High Doses of Caffeine Increase Muscle Strength and Calcium Release in the Plasma of Recreationally Trained Men

Combined Effects of Rhodiola Rosea and Caffeine Supplementation on Straight Punch Explosive Power in Untrained and Trained Boxing Volunteers: A Synergistic Approach

OBJECTIVES

This study aimed to investigate the effects of combined supplementation with Rhodiola rosea (RHO) and caffeine (CAF) on the explosive power and sustained output capacity of lead and rear straight punches in both untrained and trained volunteers, with a focus on potential synergistic effects.

METHODS

randomized, double-blind, placebo-controlled design was employed, enrolling 96 participants (48 untrained, 48 trained). Participants were stratified and randomly assigned to the control (CTR), CAF, RHO, or CAF+RHO group. All subjects completed an 8-week standardized boxing training program (twice per week). Punch performance was assessed using professional boxing equipment and a biomechanical testing system, evaluating lead and rear straight punches, ground reaction force (GRF), and a 30 s continuous punching test.

RESULTS

the CAF+RHO group showed significant improvements in both untrained and trained volunteers. Com-pared to the RHO group, this group demonstrated higher lead punch velocity, shorter bi-lateral peak force time during rear punches, and more punches in the 30 s test (p < 0.05). Compared to the CAF group, the CAF+RHO group exhibited greater rear punch force, higher bilateral peak force during lead punches, increased forefoot peak force in rear punches, and improved 30 s power output (p < 0.05). The CAF+RHO group also outperformed the CTR group across all parameters (p < 0.05).

CONCLUSIONS

Combined supple mentation with CAF and RHO significantly enhances both explosive power and sustained output in boxing performance. This may result from improved energy metabolism efficiency and neuromuscular coordination, providing a promising nutritional strategy for high-intensity intermittent exercise.

Effects of caffeinated coffee on physical and cognitive performance: Chronotype and time of day study

This study examined the effects of caffeinated coffee (3 mg/kg) compared to decaffeinated coffee (placebo) on physical and cognitive performance in trained male athletes with morning (MT) and evening (ET) chronotypes, all of whom had moderate caffeine intake. Seventeen trained male athletes participated in various tests, including CP (a flanker task), hand grip strength test, back strength test, lower body Wingate sprint tests (peak and average power), and rating of perceived exertion (using the Borg Scale). The tests were conducted at two times of day: mornings (08:00 h-10:00 h) and evenings (16:00 h-18:00 h). Results indicated that caffeinated coffee significantly enhanced handgrip strength [F(1, 15) = 11.200, p = 0.001, η2p = .427], back strength [F(1, 15) = 8.695, p = 0.001, η2p = 0.367], and lower body Wingate test performance, including peak strength [F(1, 15) = 8.384, p = 0.001, η2p = 0.359] and mean strength [F(1, 15) = 8.304, p = 0.001, η2p = 0.356], regardless of chronotype. Conversely, no significant differences were observed in the cognitive performance (CP) measured by the flanker task and in Borg's perceived exertion ratings. When analyzing the interaction between groups × CAF & PLA, significant differences were found in the handgrip strength test [F(3, 45) = 17.443, p = 0.001, η2p = 0.538], back strength test [F(3, 45) = 19.926, p = 0.001, η2p = 0.571], peak power [F(3, 45) = 12.285, p = 0.001, η2p = 0.450], and average power [F(3, 45) = 6.633, p = 0.009, η2p = 0.307]. However, no significant differences were noted in cognitive performance (CP) and Borg perceived exertion ratings. These findings suggest that chronotype, timing of training, and caffeine consumption can significantly influence physical performance in trained men with moderate caffeine intake.

Causal association among smoking, bitter beverage consumption, and risk of osteoporosis: a two-sample mendelian randomization-based study

OBJECTIVES

Two-sample MR methods were employed to analyze the impact of smoking and bitter beverage consumption on the risk of osteoporosis and osteoporosis with pathological fractures, in order to assess the causal association.

