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Background and Objective: Vitamin D increases muscle strength through protein synthesis and myogenesis and may play an important role in anaerobic and aerobic activities. This study was done to determine the vitamin D status and its relationship with physical function indexes in young Taekwondo athletes.
Methods: This descriptive-analytical study was conducted on 75 young male Taekwondo athletes, aged 18-23 years that were selected using randomized sampling method. Serum 25-hydroxyvitamin D level was measured by ELISA method. The 20-meter shuttle run, running based anaerobic sprint (RAST), vertical jump, 36-meter sprint and Illinois agility tests were used to determine aerobic and anaerobic capacities, explosive anaerobic power of the lower limbs, speed and agility, respectively. Body mass index and percent body fat was measured for each subject. Level below 20, 20-30 and more than 30 ng/ml of serum 25-hydroxyvitamin D were considered as vitamin D deficiency, insufficiency and normal status, respectively.
Results: The results showed that 48% (36 athletes) and 42.66% (32 athletes) of taekwondo athletes had deficient and insufficiency levels of vitamin D, respectively. Also, a significant correlation was detected between serum 25-hydroxyvitamin D concentration and aerobic power (r=0.897), anaerobic power (r=0.901), vertical jump performance (r=0.855), fatigue index (r=-0.838), agility (r=-0.634) and 36 meters sprint (r=-0.793) times (P<0.05). However, this association was significant in athletes with lower than normal levels of vitamin D (P<0.05), no association was found in subjects with normal vitamin D levels.
Conclusion: Vitamin D of 90.66% of young taekwondo practitioners was lower than normal level. Increasing in vitamin D level can improve the physical performance of young athletes with vitamin D deficiency or insufficiency status.