Ziyu Wang

Background: Velocity-loss (VL) thresholds may help regulate the balance between potentiation and fatigue during post-activation performance enhancement protocols; however, their effects on boxing-specific performance remain unclear. This study investigated the acute effects of bench press conditioning regulated by different VL thresholds on straight-punch performance in adolescent boxers. Methods: Eighteen male boxers (17.6 ± 0.7 years) completed four conditions in a randomized, counterbalanced crossover design: an active control condition (CON; two sets of 10 bench press repetitions using a habitual warm-up load below 30% one-repetition maximum [1RM]) and three VL conditions consisting of two sets of bench press at 85% 1RM terminated at 10% (VL10%), 20% (VL20%), or 30% (VL30%) velocity loss. Lead- and rear-hand peak punch velocity (PPV), peak punch force (PPF), and an estimated peak punch-power index (PPP) were assessed at baseline and 4, 8, 12, and 16 min after conditioning. Outcomes were analyzed using linear mixed-effects models, followed by Dunnett-adjusted comparisons of each VL condition with CON. Additional Tukey-adjusted pairwise comparisons were performed among VL10%, VL20%, and VL30%. Results: Significant condition × time interactions were observed for rear-hand PPV, lead- and rear-hand PPF, and lead- and rear-hand PPP (all p ≤ 0.046), but not for lead-hand PPV ( p = 0.391). At 8 and 12 min, VL10% and VL20% produced higher rear-hand PPV, PPF, and PPP and higher lead-hand PPP than CON ( p ≤ 0.039; Hedges’ g = 0.835–1.267). In contrast, VL30% produced lower rear-hand PPV, lead- and rear-hand PPF, and rear-hand PPP than CON at 4 min and remained lower for selected outcomes at 8–12 min ( p ≤ 0.046; g = −2.439 to −0.814). Direct VL comparisons showed no significant differences between VL10% and VL20%, whereas both conditions produced higher values than VL30% for several outcomes at selected time points ( p ≤ 0.045). Most between-condition differences were no longer evident at 16 min. Conclusion: Under the present protocol in the 18 male adolescent boxers studied, VL10% and VL20% were associated with favorable differences in several punch-performance outcomes after 8–12 min of recovery, whereas VL30% was associated with lower performance during the earlier recovery period. Direct comparisons showed no significant differences between VL10% and VL20%, whereas both conditions produced higher values than VL30% for several outcomes at selected time points. However, because repetition volume was not matched, these findings do not isolate the effect of VL threshold or establish an optimal threshold.

Background: Optimizing pre-competition priming is critical for maximizing acute performance in combat sports. Traditional percentage-based training (PBT), which uses a fixed percentage of one-repetition maximum (1RM) for a set number of repetitions, is widely used but lacks autoregulation, potentially causing suboptimal stimulus or excessive fatigue. In contrast, velocity-based training (VBT) adjusts training volume by ending sets when a prescribed velocity loss (VL) threshold is reached, providing individualized fatigue management. This study examined delayed punch-performance responses following traditional PBT and VBT performed with VL thresholds of 10%, 20%, or 30%, with each active condition evaluated relative to a low-intensity active control condition. Methods: Eighteen highly trained male boxers completed five priming conditions in a randomized crossover design, each separated by approximately 5 days: a low-intensity active control condition (CON; bench press at <30% 1RM for 3 sets of 10 repetitions with 3 min rest between sets), percentage-based training (PBT; 3 sets of 5 repetitions at 85% 1RM), and velocity-based training conditions performed at 85% 1RM with sets terminated at 10%, 20%, or 30% velocity loss. In the VBT conditions, barbell velocity was monitored on each repetition, and sets were stopped when mean concentric velocity dropped by the target percentage. Lead straight punch performance was assessed using relative peak punch force (RPF; N/kg), peak punch velocity (PPV; m/s), and an estimated relative punch-power index (RPP; W/kg) at baseline and 6 h, 24 h, and 48 h after priming. Results: The condition × time interactions were not significant for RPF, PPV, or RPP. At baseline, no active condition differed significantly from CON. At 6 h, RPP was significantly higher than CON following PBT, VL10%, and VL20%, whereas PPV was higher than CON following VL10% and VL20%; RPF did not differ significantly from CON. At 24 h, RPP was higher than CON following all active conditions; PPV was higher than CON following PBT, VL10%, and VL20%; and RPF was higher than CON following VL10%, VL20%, and VL30%. At 48 h, no active condition differed significantly from CON. Conclusion: At specific post-intervention time points, VL10% and VL20% showed higher PPV and/or RPP values than the low-intensity active control condition at 6 h and 24 h, whereas VL30% showed higher RPF and RPP values than CON at 24 h. Because the condition × time interactions were not significant and change-from-baseline contrasts were not performed, these findings represent time-specific differences from CON rather than confirmed differences in change from baseline or temporal response. The comparisons also do not establish direct differences among the active protocols, and the unequal training doses across VL conditions preclude identification of an optimal VL threshold.