METHODS

Publicly available genome-wide association study summary data were analyzed using MR methods. The exposures investigated were smoking (smoking per day, smoking initiation, and lifetime smoking index) and bitter beverages (coffee, tea, bitter alcoholic beverages, bitter non-alcoholic beverages, and total bitter beverages). The outcomes examined were the risk of osteoporosis and osteoporosis with pathological fractures. The inverse-variance weighted (IVW) method was used as the main statistical model. The stability and reliability of the results were verified by the Cochran's Q test, the Egger-intercept test, and the leave-one-out analysis.

RESULTS

Smoking per day was causally associated with the risk of osteoporosis OR = 1.417, 95% CI = 1.119-1.794, P = 0.003), and lifetime smoking index had a possible genetic causal association with the risk of osteoporosis with pathological fractures (OR = 4.187, 95% CI = 1.909-9.184, P < 0.001). No genetic causal association was found between smoking initiation or lifetime smoking index and the risk of osteoporosis (P > 0.05). No genetic causal association was identified between smoking per day or smoking initiation and the risk of osteoporosis with pathological fractures (P > 0.05). Total and bitter non-alcoholic beverage consumption showed a potential effect on the risk of osteoporosis (OR = 3.687, 95% CI = 1.535-8.858, P = 0.003 and OR = 3.040, 95% CI = 1.466-6.304, P = 0.002, respectively).

CONCLUSIONS

This study found smoking raises the risk of osteoporosis and osteoporosis with pathological fractures based on genetics. Certain bitter beverages are linked to an increased osteoporosis risk.

Association between breakfast consumption frequency and handgrip strength and standing long jump: a systematic review and meta-analysis

Background and aims

Over the past decade, numerous studies investigating the relationship between breakfast consumption frequency and handgrip strength and standing long jump have produced conflicting evidence, leading to uncertainty regarding this association. This study aimed to provide further clarity on the relationship between breakfast consumption frequency and handgrip strength and standing long jump.

Methods

A comprehensive search of the literature up to September 15, 2023, was conducted on Web of Science, PubMed, Scopus, MEDLINE, and CNKI. Six studies related to grip strength and three studies related to standing long jump performance were included in the meta-analysis. For studies defining breakfast consumption frequency as an ordinal variable, the effect sizes of the lowest and highest frequency groups were analyzed.

Results

No significant differences in handgrip strength were found between the highest and lowest breakfast consumption groups. Furthermore, unlike in men, women with the highest frequency of breakfast consumption showed significantly higher handgrip strength levels than women with the lowest frequency of breakfast consumption. No significant positive associations were found between breakfast intake frequency and standing long jump levels.

Conclusion

These results suggest that while regular breakfast consumption may enhance handgrip strength in women, it does not influence standing long jump performance in both sexes.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, CRD42024547903.

Exploring the ergogenic potential of carbohydrate-caffeine combined mouth rinse on exercise and cognitive performance: a systematic review

Carbohydrate (CHO) and caffeine (CAF) mouth rinsing have been independently reported to benefit sport performance. The proposed mechanisms by which mouth rinsing CHO exerts an influence are reported to be different from those for mouth rinsing CAF. However, the potential ergogenic effects of combining CHO and CAF in a single mouth rinse solution, are unclear. This study aimed to review the available evidence of CHO-CAF combined mouth rinse on exercise and cognitive performance in human participants. A systematic literature search was conducted using five databases until April 2024, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) recommendations. Among the nine randomized crossover studies included, only one study showed significant improvements in lower-body muscular endurance with CHO-CAF mouth rinse (effect size (ES): 0.48; p < 0.05), while two studies reported non-statistically significant improvements in repeated sprint performance compared to other mouth rinse and placebo conditions (ES: 0.20-0.81; p = 0.07-0.18). However, for other performance measures, including repeated jumps, upper-body strength and endurance, endurance cycling, and intermittent recovery run, most evidence (five studies) did not demonstrate significant ergogenic effects. Notably, of the two studies that examined cognitive performance, both reported significant improvements with CHO-CAF mouth rinse compared with the placebo condition (ES: 0.45-3.45; p < 0.05). Overall, a synergistic influence of CHO-CAF mouth rinse on physical exercise performance is not evident, but preliminary evidence suggests potential benefits on cognitive performance. Future studies are required to address various methodological issues identified in this review, while practitioners and athletes should exercise caution when considering this novel nutritional strategy.

