Creatine supplementation increases muscle total creatine but not maximal intermittent exercise performance

Abstract

This study investigated creatine supplementation (CrS) effects on muscle total creatine (TCr), creatine phosphate (CrP), and intermittent sprinting performance by using a design incorporating the time course of the initial increase and subsequent washout period of muscle TCr. Two groups of seven volunteers ingested either creatine [Cr; 6 x (5 g Cr-H(2)O + 5 g dextrose)/day)] or a placebo (6 x 5 g dextrose/day) over 5 days. Five 10-s maximal cycle ergometer sprints with rest intervals of 180, 50, 20, and 20 s and a resting vastus lateralis biopsy were conducted before and 0, 2, and 4 wk after placebo or CrS. Resting muscle TCr, CrP, and Cr were unchanged after the placebo but were increased (P < 0.05) at 0 [by 22.9 +/- 4.2, 8.9 +/- 1.9, and 14.0 +/- 3.3 (SE) mmol/kg dry mass, respectively] and 2 but not 4 wk after CrS. An apparent placebo main effect of increased peak power and cumulative work was found after placebo and CrS, but no treatment (CrS) main effect was found on either variable. Thus, despite the rise and washout of muscle TCr and CrP, maximal intermittent sprinting performance was unchanged by CrS.

Genetic parameters for carnitine, creatine, creatinine, carnosine, and anserine concentration in longissimus muscle and their association with palatability traits in Angus cattle1

“…Creatine is important to muscle energy metabolism and, under certain circumstances, creatine supplements can enhance muscle performance (Demant and Rhodes, 1999;McKenna et al, 1999). Based on data presented in the present study, a typical serving (100 g) of beef would provide an average of 526 mg of creatine.…”

The effects of different doses of oral creatine supplementation on tibial muscle resistence and fatigue in wistar rats

“…This information points to the influence of physical activity in the utilization of energetic substrates and their routes for degradation, differently from what is demonstrated in the isolated supplementation that increases the performance of high intensity activities. Cr supplemented volunteers did not present effects when they did not practice exercises, in the maximum potency peak or in resistance to fatigue in 5 sessions of 10 seconds of intermittent maximum exercise on a stationary bicycle (McKENNA et al, 1999). This highlights that exercise acts in ways which are not yet clear, over the improvement of the utilization and resynthesis of energetic substrates in the Cr supplemented groups.…”

Efectos de la ingestión de creatinina en la composición corporal y en la performance del ejercicio supino

“…Huso (2002), también utilizando una dosifi cación de 20 gramos diarios por cinco días y una dosis de manutención (dos gramos por 17 días) obtuvo un aumento de 1,6 Kg en la MCT. Utilizando una dosifi cación más elevada (30 gramos diarios por 4 semanas) Mckenna (1999) obtuvo un aumento de 2 kg en la MCT. El aumento en la MCT registrado en la presente investigación fue debido a un incremento en la masa delgada y este parece no estar asociado a la hipertrofi a muscular, pues segunda Hacha (2002) la Cr es una sustancia osmoticamente activa, y un aumento en la sileño que ingirieron durante cinco días consecutivos la cantidad de 20 gramos diarias de Cr.…”