Article

Gastrointestinal Distress After Creatine Supplementation in Athletes: Are Side Effects Dose Dependent?

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  • Fakultet za sport i turizam Novi Sad
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Abstract

The main aim of the present study was to investigate the effects of two different creatine-supplementation protocols on incidence of gastrointestinal (GI) distress in top-level athletes. Data were collected from 59 top-level male soccer players who were allocated in a double-blind design to three randomly assigned trials: ingesting creatine supplement (C5: 2 x 5-g doses, and C10: 1 x 10-g dose) or placebo (P) for 28 days. In order to assess potential side effects of the supplementation regimen, all subjects were instructed to report any adverse effects of supplementation on their GI system. Survey questions covered perceived side effects on GI system linked with creatine supplementation. In all three treatment groups, the most frequent GI complaints were diarrhoea (39.0%), stomach upset (23.8%), and belching (16.9%). We did not find a significant difference between incidence of GI distress symptoms between C5 and the placebo group after the survey. Yet, significant differences were found for incidence of diarrhoea between the C5 and C10 groups (28.6% vs. 55.6%, respectively, p < 0.05). Moreover, diarrhoea was more frequent in the C10 group as compared with the placebo group (55.6% vs. 35.0%, p < 0.05). There is no reason to believe that short-term oral creatine supplementation for 28 days has any detrimental effect on the GI tract if taken in a recommended amount (10 g per day in two equal doses). The risk of diarrhoea may be increased, however, following intake of 10 grams of creatine per single serving.

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... Potential adverse reaction or side effects of supplements can be concerning for athletes. There are reports of gastrointestinal issues as following creatine ingestion [11][12][13][14]. The most common gastrointestinal issues are cramping, vomiting and diarrhea [11,14]. ...
... There are reports of gastrointestinal issues as following creatine ingestion [11][12][13][14]. The most common gastrointestinal issues are cramping, vomiting and diarrhea [11,14]. There is not sufficient evidence to conclusively confirm creatine-induced GI issues. ...
... There is not sufficient evidence to conclusively confirm creatine-induced GI issues. Therefore, creatine is considered an effective supplement for performance with few adverse side effects [2,14]. The ergogenic effects of creatine have been well established. ...
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Creatine monohydrate is a popular ergogenic aid used by athletes, adolescents and older individuals. There are various forms of creatine supplements that are on the market, however, creatine monohydrate is the most popular. Creatine itself is considered as less stable in solution when left in solution over time. Advances in product development and science may allow for a more stable aqueous solution of creatine. One major concern of ready-to-drink creatine supplements is the potential adverse gastrointestinal effects. In this randomized, double-blind, placebo-controlled design, the potential gastrointestinal effects of stabilized creatine (CreaBev®) as compared to standard creatine monohydrate versus control was tested. Subjects were randomly assigned to receive the CreaBev® supplement, creatine monohydrate supplement or no supplement (control). Subjects were instructed to consume one serving of the supplement (delivering 5 gm creatine) on a daily basis for 28 days. Subjects underwent baseline testing and end of study testing. The Severity of Dyspepsia Analysis (SODA) questionnaire and National Institutes of Health (NIH) Cognitive Test Toolbox were used to evaluate GI effects and cognition. Additional testing included body composition analysis (including fluid balance), and exploratory measurement of the stress biomarkers, salivary alpha amylase and cortisol. Following the consumption of CreaBev, no adverse gas-trointestinal side effects were reported. Cognition via the Dimension Change Test significantly improved (pre: 104 ± 14 to post: 116 ± 14; p = 0.0017) in the CreaBev group. There was no observed differences in total body fluid status over the 28 days between the groups (p > 0.05) No significant differences in levels of salivary alpha amylase, cortisol and anthropometrics were observed. The use of CreaBev did not cause any adverse GI effects and improved cognitive performance on the Dimension Change Test.
... Cr monohydrate (CrM) (a-methyl guandino-acetic acid), a naturally occurring nitrogenous compound is both synthesized endogenously mainly in the liver as well as in pancreas and kidney from three amino acids; glycine, arginine, methionine; and provided through normal dietary intake for body [4,5]. However, there is anecdotal information about of Cr supplementation effects on various aspects of athlete's health [6][7][8][9][10]. Nevertheless, some previous studies did not show any obvious risk of ingesting Cr supplements at the recommended doses [8,9,11,12]. ...
... Despite a large number of publications on the ergogenic effects of Cr [5,9,12,17], there are limited, anecdotal reports on the possible adverse effects of this supplement [6][7][8][9]12]. Hence, this study was done to clarify the effects of CrM loading on some serum indirect markers of cellular damage in young soccer players who participated in one week circuit weight training. ...
Article
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In recent years, creatine (Cr) supplementation has received great attention in both popular and scientific media. Nevertheless, there is anecdotal information on the side effects of this supplement. Hence, we hypothesized that Cr monohydrate (CrM) loading would induce increase in serum enzymes activity as indirect markers of cellular damage. Therefore, the present study was conducted to identify the effect of short-term Cr supplementation on serum lactate dehydrogenase (LDH), creatine phosphokinase (CK), and myocardial CK isoform (CKMB) in young male soccer players.
... Anecdotally, creatine supplementation has been linked to muscle cramps and gastrointestinal distress (42,55) but little empirical data supports this notion. In the current study we found that the creatine group experienced a decrease in muscle cramps and nausea. ...
... In the current study we found that the creatine group experienced a decrease in muscle cramps and nausea. This is in agreement with most other studies (14,23,42,55,60). Greenwood et al (23) found that creatine supplementation (0.3g/kg of body weight for 5 days then 0.03g/kg of body weight for an additional 115 days) resulted in significantly less cramping than placebo. ...
