Seasonal Variation in Physical Activity Levels in Healthy Young Adults

Abstract

Environmental factors have been identified as potential barriers to physical activity (PA). However, the extent to which seasonal weather changes affect PA behavior is not well quantified. PURPOSE: To determine if seasonal variation has an impact on PA levels in South Carolina. METHODS: Data were obtained from 430 healthy individuals aged 21-35 enrolled in the Energy Balance Study. Cardiorespiratory fitness levels were assessed via graded exercise testing at baseline; and the sample was divided into fit and unfit categories, with the lowest tertile classified as unfit. Further, the sample was classified by what they considered to be their full-time status: employed or student. PA levels were measured objectively using arm-based activity monitors for 10-day periods quarterly over a year. Using trigonometric models, we estimated peak-to-trough amplitude and phase of the peaks in moderate to vigorous physical activity (MVPA) throughout the year. RESULTS: Overall, fit individuals had a mean ± SD MVPA of 88.1 ± 3.4 minutes/day. Among fit individuals, the amplitude of variation of MVPA over the year was 8.4 minutes/day (95% CI: 2.9, 13.8), which peaked in January with a corresponding trough in July. Unfit individuals did not display significant seasonal variation (95% CI: -3.6, 6.34). The overall mean MVPA for unfit individuals was 43.0 ± 3.4 minutes/day. Students exhibited an overall mean MVPA of 84.6 ± 4.3 minutes/day but did not show significant seasonal changes (95% CI: -1.1, 11.7). Lower levels of MVPA were observed in non-students who had an overall mean of 63.6 ± 3.5 minutes/day and an amplitude variation over the year of 6.7 minutes/day (95% CI: 1.7, 11.7). This mirrored the fit individuals’ peak in January and corresponding trough in July. CONCLUSION: In Columbia, SC, levels of MVPA were highest in January and lowest in July, with greater seasonal amplitude of variation observed in fit individuals and non-students. These findings display a significant association between PA behavior and seasonal weather changes. Therefore, seasonal variation should be taken into consideration for health promotion and intervention efforts aimed to increase population levels of PA. Supported by an unrestricted grant from the Coca-Cola Company.