Creatine-monohydrate (CrM) supplementation has been shown to increase body mass and fat-free mass (FFM), however, the mechanism by which CrM affects body composition has not been determined. We investigated the effects of short-term CrM supplementation on whole-body protein turnover in 27 recreationally active male and female volunteers. Subjects underwent measurements prior to and following 9-10 days of CrM (20 g/d x 5 d, 5 g/d x 4-5 d) (n =14), or placebo (PL) (n =13) supplementation. Protein turnover was assessed using L-[1-¹³C] leucine stable isotope tracer, urinary urea nitrogen (N) excretion, and N-balance (Nbal) techniques. Total body mass (TBM), leucine flux, leucine oxidation, non-oxidative leucine disposal (NOLD), 24-hr urinary urea N excretion, and Nbal were determined before and after treatment. Additionally, the effects of CrM supplementation on renal function and metabolite clearance were evaluated by measuring creatinine (CTN) excretion, plasma CTN concentration, and CTN clearance. There was no effect for CrM as compared to PL on TBM, leucine flux, leucine oxidation, or NOLD. However, leucine oxidation was lower for the CrM-treated males as compared to the PL-treated males following supplementation (P < 0.05). Leucine flux and NOLD were higher for the males vs. the females (P < 0.05). Neither urinary urea N excretion nor Nbal were affected by treatment. Plasma [CTN], CTN excretion, and CTN clearance were also unchanged for CrM vs. PL. These findings suggested that CrM supplementation may have an effect upon leucine oxidation in males, yet there were no effects seen in females, nor were other indices of leucine turnover altered by CrM supplementation. Furthermore, short-term CrM supplementation did not have any adverse effects on renal function. / Thesis / Master of Science (MSc)

Background & Rationale: During high intensity muscle contractions phosphocreatine is enzymatically degraded by creatine kinase (CK) to form creatine and the free energy which is released used to phosphorylate ADP to ATP. Creatine is then rephosphorylated during periods of relative ATP abundance (ie. rest) by CK back to phosphocreatine. Recognition of the importance of the phosphocreatine system to energy transduction has led many to believe that creatine monohydrate supplementation, which may lead to increases in phosptocreatine (PCr), may be beneficial during high intensity exercise. Several studies have demonstrated that creatine monohydrate supplementation for as few as three days can result in significant performance gains during exercise such as sprinting, or a weight lifting program. A common observation during these studies is a 1-2 kg increase in lean body mass (LBM). Although most researchers have speculated that this increase in LBM is due to water retention, some 𝘪𝘯 𝘷𝘪𝘵𝘳𝘰 work has demonstrated that creatine may stimulate protein synthesis. The purpose of this investigation was to examine whether a loading dose of creatine (20g/d x 7d) would have any affect on mixed muscle protein synthesis (MPS) in resting human skeletal muscle. Methods: A total of 22 young healthy subjects (n = 11 male, n = 11 female) were included in the study. On the day of measurement, subjects were provided with a meat free pre-packaged diet that was based upon individual diet records. Measurements of mixed muscle protein fractional synthetic rate (FSR) were completed over a 14 h resting period using a primed constant infusion of L[1-¹³C]leucine and muscle biopsies of 𝘲𝘶𝘢𝘥𝘳𝘪𝘤𝘦𝘱𝘴 𝘧𝘦𝘮𝘰𝘳𝘪𝘴 at isotopic plateau. Subjects were then randomly assigned to either a creatine (20g/d x 7d) or a placebo (isoenergetic glucose polymer) group. Following 7 days of supplementation, subjects reported to the lab under the same conditions as in the pre-trial, and resting mixed muscle protein FSR was again determined. Results: There were no significant between group differences in the baseline subject characteristics. No significant difference in FSR was observed with regards to condition (Pl: pre-0.63 ± 0.02 %/h; pst-0.71 ± 0.016 %/h; Cr: pre-0.56 ± 0.02 %/h; pst-0.58 ± 0.023 %/h) (creatine supplementation), time, or gender (Males: pre-0.06 ± 0.02 %/h; pst-0.068 ± 0.023 %/h; Females: pre-0.057 ± 0.02 %/h; pst-0.058 ± 0.015 %/h) Creatine supplementation resulted in a 13.1% increase in total creatine, however, no significant increases; in PCr or free Cr were observed. Similarly, no significant increases for fat free mass (FFM), or total mass were observed. Conclusion: It is concluded that creatine monohydrate supplementation for 7 d at 20g/d significantly increases muscle total creatine concentration, however, does not significantly affect muscle protein FSR in males or females. / Thesis / Master of Science (MSc)

