JMIR Publications

ABSTRACT

Background:

Numerous smartphone applications (apps) are targeting physical activity (PA) and/or healthy eating (HE), but empirical evidence on their effectiveness for initialization and maintenance of behavior change, especially in children and adolescents is still limited. Individuals’ behavior is embedded in social settings, therefore, core settings such as the family need to be considered when designing mobile health (mHealth) apps.

Objective:

The purpose of this study was to conceptualize a first version of a theory- and evidence-based mHealth intervention (called SMARTFAMILY (SF)) targeting PA and HE in a collective family-based setting.

Methods:

A smartphone app based on behavior change theories and -techniques was developed, implemented, and evaluated in a collective family setting with family members individually and cooperatively using the SF-app. Therefore, a cluster-randomized controlled trial including three measurement occasions was conducted. The intervention group (IG) used the app for three consecutive weeks, whereas the control group (CG) received no treatment. Baseline- (T0) and post-measurements (T1) included PA (self-reported and accelerometry) and HE measurement (self-reported fruit and vegetable intake (FVI)) as primary outcomes. Secondary outcomes (self-reported) were intrinsic motivation, behavior-specific self-efficacy, and the Family Health Climate (FHC). Four weeks following T1, a follow-up assessment (T2) was completed by participants, consisting of all questionnaire items to assess the stability of the intervention effects. Multilevel analyses were implemented in R to acknowledge the hierarchical structure of persons (level 1) clustered in families (level 2).

Results:

Overall, 48 families (22 KG, n = 68 participants; 26 IG, n = 88) were recruited for the study. Two families (1 KG, n = 4; 1 IG, n = 4) chose to drop out of the study due to personal reasons before T0. Overall, no evidence for meaningful and statistically significant increases in PA and HE levels of the intervention was observed in our physically active sample.

Conclusions:

The SMARTFAMILY trial aimed to assess the effectiveness of a mobile health (mHealth) intervention in promoting physical activity (PA) and healthy eating (HE) in families. Despite incorporating behavior change techniques rooted in family life and psychological theories, the intervention did not yield significant increases in PA and HE levels among the physically active participants. Previous studies on digital health interventions have shown mixed results and family-based mHealth interventions are scarce, with limited focus on whole-family behavior and randomized controlled trials. Enhancing intervention effectiveness may involve incorporating health literacy, just-in-time adaptive interventions, and more advanced features in future app development. Further research is needed to better understand intervention engagement and tailor mHealth interventions to individuals for enhanced effectiveness in primary prevention efforts. Clinical Trial: The study is registered with the German Clinical Trials Register under the registration number DRKS00010415. The study is funded by the German Federal Ministry of Education and Research.