Background: Traditional percentage-based training (PBT) prescribes loads according to a fixed percentage of one-repetition maximum (1RM) but does not account for daily fluctuations in performance readiness. In contrast, auto-regulated resistance training (ART)—including velocity-based training (VBT), autoregulatory progressive resistance exercise (APRE), and Rating of Perceived Exertion (RPE)/Repetitions in Reserve (RIR)-based autoregulatory training (RPE-AT)—and variable resistance training (VRT) provide more adaptive load adjustments. However, their relative effectiveness for improving lower-body maximal strength and explosive power remains unclear. Objective: To systematically evaluate and compare different resistance-training modalities, including APRE, VBT, RPE-AT, VRT, and PBT, on maximal lower-body strength and explosive power in healthy and active individuals using a network meta-analysis (NMA) method, and to provide a ranking of therapeutic effects. Method: Following the PRISMA-NMA guidelines, a systematic search was conducted across the Web of Science, PubMed, Embase, Scopus, SportDiscus, and ProQuest databases, ensuring a comprehensive and transparent approach to study retrieval. Randomized controlled trials (RCTs) comparing the effects of APRE, VBT, RPE-AT, VRT and PBT on lower extremity performance were included. The quality was evaluated using the Cochrane Risk of Bias assessment tool. Pairwise meta-analysis and NMA under the frequentist framework were conducted using R software. The standardized mean difference (SMD) and its 95% confidence interval (CI) were calculated, and the intervention measures were ranked by the cumulative area under the ranking probability curve (SUCRA). Results: A total of 27 RCTs involving 694 participants were included, consistent with the sample size and study quantity reported in relevant systematic reviews and meta-analyses of RCTs. For back squat 1-repetition maximum (1RM, a measure of maximal lower-body strength), NMA showed that VRT (SMD = 0.62, 95% CI [0.29, 0.95]), APRE (SMD = 0.59, 95% CI [0.16, 1.02]), and VBT (SMD = 0.41, 95% CI [0.10, 0.73]) significantly improved performance compared to PBT, while RPE-AT (SMD = 0.12, 95% CI [-0.31, 0.56]) showed no significant difference from PBT. The SUCRA ranking for back squat 1RM was: VRT (83.1%) > APRE (79.1%) > VBT (57.1%) > RPE-AT (23.4%) > PBT (7.4%). For countermovement jump (CMJ, a measure of lower-body explosive power), APRE (SMD = 1.08, 95% CI [0.30, 1.87]) and VBT (SMD = 0.62, 95% CI [0.23, 1.02]) were significantly superior to PBT, while VRT (SMD = 0.27, 95% CI [-0.14, 0.69]) showed a non-significant trend toward improvement. The SUCRA ranking for CMJ was: APRE (96.6%) > VBT (74.4%) > VRT (49.7%) > PBT (23.6%) > RPE-AT (5.7%). Conclusion: APRE, VBT, and VRT were generally associated with more favorable adaptations than PBT in lower-body strength and power outcomes. VRT showed the highest probability of being most effective for back squat 1RM, whereas APRE ranked highest for CMJ performance. These findings provide a comparative synthesis of current evidence and may assist practitioners in selecting resistance training strategies according to specific performance goals, while acknowledging the need for cautious interpretation given variability across studies. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251172410 , identifier CRD420251172410.

