The effects of creatine supplementation on muscular performance and body composition responses to short-term resistance training overreaching

Abstract

To determine the effects of creatine supplementation during short-term resistance training overreaching on performance, body composition, and resting hormone concentrations, 17 men were randomly assigned to supplement with 0.3 g/kg per day of creatine monohydrate (CrM: n=9) or placebo (P: n=8) while performing resistance exercise (5 days/week for 4 weeks) followed by a 2-week taper phase. Maximal squat and bench press and explosive power in the bench press were reduced during the initial weeks of training in P but not CrM. Explosive power in the bench press, body mass, and lean body mass (LBM) in the legs were augmented to a greater extent in CrM ( P<or=0.05) by the end of the 6-week period. A tendency for greater 1-RM squat improvement ( P=0.09) was also observed in CrM. Total testosterone (TT) and the free androgen index (TT/SHBG) decreased in CrM and P, reaching a nadir at week 3, whereas sex hormone binding globulin (SHBG) responded in an opposite direction. Cortisol significantly increased after week 1 in CrM (+29%), and returned to baseline at week 2. Insulin was significantly depressed at week 1 (-24%) and drifted back toward baseline during weeks 2-4. Growth hormone and IGF-I levels were not affected. Therefore, some measures of muscular performance and body composition are enhanced to a greater extent following the rebound phase of short-term resistance training overreaching with creatine supplementation and these changes are not related to changes in circulating hormone concentrations obtained in the resting, postabsorptive state. In addition, creatine supplementation appears to be effective for maintaining muscular performance during the initial phase of high-volume resistance training overreaching that otherwise results in small performance decrements.

The effects of creatine supplementation on thermoregulation and physical (cognitive) performance: a review and future prospects

“…1915;Hunter 1922). Cr supplementation has been reported to improve physical performance during a variety of different exercise modalities, intensities and durations and to promote greater gains in strength, muscle mass, bone mineral density and neuromuscular function in populations ranging from trained healthy individuals to the elderly with sarcopenia undergoing exercise rehabilitation (Bosco et al 1997;Grindstaff et al 1997;Mihic et al 2000;Metzl et al 2001;Mihic et al 2000;Hespel et al 2001;Volek et al 2004;Pearlman and Fielding, 2006;Bazzucchi et al 2009;Bemben et al 2010;Devries and Phillips, 2014;Gualano et al 2011;Gualano et al 2014;Candow et al 2015;Chillibeck et al, 2015;Griffen C et al 2015;Martone et al 2015;Ramirez-Campilo et al, 2015;Wilkinson et al 2015, Phillips, 2015 (see Table 1). The mechanism(s) responsible for these effects range from Cr-induced increases in intramuscular phosphocreatine (PCr) levels and the PCr/ATP energy charge ratio, as well as a greater resynthesis rate of PCr following intense exercise, leading to a higher efficiency of ATP utilisation (Wallimann et al 2011) and to attenuated cardiovascular and thermoregulatory responses during prolonged exercise in the heat (Demant and Rhodes, 1999;Terjung et al 2000;Lopez et al 2009).…”

Effect of supplementation of guanidinoacetic acid and arginine in vegetable diets for broiler on performance, carcass yield and meat quality

“…Some studies have demonstrated positive effects (VOLEK; BRANCH, 1998;VOLEK et al, 2004;RINGEL et al, 2008;DILGER et al, 2013), while others did not observe changes (LOUIS et al, 2003). A study developed by the EFSA Journal (2009) with 1-to 42-dayold broilers, using a pelleted vegetable diet (corn/ wheat/soybean meal), supplemented with 0 to 800 continuation mg GAA per kg of diet, improved weight gain with supplementation of between 400 and 800 mg kg -1 , while feed conversion was significantly improved from 400 mg kg -1 .…”

High-intensity exercise and recovery during short-term supplementation with creatine plus a protein-carbohydrate formula

“…It has been reported that there are benefits to enhancing the skeletal muscle store of creatine. These include improved maintenance of maximal power outputs, 1,2,4,5,17,18,31 more rapid recovery from high-intensity exercise, 14,15,27,35,36 and diminished post-exercise muscular pain. 35,36 Creatine supplementation in combination with high-intensity exercise training has been shown to improve short-term power output, and is reportedly most beneficial for maximising repeated high-intensity work performance.…”