Vitamin D concentration in 342 professional football players and association with lower limb isokinetic function

Objectives: This study aimed to evaluate both the epidemiology of Vitamin D deficiency in Qatar-based footballers originating from a variety of countries and the existence of any relationship between 25 hydroxy-cholecalciferol (25(OH)D) concentration and lower limb isokinetic performance (peak torque) in well trained professional football players.

Design: Cross-sectional clinical.

Methods: Three hundred and forty-two professional footballers based in Qatar were evaluated as part of their routine annual medical assessment. History, examination, blood tests and a lower limb isokinetic evaluation were performed. Association between 25(OH)D concentrations and lower limb isokinetic peak torque was assessed.

Results: Eighty four percent of players had 25(OH)D concentrations less than 30 ng/ml; 12% were severely deficient (<10 ng/ml) and there was a significant difference in 25(OH)D level depending on the country of origin of the player. Total body mass and lean mass was significantly higher in players with 25(OH)D levels greater than 20 ng/ml, when compared with the less than 10 ng/ml group. There was no consistent association found between lower limb isokinetic peak torque and 25(OH)D concentration.

Conclusions: 25(OH)D deficiency is highly prevalent in Qatar based footballers. Severe 25(OH)D deficiency is associated with lower body mass, and lower lean mass, when compared with footballers with concentrations >20 ng/ml. Vitamin D deficiency was not shown to have a consistent association with lower limb isokinetic peak torque and both the clinical and performance related significance of this high prevalence of Vitamin D deficiency remains unclear.