Evidence for acute caffeine supplementation in swimming remains inconsistent across reviews, likely due to between-study heterogeneity and methodological differences. Five databases were searched for randomized placebo-controlled crossover trials exploring the effects of caffeine on swimming performance in competitive swimmers. Performance outcomes were pooled as standardized mean differences (SMD; Hedges' g), with time outcomes sign-reversed so that positive values indicated improved performance. Dependence among multiple outcomes within studies was addressed using three-level random-effects models (REML). As a supplementary, interpretable metric, log ratios of means (lnRoM) were meta-analysed and expressed as percentage change. Post-exercise blood lactate (mmol/L) was pooled as mean differences (MD). Risk of bias was assessed using RoB 2 and certainty of evidence using GRADE. Prespecified exploratory moderator analyses examined potential effect modification (dose, timing, distance, administration form, stroke, gender, and athlete level). Thirteen studies were included (144 men and 48 women), which contributed 28 performance effect sizes. Caffeine improved swimming performance (SMD = 0.57, 95% CI: 0.20 to 0.94; p = 0.005), corresponding to a +1.71% improvement in lnRoM (95% CI: +1.01% to +2.41%; p < 0.001). Heterogeneity was substantial (I²_total = 64.7%) and primarily between studies. Eight studies contributed 24 blood lactate effect sizes. In the meta-analysis, caffeine increased post-test lactate (MD = 0.85 mmol/L, 95% CI: 0.22 to 1.49; p = 0.016) with high heterogeneity (I²_total = 76.5%). Exploratory moderator analyses suggested a possible dose-related pattern for swimming performance, with larger pooled effects at ≥6 mg/kg (SMD = 0.95, 95% CI: 0.52 to 1.38) than at p _difference = 0.017). Other performance moderators did not show clear between-subgroup differences. For lactate, exploratory subgroup analyses suggested larger increases in freestyle and short-distance events, although these patterns were more sensitive to modelling assumptions and should be interpreted cautiously. Acute caffeine ingestion confers a moderate ergogenic benefit for swimming performance (SMD = 0.57, 1.7% improvement) and is associated with higher post-test blood lactate (MD = 0.85 mmol/L). Dose (≥6 mg/kg) may be associated with larger performance benefits, whereas lactate responses appear more pronounced in freestyle and shorter events. However, these subgroup findings are hypothesis-generating and require exploration.

Background: Chronic non-specific low back pain (CLBP) imposes a substantial healthcare burden. For CLBP, non-pharmacologic pain management within physical therapy/rehabilitation commonly relies on therapeutic exercise (exercise therapy). Aquatic interventions such as exercise and balneotherapy are widely prescribed to treat CLBP, but their comparative effectiveness against land-based exercise, and multi-model programs remain unclear. We performed a network meta-analysis of randomized controlled trials to compare the effects of aquatic, land-based exercise, and multi-modal interventions on pain and disability in patients with chronic low back pain. Methods: We searched from inception to May 2025 for randomized controlled trials in adults with chronic non-specific low back pain that evaluated water-based therapies (aquatic exercise, hydrotherapy/balneotherapy). All randomized arms within eligible trials were retained, allowing comparisons with land-based exercise, combined aquatic + land-based programs, and general care/blank control. Results: We included 26 RCTs, forming a 9-node network (blank control, general care, land-based exercise, aquatic exercise, balneotherapy, and their combinations with general care/land-based exercise). For pain intensity, compared with blank control, balneotherapy + general care (SMD = 2.51, 95% CI 1.26–3.76; p < 0.001), aquatic exercise + general care (SMD = 1.96, 95% CI 0.44–3.48; p = 0.011), balneotherapy + land-based exercise (SMD = 1.68, 95% CI 0.58–2.78; p = 0.003), aquatic exercise (SMD = 1.58, 95% CI 0.83–2.32; p < 0.001), land-based exercise (SMD = 1.45, 95% CI 0.56–2.34; p = 0.001), and balneotherapy (SMD = 1.27, 95% CI 0.19–2.35; p = 0.021) significantly reduced pain. By contrast, land-based exercise + general care (SMD = 1.55, 95% CI − 0.18–3.27; p = 0.078) and general