Running App “Zombies,Run!” Users' Engagement with Physical Activity: A Qualitative Study

Abstract

Introduction:

Sufficient physical activity (PA) is important for all aspects of health. Smartphone apps and the use of gamification, such as narrative-based augmented reality (AR), have a great potential to engage a variety of people in more PA. Zombies, Run! (ZR) is the world's most popular running exergame app and therefore a suitable model to understand what users find engaging.

Objective:

To understand people's motivation and experience of using a narrative-based AR exergame app ZR for PA.

Materials and Methods:

ZR users were randomly selected for interview from a quantitative ZR user's survey. Interviews which were guided by a semistructured topic guide were audio-recorded, transcribed, and analyzed using inductive and deductive thematic analysis.

Results:

Participants were 15 males and 15 females aged 16–53 years (mean = 36, SD = 10), from 13 countries, with the largest proportions from the United States (30%) and United Kingdom (23%). The majority (73%) used ZR while running, followed by cycling and walking. Four overarching themes that emerged were: “Reasons for starting and staying with ZR,” “Preferred features,” “Perceived effects of ZR,” and “Pros and cons of the app.” Sixteen subthemes included the attraction of gamification and narrative appeal, desire to add something fun to PA, or to distract from the negative physiological effects of PA. Users' favorite features were the feelings of immersion and presence through narrative, story line, and characters. The narrative motivated participants to engage in PA for longer sessions and encouraged long-term use.

Conclusions:

This study identified a number of factors that users found attractive in an AR running exergame, particularly narrative. Our findings suggest that ZR may engage people in exercise by modifying their perception of PA through a story line or narrative, dissociating the players from the effort of exertion. AR narrative-based apps may be an effective way of engaging people with health-related behaviors or habit-forming activities.

Introduction

Regular participation in physical activity (PA) reduces the risk of multiple conditions, including cardiovascular disease, diabetes, obesity, some cancers, poor sleep, stress, depression, and cognitive decline.^1–9 However, population levels of PA are too low worldwide with an estimated 80% of adults classified as inactive.¹⁰ Interventions that can engage larger numbers of the population in PA are required. Smartphones represent a potential avenue to reach a large proportion of people. A total of 3.5 billion people (45%) worldwide own a smartphone and this figure is continually increasing.¹¹ Mobile games contribute to the growing usage of smartphones with the revenue for smartphone games in 2020 estimated at over $63 billion worldwide, with this number estimated to reach $100 billion by 2023.¹² Smartphones can promote PA by allowing people to access a variety of tools, such as reminders, platforms, or even exergames.

Exergames for PA

Exergames are able to exploit the mobility and technical abilities (Wi-Fi, global positioning system (GPS), audio, and camera) of a smartphone to create a personalized and highly responsive experience for the user, without being constrained to a console and usually at much lower costs than gymnasiums, exercise classes, or virtual reality (VR) technology.^13,14 However, previous studies on the use of narratives in active videogame play have found that interest in the gameplay of exergames can decline quickly^15,16 and there is need to understand the factors that might facilitate sustained engagement. The use of a narrative has been shown to significantly influence PA behavior and might encourage long-term use because it maintains novelty and surprise.¹⁶ One smartphone exergame that uses narrative as a central feature is Zombies, Run! (ZR).

ZR smartphone exergame app

ZR (Six to Start, London) is a popular running app available on the Apple (Apple, Inc., CA) and Google Play Store (Google, CA). Released in 2012, it was cocreated with a novelist, Naomi Alderman.¹⁷ ZR is an “ultra-immersive post-apocalyptic audio-augmented reality (AR) story” (Apple, Inc., 2021), where the user is one of the few remaining survivors in a zombie-infested world. The user is given a nickname “Runner 5,” and needs to collect supplies to build back a base called “Abel Township” for remaining survivors. ZR uses narrative-based AR, also termed augmented narrative (AN) or ‘reactive storytelling’. The users can leave the game running in the background when performing any form of PA and link the app to the popular music libraries such as Spotify (Spotify Technology S.A., Sweden) to add their own music.

Since its release, ZR has accrued 8.5 million downloads, with 2 million alone during the COVID-19 pandemic, with ∼200,000 monthly active users (Six to Start data). Users can choose from a number of in-app purchase options ranging from £5.49 to £87.99 per year, some with monthly or unlimited access.¹⁸ ZR was evaluated in two pilot studies in adolescents (<51 participants), which found no significant differences when compared with other narrative apps or forms of exercise¹⁹ and N = 40.²⁰

Much can be learned from interviewing long-term users of a technology to understand which features appeal to ZR users and this information can be used to optimize future exergaming apps. The value of qualitative research is to learn about people's experiences and use to inform the future development, engagement, tailoring, and improvements. This study was part of a larger project vEngage.²¹ We followed the Medical Research Council's (MRC) framework for developing and evaluating complex interventions.²² The MRC framework consists of five steps, the third and fourth steps being “evaluation” and “reporting,” which this study falls under.

