Academic literature on the topic 'Oral creatine monohydrate'

Abstract We report the case of a renal transplant recipient presenting with elevated serum creatinine levels whilst taking oral creatine ethyl ester (CEE), but not creatine monohydrate (CM). Standard investigations for allograft dysfunction, including Doppler ultrasound and renal biopsy, were normal. Serum creatinine normalized following cessation of the supplement. CM is poorly absorbed and does not affect creatinine. In contrast, CEE is converted and absorbed as creatinine, elevating serum levels. In such cases, creatinine is not a valid surrogate for glomerular filtration rate (GFR). Alternate methods of GFR measurement should be considered and a rigorous clinical and drug history taken.

The effect of oral creatine supplementation on brain metabolite concentrations was investigated in gray matter, white matter, cerebellum, and thalamus of healthy young volunteers by means of quantitative localized proton magnetic resonance spectroscopy in vivo (2.0 T, stimulated echo acquisition mode sequence; repetition time = 6,000 ms, echo time = 20 ms, middle interval = 10 ms, automated spectral evaluation). Oral consumption of 4 × 5 g creatine-monohydrate/day for 4 wk yielded a statistically significant increase (8.7% corresponding to 0.6 mM, P < 0.001) of the mean concentration of total creatine (tCr) when averaged across brain regions and subjects ( n = 6). The data revealed considerable intersubject variability (3.5–13.3%), with the smallest increases observed for the two male volunteers with the largest body weights. A regional analysis resulted in significant increases of tCr in gray matter (4.7%), white matter (11.5%), and cerebellum (5.4%) and was most pronounced in thalamus (14.6% corresponding to 1.0 mM). Other findings were significant decreases of N-acetyl-containing compounds in cerebellum and thalamus as well as of choline-containing compounds in thalamus. All cerebral metabolic alterations caused by oral Cr were reversible, as evidenced by control measurements at least 3 mo after the diet. This work demonstrates that excess consumption of Cr yields regionally dependent increases of the tCr concentration in human brain over periods of several weeks.

Creatine supplementation has been shown to augment muscle PCr content and increase the rate of ATP resynthesis. Thus, we hypothesized that creatine supplementation might enhance sprinting performance. Eighteen subjects completed both of two testingsessions(control and postsupplement) 1 week apart, wherein they sprinted three 60-m distancetrialsthat were recorded with videotape. Following the control session, for 7 days, subjects in the treatmentgroupingested a creatine-glucose mixture, while the placebogroupconsumed a glucose powder, followed by the postsupplementation session. Velocities of the subjects through three testingzoneswithin the 60-m sprint were calculated from the videotape. Resultant velocities were analyzed using a MANOVA with a2x2x3x3 (Group x Session x Trial x Zone) design. Results indicated that there were no statistically significant main or interaction effects on velocity between groups for session, trial, or zone. These data do not support the hypothesis that supplementary creatine ingestion will enhance velocity during the early or latter segments of a 60-m sprint.

The purpose of this investigation was to examine the effects of preceding oral creatine monohydrate with a lacto-ovo-vegetarian diet on muscle creatine concentration. Thirty-two healthy men, who regularly consumed an omnivorous diet, were randomly assigned to consume a weight maintaining, lacto-ovo-vegetarian (LOV; n = 16) or omnivorous (Omni; n = 16) diet for 26 days. In addition to their assigned diet, on day 22 of the study, subjects were assigned in a double-blind manner to receive either creatine monohydrate (CM; 0.3 g · kg · d−1 + 20 g Polycose) or an equivalent dose of placebo (PL) for 5 days. There were no significant differences between the LOV and Omni groups at baseline with respect to age, height, and weight. The results demonstrated that consuming a LOV diet for 21 days was an effective procedure to decrease muscle creatine concentration (p < .01) in individuals who normally consume meat and fish in their diet. However, muscle total creatine (TCr) following creatine supplementation did not differ statistically between LOV and Omni diet groups (148.6 ± 4.5 vs. 141.7 ± 4.5 mmol · kg−1 d.m.).

Purpose:We examined the effects of creatine supplementation on the response to repeated bouts of resistance exercise.Methods:Young men (24.1 ± 5.2 yr) were divided into Creatine (CM, n = 9) and Placebo (PL, n = 9) groups. On day (D) 1 and D15, subjects performed four sets of bicep curls at 75% 1-RM to concentric failure. On D8-D13, subjects consumed either 20g/d creatine monohydrate or placebo. Muscle soreness and elbow joint range of motion (ROM) were assessed on D1-D5 and D15-D19. Serum creatine kinase activity (CK) was assessed on D1, D3, D5, D15, D17, and D19.Results:The first exercise bout produced increases in muscle soreness and CK, and decreases in ROM in both groups (p < .001). The second bout produced lesser rises in serum CK, muscle soreness, and a lesser decrease in ROM (bout effect, p < .01 for all), with greater attenuation of these damage markers in CM than PL. CK levels on D17 were lower (+110% over D15 for CM vs. +343% for PL), muscle soreness from D15–19 was lower (–75% for CM vs. –56% for PL compared with first bout), and elbow ROM was decreased in PL, but not CM on D16 (p < .05 for all).Conclusions:Creatine supplementation provides an additive effect on blunting the rise of muscle damage markers following a repeated bout of resistance exercise. The mechanism by which creatine augments the repeated bout effect is unknown but is likely due to a combination of creatine’s multifaceted functions.

