• Jacob E Simmering, Linnea A Polgreen, Shelby L Francis, Austin J Strom, Alberto M Segre, and Philip M Polgreen.
• Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
• Mil Med. 2024 Jun 3.

IntroductionPhysical inactivity, hereafter inactivity, is a serious health problem among U.S. veterans, hereafter veterans. Inactive adults are at risk for adverse cardiac events and premature mortality. Specifically, among veterans, inactivity has been associated with a 23% increase in mortality. In order to increase physical activity among veterans, we developed Veterans Affairs (VA) MapTrek, a mobile-phone-based web app that allows users to take a virtual walk in interesting locations around the world while tracking their progress against that of others like themselves on an interactive map. Steps are counted by a commercially available Fitbit triaxial accelerometer, and users see their progress along a predefined scenic path overlaid on Google Maps. The objective of this study was to determine the effectiveness of VA MapTrek to increase physical activity in a population of veterans at risk for obesity-related morbidity.Materials And MethodsWe recruited overweight and obese veterans obtaining care at the Iowa City Veterans Affairs Health Center. Half of the veterans were assigned to participate in VA MapTrek. Each week, participants were assigned virtual walking races (Monday through Saturday), which followed a predetermined route that is displayed on Google Maps. The participant's position on the map is automatically updated each time their Fitbit syncs to their phone. In addition, challenges were issued periodically. Veterans in the control group were only given a Fitbit. We regressed daily step counts on the days of the week, the days since the start of the intervention period, whether the user was in the VA MapTrek or Control group, and an interaction between the study group and the days since the start of the intervention period. We included subject-specific random intercepts and subject-specific random slopes. This model was estimated using Bayesian Hamiltonian Monte Carlo using Stan's No-U-Turns sampler. We set vague, uniform priors on all the parameters.ResultsWe enrolled 276 participants, but only 251 (102 in the control group and 149 in the VA MapTrek group) contributed data during the intervention period. Our analysis suggests an 86.8% likelihood that the VA MapTrek intervention led to a minimum increase of 1,000 daily steps over the 8-week period, compared to the control group. Throughout the 8-week intervention, we project that VA MapTrek participants would have taken an extra 96,627 steps, equivalent to 77.8 additional kilometers (km) (48.3 additional miles), assuming an average of 1,242 steps per km (2,000 steps per mile).ConclusionsOur study underscores the potential of VA MapTrek as an intervention for promoting walking among veterans who face elevated risks of obesity and cardiac issues. Rural veterans are a high-risk population, and new interventions like VA MapTrek are needed to improve veterans' health.© The Association of Military Surgeons of the United States 2024. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site–for further information please contact journals.permissions@oup.com.

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