Mohammad Hemmatinafar

Background: Fatigue is common in sports and can impair athletic performance. Objectives: This study examined the effects of green tea supplementation combined with TheraBand-based resistance training on performance outcomes and time to exhaustion after muscular fatigue in elite volleyball players. Methods: A controlled quasi-experimental design was used, with group allocation performed using random number generation software. Forty elite male volleyball players aged 19.27 ± 1.88 years were randomly assigned to four groups of 10 participants each: TheraBand, green tea, combined TheraBand and green tea, and control. The fatigue protocol was administered on days 1 and 2, and on day 3, agility, vertical jump, and time to exhaustion were measured at pretest. Subsequently, TheraBand exercises and green tea consumption were implemented in the experimental groups for 6 weeks. After 6 weeks, the fatigue protocol was re-administered, and posttesting was conducted on the following day. The control group received no intervention. A mixed repeated-measures ANOVA was used for statistical analysis. Results: A significant time × group interaction was observed for time to exhaustion (P < 0.001, ηp2 = 0.73), vertical jump performance (P < 0.001, ηp2 = 0.42), and agility (P < 0.001, ηp2 = 0.50). Significant main effects of time were also observed for time to exhaustion (P < 0.001, ηp2 = 0.78), vertical jump performance (P < 0.001, ηp2 = 0.47), and agility (P < 0.001, ηp2 = 0.39). A significant main effect of group was observed for time to exhaustion (P < 0.001, ηp2 = 0.40), but not for vertical jump performance or agility (P > 0.05). Conclusions: Taken together, these results indicate that combining TheraBand training with green tea supplementation may improve physical performance and time to exhaustion in elite male volleyball players, with training appearing to be the primary driver of the observed adaptations and green tea supplementation serving a supportive role.

Competitive combat athletes are routinely exposed to high training loads, rapid weight-making practices, psychological stress, and frequent injuries—all of which may adversely affect the gut microbiome and, consequently, multiple physiological systems relevant to performance. Growing scientific interest in the role of probiotics and host–microbiome interactions suggests that targeted modulation of gut bacteria may offer functional benefits for athletes. This narrative review synthesizes current evidence on probiotics and microbiome-mediated pathways influencing performance, recovery, and health in combat-sports athletes. A comprehensive literature search was conducted across PubMed, Web of Science, and Google Scholar, with no date limits, including studies published up to October 2025. Search terms covered the gut microbiome, probiotics, athletic performance, combat sports, gastrointestinal barrier function, immune responses, psychological factors, nutrient absorption, hypoxia, weight cutting, and sex-specific considerations. Reference lists of relevant reviews and grey literature were manually screened. Across the available literature, probiotic supplementation has been associated with a range of effects that could be relevant to combat athletes. Evidence, largely from non‑combat and mixed‑population studies, suggests that probiotics may influence several physiological systems, including: (1) inflammatory and oxidative stress responses and injury rehabilitation; (2) immune function and upper respiratory tract infection outcomes; (3) gastrointestinal permeability and nutrient absorption, particularly after rapid weight loss; (4) psychological factors via the gut–brain axis; (5) muscle recovery through inflammatory and metabolic pathways; (6) body composition and weight regulation; (7) oral and skin microbiome composition; and (8) gut microbial changes during hypoxia or hormonal fluctuations. However, most of these findings are indirect, with very few studies conducted specifically in competitive combat‑sport athletes, and the overall evidence base remains heterogeneous. Probiotic and gut microbiome-targeted strategies may serve as potential adjunctive strategies to support health, recovery, and performance in combat athletes. However, because the current evidence is largely derived from non-combat and predominantly male populations, strain-, dose-, and sport-specific recommendations cannot yet be made. There is a clear need for randomized controlled trials in combat-sport athletes—including women—that employ standardized probiotic protocols and sport-specific outcome measures.

1. Volleyball is characterized by frequent movements with explosive stretch–shortening muscle actions—such as repeated jumping, blocking, and spiking—that impose substantial eccentric loads on the ...