Phosphorus‒31 saturation‒transfer NMR spectroscopy provides an elegant means to study fluxes through the creatine kinase reaction in human skeletal muscle. To obtain reliable quantitative kinetic information, experimental imperfections, such as incomplete saturation and radiofrequency bleed over need to be addressed appropriately. In resting muscle, creatine kinase was near equilibrium both in normal controls and in a patient with impaired oxidative phosphorylation. Oral intake of high doses of creatine monohydrate for several days resulted in significantly increased concentrations of phosphocreatine but had no measurable effect on the phosphocreatine resynthesis rate in resting muscle.

碩士
中國文化大學
運動教練研究所
90
The purpose of this study was to investigate effects of 4-wk resistance training and oral creatine monohydrate supplementation on dynamic muscular strength and self-health assessment of college women. Thirty collegiate women were randomly assigned to a treatment (OR, N=10), placebo (R, N=10), or control group (C, N=10). Both of the OR group and the R group trained 4 weeks of resistance training. During the period of resistance training, the OR group ingested 3 g‧d-1 of creatine monohydrate, the R group ingested 3 g‧d-1 of placebo, and the C group without ingesting any nutrition supplementation. Subjects were measured the dynamic muscular strength and wrote down the questionnaire--- “ self- health assessment of college students” before and after the experiment. All the data of the measurement were treated by the t-test and One-Way ANOVA statistics. The study indicated the 1 RM muscular strength of leg press, bench press, and leg extension will obviously increase in the OR and R group. However, in C group, there is no difference. As for the part of the questionnaire--- “ self- health assessment of college students”, the resistance training might affect the status of self-health and sleep--- the day to sleep 7 to 8 hours a day would increase with the supplementation of the oral creatine monohydrate. The study suggested that the resistance training of three day a week for 4 weeks would increase 1-RM muscular strength and the status of health. Key word: college women, resistance training, oral creatine monohydrate, dynamic muscular strength, self-health assessment.

Two studies were conducted to examine the effect of oral creatine monohydrate supplementation on prolonged high-intensity intermittent exercise that simulated team sport play. Study 1 aimed at developing and validating a team sport play simulation. An activity profile representative of team sport play was developed. The activity profile was based on a number of time and motion studies of various sports including soccer, rugby union, basketball and Australian rules football. The activity profile was based around a 15 min protocol comprised of standing still, walking, jogging, running, fast running and sprinting. Each movement category speed was based on a percentage of the participant's peak sprinting speed. There were 94 changes in speed with a mean change in speed every 9.6 s during the 15 min activity profile. These changes in speed included three 3 s sprints and three 6 s sprints throughout the 15 min activity profile. The 15 min activity profile was repeated three times (45 min), followed by a 15 min break, followed by another three 15 min periods (45 min) for a total work duration of 90 min. The team sport play simulation was conducted on a non-motorised treadmill to allow participants to sprint more effectively than on a motorized treadmill and also allow changes in sprint speed to be measured. A Woodway non-motorised treadmill was instrumented to allow the measurement of force, power, speed and distance. Measures of oxygen uptake, heart rate, blood lactate and RPE were also collected. Five participants covered a mean distance of 10196 ± 403 m over the 90 min protocol, which is within the values typically observed during team sport play (Reilly, 1994). Heart rate and oxygen uptake throughout the protocol averaged 170 b·min⁻¹and 74% Vo₂max respectively, which compare favourably to actual match-play (Bangsbo, 1994). Blood lactate concentration averaged 8.7 mmol·L⁻¹over the course of the simulation, which is somewhat higher than previously reported during actual match play (Reilly and Doran, 2001). Peak sprint speed declined significantly from 24.9 ± 0.9 km·h⁻¹in the first half to 23.6 ± 0.7 km·h⁻¹in the second half. While no previous studies have reported the changes in peak sprint speed during team sport play, Bangsbo (1994) reported that mean 20 m sprint speed declined by 2.3% in soccer players following a match. The team sport play simulation was found to have acceptable reliability (coefficient of variation) for the total distance covered (2.2%) and peak sprint speed (4.1% and 3.5% for the 3 s and 6 s sprints, respectively). However, peak sprint power was found to be an unreliable measure with a coefficient of variation of 8.8% for the 3 s sprints and 10.2% for the 6 s sprints. The results of Study 1 strongly suggest that the treadmill protocol effectively recreated the movement patterns and physiological responses to team sport play and therefore demonstrated both logical and criterion validity. Study 2 extended the validated treadmill protocol to the examination of the effect of oral creatine monohydrate supplementation for team sport play. Twelve participants completed the protocol following either five days of oral creatine monohydrate supplementation or placebo supplementation. Participants allocated to the creatine group were required to supplement their normal diet with creatine monohydrate (Creatine Plus, Sport-Test, Australia) at a rate of 20 g·day⁻¹. Participants were required to consume 5 g of creatine monohydrate plus 1 g of glucose four times per day. Muscle biopsies were performed prior to and following each simulation. Muscle samples were analysed for glycogen, phosphocreatine, ATP, free creatine, total adenine nucleotides and lactate. There were no significant differences between the creatine and placebo groups for the performance measures of total distance covered, mean peak sprint speed or sprint distance. There were also no significant differences between the groups for any of the physiological measures including heart rate, oxygen uptake, plasma lactate, RPE, body mass and plasma uric acid. While the results suggest that creatine-loading does not enhance team sport play performance, there was no significant difference in total muscle creatine concentration between the treatment and placebo groups prior to the team sport play simulation. There were a number of limitations in the design of the present study, such as the lack of a presupplementation muscle biopsy and a small sample size that have reduced the value of the present study. Consequently, no conclusions regarding the efficacy of creatine supplementation for team sport players can be drawn from the current study. Further detailed experiments are required before the practice of oral creatine monohydrate supplementation can be recommended for team sport players.