Physical inactivity is the fourth leading risk factor for global mortality (1). Insufficient physical activity (PA) has major implications for global health and the prevalence of lifestyle diseases, such as cardiovascular conditions, diabetes and cancer, and their associated risk factors (1, 2). Compared to inactive adults, active individuals have lower rates of all-cause mortality, lower risk to develop lifestyle diseases, lower risk of an injury, higher level of cardiorespiratory and muscular fitness, and healthier body mass and composition (3, 4).

According to the WHO 2020 guidelines on PA for health, adults aged 18–64 should perform 150–300 min of moderate-intensity PA per week, or at least 75–150 min of vigorous-intensity PA per week, or an equivalent combination, irrespective of gender, race, ethnicity or income level (5). Worldwide, nearly one third of adults are physically inactive (6). In Norway, only one third of the adult population meets the minimum recommendations on PA (7). In Northern Norway, a region characterized by a high peripherality and adverse weather conditions, PA levels are lower than in Southern Norway (8).

Inactive individuals may not know how, when, where, and with whom they can increase their PA (9). It is especially important to address the key barriers in inactive populations such as psychological factors (lack of motivation, lack of skills/knowledge), environmental obstacles (lack of facilities, bad weather), time constraints (lack of time), and social limitations (lack of social support) (9, 10). Interventions based on behavior change techniques, including goal setting, feedback and monitoring, and social support (11), have been proven to be effective at increasing PA levels in young adults in the shorter-term (12). Further research is needed to determine strategies to achieve longer-term effectiveness of PA interventions (12).

Digital technologies such as wearables, websites and mobile apps are increasingly used in interventions targeting PA together with behavior change techniques and computer-tailored methods (13, 14). Due to their broad availability, digital interventions have the potential to make PA more accessible and feasible for all groups, reduce health inequalities and support long-term adherence to PA recommendations (9, 14).

Consumer-based wearable activity trackers and smartphone apps are now widely available and may offer an alternative method for assisting individuals to remain physically active (9, 15). These devices provide individuals with the ability to objectively monitor their PA levels by features such as distance walked, number of steps, frequency or duration of activity (16) or time spent in various intensities of PA (17). Unlike other PA metrics, heart rate changes reflect the body's response to exercise regardless of the type of activity performed (16). Some apps can also provide tailored feedback through specifically designed algorithms (15). An example is the Personal Activity Intelligence (PAI), which takes into account age, sex and heart rate patterns to provide a single score indicating whether the current PA level is sufficient to obtain or sustain good health (16, 18). Despite representing a promising tool for delivering accessible and appealing PA interventions (19, 20), the evidence supporting the effectiveness of activity trackers and smartphone apps to increase PA is modest at best (15, 21–23). Moreover, there is limited insight into the sustainability of increased PA levels and long-term adherence, and further research should include long-term follow-up assessments (21).

Wearable activity trackers can be used either as the primary component of an intervention or as part of a broader PA intervention (15) which could include other useful components and behavior change techniques. Home-based exercise programs have been shown to be effective in promoting PA in low-active older adults (24). While short-terms effects seem to be achievable, poor adherence to home-based exercise can limit the long-term benefits (25). Home-based online training can provide a platform to scale effective support for sustainable behavior change, thus empowering adults to perform regular PA and increasing engagement over time (20). Participation in home exercise video programmes has been piloted and proven to be feasible (26). Peer support groups represent another well-documented technique to ensure adherence to PA among adults and maintenance of behavior change (27). Peer support provided via social media has the potential to support lifestyle change among young adults (28) and further increase the effectiveness of PA interventions and long-term adherence (29, 30). Moreover, the provision of educational information, simple self-monitoring strategies and regular feedback from peers challenging the individuals' capability might help people to maintain PA (31).

This hybrid type I effectiveness-implementation randomized controlled trial (RCT) aims to explore longitudinal changes in PA, long-term exercise maintenance, health and implementation outcomes of an activity tracker with the personalized metric PAI, home-based online training and peer support via social media among inactive adults. These digital interventions have the potential to promote PA among high-risk populations, thus resulting in better health and prevention of lifestyle diseases.

The ONWARDS study aims to explore longitudinal changes in PA, long-term exercise maintenance, health and implementation outcomes among inactive adults using three different digital interventions for PA promotion, namely an activity tracker with the personalized metric PAI, home-based online training via Les Mills+ and peer support via a Facebook closed-group. Inactive adults often do not access a training facility or use equipment for home exercise. A control group receiving “standard care” was therefore deemed to be unfair for these individuals. All participants in this study will therefore be provided with at least an activity tracker. The presence of three interventional groups will allow testing of which combination of strategies is more effective in increasing PA levels and maintaining them over the long-term.

