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Resistance-type exercise (RE) elicits distinct acute metabolic and hormonal responses, which can be modulated by the manipulation of training variables. The purpose of this study was to compare the metabolic (blood lactate and estimated lactic anaerobic system energy expenditure) and hormonal (growth hormone [GH]) responses to RE sessions composed exclusively of multijoint (MULTI) or single-joint (SINGLE) exercises. Assessments of creatine kinase (CK) levels were also performed. In a crossover design, 10 recreationally resistance-trained men (age: 26.9 ± 3.0 years, total body mass: 83.2 ± 13.8 kg; height: 176 ± 7.0 cm; training experience: 5.5 ± 2.4 years) were randomly submitted to both protocols. Blood collections were made pre, 3 minutes after, and 36 hours after each experimental session. No significant difference between MULTI vs. SINGLE was observed for the rises in blood lactate (p = 0.057) and GH (p = 0.285) levels. For CK, a significant difference between the protocols was noted, in which MULTI resulted in significant rises after 3 minutes (p = 0.017) and 36 hours (p = 0.043) compared with SINGLE. In conclusion, the findings of this study suggest that resistance-trained individuals display similar metabolic and hormonal responses when performing MULTI and SINGLE exercise protocols. Also, RE sessions comprising MULTI exercises induce a higher magnitude of muscle damage, which may require a longer recovery period compared with SINGLE. [ABSTRACT FROM AUTHOR]

The aim of the present study was to assess the effects of beta-alanine supplementation on muscle strength and thickness. Nineteen resistance-trained men (age: 27.3 ± 5.5 years; height: 178 ± 10 cm; body mass: 83.4 ± 9.7 kg; training experience: 5.9 ± 3.9 years) were allocated to one of the following groups: Beta-alanine (BA) (6.4 g/day of beta-alanine) or Placebo (PLA) (6.4 g/day of maltodextrin). Subjects completed 4 resistance training sessions per week for 8 weeks. The following assessments were performed before and after intervention periods: 1 repetition maximum (1RM) and 60%1RM tests in the bench press (60%1RM BENCH ) and back squat (60%1RM SQUAT ) exercises; muscle thickness assessment of biceps brachialis (MT BB ), triceps brachialis (MT TB ) , and vastus lateralis (MT VL ) by ultrasonography. No significant difference between groups was observed for the absolute increase (pre-post intervention) in the 1RM BENCH (mean difference = 0.8 kg; p = 0.679), 1RM SQUAT (mean difference = 0.1 kg; p = 0.992), MT BB (mean difference = 0.7 mm; p = 0.637), MT TB (mean difference = 1.4 mm; p = 0.282), MT VL (mean difference = 1.6 mm; p = 0.311), 60%1RM BENCH (mean difference = 0.5 repetitions; p = 0.670) and 60%1RM SQUAT (mean difference = 0.7 repetitions; p = 0.690). In conclusion, the 8-week training period induced significant strength and morphological responses. However, the addition of beta-alanine supplementation did not enhance these adaptive outcomes., Competing Interests: The authors declare have not potential conflict of interest in relation to this paper., (Copyright © Biology of Sport 2023.)

The adoption of resistance training (RT) programs has been shown to positively influence sports performance-related parameters. However, the chronic effects of maximal strength protocols on the performance of soccer players are not completely investigated. The aim of this study was to evaluate the effects of performing two repetition maximum (2RM) before a resistance training session on the physical performance of youth soccer players. Seventeen players (under-20 category) were allocated in one of the following groups: 2RM + resistance training group (2RM + RT, n = 8) and resistance training group (RTG, n = 9). Both groups performed the same RT protocol during experimental weeks. However, the 2RM + RT performed 1 set of 2RM for 4 exercises, previously to RT protocol. Pre and post intervention period, one repetition maximum of the back squat exercise (1RM SQUAT ), sprint time (15m-sprint test), countermovement jump (CMJ), repeated sprint ability (RSA BEST and RSA MEAN ), and yo-yo intermittent recovery test level-2 (YYIRT2) were assessed. Total load lifted (TLL) during the experimental weeks was also collected. Significant increases in 1RM SQUAT (2RM + RT: +45.1%, d = 4.40; RTG: +32.3%, d = 1.84), 15m sprint (2RM + RT: -9.0%, d = 7.9; RTG: -8.8%%, d = 3.2), CMJ (2RM + RT: +2.3%, d = 0.17; RTG: +0.8%, d = 0.07), RSA BEST (2RM + RT: -2.4%, d = 0.6; RTG: -2.3%, d = 1.04), RSA MEAN (2RM + RT: -2.9%, d = 1.33; RTG: -3.4%, d = 1.78), YYIRT2 (2RM + RT: +12.0%, d = 0.82; RTG: +12.1%, d = 0.63) (all p < 0,05) were observed for both groups on pre to post-intervention periods, with no significant difference between groups. Therefore, the 2RM + RT protocol did not promote additional increase on performance of young soccer players.