Physical-Activity Monitors May Boost Activity Levels in Adults: Review

By Brandon May

February 09, 2022

NEW YORK (Reuters Health) - Physical-activity monitors (PAMs), which provide direct feedback to wearers on their daily activity levels, appear to be effective at increasing physical activity in adults, although the evidence is not strong, findings of a systematic review and meta-analysis suggest.

"PAM based interventions are safe and effectively increase physical activity and moderate to vigorous physical activity," Dr. Rasmus Tolstrup Larsen of the University of Copenhagen, Denmark, and colleagues write in The BMJ.

"Because of the certainty of evidence, future studies could change the overall estimates and are encouraged to investigate how PAMs can be used in combination with other interventions or how PAMs can be used to reduce sedentary time," they caution.

Previous studies of PAMs' effect on physical activity have been inconsistent, the researchers note. In their review of the literature, they identified a total of 121 randomized trials with a total of 16,743 participants (median age, 47 years). Many studies were done in healthy participants (47%), but some included people who were overweight (17%) and/or had cancer (12%).

The PAMs studied were electronic or mechanical, portable or wearable, and were powered by pedometers, accelerometers, or GPS.

At baseline, the overall median daily step count was 6,994, and the median BMI was 27.8 kg/m2. Across studies, PAM-based interventions demonstrated a moderate effect on physical activity (standardized mean difference, 0.42; 95% CI, 0.28 to 0.55) that corresponded to 1,235 daily steps in favor of the intervention (low-certainty evidence).

Additionally, PAMs produced a small effect on moderate-to-vigorous physical activity (SMD, 0.23; 95% CI, 0.16 to 0.30) that was equivalent to 48.5 weekly minutes also favoring the interventions (moderate-certainty evidence).

"This study shows that PAMs may be another tool we can use to help people move more for everyone's benefit," said Dr. Naomi Parrella, chief of Lifestyle Medicine at Rush University Medical Center, in Chicago, who wasn't involved in the study.

"And this is particularly important as we approach two years of the pandemic when many people have been less active, working from home, going out less and having less freedom of movement," she told Reuters Health by email.

Dr. Brian Cruickshank, a sports-medicine specialist at the Renaissance School of Medicine at Stony Brook University, New York, told Reuters Health by email that the increase in physical activity associated with a physical activity monitor would undoubtedly cause a positive effect on any given individual.

"It is widely accepted that increased physical activity has been shown to promote multiple improvements in health," said Dr. Cruickshank, who wasn't involved in the research study. "We also know that it benefits mental health with improvements in sleep, boosting memory and brain function, and can help with depression and anxiety."

While Dr. Larsen and colleagues say the effects observed in the study were small to moderate, they are still likely to provide benefits at the individual level, explained Dr. Cruickshank. "If people are consistent with any form of increased physical activity and use this as more of a lifestyle change to become more active, those are the people that would see the most benefit."

He added that additional study may be needed to determine the effects of today's smartwatches on physical activity and other health metrics. "I believe this technology can be important in the future of how we study and monitor people's physical activity, but more research needs to be done with respect to this now very common piece of technology."

Jeffrey Lucchino, director of Sports Nutrition at the University of Pittsburgh Medical Center Sports Medicine, in Philadelphia, noted that physical activity monitors "can be a useful accountability and engagement tool to assist in motivation and awareness of certain metrics."

But Lucchino, who also wasn't involved in the study, cautioned that many wearables do not accurately measure caloric expenditure and suggested the devices may not be useful if used as a sole tool for monitoring weight-loss efforts.

The study had no commercial funding, and the researchers report no conflicts of interest.

Dr. Larsen was not available for comment by press time.

SOURCE: The BMJ, online January 26, 2022.