ABSTRACT
The aim of this study was to evaluate the effect of caffeine intake on critical power model parameters determined on a cycle ergometer. Eight male subjects participated in this study. A double-blind protocol consisting of the intake of pure caffeine (6 mg/kg) or placebo (maltodextrin) 60 min before testing was used. Subjects were submitted to four constant-load tests on a cycle ergometer. These tests were conducted randomly in the caffeine and placebo groups [checar] at intensities of 80, 90, 100 and 110% maximum power at a rate of 70 rpm until exhaustion to determine the critical power. As a criterion for stopping the test was adopted any rate fall without recovery by more than five seconds. The critical power and anaerobic work capacity were obtained by nonlinear regression and fitting of the curve to a hyperbolic power-time model. The Shapiro-Wilk test and paired Student t-test were used for statistical analysis. No significant differences in critical power were observed between the caffeine and placebo groups (192.9 ± 31.3 vs 197.7 ± 29.4 W, respectively). The anaerobic work capacity was significantly higher in the caffeine group (20.1 ± 5.2 vs 16.3 ± 4.2 W, p<0.01). A high association (r2) was observed between the caffeine and placebo conditions (0.98 ± 0.02 and 0.99 ± 0.0, respectively). We conclude that caffeine intake did not improve critical power performance but increased anaerobic work capacity by influencing performance at loads of higher intensity and shorter duration.
The aim of this study was to evaluate the effect of caffeine intake on critical power model parameters determined on a cycle ergometer. Eight male subjects participated in this study. A double-blind protocol consisting of the intake of pure caffeine (6 mg/kg) or placebo (maltodextrin) 60 min before testing was used. Subjects were submitted to four constant-load tests on a cycle ergometer. These tests were conducted randomly in the caffeine and placebo groups [checar] at intensities of 80, 90, 100 and 110% maximum power at a rate of 70 rpm until exhaustion to determine the critical power. As a criterion for stopping the test was adopted any rate fall without recovery by more than five seconds. The critical power and anaerobic work capacity were obtained by nonlinear regression and fitting of the curve to a hyperbolic power-time model. The Shapiro-Wilk test and paired Student t-test were used for statistical analysis. No significant differences in critical power were observed between the caffeine and placebo groups (192.9 ± 31.3 vs 197.7 ± 29.4 W, respectively). The anaerobic work capacity was significantly higher in the caffeine group (20.1 ± 5.2 vs 16.3 ± 4.2 W, p<0.01). A high association (r2) was observed between the caffeine and placebo conditions (0.98 ± 0.02 and 0.99 ± 0.0, respectively). We conclude that caffeine intake did not improve critical power performance but increased anaerobic work capacity by influencing performance at loads of higher intensity and shorter duration.
ABSTRACT
Neste artigo, os autores pretendem construir o perfil de consumo de creatina em fisiculturistas de Vitória da Conquista-BA. Para tal, fez-se 100 entrevistas em centros de fitness durante 2007 O entrevistado foram choiced aleatoriamente entre os usuários de creatina. Observou-se uma média de 24,41 (± 3,87) anos, cuja maioria era homens (96%) que praticavam força treinamento semanal por 5 ou mais dias (82%), como a única atividade (74%). A maioria dos entrevistados pessoas usaram creatina por 3 meses (62%). Auto prescrição foi relacionado por 52%, seguido por amigos indicação (18%). Kinesiologists e instrutor de fitness foram os mais responsáveis (16%) para a prescrição suplementar. Alguns entrevistados (6%) relacionados ter sido guiado por produtos farmacêuticos ou médicos e nenhum foi orientada por um nutricionista. Apesar da existência de orientação nutricional, 57% disseram que mantiveram uma dieta equilibrada. Aumenta a resistência era apontada como a principal razão para o uso suplementar (45%), seguida por motivos estéticos (36%). Cinqüenta e nove por cento disseram ter ganho de massa muscular. A creatina foi associada a outras suplementos de aminoácidos, principalmente proteínas, e em 60% dos casos, com o ganho de massa muscular relativamente (RR 1,52; IC 95% 1,03 ≤ μ ≤ 2,23, p = 0,02). Era evidente que o consumo de creatina bem como suplementos associados foi feita sem prescrição profissional, com estética e objectivos de resistência.
In this article, the authors intended to build up creatine consumption profile in bodybuilders from Vitória da Conquista-BA. For such, it was made 100 interviews in fitness centers during 2007. The interviewed were randomly choiced among creatine users. It was observed an average of 24.41 (±3.87) years, whose majority was men (96%) that practiced strength training weekly for 5 or more days (82%), as the only activity (74%). Most of the interviewed people used creatine for 3 months (62%). Self prescription was related for 52%, followed by friends indication (18%). Kinesiologists and fitness instructor were the most responsible (16%) for supplemental prescription. Some interviewed (6%) related to have been guided by pharmaceuticals or doctors and none were oriented by a nutritionist. Despite the existence of nutritional orientation, 57% said that maintained a balanced diet. Resistance enhances was pointed out as the main reason for supplemental use (45%), followed by esthetical reasons (36%). Fifty nine per cent said to have muscle mass gain. Creatine was associated to other supplements, mainly aminoacids and proteins, in 60% cases, with muscle mass gain relation (RR 1.52; IC 95% 1.03 ≤ µ ≤ 2.23; p=0.02). It was evident that creatine consumption as well as associated supplements was made without professional prescription, with esthetical and resistance objectives.