معراج میرزائی

Purpose. Taekwondo is an official Olympic high-intensity sport that needs both aerobic and anaerobic systems together with agility, as a prerequisite for success. Oxidative stress can lead to decreased muscle function, impaired sports performance, and muscle fatigue, especially in adolescents. Consumption of antioxidants derived from natural fruits is suggested as a more effective and safer nutritional strategy to prevent the damaging effects of oxidative stress. The antioxidant capacity of beetroot juice is significantly higher than other vegetables and fruits.

The aim of this Randomized, double-blind, placebo-controlled trial was the short-term effect of beetroot juice supplementation on salivary ۸-oxo-dG and performance in adolescent taekwondo (TKD) athletes.

Methods. Forty adolescent taekwondo athletes were randomly divided into ۴ groups (n= ۱۰): Exercise + Supplement (ES), Exercise (Ex), Supplement (Sp) and Placebo (Pl). The TKD athletes consumed ۲ servings of ۱۰۰ ml of the beetroot juice supplement or placebo for ۷ days. The TAAA test performed ۷۲ hours before beginning of supplementation, ۱۲ hours after the last serving of supplementation, ۹۰ min after ۲^nd test, and ۲۴ hours after ۳^rd test. Saliva sampling was performed ۷۲ hours after ۱^st TAAA test and before beginning of supplementation, ۱۲ hours after the last serving of supplementation, immediately after ۲^nd TAAA test, ۹۰ min after ۲^nd test and before the ۳^rd test, ۲۴ hours after ۳^rd test and before ۴^th test.

Results. According to the effect that is important in the comparison of the one-way variance analysis test, there was a significant difference between the changes of ۸-oxo-dG, aerobic and anaerobic power, and agility records in different groups. The variance analysis of ۸-oxo-dG, aerobic power, anaerobic power, and agility record showed a significant difference in the second, third, and fourth stages compared to the baseline.

Conclusion. It seems that ۷ days supplementation of beetroot juice (۲۰۰ ml per day) could reduce the oxidative stress in male adolescent TKD athletes and improve aerobic, anaerobic and agility of them.