination of several physical exercise such as squats, jumps and other different workout routines as shown in Table 1.

Devices, tools & technologies
Research confirms that the most common devices and technologies used with exergames include smartphones equipped with accelerometer and GPS sensors. These sensors are used primarily to estimate distance rather than for tracking player location, although some form of exergames require the location of players to move onwards in the game [19], [29], [44]. In the current review several of the included studies have used commercially available wrist-worn wearables such as the Xiaomi Mi Band 2, the Microsoft Band, and a less common sock-type wearable device, the Sensoria Fitness Sock. Although numerous other health monitoring devices with built-in sensors are available, they have not been used in the selected studies mainly because they are typically seen in medical settings, for instance, EEG, ECG, EMG and electrodermographs (EDG).

Presence of social components
Twenty out of n=34 studies included a combination of different social components in their exergames such as: sharing achievements; players communicating among each other via chat systems; and trading game elements on social networking sites, as presented in Table 2. Other types of social interaction reported were the creation of communities around a particular exergame -where players communicate in online forums, Facebook groups and pages to discuss matters related to the exergame.

Theoretical framework
In the reviewed articles, 16 out of 34 studies were theoretically driven. This information is presented in Table 3.
The most commonly applied were the Self-Determination Theory (SDT), Transtheoretical Model (TTM) and Dual Flow Theory. These behaviour change theories and models used in the design and implementation of behaviour change interventions that use exergames will be further discussed in the next sections. It has been observed that multidisciplinary research was based on theories, compared to single research areas.

Main characteristics of exergames to encourage Physical Activities and Nutrition (PAN)
The characteristics of different types of exergames to encourage PAN can be illustrated using a classification scheme developed to support this review (see Figure. 2). Exergames are classified through (1) their development type, (2) the platform on which they are deployed and played, (3) their purpose, (4) their genre and, (5) their type of interaction modes. Each of these nodes have different characteristics, which are described in the subsequent section. Part of the classification was drawn upon existing published works [45]- [47]. This enhanced classification is expected to be used as a solid foundation for further research work in the exergaming area for enhanced adaptation to various targeted behaviours.
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Description of Classification Nodes
While most of the nodes are self-descriptive, a brief definition is provided in Table 4. to ensure unambiguity.

Platform
The Platform branch relates to the type of hardware and/or software ecosystem through which users can engage with the exergame.

Purpose
Exergames are developed with goals and objectives for the targeted user-group. To achieve them, designers have to identify and incorporate suitable components adapted to the specific context. Often, exergames have a combination of two or more purposes rather than just a single one.

Interaction
All exergames require that users interact with the system and these interactions differ based on the platforms used, the purpose and the genre. Interaction is also impacted by the single-player mode or multi-player mode.
1.13 Single-Player: A user will engage with the exergame without interacting other participants. Although there might be elements of collaboration (5.1.1) or competition (5.1.2), these would be mostly with/against oneself or some kind of Artificial Intelligence (AI) system or 'Non-player characters' (NPCs) 1.14 Multiplayer: Groups of users can participate in an exergaming session.
This enables collaborative/team-based activities (5.2.1) and also provide users with the opportunity to compare/compete (5.2.2) against one another.

