Supplemental vitamin D3 does not affect musculoskeletal or psychomotor performance in college aged males

Abstract

The experiment examined the effects 4 weeks of vitamin D (Vit D) supplementation versus placebo on musculoskeletal and psychomotor performance. Thirty-two college age males (Age: 22±4 y, Height: 177.7±8.3cm, Weight: 81.5±14.6kg, BF%: 19.6±7.9, Vit D: 20.0±7.2ng/ml). Participants were assigned to group (Vit D vs placebo) and remained blind throughout the study. The treatments were 4000IU of Vit D3 or placebo (dextrose) administered daily for 4 weeks. The participants underwent baseline testing for isometric strength, explosive ability and psychomotor performance, which was repeated at week 2 and week 4. Isometric tests consisted of an Isometric Mid Thigh Pull on a Force Plate (IMTP) and an upper body isometric test (UBIST) using a load cell. Peak force during a countermovement jump (CMJ) was also determined via force plate. A psychomotor vigilance test (PVT) was used to measure sustained reaction time. Analysis of the UBIST data did not reveal a significant group×time interaction (p=0.14; Vit D pre: 553.7±168.3N, post: 585.5±150.2N; Placebo pre: 677.7±182.3N, post: 649.8±236.9N). For IMTP no significant group×time interaction (p=0.83; Vit D pre: 2596.4±342.3N, post: 2606.9±378.3N; Placebo pre: 2684.0±432.9N, post: 2762.6±440.4N) was found. CMJ analysis did not reveal interaction effects for group×time (p=0.21; Vit D pre: 4429.7±1619.0N, post: 4938.5±2374.8N; Placebo pre: 5537.3±3027.0N, post: 6266.9±4577.3N). For PVT (mean reaction time) there was no significant interaction effects for group×time (p=0.35; Vit D pre: 0.304±0.041sec, post: 0.301±0.053sec; Placebo pre: 0.295±0.044sec, post: 0.284±0.029sec). In conclusion, four weeks of Vit D supplementation was not effective in increasing musculoskeletal or psychomotor performance.