Abstract
Studies investigating the relationship between vitamin D and physical fitness in youth have provided inconsistent findings. Recent evidence indicates that the expression of receptors and vitamin D-modulated genes in young subjects has a seasonal profile. Therefore, we investigated the role of vitamin D on physical fitness across seasons in a total of 977 male adolescents. Anthropometrics, lifestyle, dietary habits, biochemical profiles and physical fitness were studied. Multiple linear regression models, including pairwise interaction terms involving total 25-OH-vitamin D, were fitted. The interacting effect of season and total 25-OH-vitamin D had a significant influence on physical fitness performance (spring and total 25-OH-vitamin D: ß 0.19, SE 0.07, p = 0.007; summer and total 25-OH-vitamin D: ß 0.10, SE 0.06, p = 0.11; autumn and total 25-OH-vitamin D: ß 0.18, SE 0.07, p = 0.01), whereas the main effect of total 25-OH-vitamin D alone was not significant (p = 0.30). Body fat percentage, recreational physical activity level, time spent per day gaming/TV-watching, smoking, and hemoglobin levels were also related to the physical fitness performance score. Future studies should further explore the role of seasonal-dependent effects of vitamin D on health.
Highlights
Physical fitness in youth is a predictor of cardiovascular and musculoskeletal health in a dulthood[1]
This study aimed to investigate the effect of vitamin D on physical fitness performance across seasons in a large sample of male adolescents
The results of this study conducted in a sample of approximately 1000 male late adolescents support previous evidence that body fat, time spent gaming/TV-watching, and smoking are inversely related to physical fitness performance
Summary
Physical fitness in youth is a predictor of cardiovascular and musculoskeletal health in a dulthood[1]. The few clinical studies focusing on the relationship between vitamin D and physical fitness among adolescents have provided inconsistent findings[8,9], while recent observations on adults found an important association between serum vitamin D levels and physical fitness[10]. Vitamin D values peak in summer and fall in winter[16], and recent findings in youth have shown that the expression of genes modulated by vitamin D shows a seasonal p rofile[17]. This hypothesis has never been investigated, it is tempting to assume an annual rhythm cycle in vitamin D action. This study aimed to investigate the effect of vitamin D on physical fitness performance across seasons in a large sample of male adolescents
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