More real-world trials are needed to establish if web-based physical activity interventions are effective

Despite the positive health benefits of physical activity, physical inactivity remains highly prevalent. To address this public health issue, population-based interventions that can effectively reach large numbers of people at low cost are needed. Numerous randomised controlled trials (RCT) have examined the effectiveness of web-based physical activity interventions, and overall, these intervention studies have found to increase participants’ physical activity levels. Few studies, however, have examined how well these interventions work in ‘real world’ or ecologically valid settings, where there are no repeated contacts with research staff, comprehensive assessments or incentives. A recent systematic review examined mobile health (mHealth) clinical trial study methodology for trials conducted in 2014 and 2015 and did not identify a single ecological trial, yet RCTs were dominant (80%, 51/71). To address this, we conducted two studies using the same web-based physical activity interventions: a RCT and a randomised ecological trial (RET).