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Short-term (3-7 days), high doses of creatine (20g/d) and/or sodium bicarbonate (0.5g/kg body weight) supplementation increase exercise performance during short term high intensity activities; however, it remains unclear whether long-term, low doses of these supplements have a positive impact on exercise performance. The purpose of this study was to determine the effects of long-term (8 weeks), low dose creatine supplementation on exercise performance, and whether combining creatine and sodium bicarbonate supplementation has an additive effect. Sixty-three healthy, habitually active, adults (28 M, 35 W; 22+2 years; 23+ 3 BMI) were randomly assigned by sex to one of three supplement groups: placebo (PL), creatine only (3g/day; Cr), or creatine plus sodium bicarbonate (3g creatine plus 1g sodium bicarbonate; Cr+Sb) for 8 weeks. Before and after supplementation subjects completed two exercise performance tests on separate days. Subjects completed repeated Wingate sprint tests (6 x 10 second sprints) and changes in the slope across the 6 sprints (rate of decline) was analyzed between groups. We also collected 5 km time-trial and the data were analyzed using repeated measures ANOVA. In the repeated sprint test, peak power output slope was significantly decreased (P=0.04) in PL (-83%) and Cr+Sb (-82%) but did not change in Cr alone and was significantly better (P=0.03) than Pl and Cr+Sb. Similarly, mean power output slope significantly decreased (P0.05) in time to completion. However, Cr alone significantly improved time to completion (-3%; P=0.01). Taken together, these data suggest that long-term, low dose creatine supplementation increases exercise performance but adding sodium bicarbonate supplementation has no beneficial impact on exercise performance.
... To our knowledge, there are no studies of the effects of creatine supplementation on the gut microbiota. Higher doses of creatine (≥10g) increase gastrointestinal distress and the risk of diarrhea (242). However, lower doses of creatine do not affect gastrointestinal symptoms (242) and research in mice suggests that glycine amidinotransferase (GATM), the enzyme that catalyzes the rate-limiting step of creatine biosynthesis, has a beneficial effect on gastrointestinal barrier integrity (243). ...
... Higher doses of creatine (≥10g) increase gastrointestinal distress and the risk of diarrhea (242). However, lower doses of creatine do not affect gastrointestinal symptoms (242) and research in mice suggests that glycine amidinotransferase (GATM), the enzyme that catalyzes the rate-limiting step of creatine biosynthesis, has a beneficial effect on gastrointestinal barrier integrity (243). ...
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The athlete's goal is to optimize their performance. Towards this end, nutrition has been used to improve the health of athletes' brains, bones, muscles, and cardiovascular system. However, recent research suggests that the gut and its resident microbiota may also play a role in athlete health and performance. Therefore, athletes should consider dietary strategies in the context of their potential effects on the gut microbiota, including the impact of sports-centric dietary strategies (e.g., protein supplements, carbohydrate loading) on the gut microbiota as well as the effects of gut-centric dietary strategies (e.g., probiotics, prebiotics) on performance. This review provides an overview of the interaction between diet, exercise, and the gut microbiota, focusing on dietary strategies that may impact both the gut microbiota and athletic performance. Current evidence suggests that the gut microbiota could, in theory, contribute to the effects of dietary intake on athletic performance by influencing microbial metabolite production, gastrointestinal physiology, and immune modulation. Common dietary strategies such as high protein and simple carbohydrate intake, low fiber intake, and food avoidance may adversely impact the gut microbiota and, in turn, performance. Conversely, intake of adequate dietary fiber, a variety of protein sources, and emphasis on unsaturated fats, especially omega-3 (ɷ-3) fatty acids, in addition to consumption of prebiotics, probiotics, and synbiotics, have shown promising results in optimizing athlete health and performance. Ultimately, while this is an emerging and promising area of research, more studies are needed that incorporate, control, and manipulate all 3 of these elements (i.e., diet, exercise, and gut microbiome) to provide recommendations for athletes on how to "fuel their microbes."
... Syrotuik and Bell [31] reported that responders (increased total CR by >20 mmol kg −1 dw) had lower initial levels of free CR and phosphocreatine, a greater percentage and cross-sectional area of type II muscle fibers, and a larger fat-free mass compared to non-responders [31]. Other factors influencing an individual's response to creatine supplementation include hydration status, dietary factors, caffeine use, and the dose of creatine ingested [24,26,[32][33][34][35].Until recently, most studies on the effects of CR supplementation have focused upon its ability to enhance athletic performance and recovery [8,[14][15][16][17][18][19]. In this review, we will examine evidence to determine how CR impacts both the innate and adaptive arms of the immune system, and what effect this may have on individuals using CR as an ergogenic aid. ...
Article
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The use of dietary supplements has become increasingly common over the past 20 years. Whereas supplements were formerly used mainly by elite athletes, age and fitness status no longer dictates who uses these substances. Indeed, many nutritional supplements are recommended by health care professionals to their patients. Creatine (CR) is a widely used dietary supplement that has been well-studied for its effects on performance and health. CR also aids in recovery from strenuous bouts of exercise by reducing inflammation. Although CR is considered to be very safe in recommended doses, a caveat is that a preponderance of the studies have focused upon young athletic individuals; thus there is limited knowledge regarding the effects of CR on children or the elderly. In this review, we examine the potential of CR to impact the host outside of the musculoskeletal system, specifically, the immune system, and discuss the available data demonstrating that CR can impact both innate and adaptive immune responses, together with how the effects on the immune system might be exploited to enhance human health.
... These side effects are primarily due to the presence of large quantities of undissolved creatine particles residing within the intestinal compartment especially after a large loading dose. 65 Since the absorption process of creatine mediated by CRT involves the cotransport of Na + and Cl − , it has the propensity to draw water into the body compartment where the transport process is occurring. If the body compartment is the intestine, then excessive water absorption may lead to diarrhea and intestinal cramps. ...
Article
Membrane transporters play a pivotal role in many organs to maintain their normal physiological functions and contribute significantly to drug absorption, distribution and elimination. Knowledge gained from gene modified animal models or human genetic disorders has demonstrated that interruption of the transporter activity can lead to debilitating diseases or organ toxicities. Herein we describe transporter associated diseases and organ toxicities resulting from transporter gene deficiency or functional inhibition in the liver, kidney, gastrointestinal tract (GIT) and central nervous system (CNS). While proposing additional transporters as targets for drug-induced organ toxicity, strategies and future perspectives are discussed for transporter risk assessment in drug discovery and development.
... Thus, the present study was carried to investigate the current uncertainties about the influence of creatine and caffeine associated with power exercise on the LBM composition and on the counteraction of these ergogenic agents. We also considered that the consumption of supplements in excessive doses might expose users to serious side effects [26,27], and that studies on human body composition are carried out using indirect measurements of the LBM [5,11,28,29]. Thus, by using direct measurement of the LBM composition on a rat model, the purpose of this study was to determine whether high doses of caffeine and creatine supplementation, either solely or combined, affect the LBM composition of rats submitted to a power training regime based on a model of intermittent vertical jumps. ...
