Vitamin D Supplementation and Physical Performance in Adolescent Swimmers

Abstract

It is hypothesized that vitamin D insufficiency in athletes might negatively affect sport performance. The objective of this study was to examine the effect of vitamin D3 supplementation on physical performance of adolescent swimmers with vitamin D insufficiency. Fifty-three adolescent competitive swimmers with vitamin D insufficiency (serum 25-hydroxyvitamin-D concentrations (25(OH)D) < 30 ng/ml, mean 24.2 ± 4.8 ng/ml) were randomized to receive 2,000 IU/day of vitamin D3 or placebo for 12 weeks. Swimming performance at several speeds, arm-grip strength, and one-legged balance, were measured before and after supplementation. The age-adjusted changes in performance variables during the study were compared between groups. 25(OH) D concentrations at study end were significantly higher in the vitamin group compared with the placebo group (29.6 ± 6.5 ng/ml vs. 20.3 ± 4.2 ng/ml, p < .001), yet only 48% of the vitamin group became vitamin D sufficient with this dosing. No between-group differences were found in the changes of the performance variables tested. No significant differences in performance were found between participants that became vitamin D sufficient, and those who did not. No significant correlation was found between the change in serum 25(OH)D and age-adjusted balance, strength or swimming performance at study end. Vitamin D3 supplementation that raised serum 25(OH)D concentrations by a mean of 9.3 ng/ml above placebo in adolescent swimmers with vitamin D insufficiency, did not improve physical performance more than placebo.

Vitamin D status associates with skeletal muscle loss after anterior cruciate ligament reconstruction

“…In our study, participants with 25(OH)D of 30 ng/mL or higher did not show better maintenance of normalized peak torque or RTD 20%–80% after ACLR when compared to those with concentrations of less than 30 ng/mL. Some studies supplementing athletes with vitamin D have not demonstrated efficacy in improving strength or functional outcomes ( 49 ). For instance, in one trial, adolescent swimmers with 25(OH)D of less than 30 ng/mL took vitamin D drops providing 2000 IU/day for 12 weeks with the goal of reaching 30 ng/mL.…”

The effects of Vitamin D3 supplementation on Spermatogram and endocrine factors in asthenozoospermia infertile men: a randomized, triple blind, placebo-controlled clinical trial

“…Additionally, Backx et al in their study reported similar results within three-month supplementation of 2200 IU VD3; however, higher concentration of 25(OH) VD3 was observed after 12 months of intervention [ 66 ]. In contrast, there are studies reporting the increased serum 25(OH)VD3 concentration compared to the baseline after 12 weeks of the supplementation with 2000 IU/day of VD3 [ 67 , 68 ]. It has been shown that inter-individual differences and genetic variation in VD3 binding protein affect the response to this supplementation [ 69 ].…”

Mechanisms of vitamin D action in skeletal muscle

“…The effects of supplementation of vitamin D on exercise and muscle health have recently been reported in soccer and rugby players, elite ballet dancers, and in active adult males that were vitamin D insufficient at the baseline (113,(130)(131)(132)(133)(134)(135)(136) . Four studies (113,130,131,136) have found that supplementation of vitamin D significantly increased strength, power and exercise performance even with a small sample size, while three studies reported no significant effect of vitamin D on any physical parameter (132)(133)(134) . Further, a reduced injury incidence was reported in a group of elite ballet dancers following 4 months of 2000 IU/d of vitamin D supplementation (113) .…”

“…In contrast, recent metaanalyses have not been consistent with these outcomes, though many variables need to be considered when comparing studies, for example, the parameters analysed, age of the population, if participants live in residential institutions, dose and cut points of vitamin D, ethnicity, period of the intervention, instruments to assess Ca and vitamin D intake and sunlight exposure, and many others (129) . Another important variable to consider in supplementation studies is if the participant is classified as sufficient or deficient in vitamin D since the baseline period, as many of the biological effects of vitamin D are evident when status of vitamin D is corrected from deficient to normal levels (113,122,(130)(131)(132)(133)(134)(135)(136)(137) .…”