Caffeine is a well-known ergogenic aid that can enhance physical and cognitive performance. However, it often induces side effects, such as anxiety and overstimulation, which can be problematic in high-pressure sports like wrestling. L-theanine, a non-stimulant amino acid found in tea, may help mitigate these effects by promoting a calm yet focused mental state. This study aimed to investigate the acute effects of caffeine, L-theanine, and their combination on physical performance, cognitive function, and anxiety in elite male wrestlers. In a double-blind, placebo-controlled, crossover design, 12 elite male wrestlers (21.8 ± 2.1 years) completed four test sessions under randomized conditions: placebo (PLA), caffeine (CAF; 3 mg/kg), L-theanine (THE; 3 mg/kg), and caffeine + L-theanine (CAF+THE; 3 mg/kg each). After 60 minutes, athletes performed the wall-squat test, vertical jump height (VJH), medicine ball throw (MBT), handgrip strength, and the Specific Wrestling Fitness Test (SWFT). Cognitive function was assessed pre- and post-SWFT using a computerized Stroop test. Anxiety was assessed using the State-Trait Anxiety Inventory (STAI), and side effects were recorded. CAF+THE outperformed PLA in wall-squat time (p = 0.001), MBT (p = 0.005), VJH (p = 0.011), and grip strength (p = 0.004). SWFT throw count was highest in CAF+THE versus all other conditions (p < 0.001). Post-SWFT Stroop reaction time was faster in CAF+THE than PLA (p = 0.004) and THE (p = 0.036), and accuracy was also higher (p = 0.009 vs PLA). CAF alone increased state anxiety compared to PLA (p = 0.021), while CAF+THE reduced anxiety to below placebo levels (8% incidence vs 33%). Trait anxiety was lower in CAF+THE compared to CAF (p = 0.018). The prevalence of caffeine-induced tachycardia (92%) was notably reduced under CAF+THE (17%). CAF+THE (3 mg/kg each) enhances elite wrestlers' strength, endurance, cognitive speed, and accuracy while reducing anxiety and physiological side effects commonly associated with caffeine alone. This combination represents a safe, practical supplement strategy for combat sports athletes who must maintain explosive performance and mental control under stress. Coaches are encouraged to trial CAF+THE protocols during training to personalize timing and dosage.

Background: The gut–muscle axis is believed to influence training adaptations through microbiota-derived signals and the regulation of inflammation, but evidence in elite swimmers is limited and mixed. This study aims to determine whether synbiotic supplementation (probiotics + omega-3) combined with ultra-short race-pace training (USRPT) improves sprint-related upper-body strength. Methods: In a randomized, double-blind, 8-week trial of male elite sprint freestyle swimmers, participants completed USRPT and were allocated to either synbiotic supplementation or its single-component arms (probiotic or omega-3) or placebo. Primary outcomes indexed dynamic/explosive strength (isokinetic shoulder torque and power at 180°/s, rate of force development, time-to-peak torque); secondary outcomes included maximal strength (MVIC; 60°/s) and field/strength-endurance tests (dead-hang, handgrip, medicine-ball throw). Analyses reported p-values with effect sizes. Results: The synbiotic group showed greater improvements in high-velocity, sprint-relevant measures versus comparators—higher 180°/s torque and power, increased rate of force development, and shorter time-to-peak torque (Time × Group p < 0.05 across domains; effects in the medium–large range). Changes in handgrip and medicine-ball throw were small and not different between groups (p > 0.05). Conclusions: Synbiotic supplementation concurrent with USRPT preferentially enhances dynamic (explosive) upper-body strength in elite sprint swimmers, whereas non-stroke-embedded field tests show limited added value. Any reference to gut–muscle-axis modulation is hypothesis-generating, as stool sequencing and metabolite profiling were not performed. Larger, sex-inclusive trials incorporating in-water, stroke-embedded assessments and microbiome/metabolomic profiling are warranted.

