Physical activity monitoring devices may be useful to boost activity levels in adults

Physical activity monitors, such as fitness apps and wearable activity trackers, that provide direct feedback to users do help to boost activity levels in adults, finds a summary of the evidence, published by The BMJ today.

The effects are small to moderate - equal to 1,235 extra steps a day and almost 50 extra minutes of moderate to vigorous physical activity a week - and the certainty of evidence ranged from low to moderate. But the findings suggest that these devices may be useful at a time when many adults don't meet recommended activity levels.

Modern physical activity monitoring devices have the potential to change people's behavior, but studies looking at their effectiveness have often reached different conclusions.

To address this uncertainty, researchers in Denmark searched databases for trials comparing activity levels in adults who received feedback from physical activity monitors with control interventions in which no feedback was provided.

They found 121 randomized controlled trials involving 16,743 mainly healthy 18 to 65 year olds. Most of the trials were European (31%) or North American (40%) with a median intervention period of 12 weeks. The median age of study participants was 47 years, with a higher proportion of women (median 77%) than men.

Overall, the interventions showed a moderate effect on physical activity (equivalent to 1,235 daily steps), a small effect on moderate to vigorous physical activity (equivalent to 48.5 weekly minutes) and a small but insignificant effect on sedentary time (equal to 9.9 daily minutes).

For all outcomes, physical activity monitors that provided feedback were more effective than those that did not provide feedback.

The researchers acknowledge that the included trials varied in design and methods and say the results may not be applicable to lower-income countries.

Nevertheless, they add, this is the first systematic review to summarise the entire body of evidence across different patient populations and different types of physical activity monitors.

As such, they say this study "provides evidence for using physical activity monitors for enhancing physical activity and moderate to vigorous physical activity at a time when large, feasible, and scalable interventions are urgently needed."

And they call for future studies to investigate how physical activity monitors can be used in combination with other behavioral change strategies or how they might affect sedentary time.