Caffeine counteracts the ergogenic action of muscle creatine loading

Abstract

This study aimed to compare the effects of oral creatine (Cr) supplementation with creatine supplementation in combination with caffeine (Cr+C) on muscle phosphocreatine (PCr) level and performance in healthy male volunteers (n = 9). Before and after 6 days of placebo, Cr (0.5 g x kg-1 x day-1), or Cr (0.5 g x kg-1 x day-1) + C (5 mg x kg-1 x day-1) supplementation, 31P-nuclear magnetic resonance spectroscopy of the gastrocnemius muscle and a maximal intermittent exercise fatigue test of the knee extensors on an isokinetic dynamometer were performed. The exercise consisted of three consecutive maximal isometric contractions and three interval series of 90, 80, and 50 maximal voluntary contractions performed with a rest interval of 2 min between the series. Muscle ATP concentration remained constant over the three experimental conditions. Cr and Cr+C increased (P < 0.05) muscle PCr concentration by 4-6%. Dynamic torque production, however, was increased by 10-23% (P < 0.05) by Cr but was not changed by Cr+C. Torque improvement during Cr was most prominent immediately after the 2-min rest between the exercise bouts. The data show that Cr supplementation elevates muscle PCr concentration and markedly improves performance during intense intermittent exercise. This ergogenic effect, however, is completely eliminated by caffeine intake.

Contractile properties, fatigue and recovery are not influenced by short-term creatine supplementation in human muscle

“…Changes in daily physical activity (Robinson et al 1999) as well as caffeine consumption were controlled during the course of the study by urging participants to maintain their normal daily activities, dissolve the powdered substance in non-caffeinated beverages, and abstain from caffeine for 1 h prior to neuromuscular testing. It has been reported that caffeine alters contractile properties (Fryer & Neering, 1989;Nehlig & Debry, 1994) and may decrease Cr uptake (Vandenberghe et al 1996). Exclusion criteria involved creatine supplementation within the previous 12 months, myopathies or neuromyopathies, diabetes, alcoholism and physical activity patterns which were deemed to represent highly trained men.…”

“…Most studies report an increase in isotonic dynamic strength following Cr supplementation (Earnest et al 1995;Gordon et al 1995;Vandenberghe et al 1996), but the few studies of isometric strength are controversial. Our results of isometric elbow flexion strength are similar to those of van Leemputte et al (1999).…”

“…Most of the reports suggest that Cr supplementation enhances exercise performance (Balsom et al 1993;Greenhaff et al 1993Greenhaff et al , 1994Birch et al 1994;Earnest et al 1995;Prevost et al 1997;Maganaris & Maughan, 1998), although a number of studies have shown no effect (Febbraio et al 1995;Redondo et al 1996;Vandenberghe et al 1996). In part, it seems the disparity in the findings occurs because of differences in the exercise model employed, or the intensity, duration, and frequency of the task, and the level of fitness of the subjects.…”

Desempenho da potência anaeróbia em atletas de elite do mountain bike submetidos à suplementação aguda com creatina

“…Todos os atletas foram orientados a manter seus hábitos alimentares e rotina de treinos durante o período de suplementação, evitando qualquer outra e bebidas cafeinadas (café, chocolate, mate, pó de guaraná, bebidas energéticas, coca-cola e guaraná), uma vez que a cafeína parece anular o efeito da creatina (9) . A ingestão de água foi ad libitum.…”

Cafeína e esporte

“…Vandenberghe et al 28 , em um estudo comparativo entre os efeitos da suplementação oral de creatina e de creatina em combinação com cafeína, de-monstrou que os efeitos ergogênicos da creatina no aumento da força, durante a execução de exercícios intensos realizados de modo intermitente, foram eliminados no grupo que ingeriu também a cafeína.…”