Discussion
This paper systematically reviewed studies addressing the use of exergames in health promotion. A classification of the different types and characteristics of exergames was developed. This was intended to facilitate the assessment of exergames and their effectiveness in changing behaviours on the long-term compared to traditional physical activity and food intake tracking methods. In addition, it was important to investigate whether types of exergames impact population groups differently. This systematic review identified 34 studies making use of exergames to promote physical activity, healthy eating habits, or a combination of both, albeit the last one is rather scarce and warrants more research to examine the combination of both physical activity and nutrition. Indeed, most studies did not address nutrition and physical activity simultaneously, except for Alien Health, My Plate Picks and GameMyHealth. They promoted healthy eating by earning points for the consumption of seasonal fruits, vegetables and water, while encouraging physical activity and teamwork among participants in educational settings. Since diet and physical activity are often interlinked, it would be judicious to research EAI Endorsed Transactions on Pervasive Health and Technology 2023 | Volume 9 | e9 Exergaming Characteristics in Interventions Addressing Physical Activity and Nutrition: A Systematic Literature Review 9 the complementary relationships between diet and physical activity, especially in the context of exergames and technological tools for health promotion. It would enable the design of more effective interventions which can in turn inform health policies. The majority of studies were from the US. There are two plausible possibilities: the USA have been among the first country to encounter the obesity epidemic and research was needed to promote healthier lifestyles. At the same time, the USA experienced technological advancements, which enabled the use of technology for health, and most specifically the development of exergame research in physical activity and nutrition. Given that obesity is taking epidemic proportion worldwide, other countries will have to address the challenges faced by fast food habits combined with hectic work patterns and sedentary lifestyles [48]. Simultaneously, less developed countries will also have to bridge the technological gap [49]. Indeed, researchers from other countries can benefit from the experiences and learn from advances featured in developed countries; while research collaboration between different countries allows for different perspectives to become evident, leading to interesting health findings across different populations and cultures.
Demographic factors such as age and gender have also been able to influence engagement with exergames, whereby higher app usage has been reported among the female youth population and those displaying positive attitudes towards technology usage [45]. These gender difference can help to identify factors for adherence to exergames and remedy disengagement among male and female participants. The lower number of studies involving children could be attributed to the lengthy ethics procedures required when using children as research subjects.
Walking is recognised as the most popular type of physical activity across the different age groups and between males and females. This is in line with a large-scale study carried out by [50], using data from Fitocracy recorded over a period of 4 years from February 2011 to January 2015. Walking is less intensive compared to running, especially for those suffering from joint pains or knee problems and those who are overweight, and it can be done for longer periods of time. Walking was the preferred exercise for participants as it improves fitness, heart and mental health, prevents weight gain and other diseases associated with lack of physical activity, irrespective of age and gender.
The majority of studies in this systematic review were not theoretically driven. As a matter of fact, only 16 out of 34 studies drew on a theoretical background: mainly Self-Determination Theory (SDT), the Transtheoretical Model (TTM) and Dual Flow Theory. This finding is surprising since it is well established that the use of theories in the design and implementation of interventions improve their effectiveness [51]. Moreover, there is mounting empirical evidence on the barriers and motivators of health behaviour change [52]. This is particularly true in physical activity promotion and nutrition. Four of the most commonly used theories in health behaviour research [53] and physical activity promotion [54] are the transtheoretical model [55], social cognitive theory [56], the Health-Belief Model [57], and the theory of planned behaviour/ reasoned action [58], [59]. All four theories use an individual approach to motivate healthy behaviour; they focus largely on the abilities and capacities of individuals as individuals (such as self-efficacy, attitudes, predispositions) to explain exercise behaviour. More recently, a social approach to health and physical activity has been proposed[60]- [62]. Indeed, researchers have shown the importance of social identities, group memberships, in shaping beliefs and health behaviours [63]. It would be thus important to apply these findings in exergames and other digital interventions. We argue for the importance of interdisciplinary collaboration. It would allow for better perspectives and improve research practice. A model of behaviour change to assess the promotion and maintenance of positive health habits using exergames is essentially missing. There is a need for a model that allows intervention participants to be in control of their behaviour changes using digital means. Intervention participants need to understand the purpose of the intervention and have the ability to measure the impact of their progress on their behaviour so as to take the required actions. At present, theories and models of health behaviour change are often used in isolation, or even when used in conjunction, consist of fundamental overlaps or are overly intricate. There is a need to synthesise and integrate the different aspects of behaviour change into a unified model [64], to change physical activities and nutrition behaviours when using technology (in our case, exergames).

Conclusion
Having proper nutrition, keeping fit and overcoming a sedentary lifestyle is a major struggle for people irrespective of their age, gender, health, profession and social status. The findings of this systematic review are consistent across studies and show that exergames generally contribute to positive effects when game elements have been carefully taken into consideration in the design. The novelty factor associated with exergames makes it popular at the beginning, but after some time, players lose interest and the enthusiasm fades. A number of strategies have been used to increase the retention rate through sustained motivation and engagement with exergames. These include avatars, goal-setting, rewards, progression, timely feedback and delivering persuasive messages to actively engage players in changing their health behaviours, each of which have varying degrees of success when targeting different behaviours. There seem to be limited research in the exergame domain for group-specific motivational elements that would appeal the most and/or be more impactful with respect to age, gender and player type. Similarly, only a few experimental studies which made use of control groups were undertaken in that area.
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Implications for research using exergames and future directions
Some types of exergames are inherently apt for a post-COVID-19 pandemic society where being socially distanced is highly encouraged. Despite the fact these studies did not set out to directly address this issue, the types of exergames available can be useful in engaging people in adopting healthier lifestyles in the comfort of their homes, especially in challenging times when physical and mental health issues are on the rise. Notwithstanding the entertainment value generally conferred by exergames and their associated benefits for increased physical activity and healthy food intake, there is insufficient evidence to support the health-enhancing ability of exergames. It is challenging to evaluate whether exergames have significant health benefits, mainly because exergames tend to provide moderate-to-low intensity levels of exercise, and do not consider the need for vigorousintensity exercise. Additionally, nutrition education studies using exergames have not tested their results over extended periods of time. In order to have significant health improvements, whereby exergaming can then be suggested for PAN promotion, exergames should be used in conjunction with other methods of promoting health benefits, such as opting for incidental activities in daily routines and reducing sedentary behaviour. We recommend that future research focus on the design and development of exergames that are tailored to the players, taking into consideration the different personalities and abilities. Prolonged interventions involving thorough methods of research design, such as RCTs, are needed to assess the effectiveness of exergames in comparison with other ways of performing physical activities, for instance, traditional physical exercise without any technology use or some level of technological integration. Details about the purpose of the exergame, gameplay and the rules by which they are governed, the type of research design and the theoretical framework underpinning the research on particular types of exergames should be systematically reported. This way future research would be in a better position to create meaningful links with the types of interventions to investigate relevant physical and behavioural outcomes.