Recent investigations of smartphone app-based activity interventions suggested that these approaches have a positive, but not significant, impact on individuals' daily physical activity, according to a recent meta-analysis of published randomized controlled trials (RCTs).
Despite the limited gains, the evidence does suggest that the effect differs based on how the interventions are deployed and measured. App-based interventions examined in a short-term window had a significant positive event, for instance, and those consisting of an app alone found more success than others that incorporated dietary support.
Both of these secondary findings will require more research to build upon or confirm, particularly in light of the finding regarding single-focus interventions, the researchers wrote. But with only a handful of more than 6,000 meeting the analysis's final quantitative criteria, the researchers stressed the need for more RCTs exploring these app-based activity interventions.
"This meta-analysis highlights that relatively few high-quality studies have been conducted examining the effectiveness of physical activity smartphone interventions," they wrote in The Journal of Medical Internet Research (JMIR). "Future studies should describe their intervention and app features with adequate detail so that results are reproducible, can be learnt from, and advance this field of research."
The researchers found nine RCTs that met inclusion criteria and could be included in a qualitative synthesis, all of which were published between 2014 and 2017. These featured sample sizes ranging from 23 participants to 833, and comprised 1,740 participants. Intervention lengths ranged from six weeks to six months.
Of these RCTs, only six involving 1,178 participants reported objective physical activity through daily step counts. Compared to controls, the studies suggested a nonsignificant (P = .19) increase of 476.75 average steps per day (95% confidence interval, −229.57 steps to 1,183.07 steps).
Within sensitivity analyses, the researchers found that excluding studies with an intervention length of three or more months yielded a significant average daily step gain of 2,074.96 steps (P = .01; 95% CI, 606.80 to 3,543.11). Another analysis of studies targeting physical activity alone yielded a significant increase of 716.86 daily step (P = .01; 95% CI, 38.37 to 1,395.36), while a third review of studies targeting different participant populations fell more in line with the meta-analysis' top-level findings.
HOW IT WAS DONE
The researchers parsed seven electronic literature databases to find 6,170 studies published between 2007 and January 2018.
To be included in the final analysis, these studies need to be RCTs that focused on smartphone apps as the primary component of a physical activity intervention among healthy adults or adults with a specific health condition.
The researchers limited the analysis to those with control groups that received little or no intervention. Notably, the trials needed to quantitatively measure activity as either physical activity minutes (too few of which were found to conduct an analysis) or as daily step counts.
WHAT'S THE HISTORY?
Exercise apps of various kinds can be found across mobile app stores, and the devices' built-in step counters have long provided objective activity data for researchers. Among the more recent studies on behavior change tied to these software include a JMIR meta-analysis published in March 2019 that found nonsignificant behavior improvements from consumer fitness apps, and a Stanford University-led Lancet Digital Health study from last October that lent support short-term health-behavior changes from "minimal interventions" such as smartphone app notifications.
The new data also comes at a time when tech leaders are betting big on digital fitness subscriptions for consumers. Just this week, Apple unveiled a video-fitness-class offering delivered through its devices to compete with the likes of Peloton and Mirror.
"Future research should be directed toward enhancing understanding of the time course of intervention effects," the researchers wrote. "In particular, increased understanding of the timepoint at which peak effect size is reached, the timepoint at which user engagement decreases, and the factors that underpin these phenomena are required. This may involve future studies with longer follow-up periods and with outcome measurements taken at more regular and frequent timepoints."