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The influences of creatine and caffeine supplementation associated with power exercise on lean body mass (LBM) composition are not clear. The purpose of this research was to determine whether supplementation with high doses of creatine and caffeine, either solely or combined, affects the LBM composition of rats submitted to vertical jumping training. Male Wistar rats were randomly divided into 8 groups: Sedentary (S) or Exercised (E) [placebo (Pl), creatine (Cr), caffeine (Caf) or creatine plus caffeine (CrCaf)]. The supplemented groups received creatine [load: 0.430 g/kg of body weight (BW) for 7 days; and maintenance: 0.143 g/kg of BW for 35 days], caffeine (15 mg/kg of BW for 42 days) or creatine plus caffeine. The exercised groups underwent a vertical jump training regime (load: 20 - 50% of BW, 4 sets of 10 jumps interspersed with 1 min resting intervals), 5 days/wk, for 6 weeks. LBM composition was evaluated by portions of water, protein and fat in the rat carcass. Data were submitted to ANOVA followed by the Tukey post hoc test and Student's t test. Exercised animals presented a lower carcass weight (10.9%; P = 0.01), as compared to sedentary animals. However, no effect of supplementation was observed on carcass weight (P > 0.05). There were no significant differences among the groups (P > 0.05) for percentage of water in the carcass. The percentage of fat in the group SCr was higher than in the groups SCaf and ECr (P < 0.05). A higher percentage of protein was observed in the groups EPl and ECaf when compared to the groups SPl and SCaf (P < 0.001). The percentage of fat in the carcass decreased (P < 0.001), while those of water and protein increased (P < 0.05) in exercised animals, compared to sedentary animals. Caffeine groups presented reduced percentage of fat when compared to creatine supplemented groups (P < 0.05). High combined doses of creatine and caffeine does not affect the LBM composition of either sedentary or exercised rats, however, caffeine supplementation alone reduces the percentage of fat. Vertical jumping training increases the percentages of water and protein and reduces the fat percentage in rats.
... In contrast no gastrointestinal tract disturbances were observed by Kreider et al. (1998) and Greenhaff (1998) in subjects supplemented with 20 g of creatine per day. It was suggested that some gastrointestinal distress might happen when a single serving of more than 10 g of creatine is given to some athletes (Ostojic and Ahmetovic 2008). However, this discomfort is possibly the result of the creatine being incompletely dissolved before ingestion. ...
Article
Doubtful allegations of adverse effects of creatine supplementation have been released through the press media and through scientific publications. In the present review we have tried to separate the wheat from the chaff by looking for the experimental evidence of any such claims. Anecdotal reports from athletes have appeared on muscle cramp and gastrointestinal complaints during creatine supplementation, but the incidence of these is limited and not necessarily linked to creatine itself. Despite several unproved allegations, liver (enzymes, urea) and kidneys (glomerular filtration urea and albumin excretion rates) show no change in functionality in healthy subjects supplemented with creatine, even during several months, in both young and older populations. The potential effects (production of heterocyclic amines) of mutagenicity and carcinogenicity induced by creatine supplementation have been claimed by a French Sanitary Agency (AFSSA), which might put consumers at risk. Even if there is a slight increase (within the normal range) of urinary methylamine and formaldehyde excretion after a heavy load of creatine (20 g/day) this is without effect on kidney function. The search for the excretion of heterocyclic amines remains a future task to definitively exclude the unproved allegation made by some national agencies. We advise that high-dose (>3-5 g/day) creatine supplementation should not be used by individuals with pre-existing renal disease or those with a potential risk for renal dysfunction (diabetes, hypertension, reduced glomerular filtration rate). A pre-supplementation investigation of kidney function might be considered for reasons of safety, but in normal healthy subjects appears unnecessary.
... Gastrointestinal distress, water retention and nephritis have been reported with creatine consumption in some studies. [35][36][37] There is no enough scientific documents supporting the consumption of nutritional supplements in a healthy athlete following a balanced diet, but side effects are likely if supplements are consumed more than prescribed dosages. [34,38] The American College of Sports Medicine (ACSM), the American Dietetic Association (ADA), and the Canadian Dietetic Association, have declared that if energy intake of athletes is sufficient to maintain body weight at the time of training or competition, they do not require vitamin/mineral supplementation. ...
Article
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The consumption of nutritional supplements is high in various sports, whereas, there are not enough documents supporting the beneficial effects of supplements in athletes. In addition, there is no information about taking supplements by Iranian students who participate in sports. Therefore, the goals of this study were to assess the type and prevalence of supplement use, the frequency of use, and relationships between consumption and age, body mass index, training load and type of sport. One hundred ninety two male students from "Isfahan University of Medical Sciences" participated in this study, voluntarily. A questionnaire that included questions about type and effects of supplements, recommendation resources, place of obtaining, and type of sports were sent to students. Descriptive data were calculated as frequencies (%). Chi-square (χ2) analysis was used to analyze the correlation between supplement use and the study variables. Forty-five percent of respondents used some forms of supplements. Supplement users consumed 14 different supplements and each used as many as 1.8 ± 1.2 various supplements during the past six months. Multivitamins (64%) and vitamin C (42%) were the most popular supplements. Students, who participated in individual sports, were more likely to consume dietary supplements (P < 0.05) and ergogenic aids (P < 0.01), but team sports athletes, took more recovery nutrients (P < 0.01). Fifty seven point five percent of student bought their products from pharmacies, 40% from "sport supplements stores" and 2.5% from their friends. It can be concluded that less than half of these students consumed supplements and their information resources were inappropriate.
... No entanto, sabe-se que altas doses (acima de 10g/dose) de creatina, tomadas de uma única vez, podem provocar náuseas, vômitos, diarréia, cefaléia e mal estar geral, sem evidências de efeitos colaterais mais graves 50 . ...
