Brickwood et al. 2019, Consumer wearable activity trackers, a meta-analysis

Systematic review and meta-analysis of consumer wearable activity trackers. Trackers significantly increased daily steps and moderate-to-vigorous activity, but at low-to-very-low certainty of evidence, and sedentary behaviour did not change. Multifaceted interventions (tracker plus coaching, goal-setting or support) produced effects roughly 50% larger than a tracker used alone. Moderate.