GH003-11
Climate change, time spent outdoors, and physical activity in a moist subtropical climate in the Southeast United States

Wednesday, 9 December 2020: 07:30
Virtual
Suwei Wang, Virginia Polytechnic Institute and State University, Population Health Sciences; Translational Biology, Medicine, and Health, Blacksburg, VA, United States, Molly B Richardson, University of Alabama at Birmingham, Medicine, Birmingham, AL, United States, Connor Wu, Troy University, Social Sciences- Geography, Troy, AL, United States, Ben Zaitchik, Johns Hopkins University, Balitmore, United States and Julia Gohlke, Virginia Polytechnic Institute and State University, Population Health Sciences, Blacksburg, VA, United States
Abstract:
Background

Previous studies have indicated high temperature/humidity is a barrier to meeting physical activity guidelines. As heat wave days increase with climate change, methods to characterize reductions in physical activity due to meteorological variables, and implications for chronic disease health outcomes are needed. Previous studies show time spent outdoors is positively associated with physical activity. We hypothesized even a small amount of increased outdoor time in summer may promote physical activity while bringing minimally increased heat exposure.

Methods

Residents of urban Birmingham (N=89) and rural Wilcox County, Alabama (N=88) were enrolled. Participants were asked to perform normal activities on Days 1-2 (baseline) and spend an additional 30 minutes outdoors on Days 3-7 (intervention). Participants wore small thermometers clipped to their shoes and pedometers. Shielded thermometer-hygrometers were placed outdoors within participant neighborhoods (N=43). Daily mean and max heat index (°C) were estimated from participant thermometer temperature and humidity from the nearest weather station to participants’ homes. Linear mixed models were fitted to estimate relationships between physical activity measured by pedometer steps and individually experienced heat index on baseline versus intervention days, accounting for ambient conditions ( heat index, rain, wind speed) and individual-level sociodemographic factors.

Results

Participants carried out the intervention on 736 (83%) person-days. Rain, heat, and time conflicts were top self-reported reasons for non-compliance. Participants on average walked 637 (95%CI 83-1192) more steps during intervention compared to baseline. When stratified by location, this was only significant for rural residents who walked 1063 (95%CI 273-1852) more steps during intervention. Participants had a 0.59°C (95%CI 0.30-0.88) lower mean individually experienced heat index during intervention, accounting for ambient conditions and individual-level factors.

Conclusions

This study presents methods for estimating how physical activity is related to heat exposure associated with additional time outdoors, integrating wearable sensor data and ambient weather conditions.

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