Researchers say wearable activity trackers may not increase physical activity enough to benefit health.
The study - a year-long randomized trial involving 800 full-time workers that was conducted by Duke-NUS Medical School in Singapore - is published in The Lancet Diabetes & Endocrinology.
Pedometers and activity trackers, such as Fitbit, Garmin, Jawbone, and others are rising in popularity. However, despite this, there is little evidence they improve health.
Around 10 percent of Americans own such a device, but research suggests about a third stop using them within 6 months of purchase.
The authors of the new study wanted to see if financial incentives could encourage people to use the devices more and achieve higher levels of fitness.
Lead author Prof. Eric Finkelstein, who researches the economic causes and consequences of health behaviors, says they found while participants who wore the activity trackers showed no change in their step count, they did show a "moderate" increase in aerobic activity - by an average of 16 minutes a week.
"However," he notes, "we found no evidence that the device promoted weight loss or improved blood pressure or cardiorespiratory fitness, either with or without financial incentives."
In fact, he says that following some initial progress, once the incentives stopped, the participants did worse than if they had never been offered the inducements, and most stopped wearing the activity trackers.
Their findings follow those of another study published recently in JAMA that found using wearable devices did not improve weight loss among overweight or obese young adults.
Trial compares trackers with and without incentives
The 12-month trial involved 800 employees aged 21-65 years working in 13 organizations in Singapore, and it was designed to measure the extent to which wearing an activity tracker (a Fitbit Zip worn on the waist) with and without incentives could increase physical activity and improve health outcomes.
The participants were randomly put into four groups: a control group (no trackers), a tracker-only group, and two tracker plus incentive groups (one accumulated cash rewards and the other collected financial rewards for charities of their choice). The incentives were tied to weekly step goals over the first 6 months of the trial. Incentives were withdrawn for the second 6 months.
The results showed that regardless of their physical activity levels before they started the trial, tracker-only participants and those with trackers plus charity incentives did not raise activity levels. In fact, nearly half of participants in these groups had stopped wearing their trackers at the 6-month assessment.
In contrast, in the group offered cash rewards and trackers, regardless of their level of activity before the trial, activity levels over the first 6 months went up significantly and over 90 percent of them were still using their trackers at the 6-month assessment.
However, at the end of the trial - 6 months after the incentives were withdrawn - the tracker and cash group showed poorer step outcomes than the tracker-only group. The researchers say this suggests removing the incentives may have demotivated them and caused their activity levels to fall below what they would have been if no cash had been offered.
No significant improvements in health
Overall, the researchers found that despite differences in increased step achievements, activity trackers with or without incentives did not lead to significant improvements in measures of health.
They note, however, that their findings also suggest the type of incentive and how long it is in place for is important.
Prof. Finkelstein says they show tying financial incentives to daily steps "may not be the way to go." However, tying them to moderate-to-vigorous physical activity or aerobic steps "is worth considering."
"Yet," he notes, "the results also suggest that any incentive strategy would need to be in place for a longer period of time to generate any noticeable improvements in health benefits and to avoid any undermining effect from their removal."
In discussing important areas of future research, Dr. Courtney Monroe, from the University of South Carolina in Columbia, notes in a comment article accompanying the study report:
"Testing the use of financial incentives, wearables, or both, in conjunction with other technologies and strategies that have great potential as components of physical activity promotion (e.g., mobile phone features, gamification, and social media) is a logical future step."
Research shows that moderate intensity exercise - such as walking, cycling, or sports - can significantly improve health. For example, it can lessen risk of diabetes, cardiovascular diseases, depression, and colon and breast cancers.
According to the World Health Organization (WHO), physical inactivity is the fourth leading risk factor for premature deaths worldwide, contributing to an estimated global death toll of 3.2 million a year.
In the United States, health officials say that while some Americans are getting enough exercise, estimates suggest only around 21 percent of adults meet physical activity guidelines.
"Activity trackers alone are not going to stem the rise in chronic diseases."
Prof. Eric A Finkelstein