Psychological factors, including lack of motivation and lack of skills/knowledge, represent a major barrier to PA (9, 10). Perceived self-efficacy can affect both motivation and actions and is important for lasting changes in PA (47). Other effective behavior change techniques used in mobile apps for PA include goal setting, monitoring and feedback about whether or not one gets enough exercise (13). PAI is personalized metric based on heart rate data which can be used by everyone of all ages and fitness levels. The PAI Health mobile app sets a clear goal, which is to keep a weekly PAI score above 100 for disease prevention and health promotion. Users who struggle with keeping physically active can self-monitor their PA level via the PAI Health app, which provides a daily feedback on their current PAI score and reminds them to try to reach their goal. Thanks to these features, we expect that the participants in this study will increase their perceived self-efficacy, competence and motivation for exercise which, in turn, might result in higher PA levels and better adherence to PA recommendation.

Geographical isolation and related environmental factors (e.g., lack of facilities) are especially related to health disparities and inequality in PA (48). Access to training facilities can promote PA with equipment for strength and aerobic exercise as well as group-based classes, which are motivating and result in better long-term adherence (29). However, many people do not have access to these facilities, and others have concerns about their appearance (10). Adverse weather conditions represent another major barrier to participation in PA, and high or low temperatures, rain, snow or wind may all decrease the pleasure derived from outdoor activities (49). Lack of time is one of the most reported reasons why healthy adults do not participate in sport or physical recreation (10, 50). Northern Norway, where this study will be conducted, is a region characterized by frequent adverse weather conditions as well as a high peripherality, with several people living outside urban areas and without easy access to training facilities. Moreover, study participants will be inactive young or middle aged adults, which most likely will be studying or working and might therefore perceive lack of time as a barrier to PA. The possibility for participants in groups B and C to exercise conveniently from home supported by video programmes has the potential to empowering them to perform regular PA while addressing common issues such as lack of time or concerns about appearance. Moreover, interventions with a group atmosphere, such as Les Mills+ online programmes, can be more effective in increasing engagement over time and reducing perceived stress (20).

The lack of social support is another common barrier to PA (10). Poor adherence to home-based exercise (24), in addition to the poor adherence observed in e-health interventions (51), makes the implementation of digital technologies for PA a challenging issue. Novel strategies are needed to ensure adherence to PA among adults and maintenance of behavior change (27). Social media are nowadays widely used in many people's daily routines and are shown to be valuable for targeting lifestyle change among young adults (28). In a study examining the efficacy of a Facebook social support group to increase PA in young women, participants in a Facebook social support group increased the number of steps per day more than those in the standard walking intervention (30). Participants in group C will be offered peer support via a Facebook closed-group, where they will have the possibility to share their experiences or ask for advice from other members of the group, as well as receive educational information about PA, motivational support and rewarding messages from the project team. It is expected that peer-support via social media will result in better adherence to PA, better maintenance of PA levels over the long-term, as well as fewer dropouts.

This study can contribute to reduce disparities in PA levels among inactive adults by increasing access to PA and promoting long-term adherence. Increased PA might, in turn, result in better prevention of lifestyle diseases. Digital interventions delivered at home can become an alternative to training facilities, making PA accessible and feasible for inactive populations and overcoming known barriers to PA. If effective, such interventions could potentially be offered on a large-scale through national health portals to all citizens who do not meet the minimum recommendations on PA. Effective e-health interventions for PA could also be prescribed by general practitioners or specialists to both healthy and impaired individuals. The study will be conducted in the Troms and Finnmark county in Northern Norway. However, the results will be applicable to other regions and countries. The interventions could be also applicable to selected patient groups, particularly those with mobility impairment characterized by low levels of PA.

The studies involving human participants were reviewed and approved by Regional Committee for Medical and Health Research Ethics (66573/REK nord). The patients/participants provided their written informed consent to participate in this study.

Procured funding: PZ. Conceptualization, design, and critical review of manuscript: PZ, USM, EHS, BM, AEE, I-LA, BMN, BH, M-PG, and KA. Drafting manuscript: PZ, USM, EHS, and KA. All authors have read and approved the manuscript.

This study was funded by the Northern Norway Regional Health Authority (Project Grant HNF1428-18). The study protocol has undergone peer-review by the funding body. Access to Les Mills+ for the participants in groups B and C was provided for free by Les Mills International (Auckland, New Zealand).

Author AEE was employed by Memento U. Author BH is Head of Research at Les Mills International. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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