Therefore, the aim of this study was to explore ZR users' experience of the narrative-based AR app, and the impact on the PA performance, as well as their views on PA and gaming.

Materials and Methods

Participants

Participants were recruited via a quantitative survey of ZR users designed to explore interest in PA, exergaming, and specific app features. The survey was sent to all ZR users (those trying the app for free and those with a subscription) in an in-app notification, via an e-mail newsletter, and on the ZR Twitter account. Participants could complete the survey anonymously or provide their e-mail address if they were willing to be interviewed. We randomly selected from among survey respondents who were willing to be interviewed, contacting them by e-mail. The response rate to the interview e-mail invitation was ∼10%; we repeated this process until we reached a desired number of interviewees.²³

The randomization was stratified by gender to get equal numbers of men and women. In the survey, participants provided their age, gender (male/female/other), ethnicity, country of residence, their reported PA levels (minutes of moderate to vigorous physical activity per week), and whether they perceived their activity levels had changed because of using ZR.

Interviews were carried out from September to November 2019. Eligibility criteria to participate in interviews included age of 16 years or older and fluent in English. Participants could enter a prize draw for a £50 Amazon voucher and ZR T-shirt. The study was approved by the UCL Ethics Committee (Project ID 3777/004), and all participants provided informed written consent before the interview. Methods and results are presented in line with the COREQ checklist.²⁴

Interviews were carried out by N.F., a female health psychology researcher with experience in qualitative interviewing. Interviews were carried out by telephone or video call depending on participant preference. N.F. had no prior relationship with any study participants before approaching them to participate. They were guided by a semistructured topic guide developed by N.F., A.F., and H.W.W.P. designed to understand users' personal characteristics, considering factors such as their motivations for using a PA app, which game features were appealing and why, and which behavior change techniques they engaged in.^25,26

Although the topic guide did not have a specific theoretical basis, it formed part of a larger intervention development study²¹ conducted within the MRC framework for developing complex interventions.²⁷ The full topic guide is presented as supplementary material. All interviews were audio-recorded with the permission of the participant.

Data analysis

Audio-recorded interviews were transcribed verbatim by an external transcription company and verified against the actual recordings by N.F. and T.B. Qualitative analyses were conducted using NVivo software. The first stage included familiarization with the data. Two researchers (N.F. and T.B.) coded each of the 30 transcripts separately. Initial codes were identified, noted, edited, and grouped into emerging themes to ensure theoretical connectedness in an inductive manner.^28,29 Transcripts were further analyzed by N.F. and T.B. using an inductive and a deductive framework analysis methodology.³⁰

The themes were mapped according to the framework of the interview topic guide initially (Multimedia Appendix A1), but themes also emerged from the data. Any comparison and adjustment to the coding were made.³⁰ The final coding framework is presented in Table 2. The study team adopted reflexivity and a collaborative approach, where each stage of the analysis process was discussed to ensure correctness of the themes and their supporting data, as well as any possible reflections and projections due to personal experience or background of the researchers.³¹ Inter-rater agreement in consistency of themes, constant data comparison, and proper audit trail of material and processes were used as validation strategies.

Results

A total of 2274/5342 (43%) of those who completed the quantitative survey indicated that they would be willing to be interviewed. Of these, 250 were randomly selected and sent study information sheets and consent forms. Thirty participants consented, and their demographics are presented in Table 1. Interviews lasted between 12 and 37 minutes (mean = 25). A total of 28/30 (93%) reported that their levels of PA had increased since using ZR.

Table 1.

Demographic Characteristics of Interviewed Zombies, Run! Users

Variable	Frequency, N (%)
Gender
Male	15 (50)
Female	15 (50)
Ethnic background
White	28 (93)
Asian	1 (3)
Other	1 (3)
Age (band)
16–20	2 (7)
21–30	7 (23)
31–40	10 (33)
41–50	10 (33)
51–60	1 (3)
Country of residence
The United States	9 (30)
The United Kingdom	7 (23)
Netherlands	3 (10)
Each: Austria, Canada, China, Germany, Italy, Norway, Russia, Slovakia, Sweden, Vietnam	1 (3)
Highest level of education
Primary/elementary school	1 (3)
Secondary school/high school	3 (10)
Bachelor's university degree (e.g., BA, BSc, associate degrees)	13 (43)
Vocational qualifications (e.g., NVQ, BTECs)	1 (3)
Master's university degree (e.g., MA, MSc)	8 (27)
Professional (e.g., MD, DDS) or doctoral degree (e.g., PhD EdD)	3 (19)
Other	1 (3)
Disability or illness affecting ability to perform PA
Yes	5 (17)
No	25 (83)
Do you think your PA/exercise levels have changed because of using ZR?
Yes, they increased	28 (93)
No, they did not change	1 (3)^a
The mean length of PA in minutes/week of MVPA before using ZR?	77.3 (range 0–450)
The mean length of PA in minutes/week of MVPA after using ZR?	175.6 (range 60–300)

Where numbers do not add up to N = 30 it means the remaining responses are missing.

