Influence of Summertime Climate on Total Daily Physical Activity Values in Older, Community-Dwelling Adults

Abstract

Higher ambient temperatures, particularly when combined with excess humidity (Humidex) may negatively influence daily physical activity (PA) levels of older adults, but there is little quantitative data available on the effect of summertime weather. PURPOSE: To assess the relationship between temperature and humidity on accelerometer measured PA values in older adults. METHODS: Forty-eight healthy community-dwelling older adults (77.6 ± 4.7yrs; range 71-89yrs; 36 females) living in southwestern Ontario (Latitude 43° T N) wore a waist-borne accelerometer during waking hours for one 7-consecutive day period between 05.30.06-08.09.06. Hourly temperatures were obtained from meteorological records and linked to hourly accelerometer PA values. RESULTS: Mean daytime (7:00hr-19:00hrs) recorded PA values (ct/min) were 201.8 ± 106.2. PA participation was highly variable among individuals. Polynomial regression of the second order revealed a curvilinear relationship between temperature and PA of r2=.023. Mean PA values reported when mean daytime temperature was < 25°C were 207.5 (range 13.4–614.6). When ambient temperature rose above 25°C, mean PA declined by 15% (mean 176.8; range 26.8-329.6). A similar curvilinear relationship was observed between PA and Humidex, r2=.017. As Humidex values rose, mean daily PA values continued to decline. Above 28°C, mean PA was1 83.6, with a narrower range of 53.4-227.5.Figure: Temperature 7h to 19hCONCLUSION: When ambient daytime temperatures rose above 25°C, the PA levels of these older adults decreased substantially and the contribution of Humidex may have further reduced their daily PA. Appropriate PA assessment must account for the potential influence of climate upon daily reported PA values.