Article
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Creatine was discovered more than one century ago, but its use became importantin sports scenario in the 70’s. Since then, the improvement in knowledge and utilization protocolsmade this substance the licit ergogenic aid most studied and used by athletes nowadays. Thebenefits of supplementation in athletes served as a model for studies in diseased individuals,that present ATP synthesis or ressynthesis deficiency, neurological and muscular diseases,or that suffer from muscular atrophy or impairment of muscular metabolism
... Creatine supplements are also taken for their beneficial effect on the exercise performance of athletes who practice high-intensity and intermittent exercises with short recovery periods, such as soccer (Buford et al., 2007). However, excessive creatine intake can result in gastrointestinal distress symptoms, such as diarrhea, stomach upset and belching (Ostojic and Ahmetovic, 2008). Francaux and Poortmans (2006) indicate that great care should be taken regarding the purity of the nutrients of commercially available dietary supplements. ...
Article
Caffeine and creatine are ingredients in the most popular dietary supplements consumed by soccer players. However, some products may not contain the disclosed amounts of the ingredients listed on the label, compromising the safe usage and the effectiveness of these supplements. Therefore, the aim of this study was to evaluate the content of caffeine and creatine in dietary supplements consumed by Brazilian soccer players. The results obtained were compared with the caffeine content listed on the product label. Two batches of the supplement brands consumed by ≥ 50% of the players were considered for analysis. The quantification of caffeine and creatine in the supplements was determined by a high-performance liquid chromatography system with UV detector. Nine supplements of caffeine and 7 supplements of creatine met the inclusion criteria for analysis. Eight brands of caffeine and five brands of creatine showed significantly different values (P<0.05) as compared with the values stated on the label. There were no significant differences between the two batches of supplements analyzed, except for one caffeine supplement. It can be concluded that caffeine and creatine dietary supplements consumed by Brazilian soccer players present inaccurate values listed on the label, although most presented no difference among batches. To ensure consumer safety and product efficacy, accurate information on caffeine and creatine content should be provided on all dietary supplement labels.
... The main reports were on weight gain and water retention [1] [3] [4] with some studies reporting gastrointestinal stress [1] [3] [5] and one of these studies reporting a strong correlation between diarrhea and the CrM doses ingested [6]. These adverse effects of CrM are probably related to the mechanism of action of the substance and the dose used to ensure the efficacy of the supplement. ...
Article
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Background: Creatine supplementation is a subject that is very well studied. New forms of creatine are suggesting improvements in this supplement performance. Creatine HCl is supposed to have better solubility and absorption than creatine. The aim of this study was to compare the effects of two different doses of creatine HCl with creatine monohydrate on the strength and body composition in recreational weightlifters and to verify the relationship between strength and body composition. Methods: 40 subjects were divided in four groups: Creatine Monohydrate (CMG) 5 g/daily; Creatine HCl-1 (HCl-1) 5 g/daily, Creatine HCl-2 (HCl-2) 1.5 g/daily and Control group (CG) = 5 g of resistant starch/daily. All groups performed a resistance training program during 4 weeks. Body composition and strength were evaluated pre and post intervention. Results: The 1 RM at the Leg press was increased significantly in all groups (CMG: pre = 264.4 ± 83.8 × post = 298.1 ± 90.9; HCl-1: pre = 295.0 ± 88.3 × post = 338.3 ± 86.8 and HCl-2: pre = 274.3 ± 57.1 × post = 305.7 ± 59.4; p < 0.05), Bench press 1 RM was increased significantly only in HCl-2 (pre = 72.4 ± 25.7 × post = 76.0 ± 25.0; p = 0.003), however, there was no statistically significant difference between groups. Fatmass was significantly decreased in HCl-1 (pre = 14.5 ± 8.0 × post = 13.3 ± 8.3; p = 0.034) and * Corresponding author.
... There have been reports of adverse effects of creatine supplementation. For example, creatine supplementation has been found to bring about gastrointestinal stress and diarrhea [Ostojic and Ahmetovic 2008]. Short-term, high-dose oral creatine supplementation increases the production and thus excretion of potential cytotoxic compounds, methylamine and formaldehyde but does not have any detrimental effects on kidney permeability [Poortmans et al 2005]. ...
Article
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ENGLISH ABSTRACT: Background: There has been a dramatic increase in the use of dietary creatine supplementation among sports men and women, and by clinicians as a therapeutic agent in muscular and neurological diseases. The effects of creatine have been studied extensively in skeletal muscle, but knowledge of its myocardial effects is limited. Objectives: To investigate the effects of dietary creatine supplementation with and without exercise on 1) basal cardiac function, 2) susceptibility to ischaemia/reperfusion injury and 3) myocardial protein expression and phosphorylation and 4) mitochondrial oxidative function. Methods: Male Wistar rats were randomly divided into control or creatine supplemented groups. Half of each group was exercise trained by swimming for a period of 8 weeks, 5 days per week. At the end of the 8 weeks the open field test was performed and blood corticosterone levels were measured by RIA to determine whether the swim training protocol had any effects on stress levels of the rats. Afterwards hearts were excised and either freeze-clamped for biochemical and molecular analysis or perfused on the isolated heart perfusion system to assess function and tolerance to ischaemia and reperfusion. Five series of experiments were performed: (i) Mechanical function was documented before and after 20 minutes global ischaemia using the work heart model, (ii) A H2O filled balloon connected to a pressure transducer was inserted into the left ventricle to measure LVDP and ischaemic contracture in the Langendorff model, (iii) The left coronary artery was ligated for 35 minutes and infarct size determined