MVPA, moderate to vigorous physical activity; PA, physical activity; ZR, Zombies, Run!

Themes

Themes and subthemes are shown in Table 2. Four overarching themes were identified, and these were “The primary reasons for using the app”; “Features”; “The effect of Zombies, Run!”; and “The pros and cons of the app.” Themes and subthemes are presented with illustrative quotes (with participant age and gender).

Table 2.

Themes and Subthemes of the Interviews

Themes	Subthemes
Reasons for starting and staying with ZR	Story line, gamification of PA, or adding fun to PA Need for long-term PA
Preferred ZR features	Immersion achieved via narrative and story line and users' responses Immersion distracts from the intensity of PA Workout options for anyone
Perceived effect of ZR	Motivation Feeling rewarded when using the app Feeling of achievement Positive health effects Positive mental health benefits Identity shift
Pros and cons of the app	Tracking (pro) Characters (pro) Cost (con) Personalization (con) Technical improvements (con)

Reasons for starting and staying with ZR

Story line, gamification of PA, or adding fun to PA

Participants talked about reasons they were first attracted to the app. Half of the participants were drawn to the zombie or apocalyptic stories and themes. Those who were not were attracted by the concept of gamifying their PA. Participants initially discovered ZR by chance, word-of-mouth, specialist fitness or gaming magazines, articles and shows online, and the app store when browsing for fitness or running apps.

Need for long-term PA

Participants reported using the app from a few months to 8 years (since the app's inception). Many recognized themselves as users who wanted to increase their PA levels, such as to start running or maintain running over longer periods of time, and for different reasons such as wanting to perform PA with a different experience. Many participants felt that ZR was appealing because it was something unusual or different and more motivating because it had the potential to distract from discomfort when performing PA:

Oh wow, it was a long time ago. […] I've always liked running, I haven't done it a great deal and back then I would have had young children, so I think I was probably looking to try to get back into doing a bit of exercise. Erm, it was mostly driven by, it looks like a really fun thing. […] I just enjoyed it. I like the fact that it takes the edge off the pain of running. So, when you kind of get back into something and you're trying to get fit, well, most of the time, you know, you're pushing yourself anyway, and it's quite difficult and then getting the motivation to get out again. […] It helped to kind of continue that because you know, good story. (M,42)

Preferred ZR features

Immersion achieved via narrative, story line, and users' responses

The simulation and role-play were the most attractive features of ZR app, which helped users in starting as well as continue performing PA. For a few users, the story line was not the most appealing part. For those, the immersion element and personal response to the story line are what appealed to them:

Largely actually, it's the storyline, it keeps me engaged. Yeah, that's the… I attribute, fully, both when I was running before and then I quit for a while and then again now. Because I did Couch to 5K [another running app] again this past fall and both times I attribute Zombies, Run! to keeping me running after finishing Couch to 5K. (M,41)

Immersion distracts from the intensity of PA

The story line and immersion made PA more enjoyable and sometimes made people forget that they were performing it. This also resulted in people wanting to come back to it, because the focus was not on the discomfort but on factors such as continuing the story line, gathering supplies, and looking forward to building the base Abel Township in the app:

The story then fits into reality, I suppose. It is that little bit of escapism, and it has made me, in combination with a few other things that have made me from someone who would not really exercise at all, to be someone who actually, running is my primary method of exercise, and I like doing it, and it is partly down to things like that app just making it a little bit more of an escapism, and a little bit more fun just to take your mind off it. (M,50)

Workout options for anyone

The users valued different story missions and app features. All participants enjoyed music and narrative blending together, which motivated many people to return to the app and use it. About half the sample said that music alone, or discovering new music tracks, was boring and repetitive, and that the appeal of ZR was that it was always something new and unexpected:

Zombies, Run! is the one app that actually has character and is actively in development, so I know I have something to look forward to, for example, in the new seasons and so forth. But, well, I don't really listen to audiobooks or anything else. I prefer music, but Zombies, Run! is the perfect filler to all the music I listen to. (M,16)

The ZR app options appealed to different users in different ways, which suited their personal physical or mental health needs. The options, such as zombie chases, interval training, and radio mode, are designed to engage people in no or little PA, all the way to those training in professional environments (such as running marathons, part of physical rehabilitation therapy or for obstacle course racing, or in the military to take a few examples from the users in this study). One participant explained his favorite features, and how the narrative of the app impacted on his running:

The random zombie chases. Even though I love them I hate them at the same time. Extremely helpful. Because when you have a random hey, you better start hauling tail, for 60 seconds or whatever, that. That is a good break because it breaks the monotony even in a different way. It causes me to brush the plateaus that I may be sitting in. And I don't know when they are coming. So, it'd not something I can plan, you know. Maybe the uphill part. And my goodness. I hate when that happens. It happened this morning as a matter of fact. But it's good. Because now I need to speed it up, even though these hills would kill me most of the time. It's not like a boundary that I know I am about to push. Like when I start out, I don't know if I am going to get zero of those, or if I am going to get four of those. (M,46)