care (SMD = 1.02, 95% CI − 0.13–2.17; p = 0.081) did not reach statistical significance. Based on SUCRA for pain, balneotherapy + general care ranked first (SUCRA = 0.92; PrBest = 61.4%; mean rank = 1.7), followed by aquatic exercise + general care (0.71; 21.5%; 3.3) and balneotherapy + land-based exercise (0.62; 3.8%; 4.0), with combined interventions generally ranking above single modalities; blank control ranked last (0.01; 0.0%; 8.9). For clinical context, the observed SMDs correspond approximately to 24–48 points of pain reduction across the interventions that showed statistically significant effects. For disability, compared with blank control, balneotherapy + general care (SMD = 2.76, 95% CI 1.12–4.40; p = 0.001), balneotherapy (SMD = 2.48, 95% CI 0.50–4.45; p = 0.014), aquatic exercise + general care (SMD = 2.28, 95% CI 0.69–3.86; p = 0.005), balneotherapy + land-based exercise (SMD = 2.06, 95% CI 0.64–3.48; p = 0.004), aquatic exercise (SMD = 2.03, 95% CI 1.20–2.87; p < 0.001), land-based exercise (SMD = 1.84, 95% CI 0.80–2.88; p = 0.001), and general care (SMD = 1.66, 95% CI 0.11–3.21; p = 0.035) significantly reduced disability, whereas land-based exercise + general care did not (SMD = 1.72, 95% CI − 0.25–3.68; p = 0.086). SUCRA rankings for disability again favored multimodal care: balneotherapy + general care ranked first (SUCRA = 0.83; PrBest = 44.6%; mean rank = 2.4), followed by balneotherapy (0.71; 29.3%; 3.3) and aquatic exercise + general care (0.64; 16.9%; 3.9), with blank control consistently last (0.01; 0.0%; 8.9). Given very high heterogeneity and low-to-very-low certainty for most comparisons, these findings should be interpreted as preliminary directional evidence rather than actionable treatment recommendations. Results suggest multimodal approaches warrant investigation in future rigorously conducted trials. Conclusion: In CLBP, multimodal programs that integrate hydrotherapeutic components with general care or exercise tended to provide greater improvements than single interventions for both pain and disability. Among single modalities, effects were outcome-specific: for pain, aquatic exercise performed best and land-based exercise generally exceeded balneotherapy; for disability, balneotherapy and aquatic exercise showed larger improvements than land-based exercise. Land-based exercise remains a beneficial and pragmatic option where aquatic access is limited, while adding general care to land-based exercise did not show a consistent additional benefit. This analysis is substantially limited by very high heterogeneity ( I ² > 85%) and predominantly very low certainty evidence. Of the 36 comparisons assessed for pain intensity, 94.4% (34/36) were rated low to very low certainty; for disability, all 36 comparisons were rated very low certainty. These evidence quality profiles severely restrict ranking reliability and recommendation strength. Systematic review registration: Registered on PROSPERO. Unique Identifier: CRD42023432018. Public URL: https://www.crd.york.ac.uk/PROSPERO/view/CRD42023432018 .

The introduction of the 50-kilogram weight class in women's boxing at the Paris Olympics presents new challenges to athletes and coaching teams, necessitating rapid adaptation and a comprehensive understanding of the technical characteristics of this category. This study aimed to identify key technical indicators influencing match outcomes in the female 50-kilogram weight class and classify boxers into distinct technical styles. Data from 76 matches in the Paris Olympics, World, Continental, and National boxing events were collected, with 23 performance indicators representing offensive techniques, distances, and defensive counterattacks. The results showed that winning athletes had significantly higher performance in several technical aspects. Three technical styles were identified using these key indicators: Boxer-Punchers, Swarmers, and Out-Boxers. Distinctive offensive characteristics played a crucial role in distinguishing winners and identifying high-performance groups, while also highlighting the technical advantages of Olympic medalists. The research findings underscore the importance of accuracy, diversity and comprehensiveness in offensive techniques for success. These insights provide valuable guidance for assessing performance and formulating effective match strategies.