Background: Optimal nutrition and training regimens are essential for athletes to maximize performance and recovery. Probiotic supplementation, through the modulation of the gut microbiota, and omega-3 fatty acids, known for their anti-inflammatory properties, may enhance physiological adaptations when combined with targeted training. This study evaluated the effects of probiotics and omega-3 supplementation, alongside ultra-short race pace training (USRPT), on performance metrics in competitive sprint swimmers. Methods: In this double-blind, placebo-controlled study, 60 male sprint swimmers (age: 19.2 ± 3.6 years; height: 182.2 ± 5.2 cm; weight: 81.6 ± 4.4 kg) with a minimum of five years of training experience, were randomly assigned to six groups (n = 10 per group): (1) Control (CON), (2) USRPT only, (3) Placebo + USRPT (PLA + USRPT), (4) Probiotics + USRPT (PRO + USRPT), (5) Omega-3 + USRPT (OMEGA + USRPT), and (6) Probiotics + Omega-3 + USRPT (PRO + OMEGA + USRPT). Over the eight-week intervention, the participants in PRO + USRPT consumed one multi-strain probiotic capsule daily (4.5 × 10¹¹ CFU) and a placebo capsule. Those in OMEGA + USRPT ingested 1000 mg of fish oil after lunch (500 mg EPA and 180 mg DHA per capsule) paired with a placebo capsule. The combined supplementation group (PRO + OMEGA + USRPT) received both probiotic and omega-3 capsules. The PLA + USRPT group consumed two starch capsules daily. The USRPT protocol was implemented across all the training groups, where the swimmers performed 17 sets of 25 m and 12.5 m sprints based on weekly recorded race times. Performance assessments included pre- and post-test measurements of sprint times (50 m and 100 m freestyle), vertical jump tests (both in water and on dry land), and other strength and endurance metrics (reaction time, agility T-test, sprint index, fatigue index, and velocity). Results: The combined intervention of probiotics and omega-3 with USRPT produced the greatest improvements in performance. The PRO + OMEGA + USRPT group reduced 50 m freestyle time by 1.92% (p = 0.002, pEta² = 0.286) and 100 m freestyle time by 2.48% (p = 0.041, pEta² = 0.229), demonstrating significant Time × Group interactions consistent with a synergistic effect. Additionally, the sprint index improved (pEta² = 0.139, p = 0.013) and reaction time decreased (pEta² = 0.241, p = 0.009) in the combined group, indicating enhanced anaerobic capacity and neuromuscular responsiveness compared to single interventions. Conclusions: This study suggests that combining probiotics and omega-3 supplementation with USRPT leads to synergistic improvements in sprint swimming performance, enhancing anaerobic power and recovery beyond what is achieved with individual interventions. This integrated approach may provide a practical strategy for competitive swimmers seeking to optimize their performance. Future studies should incorporate mechanistic markers, longer intervention durations, and diverse athlete populations to clarify further and extend these findings.

Background: Purple grape juice (PGJ), a natural carbohydrate- and polyphenol-rich supplement, may enhance exercise performance. This study, incorporating individual response analysis, examined the acute effects of PGJ ingestion on endurance, explosive power, and perceived fatigue in elite male soccer players.Methodology: Twenty-two U-20 male soccer players [Age: 19.7 ± 0.3; height: 178 ± 4 cm; body mass: 72 ± 5 kg; body mass index (BMI): 22.6 ± 0.9 kg/m²] participated in an equally allocated, double-blind, crossover design study. Participants were allocated to one of two conditions: (1) purple grape juice (PGJ, n = 11) or (2) placebo (PLA, n = 11). The PGJ or placebo was ingested in four equal portions (10 ml/kg of body mass PGJ or PLA diluted with water) starting 4 h before the test and continuing every hour, with the final ingestion 60 min before the 30-15 Intermittent Fitness Test (IFT). The placebo consisted of a calorie-free, grape-flavored liquid designed to match the taste and appearance of the PGJ. A 7 days washout period was maintained between the two conditions. Perceived fatigue and standing long jump (SLJ) performance were assessed at baseline, immediately and 5 min after the IFT. Maximum oxygen consumption (VO_2max), time to exhaustion (TTE), and final velocity in the IFT (VIFT) were recorded during the test. The smallest worthwhile change (SWC) analysis was used to evaluate individual responses.Results: Purple grape juice improved VIFT (P < 0.001, Cohen’s d = 0.58), TTE (P < 0.001, Cohen’s d = 0.69), and VO_2max (P < 0.001, Cohen’s d = 0.56) compared to PLA. No effects were found for SLJ or perceived fatigue (P > 0.05), SWC analysis revealed that 77% of participants showed improvements in VIFT and VO_2max, and 54% showed improvements in SLJ 5 min post-IFT.Conclusion: Purple grape juice supplementation enhanced endurance performance parameters in most participants, with significant individual variability in response. These findings highlight the potential benefits of PGJ, particularly for athletes more responsive to its effects, emphasizing the need for personalized supplementation strategies.

