This study investigated the effects of an 8-week daily 2000 IU vitamin D₃ supplementation, administered via orodispersible films, on serum vitamin D, leukocyte count, and performance parameters in healthy recreational runners and non-runners, followed by a 12-week post-supplementation follow-up. Forty-five participants were randomized into four groups: supplemented runners (RUN-SUPPL, n = 13, age 33.4 ± 7.5 y), non-supplemented runners (RUN-CON, n = 10, age 34.8 ± 8.6 y), supplemented non-runners (NON-RUN-SUPPL, n = 11, age 29.3 ± 7.5 y), and non-supplemented non-runners (NON-RUN-CON, n = 11, age 28.3 ± 6.0 y). Assessments were conducted at baseline (T0, October, pre-supplementation), post-intervention (T1, December, after 8 weeks), and follow-up (T2, March, 12-weeks post-supplementation). Supplementation significantly increased serum 25(OH)D₃ in runners (30.45 ± 7.0 to 35.35 ± 8.9 ng/mL, p 0.05), while maximal isometric force showed a trend toward improvement in supplemented subjects ( p = 0.056). Despite these physiological benefits, no ergogenic effects on aerobic or explosive performance were observed.
Gervasi et al. (Sat,) studied this question.