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CBC Digi-Hub Blog



SMARTFAMILY – mobile health behaviour change in the family setting

By CBC Digi-Hub Blog, on 30 November 2020

Written by Dr. Kathrin Wunsch and Janis Fiedler on behalf of the SMARTFAMILY project

Everyone knows that a lack of physical activity, too much sedentary time (e.g., extended screen time and nonactive media usage), and an unhealthy diet are serious concerns in modern societies as they accelerate the development of non-communicable diseases, which are causing millions of deaths every year. Research has repeatedly shown that human beings do not sufficiently engage in physical activity and frequently make unhealthy food choices throughout their entire lifespan. Therefore, it is of great interest to public health policymakers to reverse this trend at the earliest possible life stage. Longitudinal studies have shown that behavioural patterns in childhood and adolescence are vital because of their influence on physical activity patterns in adulthood.

As health behaviours in childhood and adolescence are to a large degree formed by parental behaviours, it is fundamental to target whole families. Research shows that supportive interactions within the family setting and shared values about health behaviour affect children’s physical activity engagement and eating behaviour. This has two major advantages: 1) the provision of early interventions can enable children and adolescents to adapt a healthy lifestyle, which they will likely transfer into (older) adulthood, and 2) by targeting both adults and children, there’s the added benefit of parental support, which is an important correlate of healthy behaviour in youth, and adults are also capable of behaviour change towards an active lifestyle.

As so many people today have access to the internet (4.5 billion active internet users in 2020 worldwide) and mobile Health (mHealth) interventions are popular – especially in young people –  we decided to use mHealth technology to reach as many families as possible and to provide a cost-effective behaviour change intervention. Specifically, smartphone-based apps offer a great promise for enhancing physical activity and healthy eating as well as for making health care more accessible and scalable, more cost-effective, more equitable, and offer multiple opportunities for new, sophisticated developments.

But what are the key facets to include when developing such an intervention? To answer this question, we conducted an umbrella review of mHealth interventions targeting physical activity and healthy eating. Overall, findings suggested that the majority (59%) of e- and mHealth interventions were effective and used a theoretical foundation. In addition, we identified behaviour change techniques that were potential moderators of intervention effectiveness. However, most studies did not assess the impact of embedding interventions into social contexts (e.g. involving family members, peers or co-workers in the intervention). We did not see any mention of ‘ecological momentary interventions’ or ‘just-in-time adaptive interventions’ – i.e. interventions delivered at the right moment in time for each individual – in this umbrella review. With the possibility to tailor and to continually adapt mHealth interventions to each person’s unique needs, as well as to deliver support at the most promising moment in time, these parameters were identified by many study authors as being important to incorporate in new app designs.

With SMARTFAMILY, we wanted to fill these research gaps. As we identified mHealth to be a promising approach in our review and due to the known influence of parental support on early child and adolescent physical activity, we created an app that included all of these elements. Our app was developed based on social-cognitive and self-determination theory and included several behaviour change techniques. Importantly, we embedded the intervention in the social setting (i.e., the family) and enabled family members to set collective (instead of competitive) goals for physical activity and healthy eating. Our hypothesis is that by targeting multiple behaviours in multiple people, who can support each other to achieve goals, it should be easier to implement and maintain behaviour change. Moreover, we included gamification features into the app to enhance user engagement along with a just-in-time adaptive intervention approach and ecological momentary assessment features.

SMARTFAMILY is an app for the whole family (see Figure below), which incorporates the following features:

– an interactive goal-setting coach which provides useful facts to improve health literacy and supports goal setting within families

– device-based measured physical activity of participants with immediate feedback on goal achievement, in addition to the option to manually enter physical activity where the accelerometer has not been worn (e.g. during swimming)

– self-reported meals, common meals and common physical activity as well as physical activity where the sensor has not been worn (e.g. swimming)

– triggered and app-based ecological momentary assessment for physical activity and healthy eating; real-time measurement of behavioural and affective correlates of physical activity and fruit and vegetable intake, including current mood, stress, and exhaustion

– push notifications about inactivity sent by the coach when the participant is inactive for at least 60 minutes during waking hours (i.e. when the system detects that neither <2 sensor values at >2MET nor 100 steps has been achieved) – i.e. a just-in-time adaptive intervention; notifications are inhibited the rest of the day if the participant reaches at least 60 minutes of moderate-to-vigorous physical activity on the respective day

– a sleep-mode set by participants before going to bed and after waking up, providing the time frame during which the app was used and a resting time estimation

– gamified goal achievement, where participants gather stars for every 10% of progress towards the weekly physical activity and healthy eating goal. The goal setting coach motivates the family to achieve their goals by prompting a “this far to go” summary every morning after waking up. In addition, the families are advised about a promising goal for the following week depending on their previous goal achievement by the coach.


Overall, we aim to close identified research gaps by evaluating an mHealth app which is theory-based, incorporates several behaviour change techniques, takes the social context into account and uses sophisticated new approaches like gamification, just-in-time adaptive interventions and ecological momentary assessments in a cluster randomized controlled trial design. We expect that our research will shed light on the important factors for health behaviour change in families and help to design more efficient interventions for (early) primary prevention in the future.

More information about SMARTFAMILY (@SMARTFAMILY9):

SMARTFAMILY is supported by the German Federal Ministry of Education and Research Grant FKZ 01EL1820C within the SMARTACT consortium (PI Prof. Dr. Britta Renner), with Prof. Dr. Alexander Woll, Karlsruhe Institute of Technology, Germany, as PI of SMARTFAMILY. Besides the PI and the authors, Tobias Eckert as well as our student staff needs to be acknowledged as being part of our project.





Dr. Kathrin Wunsch (@KathrinWunsch) is a post-doctoral researcher and Project Lead (@SMARTFAMILY9) at the Karlsruhe Institute of Technology. Her research focuses on influences of physical activity and multiple health behaviours on psychological and physiological health throughout the lifespan as well as on the development and implementation of mobile health interventions.



Janis Fiedler (@FieJanis) is a doctoral student at the Karlsruhe Institute of Technology. His research focuses on mobile behaviour change interventions to enhance physical activity and healthy eating as well as different aspects of exercise physiology. In general, he is very interested in anything related to primary prevention, physical activity and nutrition.



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