Perceived effect of ZR

Motivation

The main effect of ZR was that the features in the app increased people's motivation and return to ZR and PA more frequently, pushing their boundaries and giving users a new experience of PA (as not boring). Some people claimed it made them feel like they were on a mission, which would tie in with the high score for role-play feature:

I'm really loving it. I love the fact that when it's a rainy day, it gives me that extra impetus to actually go and run, because it's a story, and I want to find out what happens next. Um, and I don't let myself play it when I am walking, so I have to go running. And it's nice to have to break up your run a little bit, and not just have the music, but to have narrative as well. (F,38)

Feeling rewarded when using the app

More frequent engagement with PA helped people feel better on many levels. Some people explained that they felt rewarded, which made them feel better about themselves:

I grew up fat, and I was constantly told, you can't do physical activity because you're just not capable, you're not fit. I kind of internalized that message, that I just wasn't capable of running. I still struggle with finding anything positive about myself. So, running was part of being able to do that, and there's a quote that I read the other day, I don't know who said it, but it was something like, “running isn't a punishment for eating, it's a celebration of what your body can do.” Um, and I'm trying to internalize that kind of message. Because when I run it's, it feels like actually I'm doing things that people told me I couldn't do, that I didn't believe I could do because I'm a fat person. And I can also help to improve my mental health, and to keep my mood up by engaging in exercise. (F,38)

Feeling of achievement

The feeling of reward was tied to achievement. Some participants felt more strongly that they had overcome particular mental or physical blocks, and therefore have achieved new goals. The feeling of achievement in performing more PA was very closely linked to being motivated to listen to the story:

I really enjoy it. It really helps me motivated. It keeps workouts from getting boring. It's really got a lot for me. And then sometimes I go back and I'm like, wow I walked that much. So, it kind of helps, uh, keep you going with it. (F,50)

The storyline and narrative is something I want to follow and keep up with. Um, but also on the runs, it's quite motivating with the in-run talk it gives you. And even the little starting bit you know, it feels like, you know, you're going to achieve something. (M,31)

Positive health effects

All users claimed that PA makes them feel better. However, some had more specific and drastic changes to both their physical and mental health. The improvement in their physical health was due to the increased motivation that ZR gave them to perform PA, which helped them change their health outcomes over time:

[running] It's just part of one of a number of things that I have incorporated back into just part of who I am. You know, I am no longer a smoker, I don't, that's not a thing I do anymore. Um, I am a runner, it's part of what I do three days a week, um. Yes, I don't eat the fast food that I used to eat, it's just not something that now me does. (M,41)

Positive mental health benefits

Half of the sample explicitly stated that ZR has had a positive impact on their mental health, whether it was just feeling better after a long stressful day, or much more significant mental health changes, such as managing mental health conditions ranging from post-traumatic stress disorder, borderline personality disorder, agoraphobia, eating disorders, anxiety, and depression. For some people, ZR alone did not seem to impact on their mental health, but they said that being more physically active helped their mental health and well-being:

And the second major point is I think, for me, is more geared toward my social anxiety, maybe shyness. Because when I am listening to such a story, I am thinking about the story itself. I do not think about like, people that surround me. So, when I listen to Zombies, Run!, it is easier for me to just generally exist in such an environment as the, compared to the gym that is full of people I don't extraordinarily know. In a way it helps with confidence, it relieves some workout anxiety. (F,26)

Identity shift

Some people indicated that they did not initially identify themselves as gamers or runners, but that the app had changed this identity to become either or both of these, while others never really thought much about these identities. Only five users identified themselves exclusively as “a runner” before using ZR in comparison with 12 after using the app. In addition, only four users identified as “both” a gamer and a runner before using the app, while 13 identified as “both” after using the app.

Pros and cons of the app

Tracking

Some users specifically mentioned how much they valued the statistics and logs, but for others the statistics were either no longer important or less important. The tracking options in ZR helped some users run longer distances in shorter time or increase their running speeds at particular points. In ZR, the tracking does not work by GPS and it is not related to actual physical distances. The app only tracks the speed and duration of movement. For some users this was a shortcoming, but for others, they preferred that the app did not track their location as it preserved their privacy:

When I first started running I was really excited about the stats and seeing my kilometre times go down and seeing my run times get shorter. And now I'm just addicted to knowing what's going to keep happening, finding out about the project that you're part of, that you don't know anything about. (F,28)

Characters

As mentioned before, one of the most appealing features of ZR was the story, which included different characters (acted by professional actors). Many people formed connections with characters and felt upset when something happened to them or if they got killed. Other people also enjoyed playing a character themselves and liked how everyone was the same character:

It's an amazing storyline I that that's the one thing that keeps me with it. The characters are believable. So, erm, I also find that when I do run, at times I forget that I am running. Which is really good because sometimes I really don't want to run, so yeah, no it's good. And I have actually been known to laugh out loud, loud occasionally as I am running. […]. I've been running with Sam Yao which is the main character for four years. And it's bizarre, they almost become like family. I absolutely love hearing his voice when I do run. (F,37)

