Asiye Aalimahmoodi - Department of Sport Sciences, Shiraz University, Shiraz, Iran.
Negar Kooroshfard - Department of Sport Sciences, Shiraz University, Shiraz, Iran.
Maryam Koushkie Jahromi - Department of Sport Sciences, Shiraz University, Shiraz, Iran.
Mohammad Hemmatinafar - Department of Sport Sciences, Shiraz University, Shiraz, Iran.

Aim: This study aimed to  investigate the effect of two weeks of vitamin D۳ supplementation on some indices of Delayed Onset of Muscle Soreness (DOMS) after  eccentric exercise. Method and Materials: In this semi experimental study, ۲۰ nonathletic male collegiate students (۱۹.۷۵±۱.۲۹ years) participated in the study voluntarily and were divided randomly into two groups of experimental (n=۱۱) and placebo (n=۹). The experimental group consumed vitamin D۳ (Cholecalciferol) containing ۵۰۰۰۰ IU while the placebo group took apparently similar capsules containing starch like, two capsules for two weeks. To induce DOMS, participants performed a step protocol that included four sets (۵ minutes for each set), with a ۱-minute of rest interval between each set using a ۴۶ cm-step. Range of Motion (ROM) of low extremity joints and circumferences, and Visual Analog Scale (VAS were measured before, immediately after (Time ۰), and ۲۴ hours (Time ۱) and ۴۸ hours (Time ۲) after eccentric exercises. Findings: This study showed that thigh Thigh circumference increased following eccentric exercise in the placebo group, while it did not change significantly in the experimental group (p>۰.۰۵). There was no significant difference between the two study groups regarding other variables (P>۰.۰۵). Vitamin D۳ supplementation with the dosage and duration used in the present study reduced the limited symptoms of DOMS. Future studies of longer duration or higher dosage of vitamin D supplementation are recommended.   Conclusions: According to the finding of this study, vitamin D۳ supplementation could not reduce the limited symptoms significantly. However, future studies are suggested to evaluate the effect of higher dose or longer duration of vitamin D supplementation on DOMS.

Delayed Onset of Muscle Soreness, Step Test, Vitamin D۳.