Objective: This study aimed to perform a comprehensive meta-analysis of randomized controlled trials examining the effectiveness of whole-body vibration training (WBVT) on muscle performance in healthy women. Methods: A systematic search of studies available up to 30 May 2024 was conducted using seven databases, including PubMed, EMBASE, Web of Science, Scopus, CINAHL, PEDro, and the Cochrane Library. Studies with a randomized and controlled protocol in which the effect of WBVT on muscle performance variables was compared to that of a) a non-exercise intervention or b) exercise intervention in healthy women were assessed for eligibility. The methodological quality of the included studies was assessed using the PEDro scale. Meta-analyses were performed using random effects models, and the results were expressed as standardized mean differences (SMDs) with corresponding 95% confidence intervals (95% CIs). Results: A total of 21 randomized controlled trials, encompassing 748 healthy women, was included in the meta-analysis. WBVT demonstrated significantly greater effects on muscle strength and power when compared with the non-exercise control groups with regard to knee extension (SMD = 0.534, 95% CI: 0.303 to 0.766, p < 0.001), leg press (SMD = 0.794, 95% CI = 0.424 to 1.163, p < 0.001), ankle plantar flexion (SMD = 0.462, 95% CI: 0.019 to 0.904, p = 0.041), and the countermovement jump performance (SMD = 0.470, 95% CI: 0.211 to 0.729, p < 0.001). However, WBVT significantly improved only the countermovement jump performance (SMD = 0.338, 95% CI: 0.037 to 0.640, p = 0.028) when compared with the exercise control groups. Subgroup analyses revealed that longer periods (≥ 12 weeks) of WBVT resulted in greater benefits for both muscle strength and power compared to the non-exercise control group. Additionally, higher frequencies (> 30 Hz, SMD = 0.736, p < 0.001; ≤ 30 Hz, SMD = 0.284, p = 0.109) provided greater benefits for improving muscle strength. Last, post-menopausal women (post-menopausal, SMD = 0.561, p = 0.001; pre-menopausal, SMD = 0.354, p = 0.076) obtained greater benefits in muscle power with WBVT than pre-menopausal women. Conclusions: WBVT is efficacious in improving lower-body muscle strength and power in healthy women. However, the potential benefits of WBVT compared to other exercise interventions were only associated with an enhancement in countermovement jump performance. Longer periods (≥ 12 weeks) of WBVT resulted in greater benefits for both muscle strength and power compared to the non-exercise control group. Additionally, higher vibration frequencies (> 30 Hz) provided greater improvements in muscle strength, while post-menopausal women reaped greater benefits in muscle power than pre-menopausal women.

Background: Both listening to music during warm-up and consuming caffeine before exercise have been independently shown to enhance athletic performance. However, the potential synergistic effects of combining these strategies remain largely unexplored. To date, only two studies have reported additional benefits to combining music during warm-up with a caffeine dose of 3 mg/kg on taekwondo-specific performance tasks. However, these studies did not evaluate whether this combination produces additive or synergistic effects on other types of sports performance. The present study aimed to assess the effects of listening to music alone or combined with caffeine intake on performance in the Wingate anaerobic test (WAnT) in physically active subjects. Methods: Twenty-four physically active male participants took part in this randomized, double-blind, crossover experiment. Participants underwent WAnT performance evaluations under three conditions: (i) no intervention (control; CON); (ii) music plus placebo (Mus + PLA), involving the intake of a placebo (maltodextrin) 60 min prior and self-selected high-tempo music during warm-up; and (iii) music plus caffeine (Mus + CAF), involving the intake of 3 mg/kg of caffeine 60 min prior and self-selected high-tempo music during warm-up. Under all conditions, participants wore the same Bluetooth headphones (with or without music), performed a 10 min standardized warm-up, and completed the 30 s WAnT with a load of 7.5% of their body weight on a calibrated ergometer. Power output was recorded at a frequency of 1 Hz throughout the exercise. The Feeling Scale was assessed both before and after the exercise test, while heart rate (HR) and the rating of perceived exertion (RPE) were measured immediately following the exercise. Results: Mus + PLA and Mus + CAF significantly improved peak power, mean power, and total work compared with CON (p < 0.05). Furthermore, peak power was higher in Mus + CAF than in Mus + PLA (p = 0.01). Post-exercise HR and RPE showed no significant differences across conditions (p > 0.05). Regarding the Feeling Scale (FS) before exercise, the Mus + PLA and Mus + CAF conditions showed significantly higher scores than CON (p < 0.05), while no differences were found after exercise. The perceived fitness metrics displayed no significant differences among conditions (p > 0.05), except for self-perceived power, which was higher in Mus + CAF than in CON (p = 0.03). Conclusions: Self-selected music during warm-up, either alone or combined with caffeine, significantly enhanced several WAnT performance metrics, including peak power, mean power, and total work. Remarkably, combining music with caffeine further improved peak power and increased self-perceived power compared with music alone. While listening to self-selected music during warm-up provided measurable benefits on anaerobic exercise performance, the combination of music and caffeine demonstrated additive effects, making it the optimal strategy for maximizing anaerobic performance.

