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

The effects of acute caffeine supplementation on muscular strength remain unclear. We examined the effects of two different doses of caffeine on muscle strength and calcium in plasma compared to placebo using a crossover, randomized, double-blind, placebo-controlled design. Twenty-one (n = 21) recreationally resistance-trained participants were randomly assigned into three experimental conditions: 6 mg·kg bw−1 of caffeine (CF6); 8 mg·kg bw−1 of caffeine (CF8); or placebo (PLA), with a 7-day washout period between conditions. Muscular strength assessments were made for both upper (bench press) and lower body muscles (squat and deadlift). Calcium release in plasma was measured on five different occasions. Bench press (CF8: 100.1 ± 1.9 kg; PLA: 94.2 ± 2.5 kg), deadlift (CF8: 132.8 ± 3.5 kg; PLA: 120.7 ± 5.7 kg), and squat (CF8: 130.1 ± 4.9 kg; PLA 119.4 ± 5.4 kg) strength were all significantly (p < 0.001) improved in CF8 compared to PLA. Calcium release in plasma was significantly increased in CF8, whereas no changes were observed in CF6 or PLA. Overall, 8 mg·kg bw−1 of caffeine appears to be an effective dose to optimize upper and lower body muscular strength and calcium release in recreationally trained participants.

Reduced Dose of Beta-Alanine Is Sufficient to Maintain Performance in Repeated Sprints.

ABSTRACT: Zandona, BA, Ramos, RA, de Oliveira, CdS, McAnulty, SR, Ferreira, LHB, Smolarek, AC, Enes, AAN, Urbinati, KMdSS, Aragon, AA, Schoenfeld, BJ, and de Souza Junior, TP. Reduced Dose of Beta-Alanine Is Sufficient to Maintain Performance in Repeated Sprints. J Strength Cond Res 36(6): 1636-1642, 2022-Beta-alanine (BA) supplementation has been shown to be effective in improving physical performance by increasing carnosine concentration. However, it is still necessary to know the effect of a maintenance dose on performance. Thus, this study aimed to investigate the effects of a maintenance dose of BA supplementation on performance. Forty-four anaerobically trained men with 23.9 ± 3.8 years of age, 176.0 ± 0.05 cm height, 81.2 ± 7.5 kg body mass, and 15.5 ± 2.9% of body fat performed a cycle ergometer test consisting of 4 sprints of 30 s with 4 minutes of active recovery. The study comprised 3 phases: (a) presupplementation, (b) supplementation with 6.4 g·d-1 BA or placebo, and (c) postsupplementation with a maintenance dose of 1.2 g·d-1 of BA or interruption of supplementation. Data were analyzed using generalized estimated equations with a priori 0.05 level of significance. The placebo group and interruption group presented a lower power (7.28 ± 0.66 and 7.71 ± 0.42 W·kg-1 vs. 8.04 ± 0.84 and 9.25 ± 1.18 W·kg-1, respectively; p < 0.05) during the third sprint in postsupplementation, whereas the maintenance group maintained the required power (7.47 ± 1.03 vs. 8.74 ± 1.07 W·kg-1; p > 0.05). The placebo group also presented higher percentage of fatigue (44.5% ± 12.3 and 44.8% ± 7.7 vs. 37.6 ± 7.2%; p = 0.021) and higher subjective perception of exertion (8.92 ± 0.90 vs. 8.00 ± 1.60; p = 0.028). Therefore, the maintenance dose of 1.2 g·d-1 BA was effective in maintaining performance, whereas a reduction in performance was observed after supplementation interruption.

Effects of Creatine Supplementation on Properties of Muscle, Bone, and Brain Function in Older Adults: A Narrative Review.

Aging is associated with reductions in muscle and bone mass and brain function, which may be counteracted by several lifestyle factors, of which exercise appears to be most beneficial. However, less than 20% of older adults (> 55 years of age) adhere to performing the recommended amount of resistance training (≥ 2 days/week) and less than 12% regularly meet the aerobic exercise guidelines (≥ 150 min/week of moderate to vigorous intensity aerobic exercise) required to achieve significant health benefits. Therefore, from a healthy aging and clinical perspective, it is important to determine whether other lifestyle interventions (independent of exercise) can have beneficial effects on aging muscle quality and quantity, bone strength, and brain function. Creatine, a nitrogen containing organic compound found in all cells of the body, has the potential to have favorable effects on muscle, bone, and brain health (independent of exercise) in older adults. The purpose of this narrative review is to examine and summarize the small body of research investigating the effects of creatine supplementation alone on measures of muscle mass and performance, bone mineral and strength, and indices of brain health in older adults.

Effect of low dose, short-term creatine supplementation on muscle power output in elite youth soccer players.

BACKGROUND: To determine the effects of a low dose, short-term Creatine monohydrate (Cr) supplementation (0.03 g.kg.d-1 during 14 d) on muscle power output in elite youth soccer players. METHODS: Using a two-group matched, double blind, placebo-controlled design, nineteen male soccer players (mean age = 17.0 ± 0.5 years) were randomly assigned to either Cr (N = 9) or placebo (N = 10) group. Before and after supplementation, participants performed a 30s Wingate Anaerobic Test (WAnT) to assess peak power output (PPO), mean power output (MPO), fatigue index (FI), and total work. RESULTS: There were significant increases in both PPO and MPO after the Cr supplementation period (P ≤ 0.05) but not the placebo period. There were also significant increases in total work, but not FI, after the Cr supplementation and placebo periods (P ≤ 0.05). Notably, there were differences in total work between the Cr and placebo groups after (P ≤ 0.05) but not before the 14 d supplementation period. CONCLUSION: There is substantial evidence to indicate that a low-dose, short-term oral Cr supplementation beneficially affected muscle power output in elite youth soccer players.

