The aim of the present study was to investigate whether children showed similar signs of muscle overuse like adults after intense exercise. One child group (n = 10) and one adult group (n = 10) of males both had to perform five series of bench press exercises at an intensity of 80% of maximum strength until exhaustion. Maximum isometric strength, subjective perception of muscle pain, was measured before, immediately after, 48 hr, 72 hr, and 1 week after the exercise. Serum creatine kinase (CK) activity was measured before, 48 hr, 72 hr, and 1 week after the exercise. The adults showed all symptoms of muscle overuse: reduced strength, muscle pain, and elevated CK activities until 3 days after the exercise. In contrast, the children experienced only some light muscle pain, but neither showed reduced strength nor elevated CK activities. It is concluded that children’s muscles can easier withstand physical stress than adult muscles.
José M.C. Soares, Paulo Mota, José A. Duarte and Hans J. Appell
Gabriel Machado Claus, Paulo Eduardo Redkva, Gabriel Mota Pinheiro Brisola, Elvis Sousa Malta, Rodrigo de Araujo Bonetti de Poli, Willian Eiji Miyagi and Alessandro Moura Zagatto
The purpose of this study was to investigate the effects of beta–alanine supplementation on specific tests for water polo. Fifteen young water polo players (16 ± 2 years) underwent a 200-m swimming performance, repeated-sprint ability test (RSA) with free throw (shooting), and 30-s maximal tethered eggbeater kicks. Participants were randomly allocated into two groups (placebo × beta-alanine) and supplemented with 6.4g∙day-1of beta-alanine or a placebo for six weeks. The mean and total RSA times, the magnitude based inference analysis showed a likely beneficial effect for beta-alanine supplementation (both). The ball velocity measured in the throwing performance after each sprint in the RSA presented a very like beneficial inference in the beta-alanine group for mean (96.4%) and percentage decrement of ball velocity (92.5%, likely beneficial). Furthermore, the percentage change for mean ball velocity was different between groups (beta-alanine=+2.5% and placebo=-3.5%; p = .034). In the 30-s maximal tethered eggbeater kicks the placebo group presented decreased peak force, mean force, and fatigue index, while the beta-alanine group maintained performance in mean force (44.1%, possibly beneficial), only presenting decreases in peak force. The 200-m swimming performance showed a possibly beneficial effect (68.7%). Six weeks of beta-alanine supplementation was effective for improving ball velocity shooting in the RSA, maintaining performance in the 30-s test, and providing possibly beneficial effects in the 200-m swimming performance.