Cost

The accessibility of the app was another appeal. For some people, the purchase of membership may have been a barrier initially, but after trying the free version, all users purchased different options:

I had a gym membership that I hardly used. I was just getting fed up and thinking, do you know what, I can just save some money and just go running and when I saw this app, I thought that sounds like my sort of thing, since it is. (M,50)

Personalization

One of the major feedbacks regarding the features of the app was that it offered less personalization options than the users expected. Despite many app choices, there were comments about preference for more narratives (not an apocalyptic story line), app personalization such as color and music. In this study, only one user stopped using ZR for good because the story line did not fit the running settings (see Technical improvements), while others dipped in and out of use, some even repeating many seasons, returning to it to keep them motivated with PA.

Technical improvements

The users offered additional feedback for the app developers, which they believed would enhance the ZR app and the game element of the app. The base-building feature in the ZR game was most criticized, particularly by those who had used the supplies to build it and could no longer expand it or do anything with the base despite still gathering supplies. Two participants claimed they had trouble connecting ZR to Apple Watch (Apple, Inc.), which frustrated them. Only one user had stopped using the app after many years of usage due to the setting in which he or she ran (treadmill), and another user mentioned feelings of saturation with the story line, which no longer felt believable:

The feature where like an attack comes and you have to speed up to run faster, that never really works well for me on a treadmill. (M,32).

Discussion

Principal findings

This study found five overarching themes and 16 subthemes that provided a greater insight into the experience of ZR smartphone app. Users' favorite features of ZR were the perceived feeling of immersion and presence achieved through narrative (story line), the characters, and music that was linked into the game via their music libraries. The narrative/story line allowed participants to engage in PA for much longer periods of time, not only within one PA session but also over longer periods of time, leading to long-term engagement. The exergame increased people's presence, which is congruent with a number of other studies.³² The narrative also allowed participants to forget about the negative aspects of physical exertion, which has been confirmed in another randomized study that compared ZR with another popular running app Nike Run Club.³³ In a 2014 review of 27 studies, it was confirmed that a strong correlation exists between exergaming and increased energy expenditure (up to 300% higher than during resting).³⁴

Some participants valued the tracking options for greater overview and statistics of their PA, which is in line with an expert panel analysis of the important features for the effectiveness of PA.³⁵ However, other users called for more personalization features, lower cost of subscription(s), and to increase the gameplay component in the app. In addition to the app's positive influence on people's physical health and strength due to the increased motivation and enjoyment with engaging in more PA, half of the participants also reported that the exergame also positively impacted on their mental health, mostly by reducing stress, decreasing anxiety and negative self-talk, and giving them a mental break.

Motivation and perception of PA

Although ZR was designed to engage people in running, participants in this interview study used the app for other types of PA such as walking and cycling. ZR helped people change their experience of PA, via a story that acted as a filler, entertainment, and a distraction, especially from limiting thoughts and pain during physical exertion. ZR also helped people push their boundaries, achieve new goals, feel rewarded, and create ways for them to engage in PA frequently (such as a routine or a habit). These new experiences were reported as a natural result of immersion in the ZR story line and not forced or imposed by the app. Similar effects on PA have been found in other virtual environments such as VR cycling where VR conditions increased situational motivation, intrinsic motivation, internal and external regulation, and lower amotivation.³⁶

The appeal of the ZR app was the story itself and the way the story was executed, rather than the actual gameplay, which was very minimal. Participants valued that the app was supportive, but that did not require them to look at the screen while performing PA. The feedback was that in comparison to other PA apps, ZR app was very different. Although not all participants were fond of zombie or apocalyptic stories, the app was described as unique, quirky, fun, and engaging, with more than half of the sample recommending the app to their friends or family.

The users reported a shift in their perception of how it feels to engage in PA when using ZR. This study suggests that ZR can potentially create behavior change, such as seen in the Theory of Planned Behaviour³⁷ in a few ways: One, by modifying people's perception of PA by distraction (narrative/story line); two, by modifying people's perception of PA through the actual experience of it (when PA is no longer just PA, but a role-play); three, by making PA more enjoyable via an association with the story or narrative in the exergame (gamification or audio-AR aspect); and four, the feeling of euphoria after vigorous PA, which has been demonstrated in several studies.^38,39 All of these links could be explored in future studies. A study with 30 participants assessing mobile running apps (Nike Run Club and ZR) demonstrated no differences in primary motivational state outcome between the apps; however, the game-based app ZR showed greater dissociation from PA and increased enjoyment.³³

A unique style of augmentation and reactive behaviors

The popularity and satisfaction with ZR were apparent. ZR is not a conventional smartphone game or conventional running app. It does not fully fit the category of horror games because it is not focused on the elements of horror or dread, but instead focuses on the players and their effort to sustain the base and keep alive in the game (as a “Runner 5”). The game also does not fully fit the category of AR because there is very little visual element to participating in the game (apart from choosing the run/chase and deciding to pause or stop the run). It instead relies on the player's imagination to fill the gaps. The players, in a sense, become responsible for their own projection of the story, which has also been shown in other audio-augmented games (e.g., sound packman⁴⁰). The audio element and immersion are heightened using headphones that create a feeling of being in the story.⁴¹