The purpose of this thesis was to determine ways to maximize creatine uptake and retention during creatine supplementation. Since there are many factors that affect muscle creatine concentrations, a series of studies were performed. In the first study, the purpose was to determine if á-lipoic acid aided creatine uptake and retention. It was hypothesized that á-lipoic acid would increase creatine uptake, because it has been found to increase glucose disposal in animal studies and because creatine uptake has been found to be related to increased glucose transport. Results showed that phosphocreatine and total creatine increased following supplement intervention. In the second study, the purpose was to develop an optimal dose of creatine in order to minimize urinary excretion of creatine. It was hypothesized that individuals with more lean tissue mass would excrete less urinary creatine during consumption of the same loading dose. There was a high negative correlation between lean tissue mass and urine creatine excretion. Regression equations were developed for the relationship between lean tissue mass and urine total creatine and used to determine the amount of creatine to ingest relative to lean tissue mass that would result in minimal creatine losses in urine. Based on these results, a creatine dose of 0.22 [right arrow] 0.25 g/kg lean tissue mass/d was recommended. In the third study, the purpose was to determine if a habitual vegetarian diet resulted in lower muscle creatine and phosphocreatine concentrations compared to an omnivorous diet. A secondary purpose was to determine if creatine supplementation and weight training resulted in greater increases in muscle metabolite content, muscle fiber area, lean tissue mass, and strength in vegetarians compared to non-vegetarians. Results indicated that vegetarians had lower resting total creatine concentration, and that creatine supplementation and weight training led to greater increases in muscle phosphocreatine and total creatine in vegetarians compared to non-vegetarians (p < 0.0125). The supplement and exercise intervention eliminated the differences in intramuscular total creatine concentration that existed prior to the study. Type II muscle fiber area, lean tissue mass, total work output, and 1-RM bench press increased to a greater extent following creatine supplementation compared to placebo supplementation (p < 0.017), with no difference between vegetarians and non-vegetarians. (Abstract shortened by UMI.)

Introduction: Creatine is a nitrogen-containing compound that is found in many supplements that claim to increase muscle mass and there is increasing evidence that creatine supplementation can increase muscle mass in older individuals. Purpose: To evaluate the safety of 12-months creatine supplementation and resistance exercise in older adults by monitoring measures of kidney and liver function, complete blood count, and reports of adverse events. Methods: Older adults (n=70, males 50 years of age or older (39), and post-menopausal females (31) who were not performing resistance exercise were recruited for the study and randomized by computer to creatine (32; 18 males, 14 females) or placebo (38; 21 males, 17 females) groups. Other exclusionary criteria were: presence/history or kidney impairments, consumption of creatine supplement/bone altering drugs, and the presence of fragility fractures. Participants were given creatine or placebo (0.1g/kg/day) consumed before and after resistance training on exercise days and with a meal on non-exercise days. The study used a double-blind, placebo-controlled design. Blood and urine were collected to assess complete blood cell count, liver function indicators (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and Bilirubin), and creatinine clearance (kidney function) at baseline, 4 months, 8 months, and 12 months. A mixed ANOVA was used to determine differences in the kidney and liver measures within and between groups, and chi-square analysis was used to determine if the frequency counts for liver, kidney, and other adverse events were different between groups.

Thesis (M.S.Ed.)--Baylor University, 2008. / Includes bibliographical references (p. 108-112)

Thesis (M.S.)--Florida State University, 2005. / Advisor: Dr. Ross Ellington, Florida State University, College of Arts and Sciences, Dept. of Biological Science. Title and description from dissertation home page (viewed June 8, 2005). Document formatted into pages; contains xiii, 55 pages. Includes bibliographical references.

Thesis (M.S.)--Springfield College, 2002. / Includes bibliographical references.

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Faculty of Health Sciences Master of Science in Medicine 0204267n / Creatine is one of the most frequently or generally used ergogenic substances. It is used by professional and amateur athletes and the “man on the street”. Creatine is involved in energy production and protein synthesis in muscle. Although studies have been carried out on the effect of creatine on adults, no study has yet determined whether creatine would have an influence on the developing rat foetus if taken by a female during pregnancy. The aim of this study was thus to determine whether creatine had an effect on the developing foetus. Dams were divided into two groups, which we re injected between days 7-13 and on days 9 and 11 only of intra-uterine development respectively. Each group was subdivided into a control and two experimental groups. Experimental group one received a low dose of creatine (53.5mg/250g body weight); the other experimental group received a high dose of creatine (107mg/250g body weight). The control group received an equal volume (1ml) of the vehicle (saline) in which the creatine was constituted. Dams were sacrificed on day 20 of development. The foetuses were removed and their weight and length taken. Foetuses were examined for abnormalities. Two foetuses from each litter underwent skeletal staining. Tissue was excised from the remaining foetuses and processed for histology for histological investigation. Creatine positively affected the growth of the foetuses of dams injected between days 7-13, while foetuses of dams injected only on days 9 and 11 in the B-group showed reduced growth. Creatine also had a slightly negative effect on the histological structure of the liver, but enhanced skeletal muscle growth, endocrine cell formation (pancreas) and skeletal formation. From the results obtained it is hypothesized that creatine and insulin together may play a positive role from implantation to birth, while creatine given at certain stages of organogenesis delayed development of the foetus.