JMIR Publications

ABSTRACT

Background:

Insufficient physical activity (PA) is highly prevalent and associated with adverse health conditions and risk for non-communicable diseases. In order to increase levels of PA, effective interventions to promote PA are needed. Present-day technologies such as smartphones, smartphone apps and activity trackers offer possibilities in health promotion.

Objective:

This study explored the use and short-term effects of an app-based intervention Active2Gether to increase levels of PA in young adults.

Methods:

Young adults aged 18-30 years were recruited (N=104) using diverse recruitment strategies. The participants were allocated to the Active2Gether-Full condition (tailored coaching messages, self-monitoring, social comparison), Active2Gether-Light condition (self-monitoring, social comparison) and the Fitbit-only control condition (self-monitoring). All participants received a Fitbit One activity tracker - that could be synchronized with the intervention apps - to monitor PA behavior. A 12-week quasi-experimental trial was conducted to explore intervention effects on weekly moderate-vigorous PA (MVPA) and relevant behavioral determinants (self-efficacy, outcome expectations, social norm, intentions, satisfaction, perceived barriers, long-term goals). The ActiGraph wGT3XBT and GT3X+ were used to assess baseline and post-intervention follow-up PA.

Results:

Compared to the Fitbit condition, the Active2Gether-Light condition showed the largest effect sizes for minutes of MVPA per day (B= 3.1, 95%CI= -6.7;12.9), and smaller effect sizes were seen for the Active2Gether-Full condition (B= 1.2, 95%CI= -8.7; 11.1). Linear and logistic regression analyses for the intervention effects on the behavioral determinants at post-intervention follow-up showed no significant intervention effects of the Active2Gether-Full and Active2Gether-Light condition. The overall engagement with the Fitbit activity tracker was high (median= 88 percent of the days), but this was lower in the Fitbit condition. Participants in the Active2Gether conditions reported more technical problems than in the Fitbit condition.

Conclusions:

The current study showed no statistically significant differences in MVPA or determinants of MVPA after exposure to the Active2Gether-Full condition as compared to Active2Gether-Light or Fitbit condition. This might partly be explained by the small sample size and the low rates of satisfaction in the participants in the two Active2Gether conditions that might be due to the high rates of technical problems. Clinical Trial: Dutch Trial Registry Registration number NTR5630