Low Vitamin D is Associated with Lower Extremity Strains and Sports Hernia Injuries in NFL Combine Athletes

Abstract

Vitamin D has been linked to overall muscle function and strength, with recent findings depicting a correlate between preseason performance and vitamin D status in NFL athletes. The purpose of our study is to evaluate the association between serum vitamin D level and the prevalence of lower extremity muscle strains or sports hernia injuries in elite level athletes at the National Football League (NFL) combine. This is a retrospective study of 214 prospective professional athletes who participated in the 2015 NFL combine. Baseline demographic data was collected, including age, body mass index (BMI), injury history specific to lower extremity muscle strain or sports hernia, at least one missed game due to the specified injury, and Functional Movement Screen (FMS) testing scores. Serum 25(OH) vitamin D was collected at the combine visit; and defined as normal ≥32 ng/mL. Overall summary statistics were calculated in terms of means and standard deviations for continuous variables and frequencies and percentages for categorical variables. There were 107 (50%) players reporting previous sports hernia or lower extremity strains, who also had lower vitamin D levels than athletes without associated injury history (29.7 ± 11 ng/mL vs. 34.0 ± 13 ng/mL; p=0.01). Overall incidence of below normal serum vitamin D was present in 126 players (59%); including 16 (13%) with severe deficiency (<21 ng/mL). Group comparisons between low and normal vitamin D levels showed no difference in age, race, BMI or FMS scores recorded at the NFL combine (Table I). Low serum vitamin D is associated with a history of sports hernia or lower extremity strains in NFL combine athletes. While no difference was found in FMS testing, low vitamin D may contribute to injury susceptibility or muscle dysfunction in this select population.