Common questions and misconceptions about caffeine supplementation: what does the scientific evidence really show?

Caffeine is a popular ergogenic aid that has a plethora of evidence highlighting its positive effects. A Google Scholar search using the keywords "caffeine" and "exercise" yields over 200,000 results, emphasizing the extensive research on this topic. However, despite the vast amount of available data, it is intriguing that uncertainties persist regarding the effectiveness and safety of caffeine. These include but are not limited to: 1. Does caffeine dehydrate you at rest? 2. Does caffeine dehydrate you during exercise? 3. Does caffeine promote the loss of body fat? 4. Does habitual caffeine consumption influence the performance response to acute caffeine supplementation? 5. Does caffeine affect upper vs. lower body performance/strength differently? 6. Is there a relationship between caffeine and depression? 7. Can too much caffeine kill you? 8. Are there sex differences regarding caffeine's effects? 9. Does caffeine work for everyone? 10. Does caffeine cause heart problems? 11. Does caffeine promote the loss of bone mineral? 12. Should pregnant women avoid caffeine? 13. Is caffeine addictive? 14. Does waiting 1.5-2.0 hours after waking to consume caffeine help you avoid the afternoon "crash?" To answer these questions, we performed an evidence-based scientific evaluation of the literature regarding caffeine supplementation.

Evidence-based sports supplements: A redox analysis

Despite the overwhelming number of sports supplements on the market, only seven are currently recognized as effective. Biological functions are largely regulated through redox reactions, yet no comprehensive analysis of the redox properties of these supplements has been compiled. Here, we analyze the redox characteristics of these seven supplements: bicarbonates, beta-alanine, caffeine, creatine, nitrates, carbohydrates, and proteins. Our findings suggest that all sports supplements exhibit some degree of redox activity. However, the precise physiological implications of these redox properties remain unclear. Future research, employing unconventional perspectives and methodologies, will reveal new redox pixels of the exercise physiology and sports nutrition picture.

Coffee and Alzheimer's disease

Coffee, a universally consumed beverage, is known to contain thousands of bioactive constituents that have garnered interest due to their potential neuroprotective effects against various neurodegenerative disorders, including Alzheimer's disease (AD). Extensive research has been conducted on coffee constituents such as Caffeine, Trigonelline, Chlorogenic acid, and Caffeic acid, focusing on their neuroprotective properties. These compounds have potential to impact key mechanisms in AD development, including amyloidopathy, tauopathy, and neuroinflammation. Furthermore, apart from its neuroprotective effects, coffee consumption has been associated with anticancerogenic and anti-inflammatory effects, thereby enhancing its therapeutic potential. Studies suggest that moderate coffee intake, typically around two to three cups daily, could potentially contribute to mitigating AD progression and lowering the risk of related neurological disorders. This literature underscores the potential neuroprotective properties of coffee compounds, which usually perform their neuronal protective effects via modulating nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), nuclear factor erythroid-derived 2-like 2 (Nrf2), interleukins, tumor necrosis factor-alpha (TNF-α), and many other molecules.