When it comes to the narrative utilization in games, only in cases when interactive narrative (IN) and the emergent narrative (EN) are applied can players to some extent modify the story line by the interaction with the game. In this respect, the narrative of ZR is not a case of IN or EN because the story line is more rigid and does not allow the users to modify any aspect of the narrative or the game. So, ZR follows a conventional narrative structure, but it is the integration of the game into a player's real-world environment (e.g., running outside, or on the treadmill, or cycling, or in other activities) that allows users to have freedom over real-world decisions and movements.⁴²

It is plausible that this freedom of choice provides people with a feeling of complete autonomy, a known factor to increase engagement with PA,⁴³ which is also part of a health behavior theory, Self-Determination Theory.⁴⁴ ZR can therefore be classified as an AN game or reactive storytelling according to Stobbart.⁴¹ This definition is consistent with our results showing that users enjoyed the interlace of music, the story line, and the real-world setting. This created the feeling of immersion and role-play, which were the two most popular features of the app, however, the immersion was distinct from the immersion in head-mounted display VR, which is achieved through a full visual field. This is another point by which future researchers could discern the precise mechanisms in which the audio narrative games drive PA. Other location-based games such as Pokémon Go also used AR to create immersion to activate PA in the real world.⁴⁵ For Pokémon Go, a large number of factors predicted engagement and gameplay. A scoping review of the studies points that the reasons for initiation are similar to the reasons in our study.⁴⁵ These include fun, immersion (escapism), nostalgia, social ties, and a desire for PA. Fun is also a predictor of a longer gameplay.⁴⁵

The preferences for these features are therefore universally important in apps to sustain PA but are not limited to one demographic group. Instead, they appeal to a wide variety of people and populations with diverse characteristics, in the same way as smartphones or the use of the internet on a smartphone is not limited to one demographic group.⁴⁶ It is likely that older age groups (55–64, 65–74, and 75+ years) would be least likely to use AR smartphone exergames because they are groups least likely to ever play games at home or elsewhere on a mobile phone.⁴⁷

Strengths and limitations

In this study, we have presented the qualitative experiences with the ZR app. This type of evaluation is a crucial component in addressing the development of smartphone AR apps for PA. Qualitative data provide more detailed evaluation of the engagement patterns and preferences of use of smartphone app ZR. We obtained a reasonable sample size with diverse participants.²³ However, due to the cross-sectional qualitative design of the study, the users are likely not representative of the overall ZR population or a general population. The number of people participating in this study is still likely to be indicative of some patterns of experience with the ZR app, as well as the effects of narrative-based AR exergames, but a larger sample or repeated studies would have to be carried out to learn more about the diverse experiences of people using ZR app for PA.

When asked why they had agreed to the interview, some participants said they believed it was the right thing to help researchers or developers for altruistic reasons, while others said it was because they were fans of the game and wanted to invest in it and help support it in some way. No participants in this study exclusively reported negative experiences, with only one participant stopping the subscription as he or she “no longer felt connected to it [the app].” This may have led to bias in our results as participants who did not find the app engaging or motivating for PA may have been less inclined to agree to be contacted for an interview and less likely to have seen the initial survey.

Implications

The ZR app showed a difference in the uptake and duration of engagement with PA among our participants. The app also helped people achieve significant physical and mental health benefits. Due to many people reporting mental health benefits, a future survey could expand the categories and ask participants more about the mental health history and to what extent did the decision to continue to use ZR depend on the mental health benefits.

The ZR app may be particularly useful for engaging people in PA under the current COVID-19 pandemic, where many people have lost access to or are reluctant to visit health and fitness clubs, or engage in PA with larger groups. Sharp declines in exercising have been noted during lockdowns.⁴⁸ There is the potential to develop narrative-based AR apps to target behavior change in other health-related areas, for example, pain management and depression.

It may be that the aesthetics and design of ZR mean that it works well for a niche audience, but not more broadly, and the interviewees in this study are necessarily drawn from those who like the game. Nonetheless, we suggest that the broader features enjoyed by ZR users may be applicable to other interventions to increase PA. One such feature was the narrative or story line, which was reported as the most significant factor in engagement (also long-term engagement). The mental health benefits were most likely as a result of the increased levels of PA, with known mental health benefits, but several people expressed that their mental well-being improved due to the narrative, characters, and the game, which also gave a sense of achievement and progress essential for successful public health interventions.

Conclusions

This is the first study to describe how narrative-based AR, AN, or reactive storytelling app can influence people's motivation and experiences with PA. Due to the interest and success of this study, and the current global health crisis with COVID-19, it is likely that the expansion of narrative-based AR will increase, especially in helping people form new health-related habits and behaviors.

