Does It Work? Installment #1

Posted | Posted in Does it Work?, Featured
Does It Work? is a new blog series from Duke Digital Health. We review studies on wearables, apps, and other technology-based interventions. A recent study tested the effect of text messages in addition to wearing a Fitbit on physical activity after 6 weeks. Researchers found that text messages can help people get more steps when they first start getting them, but the effects only last for about a week and then step counts return to what they were at baseline (before the intervention started). 

Welcome to our new blog series, “Does It Work?”

Each installment, we’ll review technology-based studies (on apps, wearables, SMS, etc) and discuss whether and how they provide evidence that technology can make an impact on health outcomes. 

For our first installment, we review a recently published paper by Julie B. WangPhD, MPH, Lisa A. Cadmus-BertramPhD, John P. PiercePhD and colleagues at UC San Diego, San Diego State, and UCSF in the Journal of Telemedicine and eHealth where researchers randomized 67 adults who were overweight or obese to either wear a Fitbit (control) or wear a Fitbit and get 3 text messages per day (intervention) for 6 weeks. 


As you’re already aware (unless you’ve been hiding here), chronic conditions like hypertension, type 2 diabetes, and cardiovascular disease are problems in the US.  Big ones. Getting the recommended amount of physical activity each week, in addition to eating a healthy diet, can help prevent these conditions. But! Over half of US adults don’t meet the recommended guidelines for physical activity. 

What if a wearable, plus a few texts each day with encouragement and reminders can help people get more physical activity?

Wouldn’t that be cool? 


 Who Participated?

The researchers recruited a total of 67 participants to participate in the study. They were mostly non-Hispanic white (67%) women (91%) who had graduated from college (61%). The average age of the participants was 48 years old, and the average BMI was 31. 50% of the participants said that they texted frequently and 39% reported having used a Web and/or mobile app for physical activity. 


The intervention group got:

  • A Fitbit One + the Fitbit app
  • 3 outbound texts per day for 6 weeks

And the control group got:

  • A Fitbit One + the Fitbit app
  • ***End of list

The researchers wrote a bunch of text messages with physical activity “cues to action” (i.e., nudges). Then, using EZ Texting, they sent them out to half of the participants 3 times per day, every day, for 6 weeks. A sample text message would say, 

Good morning [name]! This is your 9AM reminder to do at least a 10-minute bout of moderate-to-vigorous intensity physical activity.

Participants were not asked to respond to the text messages; they were outbound only.


At the end of 6 weeks, the intervention group (Fitbit + texts) had a slight increase in steps per day (average 24 more steps/day), while the control group (Fitbit alone) had a slight decrease in steps per day (average 433 fewer steps/day). This difference wasn’t statistically significant.

However, they found a significant increase in minutes of activity in the control group (Fitbit alone), but not in the intervention group. This difference was statistically significant. 

So – did the Fitbit + texts work?

It seems like getting text messages can give you a “step-boost” right as you start wearing a Fitbit. Since number of steps per day declined again after the first week, the researchers went to the survey data to find out why. They found that over half of the participants thought that 3 texts per day was too many, and reported having stopped reading the texts as the study went on. In conclusion, this study found that participants who wore a Fitbit did get more activity throughout the day, and text message reminders and cues helped participants get even more steps, until they got tired of them.