A new study from Greece reports that high blood vitamin D concentrations seem to increase the exercise performance of professional soccer players.
The observational study measured the blood vitamin D levels and exercise performance (muscle strength, sprinting capacity, maximal oxygen consumption) of 67 male professional soccer players (mean age 25 years) before and after a six-week off-season period (1). The study results showed that participants with high vitamin D levels had improved parameters of exercise performance. Vitamin D concentrations increased significantly following the six-week off-season period compared to baseline, while at the same time all measured performance parameters decreased.
The researchers commented that these findings confirm earlier studies which have consistently shown that higher vitamin D levels positively affect strength and performance in athletes (2). Vitamin D is thought to exert a host of physiological effects on neural and muscular tissues, the immune system, and energy homeostasis, thus affecting among other parameters physical performance (3). Reductions in exercise training stress (in the off-season) may increase vitamin D levels, suggesting a possible association of decreased vitamin levels due to training-induced stress. A growing number of studies report a high preva-lence of vitamin D insufficiency or deficiency even in regions with extensive sunlight in both athletic and non-athletic populations (4).