Probiotics comprise various strains that offer numerous health benefits. Researchers have recently focused on the relationship between probiotic consumption and improved gut microbiota function, enhanced digestion, increased nutrient absorption, and enhanced sports performance. Therefore, the present study investigated the effects of pre-sleep casein intake, coupled with probiotic strains, on soccer players' anaerobic power, lower-body-specific strength, and power performance. A randomized, double-blinded, and placebo-controlled study was conducted with forty-four male soccer players (Age: 22.81 ± 2.76 years, Height: 177.90 ± 6.75 cm, Weight: 67.42 ± 8.44 kg). The participants underwent the isokinetic strength, Wall-squat, and running-based anaerobic sprint (RAST) tests initially; then, they were randomly divided into four groups: probiotics (PRO), casein (CAS), probiotics with casein (PRO+CAS), and placebo (PLA). The PRO groups were given one probiotic capsule (containing eight bacterial strains: Lactiplantibacillus plantarum BP06, Lacticaseibacillus casei BP07, Lactobacillus acidophilus BA05, Lactobacillus bulgaricus BD08, Bifidobacterium infantis BI04, Bifidobacterium longum BL03, Bifidobacterium breve BB02, and Streptococcus thermophilus BT01, with a total dose of 4.5 × 10¹¹ CFU) during dinner, while the CAS groups consumed 20 grams of casein powder 45 minutes before bed. The PRO+CAS group was given one probiotic capsule during dinner and 20 grams of casein powder 45 minutes before bed. The participants in the PLA group were given one red capsule (containing 5 grams of starch) during dinner. All participants were instructed to take the supplements only on training days, three times a week for four weeks. Additionally, isokinetic strength parameters, including absolute peak torque (APT) and average rate of force development (AvRFD), were measured for the knee extensors (ext) and flexors (flx) muscles (concentric phase at angular velocities of 60°/s and 180°/s, using the dominant leg). One-way analysis of covariance (ANCOVA) or Quade tests with a significance level of p < 0.05 was used to analyze the collected data. The current study's findings indicated that APT-180°/s (ext) significantly increased in CAS (p = 0.008) and PRO+CAS (p = 0.003) compared to PLA. Additionally, the AvRFD-180°/s (ext) increased significantly in the PRO compared to the PLA (p = 0.007). Also, the AvRFD-60°/s (flx) increased significantly in the PRO+CAS group compared to the PLA (p = 0.014), CAS (p = 0.001), and PRO (p = 0.007). Furthermore, the AvRFD-180°/s (flx) increased significantly in the PRO+CAS compared to the CAS (p = 0.010). Moreover, the RAST average power increased dramatically in PRO+CAS compared to PLA (p = 0.003) and CAS (p = 0.02). Additionally, the Wall-squat test demonstrated a significant increase in PRO+CAS compared to PLA (p = 0.001) and PRO (p = 0.001). However, there were no significant differences in the APT-60°/s (ext&flx), APT-180°/s (flx), and AvRFD-60°/s (ext) between groups (p > 0.05). The simultaneous consumption of casein and probiotics significantly improved anaerobic power, isokinetic strength, and lower-body muscular endurance in male soccer players. These enhancements were more pronounced than those observed with casein or probiotics alone, as supported by statistical significance and effect sizes. The findings suggest a synergistic benefit of combined supplementation for athletic performance.