after 30 minutes of reperfusion by conventional TTC staining methods. (iv) Mitochondrial oxidative capacity was quantified. (v) High pressure liquid chromatography (HPLC) and Western Blot analysis were performed on blood and heart tissue for determination of high energy phosphates and protein expression and phosphorylation. Results: Neither the behavioural studies nor the corticosterone levels showed any evidence of stress in the groups investigated. Hearts from creatine supplemented sedentary (33.5 ± 4.5%), creatine supplemented exercised rats (18.22 ± 6.2%) as well as control exercised rats (26.1 ± 5.9%) had poorer aortic output recoveries than the sedentary control group (55.9 ± 4.35% p < 0.01) and there was also greater ischaemic contracture in the creatine supplemented exercised group compared to the sedentary control group (10.4 ± 4.23 mmHg vs 31.63 ± 4.74 mmHg). There were no differences in either infarct size or in mitochondrial oxygen consumption between the groups. HPLC analysis revealed elevated phosphocreatine content (44.51 ±14.65 vs 8.19 ±4.93 nmol/gram wet weight, p < 0.05) as well as elevated ATP levels (781.1 ±58.82 vs 482.1 ±75.86 nmol/gram wet weight, p<0.05) in blood from creatine supplemented vs control sedentary rats. These high energy phosphate elevations were not evident in heart tissue and creatine tranporter expression was not altered by creatine supplementation. GLUT4 and phosphorylated AMPK and PKB/Akt were all significantly higher in the creatine supplemented exercised hearts compared to the control sedentary hearts. Conclusion: This study suggests that creatine supplementation has no effects on basal cardiac function but reduces myocardial tolerance to ischaemia in hearts from exercise trained animals by increasing the ischaemic contracture and decreasing reperfusion aortic output. Exercise training alone also significantly decreased aortic output recovery. However, the exact mechanisms for these adverse myocardial effects are unknown and need further investigation. AFRIKAANSE OPSOMMING: Agtergrond: Die gebruik van kreatien as dieetaanvulling het in die afgelope aantal jaar dramaties toegeneem onder sportlui, sowel as mediese praktisyns wat dit as ‘n terapeutiese middel vir die behandeling van spier- en neurologiese siektes aanwend. Die effekte van kreatien op skeletspier is reeds deeglik ondersoek, maar inligting aangaande die miokardiale effekte van die preperaat is beperk. Doelwitte: Om die effekte van kreatien dieetaanvulling met of sonder oefening ten opsigte van die volgende aspekte te ondersoek: 1) basislyn miokardiale funksie, 2) vatbaarheid vir iskemie/herperfusie besering, 3) proteïenuitdrukking en -fosforilering in die miokardium en 4) mitochondriale oksidatiewe funksie. Metodes: Manlike Wistar rotte is ewekansig in kontrole of kreatien aanvullings groepe verdeel. Helfte van elke groep is aan oefening in die vorm van swemsessies, vir ‘n periode van 8 weke, 5 dae per week blootgestel. Gedrags- en biochemiese toetse is aangewend om die moontlike effek van die swemprotokol op die rotte se stres vlakke te bepaal. In hierdie verband is die oop area toets gebruik, asook bloed kortikosteroon vlakke gemeet deur radioaktiewe immuunessais. Harte is daarna uit die rotte gedissekteer en gevriesklamp vir biochemiese en molekulêre analise, of geperfuseer op die geïsoleerde werkhart perfusiesisteem om sodoende funksie en weerstand teen iskemie en herperfusie beskadeging te bepaal. Vyf eksperimentele reekse is uitgevoer: (i) Meganiese funksie is noteer voor en na 20 minute globale isgemie in die werkhart model; (ii) ‘n Water gevulde plastiek ballon, gekoppel aan ‘n druk omsetter, is in die linker ventrikel geplaas om sodoende linker ventrikulêre ontwikkelde druk (LVDP), asook iskemiese kontraktuur te meet; (iii) Linker koronêre arterie afbinding is vir ‘n periode van 35 minute toegepas en die infarktgrootte bepaal na 30 minute herperfusie deur gebruik te maak van standaard kleuringsmetodes; (iv) Mitochondriale oksidatiewe kapasiteit is gemeet; (v) Hoë druk vloeistof chromatografie (HPLC) en Western Blot analises is uitgevoer op bloed en hartweefsel vir die bepaling van hoë energie fosfate (HEFe), sowel as proteïenuitdrukking en -fosforilering. Resultate: Beide gedragsstudies en kortikosteroonvlakke het geen teken van stres in die betrokke groepe getoon nie. Die groep blootgestel aan kreatienaanvulling en oefening se harte het na iskemie funksioneel swakker herstel as harte van die onaktiewe kontrole groep (18.22±6.2% vs 55.9±4.35%; p<0.01), asook ‘n groter ikgemiese kontraktuur in vergelyking met die onaktiewe kontrole groep ontwikkel (31.63±4.74 mmHg vs 10.4±4.23 mmHg). Daar was geen verskille in infarktgrootte of mitochondriale suurstofverbruik tussen die verskillende groepe waargeneem nie. HPLC analise het verhoogde fosfokreatien (44.51±14.65 vs 8.19±4.93 nmol/gram nat gewig, p<0.05) en adenosientrifosfaat (ATP) bloedvlakke (781.1±58.82 vs 482.1±75.86 nmol/gram nat gewig, p<0.05) in kreatien aanvullings vergelyk met die kontrole groepe getoon. Daar was egter geen meetbare veranderings in HEF vlakke in hartweefsel nie. Gepaardgaande hiermee het kreatienaanvulling geen effek gehad op die uitdrukking va die kreatien transporter nie. In vergelyking met onaktiewe kontrole harte was GLUT4, en fosforileerde AMPK en PKB/ Akt beduidend hoër in harte van geoefende rotte met kreatienaangevulling. Gevolgtrekking: Hierdie data dui daarop dat kreatienaanvulling geen effek op basislyn miokardiale funksie het nie. Kreatienaanvulling het egter die miokardium se weerstand teen iskemiese skade verlaag in harte van rotte blootgestel aan oefening: iskemiese kontraktuur is verhoog en aorta-uitset tydens herperfusie is verlaag. Die presiese meganismes hierby betrokke is egter onbekend en vereis dus verdere studie. Thesis (PhD (Biomedical Sciences. Medical Physiology))--University of Stellenbosch, 2010. Division of Medical Physiology (University of Stellenbosch), The National Research Foundation and the Harry Crossley Fund for financial support.
... However, if an athlete or exercising individual is planning to ingest creatine over an extended period of time (> 30 days), or if avoiding potential weight gain which can sometimes occur during creatine 'loading', the creatine 'maintenance' strategy would be a viable option. Athletes who are carrying out a creatine loading phase (i.e., 20 g/day) should emphasize the smaller dosing strategies (e.g. less than or equal to 10 gram servings) throughout the day, as dosages of greater than 10 grams may potentially lead to gastrointestinal distress (i.e., diarrhea) [105]. ...