Timing Matters: Time of Day Impacts the Ergogenic Effects of Caffeine-A Narrative Review

Caffeine has attracted significant attention from researchers in the sports field due to its well-documented ergogenic effects across various athletic disciplines. As research on caffeine continues to progress, there has been a growing emphasis on evaluating caffeine dosage and administration methods. However, investigations into the optimal timing of caffeine intake remain limited. Therefore, this narrative review aimed to assess the ergogenic effects of caffeine administration at different times during the morning (06:00 to 10:00) and evening (16:00 to 21:00). The review findings suggest that circadian rhythms play a substantial role in influencing sports performance, potentially contributing to a decline in morning performance. Caffeine administration has demonstrated effectiveness in mitigating this phenomenon, resulting in ergogenic effects and performance enhancement, even comparable to nighttime levels. While the specific mechanisms by which caffeine regulates circadian rhythms and influences sports performance remain unclear, this review also explores the mechanisms underlying caffeine's ergogenic effects, including the adenosine receptor blockade, increased muscle calcium release, and modulation of catecholamines. Additionally, the narrative review underscores caffeine's indirect impact on circadian rhythms by enhancing responsiveness to light-induced phase shifts. Although the precise mechanisms through which caffeine improves morning performance declines via circadian rhythm regulation necessitate further investigations, it is noteworthy that the timing of caffeine administration significantly affects its ergogenic effects during exercise. This emphasizes the importance of considering caffeine intake timing in future research endeavors to optimize its ergogenic potential and elucidate its mechanisms.

Caffeine Does Not Alter Performance, Perceptual Responses, and Oxidative Stress After Short Sprint Interval Training

Despite the abundance of research investigating the efficacy of caffeine supplementation on exercise performance, the physiological and biochemical responses to caffeine supplementation during intermittent activities are less evident. This study investigated the acute effects of caffeine supplementation on measures of exercise performance, ratings of perceived exertion, and biomarkers of oxidative stress induced by an acute bout of sprint interval training. In a randomized crossover design, 12 healthy males (age: 26 ± 4 years, height: 177.5 ± 6 cm, body mass: 80.7 ± 7.6 kg) ingested 6 mg/kg of caffeine or placebo 60 min prior to performing sprint interval training (12 × 6 s "all-out sprints" interspersed by 60 s of rest). Performance scores and ratings of perceived exertion were assessed after every sprint. Blood samples were collected before supplementation, prior to and following each sprint, and 5 and 60 min after the last sprint. Caffeine had no effect on any performance measures, ratings of perceived exertion, or biomarkers of oxidative stress (p > .05). In conclusion, caffeine supplementation does not improve performance or decrease oxidative stress after an acute bout of sprint interval training.

The Effect of Caffeine Supplementation on Female Volleyball Players' Performance and Wellness during a Regular Training Week

BACKGROUND

caffeine is an ergogenic aid that still needs to be investigated in women's sports performance.

METHODS

Eight semi-professional women's volleyball players (height = 1.63 ± 0.08 m; weight = 66.67 ± 4.74 kg) voluntarily participated in this study. A randomized crossover design was implemented where players underwent caffeine and placebo conditions. In the caffeine condition, participants consumed 5 mg/kg of caffeine based on their body weight before acute training. The evaluations were performed over two weeks of training. In both conditions, the countermovement jump, repeated jumps for 15 s, and handgrip tests were performed. The change of direction was assessed using the 505 test. Well-being was also assessed with a wellness questionnaire. A repeated measures ANOVA and correlation analysis were performed.

RESULTS

The repeated measures ANOVA revealed a main effect of supplementation (F (1.7) = 8.41, p = 0.02, η2 = 0.54) across the training week on physical performance. Additionally, there was a positive effect on perceived fatigue (F (1.7) = 7.29, p = 0.03, η2 = 0.51).

CONCLUSIONS

Caffeine improved performance and fatigue parameters over one week of training. Further research is needed on women, focusing on physical performance and wellbeing, especially during intense periods.

Advances in Nutrition, Dietary Supplements and Ergogenic Aids for Athletic Performance: Trends and Future Prospects

Sports nutrition is a scientific discipline that explores the relationship between nutrients and physical exercise performance [...].