The effects of creatine ethyl ester supplementation combined with resistance training on body composition, muscle mass and performance, and intramuscular creatine uptake in males.

Includes bibliographical references (p. 108-112)Creatine monohydrate has become one of the most popular ingested nutritional supplements due to its potential enhancement of athletic performance. Creatine absorption from the serum into skeletal muscle occurs through the utilization of a membrane-spanning protein, CreaT1. Numerous creatine formulations have been developed primarily to maximize creatine absorption. Creatine ethyl ester (CEE) has been chemically modified by adding an ester group and is thought to increase creatine bio-availability by by-passing the CreaT1. This study examined how a seven week supplementation regimen with CEE affected body composition, muscle mass and performance, whole body creatine retention, as well physiological and molecular adaptations, associated with creatine uptake in nonresistance-trained males following a resistance-training program. Results demonstrated that CEE did not show any additional benefit to increases in muscle strength/performance or a significant increase in total muscle creatine when compared to creatine monohydrate or placebo. CEE supplementation did show a large increase in creatinine levels throughout the study.by Mike Spillane.M.S.Ed

Effects of lower- and higher- volume resistance exercise on serum testosterone and skeletal muscle androgen receptor content in men : subsequent effects on the mRNA expression of insulin- like growth factor peptide and myostatin in skeletal muscle.

Testosterone is the primary sex steroid hormone within males. Testosterone effects are ubiquitous and are categorized as either anabolic or androgenic. The androgen receptor is a specific nuclear hormone receptor through which testosterone elicits its effects. Specifically, skeletal muscle has androgen receptors present and is responsive to testosterone. The resulting activation of testosterone–androgen receptor–DNA binding increases muscle protein synthesis and reduces muscle protein breakdown. In addition, the testosterone level can alter the expression of insulin–like growth factor and myostatin which are key regulators of muscle protein balance. Higher-intensity resistance exercise in non-resistance-trained participants is known to increase endogenous serum testosterone levels. However, using resistance-trained participants the purpose of this study was to examine whether elevations in serum testosterone occur in response to a higher-intensity of resistance-exercise, and if this increase induces elevations in skeletal muscle testosterone, 5α-dihydrotestosterone (DHT), androgen receptor mRNA and protein content as well as possible interactions between muscle IGF-1 and myostatin mRNA expression. In a randomized cross-over design, venous blood was obtained in male participants immediately before and after, 30 minutes, 1 hour, 2 hours, 3 hours, and 24 hours after a single bout of resistance exercise. Muscle samples were obtained immediately before and after, 3 hours, 24 hours after exercise. Exercise bouts consisted of an upper-lower body (higher-volume) and lower-body (lower-volume) protocol. Each exercise bout was separated by one week of rest. Statistical analyses were performed by separate 2 x 7 and 2 x 4 (Session x Test) factorial analyses of variance (ANOVA) with repeated measures. The exercise protocol employed has previously been demonstrated to significantly increase serum testosterone. However, this study did not produce such a response. Neither exercise protocol significantly increased serum total or free testosterone (p > 0.05). Also, no changes were observed for muscle testosterone, DHT, androgen receptor mRNA expression or protein content (p > 0.05). In addition, no alterations in muscle IGF-1 or myostain were observed (p > 0.05). It was concluded that higher-intensity resistance exercise of the upper-body performed immediately prior to lower-body resistance exercise does not result in a significant elevation in testosterone in resistance-trained participants.Ph.D