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Supplementing with creatine is very popular amongst athletes and exercising individuals for improving muscle mass, performance and recovery. Accumulating evidence also suggests that creatine supplementation produces a variety of beneficial effects in older and patient populations. Furthermore, evidence-based research shows that creatine supplementation is relatively well tolerated, especially at recommended dosages (i.e. 3-5 g/day or 0.1 g/kg of body mass/day). Although there are over 500 peer-refereed publications involving creatine supplementation, it is somewhat surprising that questions regarding the efficacy and safety of creatine still remain. These include, but are not limited to: 1. Does creatine lead to water retention? 2. Is creatine an anabolic steroid? 3. Does creatine cause kidney damage/renal dysfunction? 4. Does creatine cause hair loss / baldness? 5. Does creatine lead to dehydration and muscle cramping? 6. Is creatine harmful for children and adolescents? 7. Does creatine increase fat mass? 8. Is a creatine ‘loading-phase’ required? 9. Is creatine beneficial for older adults? 10. Is creatine only useful for resistance / power type activities? 11. Is creatine only effective for males? 12. Are other forms of creatine similar or superior to monohydrate and is creatine stable in solutions/beverages? To answer these questions, an internationally renowned team of research experts was formed to perform an evidence-based scientific evaluation of the literature regarding creatine supplementation.
... iron, magnesium, vitamin C, and vitamin D, multi-vitamin/mineral) to maximize its beneficial effects [29], it has been wellestablished that overconsumption can be associated with a diminished state of health and performance particularly with the advancement of time [30]. Additionally, considering the high prevalence of gastrointestinal (GI) disorders among endurance runners [4], caution must be warranted when following high-fat diets, particularly use of medium-chain triglyceride oils [14] or consuming some supplements such as creatine [31] and amino acids [32], which are potentially associated with some GI distress and diarrhea. ...
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The primary nutritional challenge facing endurance runners is meeting the nutrient requirements necessary to optimize the performance and recovery of prolonged training sessions. Supplement intake is a commonly used strategy by elite and recreational distance runners to meet nutritional recommendations. This study was conducted to investigate the patterns of supplement intake among different groups of distance runners and the potential association between supplement intake and sex, age, running and racing experiences. In a cross-sectional design, from a total of 317 runners participating in this survey, 119 distance runners were involved in the final sample after data clearance, assigned into three groups of 10-km runners (n = 24), half-marathoners ( n = 44), and (ultra-)marathoners (n = 51). Personal characteristics, training and racing experiences, as well as patterns of supplement intake, including type, frequency, and dosage, were evaluated by questionnaire. Food Frequency Questionnaire was implemented to assess macronutrient intake. ANOVA and logistic regression were used for statistical analysis. While 50 % of total distance runners reported consuming supplements regularly, no differences between distance groups in consumption of carbohydrate/protein, mineral, or vitamin supplements were observed (p > 0.05). In addition, age, sex, running and racing experience showed no significant association with supplement intake ( p > 0.05). Vitamin supplements had the highest intake rate in runners by 43 % compared to minerals (34 %) and carbohydrate/protein supplements (19 %). The present findings provide a window into the targeted approaches of long-distance runners as well as their coaches and sport nutrition specialists when applying and suggesting sustainable nutritional strategies for training and competition. Trial registration : ISRCTN73074080. Retrospectively registered 12th June 2015.
... CrH2O supplementation, such as subcutaneous water retention, gastrointestinal distress, nausea, and vomiting. These may be attributed to factors, such as co-ingestion with other where 10 g or more is ingested, and increased risk of diarrhea.74,75 This effect is likely due to the fact that CrH2O is poorly soluble in liquid and consequently, poorly absorbed by the intestines where the substance then sits and draws water in to the intestinal 3% of ingested CrH2O was able to pass through the intestinal cells for upwards of a 90 min time period with the remainder being excreted by the body. ...
... With the exception of the abovementioned studies, gastrointestinal complaints associated with creatine supplementation are mostly anecdotal [64,68]. There may be an explanation for these problems: others have suggested that gastrointestinal problems arise when creatine monohydrate is not dissolved completely or when more than 10g of creatine is taken in a single serving due to an unusually high osmotic load [69]. ...
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METC protocol NL44547.068.13. (PDF)
... Similar to anecdotal reports in other systems of the body, the empirical evidence does not support this, with no difference in the incidence of gastrointestinal discomfort reported between active supplement and control groups ( 48 ). It is possible that gastrointestinal disturbances in response to supplementation is dose dependent ( 92 ). Having said that, the response to all nutritional supplements is highly individual and it is recommended that individuals test their response to creatine supplementation outside of the competitive season. ...
... Alternately, evidence suggests that individuals who wish to bypass the loading stage can achieve ergogenic elevations in muscle creatine storage by consuming maintenance doses for approximately four weeks (Hultman et al., 1996). A large body of evidence suggests creatine is safe and well-tolerated with any gastrointestinal discomfort alleviated by splitting the total creatine intake into smaller doses (Ostojic and Ahmetovic, 2008). The most consistent side effect is an abrupt increase in body mass, typically in the range of 1-2 kg. ...
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The popularity of physique sports is increasing, yet there are currently few comprehensive nutritional guidelines for these athletes. Physique sport now encompasses more than just a short phase before competition and offseason guidelines have recently been published. Therefore, the goal of this review is to provide an extensive guide for male and female physique athletes in the contest preparation and recovery period. As optimal protein intake is largely related to one’s skeletal muscle mass, current evidence supports a range of 1.8-2.7 g/kg. Furthermore, as a benefit from having adequate carbohydrate to fuel performance and activity, low-end fat intake during contest preparation of 10-25% of calories allows for what calories remain in the “energy budget” to come from carbohydrate to mitigate the negative impact of energy restriction and weight loss on training performance. For nutrient timing, we recommend consuming four or five protein boluses per day with one consumed near training and one prior to sleep. During competition periods, slower rates of weight loss (≤0.5% of body mass per week) are preferable for attenuating the loss of fat-free mass with the use of intermittent energy restriction strategies, such as diet breaks and refeeds, being possibly beneficial. Additionally, physiological and psychological factors are covered, and potential best-practice guidelines are provided for disordered eating and body image concerns since physique athletes present with higher incidences of these issues, which may be potentially exacerbated by certain traditional physique practices. We also review common peaking practices, and the critical transition to the post-competition period.
... GIT disturbances reported in male or mixed sex populations have been associated with higher dosing regimens, dosing regimens in excess of those recommended by the manufacturer, or concomitant supplementation regimens [96,133,134]. Our findings support other published literature that found no evidence of a significant effect on GIT symptoms, muscle cramping, or renal and hepatic changes across placebo-controlled trials [15,19,90,94,[134][135][136][137][138]. ...
