4. Discussion
swelling, muscle soreness, EIMD, muscle damage, muscular endurance
This study was conducted to determine the effect of BRJ supplementation after EIMD on the recovery of functional parameters (endurance and flexibility of leg muscles and vertical jump performance) and muscle soreness symptoms (PPT, Sw_T, perceived muscle soreness). The findings showed that BRJ supplementation improved muscle endurance, Sw-T, and perceived muscle soreness after EIMD in female volleyball players. However, no significant differences were observed between PLA and BRJ in PPT, VSFT, and VJH. Therefore, BRJ supplementation may have beneficial effects on some muscle recovery indicators.In line with these findings, a prior meta-analysis showed the beneficial effects of BRJ supplementation on reducing the perception of muscle soreness (especially at 48 and 72 h after various exercises) [The analgesic effects of BRJ supplementation have been mainly attributed to its active phytochemicals (betalain and plant polyphenols) [The findings showed that BRJ supplementation led to concomitant reductions in muscle soreness and increases in Wall-sit performance (muscular endurance) after EIMD (Increasing the duration of the wall-sit test shows that BRJ supplementation can improve the recovery of isometric endurance performance. This function can be translatable, as volleyball players usually adopt similar positions to wall-sit or static squats to receive serves or spiking from the opponent’s team. On the other hand, Jonvik et al. (2020) showed that six days of BRJ did not significantly improve endurance performance and muscle strength in recreationally active men when compared to PLA supplementation [The present study found that Sw-T and muscle soreness decreased significantly after BRJ supplementation. One possible explanation for the significant improvement in wall-sit performance and non-significant VSFT is the reduction in muscle soreness and related mechanisms, such as the reduction in tissue swelling [The present study has some limitations, such as the lack of measurement of the markers related to muscle damage. In addition, cognitive indicators, arousal, and other psychological variables affecting muscle function were not evaluated in the present study. Therefore, future studies should include the evaluation of these variables to expand on our findings. Moreover, some repeated bout effects may have confounded the results of the present study. Furthermore, it is important to note that the sample size used in this research was limited due to the nature of a complete volleyball team, which typically consists of 12 to 14 players. Consequently, the findings obtained from this study should be approached with careful consideration and interpreted with caution.