The effectiveness of a wearable activity tracker (WAT)-based intervention to improve physical activity levels in sedentary older adults: A systematic review and meta-analysis

•A WAT-based intervention grounded in BCTs improve PA levels in older adults.•A traditional pedometer and WAT-based intervention seem to have similar improvements in older people’ PA levels.•More clinical trials are still required to see the long term effects of WAT-based intervention. The evidence shows that WAT-based interventions enhance the physical activity (PA) levels of young people by sustainably delivering behavior change techniques (BCTs). These results may not be replicable among older adults. This paper aims to evaluate the effectiveness of WAT-based interventions in improving PA levels in sedentary older adults. Eight electronic databases were searched for randomized controlled trials published January 2008 to December 2018. BCTs delivered by WAT aimed at increasing PA levels using step counts or time spent on moderate-to-vigorous (MVPA) exercise as an outcome were eligible for inclusion. In nine out of the ten included studies, higher PA levels were seen in the intervention group than in the control group. One study where the participants’ mean age was 80+ showed no significant increase in PA levels. Significant effects were also demonstrated from the meta-analysis, which included four studies using a passive control (i.e., the usual care or health information) on step counts (n = 207, Hedges g = 1.27, 95 % CI = 0.51–2.04, p = 0.001) and two studies on MVPA (n = 83, Hedge’s g = 1.23, 95 % CI = 0.75–1.70, p < 0.001). A non-significant effect was found on step counts (n = 201, Hedge’s g = 0.22, 95 % CI = −0.62 to 1.06, p = 0.61) in three studies that used an active control comparison group (i.e., traditional pedometer). A WAT-based intervention is effective at improving PA levels among older adults over the short term when compared with the usual care or health information. However, when compared with a traditional pedometer or when used among old-old adults, the results were inconclusive.