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Creatine Monohydrate (CrM) is a dietary supplement routinely used as an ergogenic aid for sport and training, and as a potential therapeutic aid to augment different disease processes. Despite its increased use in recent years, studies reporting potential adverse outcomes of CrM have been mostly derived from male or mixed sex populations. A systematic search was conducted, which included female participants on CrM, where adverse outcomes were reported, with meta-analysis performed where appropriate. Six hundred and fifty-six studies were identified where creatine supplementation was the primary intervention; fifty-eight were female only studies (9%). Twenty-nine studies monitored for adverse outcomes, with 951 participants. There were no deaths or serious adverse outcomes reported. There were no significant differences in total adverse events, (risk ratio (RR) 1.24 (95% CI 0.51, 2.98)), gastrointestinal events, (RR 1.09 (95% CI 0.53, 2.24)), or weight gain, (mean difference (MD) 1.24 kg pre-intervention, (95% CI −0.34, 2.82)) to 1.37 kg post-intervention (95% CI −0.50, 3.23)), in CrM supplemented females, when stratified by dosing regimen and subject to meta-analysis. No statistically significant difference was reported in measures of renal or hepatic function. In conclusion, mortality and serious adverse events are not associated with CrM supplementation in females. Nor does the use of creatine supplementation increase the risk of total adverse outcomes, weight gain or renal and hepatic complications in females. However, all future studies of creatine supplementation in females should consider surveillance and comprehensive reporting of adverse outcomes to better inform participants and health professionals involved in future trials.
... As identical crystals were also present in the absence of fruit squash and their numbers increased with increasing GLN concentration, it is reasonable to assume that the crystal structures observed were undissolved GLN. GI tolerance to undissolved GLN is unknown, however, ingestion of supersaturated creatine and l-arginine solutions has previously been suggested to trigger gastric distension and/or aggravate the intestinal mucosal lining [36,37]. Previous studies reported that l-arginine could result in high concentrations of nitric oxide, resulting in secretagogue functions for water and electrolytes [38]. ...
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l-Glutamine (GLN) is a conditionally essential amino acid which supports gastrointestinal (GI) and immune function prior to catabolic stress (e.g., strenuous exercise). Despite potential dose-dependent benefits, GI tolerance of acute high dose oral GLN supplementation is poorly characterised. Fourteen healthy males (25 ± 5 years; 1.79 ± 0.07 cm; 77.7 ± 9.8 kg; 14.8 ± 4.6% body fat) ingested 0.3 (LOW), 0.6 (MED) or 0.9 (HIGH) g·kg·FFM−1 GLN beverages, in a randomised, double-blind, counter-balanced, cross-over trial. Individual and accumulated GI symptoms were recorded using a visual analogue scale at regular intervals up to 24-h post ingestion. GLN beverages were characterised by tonicity measurement and microscopic observations. 24-h accumulated upper- and lower- and total-GI symptoms were all greater in the HIGH, compared to LOW and MED trials (p < 0.05). Specific GI symptoms (discomfort, nausea, belching, upper GI pain) were all more pronounced on the HIGH versus LOW GLN trial (p < 0.05). Nevertheless, most symptoms were still rated as mild. In comparison, the remaining GI symptoms were either comparable (flatulence, urge to regurgitate, bloating, lower GI pain) or absent (heart burn, vomiting, urge to defecate, abnormal stools, stitch, dizziness) between trials (p > 0.05). All beverages were isotonic and contained a dose-dependent number of GLN crystals. Acute oral GLN ingestion in dosages up to 0.9 g·kg·FFM−1 are generally well-tolerated. However, the severity of mild GI symptoms appeared dose-dependent during the first two hours post prandial and may be due to high-concentrations of GLN crystals.
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Guanidinoacetic acid (GAA) is a natural precursor of creatine and underinvestigation as a novel dietary supplement. However, its use in human nutrition ishampered by limited knowledge on its physiological effectiveness and safety aftersupplementation. The main aims of the present study were: (a) to identify if oral GAAaffects human performance and body composition; (b) to determine the most effectivedose regimen of GAA; and (c) to analyze the incidence and severity of adverse effects ofGAA supplementation. Fifty two (n = 52) male and female college athletes who wereexperienced in exercise training (> 2 years), and who were between 20 and 25 years ofage were included in the study. Participants were randomized in a double-blind design toreceive three different dosages of GAA (1.2 g/day, 2.4 g/day, and 4.8 g/day) or placebo(inulin) by oral administration for 6 weeks. Two-way mixed model ANOVA revealedsignificant increase in lean body mass (P = 0.006), handgrip strength (P = 0.03), andbench press performance (P = 0.014) in participants supplemented with GAA.Supplementation with GAA for 6 weeks had no major effect on indices of anaerobicpower and capacity. Low-dose GAA (1.2 g/day) can be considered as the minimumeffective dose for improving performance characteristics, while the effects are mostconsistently seen in participants receiving 2.4 g/day of GAA. Except for the dose of 4.8g/day of GAA, reported side effects of GAA administration are rather mild (e.g., weightgain, gastrointestinal distress). The findings of this study demonstrate that oral GAA is aneffective performance-enhancing agent with dose-dependent effects and mild side effectsexperienced when ingested over 6 weeks
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To determine the effects of 28 d of creatine supplementation during training on body composition, strength, sprint performance, and hematological profiles. In a double-blind and randomized manner, 25 NCAA division IA football players were matched-paired and assigned to supplement their diet for 28 d during resistance/agility training (8 h x wk[-1]) with a Phosphagen HP (Experimental and Applied Sciences, Golden, CO) placebo (P) containing 99 g x d(-1) of glucose, 3 g x d(-1) of taurine, 1.1 g x d(-1) of disodium phosphate, and 1.2 g x d(-1) of potassium phosphate (P) or Phosphagen HP containing the P with 15.75 g x d(-1) of HPCE pure creatine monohydrate (HP). Before and after supplementation, fasting blood samples were obtained; total body weight, total body water, and body composition were determined; subjects performed a maximal repetition test on the isotonic bench press, squat, and power clean; and subjects performed a cycle ergometer sprint test (12 x 6-s sprints with 30-s rest recovery). Hematological parameters remained within normal clinical limits for active individuals with no side effects reported. Total body weight significantly increased (P < 0.05) in the HP group (P 0.85 +/- 2.2; HP 2.42 +/- 1.4 kg) while no differences were observed in the percentage of total body water. DEXA scanned body mass (P 0.77 +/- 1.8; HP 2.22 +/- 1.5 kg) and fat/bone-free mass (P 1.33 +/- 1.1; HP 2.43 +/- 1.4 kg) were significantly increased in the HP group. Gains in bench press lifting volume (P -5 +/- 134; HP 225 +/- 246 kg), the sum of bench press, squat, and power clean lifting volume (P 1,105 +/- 429; HP 1,558 +/- 645 kg), and total work performed during the first five 6-s sprints was significantly greater in the HP group. The addition of creatine to the glucose/taurine/electrolyte supplement promoted greater gains in fat/bone-free mass, isotonic lifting volume, and sprint performance during intense resistance/agility training.