Effect of 1 Repetition Maximum, 80% Repetition Maximum, and 50% Repetition Maximum Strength Exercise in Trained Individuals on Variations in Plasma Redox Biomarkers.

Polotow, TG, Souza-Junior, TP, Sampaio, RC, Okuyama, AR, Ganini, D, Vardaris, CV, Alves, RC, McAnulty, SR, and Barros, MP. Effect of 1RM, 80%RM, and 50%RM strength exercise in trained individuals on variations in plasma redox biomarkers. J Strength Cond Res 31(9): 2489-2497, 2017-For decades, scientists have examined the participation of oxygen/nitrogen species in anaerobic-like exercises, especially weightlifting and resistance exercises. The balance between the production of oxyradicals and antioxidant responses during anaerobic-like exercises is essential to assure adaptation to the physiological benefits of strength training and to prevent chronic harmful effects. The aim of this study is to examine the hypothesis that different weight loads (1 repetition maximum (RM), 80%RM, and 50%RM) lifted until exhaustion could impose distinct oxidative insults and elicit diverse antioxidant responses in plasma of young trained subjects. Glucose (+10%), lactate (+65%), urea (+30%), free iron (+65%), reduced/oxidized glutathione (+14 and +23%, respectively), and xanthine oxidase activity (2.2-fold) significantly increased after the 1RM test, whereas plasma antioxidant capacity dropped by 37%. When lower weight loads were applied (80%RM and 50%RM tests), heme-iron (+15 and +20%, respectively) became the prevalent pro-oxidant, although glutathione responses were only detected after 80%RM (+14%). Lactate concentration in plasma continuously increased, by 2.9-fold (80%RM) and 3.6-fold higher (50%RM test). We demonstrated that 1RM tests significantly diminish the antioxidant capacity of plasma because of iron overload, whereas 80%RM tests require higher involvement of glutathione molecules to counteract heme-iron oxidative insult. Mild redox imbalances promoted by heme-iron were found in plasma after 50%RM. Although we did not observe overall changes in muscle damage in young trained subjects, we cannot exclude the need for specific antioxidant supplementation depending on the strength protocols applied, especially for less responsive groups, such as sedentary and elderly populations.

Tai Chi and Kung-Fu practice maintains physical performance but not vascular health in young versus old participants.

OBJECTIVES: Kung-Fu and Tai Chi along with other martial arts are gaining popularity but studies examining the benefits of martial arts on physical fitness, vascular health, nutrition, and psychological wellness are limited. Aging is associated with declines in these health components. The objectives of this study were to examine whether Tai Chi and Kung-Fu training would maintain physical fitness, vascular health, and psychological wellness components on older versus younger practitioners. METHODS: Seventeen subjects were recruited and divided into Young (age <40 years, n=9) and Old (age 40 years and above, n=8). Participants reported twice for health screens, vascular and nutrition assessment, and fitness tests. Mean differences were compared between groups for all tests using Student's t-tests. RESULTS: Age, months of practice, systolic blood pressure, and cardiovascular augmentation index were significantly greater in Old versus Young (p=0.001, p=0.007, p=0.049, and p=0.011, respectively). Psychologically, old practitioners experienced greater sleep interference (p=0.035) and overall pain (p=0.036). No other differences existed for any variable. CONCLUSION: Our study indicates that the practice of Tai Chi and Kung-Fu maintains physical fitness in older compared to younger practitioners. However, age associated changes in cardiovascular stiffness, systolic blood pressure, and pain were not prevented.

Effects of acute creatine supplementation on iron homeostasis and uric acid-based antioxidant capacity of plasma after wingate test.

BACKGROUND: Dietary creatine has been largely used as an ergogenic aid to improve strength and athletic performance, especially in short-term and high energy-demanding anaerobic exercise. Recent findings have also suggested a possible antioxidant role for creatine in muscle tissues during exercise. Here we evaluate the effects of a 1-week regimen of 20 g/day creatine supplementation on the plasma antioxidant capacity, free and heme iron content, and uric acid and lipid peroxidation levels of young subjects (23.1 ± 5.8 years old) immediately before and 5 and 60 min after the exhaustive Wingate test. RESULTS: Maximum anaerobic power was improved by acute creatine supplementation (10.5 %), but it was accompanied by a 2.4-fold increase in pro-oxidant free iron ions in the plasma. However, potential iron-driven oxidative insult was adequately counterbalanced by proportional increases in antioxidant ferric-reducing activity in plasma (FRAP), leading to unaltered lipid peroxidation levels. Interestingly, the FRAP index, found to be highly dependent on uric acid levels in the placebo group, also had an additional contribution from other circulating metabolites in creatine-fed subjects. CONCLUSIONS: Our data suggest that acute creatine supplementation improved the anaerobic performance of athletes and limited short-term oxidative insults, since creatine-induced iron overload was efficiently circumvented by acquired FRAP capacity attributed to: overproduction of uric acid in energy-depleted muscles (as an end-product of purine metabolism and a powerful iron chelating agent) and inherent antioxidant activity of creatine.