Footnotes

Acknowledgments

The authors are extremely grateful to all the participants around the world who agreed to be interviewed and share their experiences.

Author Disclosure Statement

This research is sponsored by the Medical Research Council industry partnership grant in support of the development of a VR game licensed by Six to Start. There is no legal, financial, or commercial conflict with our industry partner company, Six to Start.

Funding Information

The vEngage study was funded by the Medical Research Council (Grant number MR/R015430/1).

Multimedia Appendix A1. Interview Schedule

References

Whelton

, Chin

, Xin

, He

. Effect of aerobic exercise on blood pressure: A meta-analysis of randomized, controlled trials. Ann Intern Med, 2002; 136:493–503.

Kredlow

, Capazzoli

, Hearon

, et al. The effects of physical activity on sleep: A meta-analytic review. J Behav Med, 2015; 38:427–449.

Baillot

, Romain

, Boisvert-Vigneault

, et al. Effects of lifestyle interventions that include a physical activity component in class II and III obese individuals: A systematic review and meta-analysis. PLoS One, 2015; 10:e0119017.

Arem

, Moore

, Patel

, et al. Leisure time physical activity and mortality: A detailed pooled analysis of the dose-response relationship. JAMA Intern Med, 2015; 175:959–967.

Reiner

, Niermann

, Jekauc

, Woll

. Long-term health benefits of physical activity-a systematic review of longitudinal studies. BMC Public Health, 2013; 13:813.

World Health Organisation (WHO). Global Status Reports on Noncommunicable Diseases. World Health Organisation. 2014. https://www.who.int/nmh/publications/ncd-status-report-2014/en/ (accessed January 22, 2021).

Hamer

, Sabia

, Batty

, et al. Physical activity and inflammatory markers over 10 years: Follow-up in men and women from the Whitehall II cohort study. Circulation, 2012; 126:928–933.

Warburton

, Nicol

, Bredin

. Health benefits of physical activity: The evidence. CMAJ, 2006; 174:801–809.

Fox

KR.

The influence of physical activity on mental well-being. Public Health Nutr, 1999; 2:411–418.

10.

World Health Organisation (WHO). Physical Activity. World Health Organisation. 2020. https://www.who.int/news-room/fact-sheets/detail/physical-activity (accessed January 22, 2021).

11.

Statista. Number of Smartphone Users Worldwide from 2016 to 2023 (in billions). Statista.com. 2021. https://www.statista.com/statistics/330695/number-of-smartphone-users-worldwide/ (accessed April 9, 2021).

12.

Statista. Mobile Gaming Market in the

U.S

. —Statistics and

Facts

. Statista.com. 2021. https://www.statista.com/topics/1906/mobile-gaming/ (accessed April 9, 2021).

13.

Barnett

, Bangay

, McKenzie

, Ridgers

. Active gaming as a mechanism to promote physical activity and fundamental movement skill in children. Front Public Health, 2013; 1:74.

14.

Robertson

. The Ultimate VR Headset Buyer's

Guide

. The

Verge

. 2020. https://www.theverge.com/a/best-vr-headset-oculus-rift-samsung-gear-htc-vive-virtual-reality (accessed April 9, 2021).

15.

Haichun

Impact of exergames on physical activity and motivation in elementary school students: A follow-up study. J Sport Health Sci, 2013; 2:138–145.

16.

, Baranowski

, Hong

, et al. The narrative impact of active video games on physical activity among children: A feasibility study. J Med Internet Res, 2016; 18:e272.

17.

Martin

. Getting Fit with the Undead: The

Zombies

, Run

Story

. Alphr. 2017. https://www.alphr.com/business/1005907/getting-fit-with-the-undead-the-zombies-run-story/ (accessed April 9, 2021).

18.

Apple (Inc). App Store: Zombies, Run!. 2021. https://apps.apple.com/gb/app/zombies-run/id503519713 (accessed March 20, 2021).

19.

Direito

, Jiang

, Whittaker

, Maddison

. Apps for IMproving FITness and Increasing Physical Activity Among Young People: The AIMFIT Pragmatic Randomized Controlled Trial. J Med Internet Res, 2015; 17:e210.

20.

Cowdery

, Majeske

, Frank

, Brown

. Exergame apps and physical activity: The results of the ZOMBIE trial. Am J Health Educ, 2015; 46:4, 216–222.

21.

Farič

, Smith

, Hon

, et al. A virtual reality exergame to engage adolescents in physical activity: Mixed methods study describing the formative intervention development process. J Med Internet Res, 2021; 23:e18161.

22.

Craig

, Dieppe

, Macintyre

, et al. Developing and evaluating complex interventions: The new Medical Research Council guidance. BMJ, 2008; 337:a1655–a1655.

23.

Fugard

, Potts

. Supporting thinking on sample sizes for thematic analyses: A quantitative tool. Int J Soc Res Methodol, 2015; 18:669–684.

24.

