Efeito da suplementação de arginina sobre marcadores indiretos de dano muscular induzido pelo exercício de força / Effect of arginine supplementation on indirect markers of muscle damage induced by resistance exercise

O objetivo do presente estudo foi avaliar o efeito da suplementação de arginina (ARG) sobre marcadores indiretos do dano muscular induzido pelo exercício (DMIE). Participaram do estudo 24 jovens universitários do sexo masculino, com experiência mínima de 1 ano em treinamento de força. Os indivíduos foram alocados em 2 grupos, em seguindo delineamento experimental duplo -cego: suplementado com 7g de arginina (ARG, n=12) ou suplementado com 7g de placebo (PLA, n =12 ). O suplemento foi oferecido 30 min antes da realização do protocolo de 10 séries de 10 repetições máximas (RMs) realizadas no supino. Foram aferidas a circunferência torácica, a dor muscular de in ício tardio (DMIT), por meio da escala visual analógica (EVA), e a carga do teste de uma repetição máxima (1 RM) em repouso, 24h, 48h e 72h após a sessão de treinamento (ST). Os resultados foram analisados utilizando teste de análise de variância ANOVA de dois fatores), seguido pelo teste de Bonferroni. A DMIT apresentou maior magnitude no PLA, em todos momentos avaliados após a ST, em comparação ao grupo ARG (p<0,01). Foi observado maior decréscimo da produção de força no grupo PLA, em 72h após a ST , comparado ao grupo ARG (p<0,05). A suplementação aguda de ARG parece ter atenuado a magnitude da DMIT e acelerado a recuperação da força...(AU)

The purpose of this study was to investigate the effect of arginine (ARG) supplementation o nindirect markers of exercise-induced muscle damage (EIMD). Twenty-four male graduate students, with a minimum of one year of experience in resistance training participated in the study . T he subject s were allocated in 2 groups in a double-blind experimental design: supplemented with 7 g o f argin ine (ARG, n=12) or supplemented with 7g of placebo (PLA, n=12). The dietary supplement was co n sum e d at 3 0 minutes prior to a protocol of 10 sets of 10 maximum repetitions performed in the bench press. Measurements of thoracic circumference, delayed onset muscle soreness (DOMS) using visual an alo gue scale (VAS), and one-repetition maximum (1RM) at rest, 24h, 48h and 72h after the training session (TS). The data were analyzed by ANOVA-two way, followed by the Bonferroni test. DOMS presented a reater magnitude for PLA, in all moments evaluated after TS, compared to the ARG group (p<0.01). There was a greater decrease in the strength for PLA, at 72h after TS, compared to ARG (p<0 .05 ). The acute ARG supplementation seems to attenuate the magnitude of DOMS and accelerate recovery of strength...(AU)

Sodium citrate supplementation enhances tennis skill performance: a crossover, placebo-controlled, double blind study.

BACKGROUND: The efficacy of sodium citrate supplementation (SC) in exercise performance is unclear. Therefore, the aim of this study was to investigate the effect of SC on skilled tennis performance. METHODS: Ten Brazilian nationally-ranked young male tennis players (age: 17 ± 1 yrs.; stature: 176.7 ± 5.2 cm; body mass: 68.4 ± 7.9 kg) participated in this crossover, placebo-controlled, double-blind study. Upon arrival, at baseline, in both experimental sessions blood was collected, then subjects ingested either sodium citrate (SC - 0.5 g.kg-1BM in capsules of 500 mg) or a placebo (PLA). Two hours later, pre-match blood was collected then skills tests (skill tennis performance test - STPT, repeated-sprint ability shuttle test - RSA) were performed followed by a 1-h simulated match. Immediately following the match, blood was again collected, and STPT, and RSA were administered. RESULTS: All metabolic parameters (i.e. base excess, pH, bicarbonate, and blood lactate) increased (p < 0.001) from baseline to pre-match and post-match in SC condition. Each metabolic parameter was greater (p < 0.001) in SC compared to PLA condition at both pre- and post-match. The SC condition elicited a greater (p < 0.01) shot consistency at post-match in the STPT vs. PLA condition (SC: 58.5 ± 14.8% vs. PLA: 40.4 ± 10.4%). A greater (p < 0.001) amount of games won was observed in the simulated match for SC condition vs. PLA condition (SC: 8.0 ± 1.6 vs. PLA: 6.0 ± 1.7). Additionally, the games won during the simulated match in SC condition was positively correlated with percentage shot consistency (r = 0.67, p < 0.001). CONCLUSIONS: The current findings suggest that SC supplementation is an effective ergogenic aid to enhance skilled tennis performance.

Physiological Responses of Young Tennis Players to Training Drills and Simulated Match Play.

The aim of this study was to investigate the responses of young tennis players during 5 different training drills and to compare the responses between drills. Ten (17.0 ± 1.2 years) male tennis players participated in this study. Each athlete completed 5 total training drills. Drills 1-4 consisted of each player returning balls from a ball-serving machine and were stroke/time-controlled over 6 points. The fifth drill was a simulated match (SM) play, between 2 opposing players, and also lasted 6 points. The 4 stroke/time-controlled drills had the following strokes/time for each point: drill 1: 2 strokes/∼4 seconds, drill 2: 4 strokes/∼8 seconds, drill 3: 7 strokes/∼14 seconds, drill 4: 10 strokes/∼20 seconds. Peak heart rate (HR), blood lactate concentration (LA), and rating of perceived exertion (RPE) were measured after the first, third, and sixth point of each drill. Drills were performed in a randomized crossover design; a 2-way repeated-measures analysis of variance was used with significance set at p ≤ 0.05. All dependent variables (HR, LA, and RPE) significantly increased (p ≤ 0.05) as strokes, and time per rally increased in each drill. Furthermore, all variables were elevated to a greater magnitude (p ≤ 0.05) during the 7 and 10 stroke drills after the first, third, and sixth points when compared with the SM and the 2 and 4 stroke drills at the corresponding time points. These results suggest that the physiological responses to tennis training drills were stroke/time-dependent. Therefore, because of the intense intermittent nature of tennis, stroke/time-controlled drills, which require significant physiological demands, should be incorporated along with technically focused shorter drills to fully mimic the conditions of competitive match play.

Effect of carbohydrate supplementation on the physiological and perceptual responses to prolonged tennis match play.

Carbohydrate supplementation is a popular nutritional practice used in tennis to enhance physical capacities, motor-skill performance, and delay fatigue. However, the effects of carbohydrate supplementation on physiological and perceptual responses during tennis match play are not established. This double blind, randomized, placebo (PLA)-controlled crossover study was designed to determine the influence of carbohydrate supplementation (0.5 g·kg·h) on glycemia, salivary hormones (cortisol and testosterone) concentration, salivary immunoglobulin A (IgA) concentration, and rating of perceived exertion (RPE) during 3 hours of tennis match play in 12 well-trained tennis players. The only significant difference between the 2 conditions was a lower salivary cortisol concentration postmatch in the carbohydrate trial (p < 0.05); however, there was a trend for higher glucose concentration (p = 0.06) and lower session-RPE (p = 0.08) after tennis match play in the carbohydrate condition, which may have some practical implications. There was no change in salivary testosterone, salivary IgA, and RPE responses during tennis match play between conditions (p > 0.05). These data indicate that carbohydrate ingestion during 3 hours of competitive tennis match play helps to maintain glycemia and attenuates the increase in salivary cortisol concentration compared with PLA.