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.

Effect of 12 Weeks of Resistance Training on Motor Coordination and Dynamic Balance of Older Woman.

Resistance training (RT) is considered a viable strategy to enhance the autonomy and functionality of older populations. We randomized 49 older women (64.2 ± 3.8) into one of two groups: an intervention group (IG) (n = 29) that performed regimented RT or a nontraining control group (CG) (n = 20). The RT protocol was carried out three times a week for both the upper and lower limbs over a 12-week study period. A 30-second arm flexion test was used to test upper limb endurance and a 30-second chair stand test was used to analyze lower limb endurance. Dynamic balance was tested by a Y balance test normalized by leg length. A Soda Pop test was employed to analyze coordination. Results showed significant improvements in IG versus CG in both upper limb (19.50 ± 1.52 vs. 11.40 ± 2.87, p = 0.001) and lower limb muscular endurance (14.90 ± 3.10 vs. 26.56 ± 3.17, p = 0.001). Moreover, the training group showed superior improvements in anterior and posterolateral balance compared to CG (63.9% ± 3.1% to 70.2 ± 2.1 and 88.1 ± 3.9 to 94.2 ± 2.7 with p = 0.001, respectively). There were no significant differences in coordination outcomes between groups. In conclusion, we demonstrate that RT is effective in developing muscular endurance and dynamic balance in postmenopausal women, but does not influence muscular coordination in the measures studied. Study registered in the Brazilian Registry Clinical Trials Registry (No. RBR-7MZ2KR).