Background: Numerous meta-analyses have assessed the efficacy of creatine supplementation in increasing muscle strength. However, most have not considered the effect of the participants’ age, training duration, or other confounding variables on strength outcomes. Therefore, the purpose of this study was to consider the effect of these variables on the potential efficacy of creatine supplementation and resistance training for improving measures of muscle strength. Methods: Four databases were searched (MEDLINE, Scopus, Embase, and SPORTDiscus) with a search end date of 22 May 2024. Twenty-three studies were included, with 20 studies involving males (447 male participants), 2 studies involving females (40 female participants), and 1 study involving both males and females (13 male participants and 9 female participants). Results: In comparison with a placebo, creatine supplementation combined with resistance training significantly increased upper-body (WMD = 4.43 kg, p < 0.001) and lower-body strength (WMD = 11.35 kg, p < 0.001). Subgroup analyses showed a trend for greater upper-body strength improvements for males on creatine compared with females on creatine (p = 0.067, Q = 3.366). Additionally, males who consumed creatine combined with resistance training significantly increased both upper- and lower-body strength, whereas females showed no significant gains. There was a trend indicating greater lower-body strength gains from high-dose creatine compared with lower doses (p = 0.068, Q = 3.341). No other variables influenced the effect of creatine supplementation. In conclusions, creatine supplementation with resistance training enhances upper- and lower-body muscle strength in adults aged < 50, with greater benefits likely to be seen in males than females.

Post-activation performance enhancement (PAPE) is a physiological phenomenon that refers to an acute excitation of the neuromuscular system following intense exercise that ends in enhanced physical performance in a subsequent bout of exercise. The scientific literature has primarily examined the effectiveness of PAPE alone or combined with caffeine (CAF) intake in all-out tests lasting ≤10 s, as the effect of PAPE is transitory. The aim of the present study was to determine the effect of a protocol to induce PAPE alone or in combination with caffeine intake on the 30 s Wingate Anaerobic Test in highly trained boxers. Twenty-five male and highly trained boxers (mean age: 20 ± 1 years) participated in a double-blind, randomized crossover study consisting of three different experimental conditions: (i) control (CON), with no substance intake and no PAPE protocol before the Wingate Anaerobic Test; (ii) PAPE + PLA, involving the intake of a placebo 60 min before and a PAPE protocol comprising a 10 s cycling sprint overloaded with 8.5% of the participants’ body weight 10 min before the Wingate Anaerobic Test; and (iii) PAPE + CAF, involving the intake of 3 mg/kg of caffeine 60 min before and the same PAPE protocol used in the (ii) protocol before the Wingate Anaerobic Test. In all conditions, the participants performed the 30 s version of the Wingate Anaerobic Test with a load equivalent to 7.5% of their body weight, while the cycle ergometer setting was replicated. Immediately following the Wingate test, heart rate (HR), the rating of perceived exertion (RPE), and blood lactate concentration (Bla) were measured. In comparison to CON, PAPE + PLA enhanced mean power (p = 0.024; Effect size [ES] = 0.37) and total work (p = 0.022; ES = 0.38) during the Wingate test, accompanied by an increase in post-test blood lactate concentration (p < 0.01; ES = 0.83). In comparison to CON, PAPE + CAF enhanced mean power (p = 0.001; ES = 0.57), peak power (p = 0.013; ES = 0.57), total work (p = 0.001; ES = 0.53), post-test blood lactate concentration (p < 0.001; ES = 1.43) and participants’ subjective perception of power (p = 0.041). There were no differences in any variable between PAPE + PLA and PAPE + CAF. In summary, a PAPE protocol that involves a 10 s all-out sprint 10 min before the Wingate Anaerobic Test was effective in enhancing Wingate mean power in highly trained boxers. The addition of 3 mg/kg of caffeine to the PAPE protocol produced an effect on mean power of a higher magnitude than PAPE alone, and it enhanced peak power along with participants’ subjective perception of power. From a practical point of view, PAPE before exercise seems to be an effective approach for increasing Wingate performance in highly trained boxers, while the addition of caffeine can increase some benefits, especially peak power.