Effect of Beetroot Juice Supplementation on Muscle Soreness and Performance Recovery after Exercise-Induced Muscle Damage in Female Volleyball Players.

BACKGROUND: Beetroot juice (BRJ) contains various bioactive compounds suggested to be effective in improving athlete recovery. However, the number of studies evaluating the effects of BRJ on recovery and muscle soreness (MS) indicators in female athletes is limited. Therefore, the present study aimed to determine the effects of BRJ consumption on the performance recovery indicators and MS after exercise-induced muscle damage (EIMD) in female volleyball players. METHODS: Twelve young female volleyball players were evaluated in this study. We utilized a randomized, cross-over, and double-blind design during two phases with a 30-day interval (wash-out). During each phase, EIMD was performed first, followed by BRJ or placebo (PLA) supplementation for two days (eight servings of 50 mL). Recovery monitoring of performance indicators and MS was performed after EIMD. The results of wall-sit, V sit and reach (VSFT), vertical jump height (VJH), pressure pain threshold (PPT), and thigh swelling (Sw-T) tests were recorded 48 h after EIMD. Also, the Perceived Muscle Soreness was recorded using the visual analog scale (VAS) 12 (MS-12 h), 24 (MS-24 h), and 48 (MS-48 h) hours after EIMD. RESULTS: The data were analyzed using two-way repeated measures of ANOVA at p < 0.05. Compared to PLA, BRJ supplementation improves wall-sit performance after EIMD (p < 0.05), while reducing Sw-T and perceived muscle soreness (p < 0.05). However, no significant difference was observed between PLA and BRJ in VJH and VSFT performance after EIMD (p > 0.05). CONCLUSIONS: Our findings indicate that the consumption of BRJ in female volleyball players can be useful for improving some recovery indicators, such as muscle endurance, perceived muscle soreness, and tissue edema, after EIMD.

Effects of Different Doses of Caffeine Supplementation on Collegiate Male Volleyball Players' Specific Performance and Skills: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study.

BACKGROUND: The improvement of performance and skill indices of volleyball players can affect their success rate. Therefore, the present study aimed to evaluate the effects of acute caffeine supplementation of varied doses on collegiate volleyball players' specific performance and skills. METHOD: This research was a randomized, double-blind, crossover design study in which 15 male volleyball players aged 18 to 25 years participated voluntarily. Participants were randomly placed in three different conditions, including 3 mg of caffeine per kilogram of body weight (C3), 6 mg of caffeine per kilogram of body weight (C6), and a placebo (PLA) with a one-week wash-out period between exercise trials. The supplement was taken 60 min before each exercise session. Ball throwing, hand movement speed, agility, Sargent's jump and handgrip, and attacking and serving skill tests were measured and analyzed to check the performance and skill of the volleyball players. RESULTS: This study showed a significant increase in agility test in C6 compared with the PLA condition (p = 0.02). Additionally, there was a significant improvement in Sargent's jump in C6 compared with PLA (p = 0.00) and C6 compared with the C3 condition (p = 0.00). Also, attacking skill significantly increased in C3 compared with PLA (p = 0.00) and C6 compared with the PLA condition (p = 0.00). In addition, there was a significant increase in serving skill for C6 compared with PLA (p = 0.00) and C3 (p = 0.00). However, there were no significant differences in hand movement speed (p = 0.06), left handgrip (p = 0.85), right handgrip (p = 0.47), or medicine ball throwing (p = 0.22) between the three conditions. CONCLUSIONS: In conclusion, the findings of the current study suggested that a higher dose of caffeine compared with a lower dose may be more effective in movements requiring lower-body explosive power and the ability to change direction. Also, according to the findings, it seems that caffeine can lead to the improvement of complex skills, such as serving and attacking in volleyball.

Repeated mouth rinsing of coffee improves the specific-endurance performance and jump performance of young male futsal players.

BACKGROUND: Mouth-rinsing with ergogenic solutions such as carbohydrate and caffeinated drinks has been considered among athletes as a practical nutritional strategy. Therefore, this study aimed to determine the effect of repeated coffee mouth-rinsing (CMR) doses on specific performances of futsal players. METHOD: Twenty-four male futsal players randomly participated in this randomized, double-blind, and crossover design study. During the intervention, participants were randomly placed in four different conditions including 1. low-dose CMR (LDC, n = 6, ~60 mg caffeine); 2. high-dose CMR (HDC, n = 6, ~125 mg caffeine); 3. decaffeinated CMR (PLA, n = 6, ~10 mg caffeine); and 4. no CMR (CON, n = 6). Vertical jump height was measured at baseline, baseline after CMR (baseline-CMR), immediately after the intermittent futsal endurance test (FIET) (IA-FIET), 5 min after the FIET (5"A-FIET) and 10 min after the FIET (10"A-FIET). Perceived fatigue was also measured by visual analogue scale (VAS) at baseline, IA-FIET, 5"A-FIET, and 10"A-FIET. CMR was also performed at baseline, during FIET (Repeated between levels), and 10'A-FIET. The collected data were analyzed (with SPSS software) by one- and two-way repeated measure ANOVA and Bonferroni post hoc test at P < 0.05 level. RESULTS: The findings of the present study illustrated that the perceived fatigue in IA-FIET increased significantly compared to the baseline which was accompanied by a significant decrease in 5"A-FIET and 10"A-FIET compared to IA-FIET (P < 0.05), and no significant difference was observed between conditions in the baseline, IA-FIET, 5"A-FIET, and 10"A-FIET (P > 0.05). However, HDC and LDC rose significantly the distance covered in FIET compared to CON and PLA (P < 0.05). In addition, HDC increased the FIET performance more than LDC (P < 0.05). Although there was no difference between any of the conditions at baseline (P > 0.05), baseline-CMR increased significantly the vertical jump height (P < 0.05). At IA-FIET, vertical jump height decreased to baseline levels in CMR conditions but increased in 5"A-FIET, which remained constant until 10"A-FIET (P < 0.05). In addition, vertical jump height in HDC and LDC conditions was significantly higher than CON in IA-FIET, 5"A-FIET, and 10"A-FIET. CONCLUSION: This study showed that repeated CMR with low and high doses is a useful strategy to improve specific futsal performance. However, higher dose CMR appears to have more profound effects on performance improvement than lower doses.