Physical Activity Dependence on Relative Temperature and Humidity Characteristics in a Young, Insufficiently Active Population: A Weather-Typing Analysis

Physical activity (PA) is an important contributor to one’s physical and mental health both acutely and across the lifespan. Much research has done on the ambient environment’s impact on PA, however, these studies have used absolute values of atmospheric measures such as temperature and humidity, which vary spatiotemporally and make comparisons between studies which differ in location or time of year difficult to square with one another. Here, we employ the Global Weather Type Classification, Version 2 (GWTC-2), a spatiotemporally relative weather typing scheme set on a grid for full global coverage, to determine the combined impact of temperature and humidity on PA in a sample of insufficiently active young adults. We conducted secondary analyses of data from a single-group behavioral intervention trial that varied the number of digital messages sent daily. Young adults (n=81) wore Fitbit Versa smartwatches for a six-month period sometime between April 2019 and July 2020 and location was tracked using a custom smartphone application. Mixed linear models indicated that, across 8,179 person-days, physical activity was significantly lower on days with humid conditions and significantly higher on Warm Dry days, though the latter relationship was no longer significant when controlling for timing in relation to the COVID-19 pandemic declaration. Demographic factors did not affect the relationship between weather and PA. Results are a first step in providing additional guidance for encouraging PA in insufficiently active individuals given forecasted daily weather conditions. Future work should examine seasonal variability in the weather type-PA relationship without the influence of a world-altering event influencing results.