Tong

, Sainsbury

, Craig

. Consolidated criteria for reporting qualitative research (COREQ): A 32-item checklist for interviews and focus groups. Int J Qual Health Care, 2007; 19:349–357.

25.

Michie

, Richardson

, Johnston

, et al. The behavior change technique taxonomy (v1) of 93 hierarchically clustered techniques: Building an international consensus for the reporting of behavior change interventions. Ann Behav Med, 2013; 46:81–95.

26.

Michie

, van Stralen

, West

. The behaviour change wheel: A new method for characterising and designing behaviour change interventions. Implement Sci, 2011; 6:42.

27.

Medical Research Council (MRC). Developing and Evaluating Complex Interventions. MRC.UKRI.ORG. 2019. https://mrc.ukri.org/documents/pdf/complex-interventions-guidance/ (accessed March 20, 2021).

28.

Gale

, Heath

, Cameron

. et al. Using the framework method for the analysis of qualitative data in multi-disciplinary health research. BMC Med Res Methodol, 2013; 13:117.

29.

Lorelli

, Norris

, White

, Moules

. Thematic analysis: Striving to meet the trustworthiness criteria. Int J Qual Methods, 2017; 16. DOI: 10.1177/1609406917733847.

30.

Braun

, Clarke

. Using thematic analysis in psychology. Qual Res Psychol, 2006; 3:77–101.

31.

Griffiths

, Lever Taylor

, Morant

, et al. A qualitative comparison of experiences of specialist mother and baby units versus general psychiatric wards. BMC Psychiatry, 2019; 19:401.

32.

Slater

, Wilbur

. A Framework for Immersive Virtual Environments (FIVE): Speculations on the role of presence in virtual environments. Presence Teleoperators Virtual Env, 1997; 6:603–616.

33.

Gillman

, Bryan

. Effects of performance versus game-based mobile applications on response to exercise. Ann Behav Med, 2016; 50:157–162.

34.

Sween

, Wallington

, Sheppard

, et al. The role of exergaming in improving physical activity: A review. J Phys Act Health, 2014; 11:864–870.

35.

Dallinga

, Janssen

, van der Werf

, et al. Analysis of the features important for the effectiveness of physical activity-related apps for recreational sports: Expert panel approach. JMIR Mhealth Uhealth, 2018; 6:e143.

36.

Liu

, Zeng

, Pope

, et al. Acute effects of immersive virtual reality exercise on young adults' situational motivation. J Clin Med, 2019; 8:1947.

37.

Ajzen

1985. From intentions to actions: A theory of planned behavior. In: J. Kuhl, J. Beckmann (Eds.), Action-Control: From Cognition to Behavior. Heidelberg: Springer. pp. 1 l–39.

38.

Sonnenblick

, Taler

, Bachner

, Strous

. Exercise, dehydroepiandrosterone (DHEA), and mood change: A rationale for the “runners high”?. Isr Med Assoc J, 2018; 20:335–339.

39.

Prabakaran

Endocannabinoids mediate runner's high. Sci Signaling, 2015; 8:ec322.

40.

Chatzidimitris

, Gavalas

, Michael

SoundPacman: Audio augmented reality in location-based games. In: 18th Mediterranean Electrotechnical Conference (MELECON), Lemesos, Cyprus, 2016, pp. 1–6.

41.

Stobbart

2019. Videogames and Horror. From Amnesia to Zombies, Run!. 1st Edition. Cardiff: University of Wales Press.

42.

Louchart

, Swartjes

, Kriegel

, Aylett

Purposeful authoring for emergent narrative. In: Spierling U., Szilas N. (eds) Interactive Storytelling. ICIDS 2008. Lecture Notes in Computer Science, Vol 5334.Berlin, Heidelberg: Springer.

43.

Sanders

, Juvancic-Heltzel

, Williamson

, et al. The effect of increasing autonomy through choice on young children's physical activity behavior. J Phys Act Health 2016:428–432.

44.

Ryan

, Deci

. Self-determination theory and the facilitation of intrinsic motivation, social development, and well-being. Am Psychol, 2000; 55:68–78.

45.

Baranowski

, Lyons

. Scoping review of pokémon go: comprehensive assessment of augmented reality for physical activity change. Games Health J, 2020; 9:71–84.

46.

Statista. Share of Individuals Who Accessed the Internet Via A Mobile phone in Great Britain in 2019 by age and gender. 2021. https://www.statista.com/statistics/275985/mobile-internet-penetration-in-great-britain-by-age-and-gender/#:~:text=As%20of%202018%2C%2095%20percent,own%20a%20smartphone%20is%20growing (accessed July 7, 2021).

47.

Statista. Do you ever play games at home or elsewhere on a mobile phone? 2021. Available at: https://www.statista.com/statistics/300522/mobile-gaming-in-the-uk-by-age/ (accessed July 7, 2021).

48.

McCarthy

, Potts

HWW

, Fisher

. Physical activity behavior before, during, and after COVID-19 restrictions: Longitudinal smartphone-tracking study of adults in the United Kingdom. J Med Internet Res, 2021; 23:e23701.