Nutritional strategies are critical for optimizing soccer players' performance and body composition. Spirulina, a protein-rich plant-based supplement, and probiotics offer individual benefits. However, their combined effects remain underexplored. This study investigated the effects of co-supplementation with spirulina and probiotics on body composition, isokinetic, isometric strength, and performance metrics in male soccer players. In a double-blind, placebo-controlled trial, forty soccer players were randomly assigned to four groups: placebo (PLA), probiotics (PRO), spirulina (SPI), and combined probiotics-spirulina (PRO + SPI). The PRO group received two probiotic capsules (a total dose of 4.5 × 1011 CFU) daily, with breakfast and dinner. The SPI group consumed two 1-g spirulina tablets twice daily (2 g total), with breakfast and dinner. The PRO + SPI group received both supplements in the same dosing regimen, while the PLA group consumed starch-based placebo capsules. Over eight weeks, participants followed identical training regimens. Pre- and post-intervention assessments included body composition (weight, BMI, fat percentage, fat weight, muscle weight), performance metrics (vertical jump, agility, speed, anaerobic sprint tests), and isokinetic and isometric knee strength tests. Statistical analyses utilized repeated measures and Bonferroni post-hoc tests. The PRO + SPI group demonstrated more significant reductions in weight (P = 0.012) and fat weight (P = 0.001) compared to the PLA group, while the SPI group showed a significant reduction in fat percentage (P = 0.034). Agility scores improved significantly in the PRO + SPI group compared to the PLA (P = 0.001) and SPI (P = 0.004) groups. Isokinetic performance metrics, including average power during knee extension at 60°/s and 180°/s, improved significantly in the PRO + SPI group compared to the PLA group (P = 0.018 and P = 0.009, respectively). Similarly, the PRO and SPI groups outperformed the PLA group in isokinetic measures such as absolute peak torque at 60°/s (P = 0.032) and 180°/s (P = 0.006). Also, maximum voluntary isometric contraction (MVIC) improved significantly in the PRO and SPI groups compared to the PLA group (P = 0.001 for both). From gut to skeletal muscle, spirulina, and probiotic co-supplementation significantly enhanced body composition, reduced weight and fat mass, and improved agility and isokinetic strength compared to placebo or individual supplementation. These results emphasize the synergistic potential of this nutritional strategy for optimizing athletic performance and recovery, warranting further investigation across diverse athletic populations.

Beetroot juice (BRJ) contains various bioactive compounds which can enhance athletes" performance. However, there is a limited number of studies assessing the effects of BRJ on climbers" performance and indicators of muscle soreness (MS). Thus, the present study aimed to investigate the effect of consuming beetroot juice acutely before climbing on lower-body isokinetic and isometric strength, aerobic power, and muscle soreness in mountain climbers. In a randomized, placebo-controlled, double-blinded study, 27 climbers (14 males and 13 females) were divided into three groups: Control (CON), Placebo (PLA), and Beetroot Juice (BRJ), with 9 participants in each group. The study evaluated swelling around the thigh (Sw-T), pressure pain threshold (PPT), isokinetic and isometric strength, horizontal jump (HJ), wall-sit, handgrip strength (HGS), flexibility, and the Queen's College Step test. Testing occurred in three sessions: baseline, climbing, and posttest. At baseline, all participants completed the full battery of tests at Shiraz University. One week later, during the climbing session, they consumed 70 mL of BRJ (400 mg nitrate), PLA, or water 2.5 hours before ascending to 3720 meters. Functional tests (HJ, wall-sit, and estimated VO₂_max) were performed at the altitude. After completing these tests, participants immediately descended the mountain. DOMS was assessed using a visual analog scale (VAS) for the quadriceps, hamstrings, and gastrocnemius muscles at the following time points: 2 hours before climbing, and 0 (immediately), 12, 24, 48, and 72 hours after descending. The posttest session, held 72 hours after descending, repeated all baseline assessments. The results revealed a statistically significant decrease in DOMS in the gastrocnemius muscles 24 hours post-descending in the BRJ group compared to the control group (p = 0.003, pEta² = 0.204). However, no changes in DOMS were observed for the quadriceps (p = 0.090, pEta² = 0.090) and hamstring (p = 0.254, pEta² = 0.056) muscles. Moreover, notable improvements were observed in PPT (p = 0.001, pEta² = 0.374), Estimated VO_2max (p = 0.016, pEta² = 0.291), HGS (p = 0.004, pEta² = 0.270), flexibility (p = 0.003, pEta² = 0.407), HJ (p = 0.008, pEta2 = 0.155), and isokinetic (peak torque, average power and rate of force development) and isometric (Maximum voluntary isometric contraction) strength indicators in the BRJ groups compare to the other groups (p˂0.05). However, no significant differences were observed in Sw-T between groups (p = 0.305). The study suggested that acute consumption of BRJ before climbing improves climbers' lower-body isokinetic and isometric strength, power, and endurance performance, and it is associated with a reduced perception of muscle soreness.