Can Promotion of Outdoor Activities Impact People’s Vitamin D Levels?

Growing attention has lately been given to the importance of Vitamin D as a factor protecting people’s health. As an exploratory study, we investigated the relationship between physical activity, light level and individuals’ vitamin D status within an intervention promoting physical activity. Fourteen adults (age 49.2±8.0 yr.) underwent a short exercise-intervention (two exercise sessions within one week) either indoors or outdoors. Physical activity levels and light levels (Lux) were measured by ActiSleep+ (ActiSleep+, ActiGraph, Pensacola, US), and 25-OH-D concentration was measured in serum at three time-points. No significant differences between the groups during the intervention, although the outdoor-exercise group tended to improve while the indoor-exercise group tended to decrease the vitamin D status. Study of correlation (Pearson r) found positive associations between vitamin D levels and different parameters of physical activity, and also between vitamin D levels and Lux. These results support the importance of promoting outdoor physical activities in order to achieve and maintain high vitamin D levels.