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Creatine, a natural nutrient found in animal foods, is alleged to be an effective nutritional ergogenic aid to enhance sport or exercise performance. Research suggests that oral creatine monohydrate supplementation may increase total muscle creatine [TCr], including both free creatine [FCr] and phosphocreatine [PCr]. Some, but not all, studies suggest that creatine supplementation may enhance performance in high-intensity, short-term exercise tasks that are dependent primarily on PCr (i.e., < 30 seconds), particularly laboratory tests involving repeated exercise bouts with limited recovery time between repetitions; additional corroborative research is needed regarding its ergogenic potential in actual field exercise performance tasks dependent on PCr. Creatine supplementation has not consistently been shown to enhance performance in exercise tasks dependent on anaerobic glycolysis, but additional laboratory and field research is merited. Additionally, creatine supplementation has not been shown to enhance performance in exercise tasks dependent on aerobic glycolysis, but additional research is warranted, particularly on the effect of chronic supplementation as an aid to training for improvement in competitive performance. Short-term creatine supplementation appears to increase body mass in males, although the initial increase is most likely water. Chronic creatine supplementation, in conjunction with physical training involving resistance exercise, may increase lean body mass. However, confirmatory research data are needed. Creatine supplementation up to 8 weeks has not been associated with major health risks, but the safety of more prolonged creatine supplementation has not been established. Creatine is currently legal and its use by athletes is not construed as doping.
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Oral creatine supplementation is widely used in sportsmen and women. Side effects have been postulated, but no thorough investigations have been conducted to support these assertions. It is important to know whether long-term oral creatine supplementation has any detrimental effects on kidney function in healthy population. Creatinine, urea, and plasma albumin clearances have been determined in oral creatine consumers (10 months to 5 yr) and in a control group. There were no statistical differences between the control group and the creatine consumer group for plasma contents and urine excretion rates for creatinine, urea, and albumin. Clearance of these compounds did not differ between the two groups. Thus, glomerular filtration rate, tubular reabsorption, and glomerular membrane permeability were normal in both groups. Neither short-term, medium-term, nor long-term oral creatine supplements induce detrimental effects on the kidney of healthy individuals.
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31P NMR was used to assess the influence of two weeks creatine supplementation (21g x d(-1)) on resting muscle PCr concentration, on the rate of PCr repletion (R(depl)), and on the half-time of PCr repletion (t 1/2). Body mass (BM) and volume of body water compartments were also estimated by impedance spectroscopy. Fourteen healthy male subjects (20.8+/-1.9 y) participated in this double-blind study. PCr was measured using a surface coil placed under the calf muscle, at rest and during two exercise bout the duration of which was 1 min. They were interspaced by a recovery of 10 min. The exercises comprised of 50 plantar flexions-extensions against weights corresponding to 40% and 70% of maximal voluntary contraction (MVC), respectively. Creatine supplementation increased resting muscle PCr content by approximately 20% (P= 0.002). R(depl) was also increased by approximately 15% (P< 0.001) and approximately 10% (P = 0.026) during 40% and 70% MVC exercises, respectively. No change was observed in R(repl) and t1/2. BM and body water compartments were not influenced. These results indicate that during a standardized exercise more ATP is synthesized by the CK reaction when the pre-exercise level in PCr is higher, giving some support to the positive effects recorded on muscle performance.
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Creatine (Cr) supplementation has become a common practice among professional, elite, collegiate, amateur, and recreational athletes with the expectation of enhancing exercise performance. Research indicates that Cr supplementation can increase muscle phosphocreatine (PCr) content, but not in all individuals. A high dose of 20 g x d(-1) that is common to many research studies is not necessary, as 3 g x d(-1) will achieve the same increase in PCr given time. Coincident ingestion of carbohydrate with Cr may increase muscle uptake; however, the procedure requires a large amount of carbohydrate. Exercise performance involving short periods of extremely powerful activity can be enhanced, especially during repeated bouts of activity. This is in keeping with the theoretical importance of an elevated PCr content in skeletal muscle. Cr supplementation does not increase maximal isometric strength, the rate of maximal force production, nor aerobic exercise performance. Most of the evidence has been obtained from healthy young adult male subjects with mixed athletic ability and training status. Less research information is available related to the alterations due to age and gender. Cr supplementation leads to weight gain within the first few days, likely due to water retention related to Cr uptake in the muscle. Cr supplementation is associated with an enhanced accrual of strength in strength-training programs, a response not independent from the initial weight gain, but may be related to a greater volume and intensity of training that can be achieved. There is no definitive evidence that Cr supplementation causes gastrointestinal, renal, and/or muscle cramping complications. The potential acute effects of high-dose Cr supplementation on body fluid balance has not been fully investigated, and ingestion of Cr before or during exercise is not recommended. There is evidence that medical use of Cr supplementation is warranted in certain patients (e.g.. neuromuscular disease); future research may establish its potential usefulness in other medical applications. Although Cr supplementation exhibits small but significant physiological and performance changes, the increases in performance are realized during very specific exercise conditions. This suggests that the apparent high expectations for performance enhancement, evident by the extensive use of Cr supplementation, are inordinate.
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The consumption of oral creatine monohydrate has become increasingly common among professional and amateur athletes. Despite numerous publications on the ergogenic effects of this naturally occurring substance, there is little information on the possible adverse effects of this supplement. The objectives of this review are to identify the scientific facts and contrast them with reports in the news media, which have repeatedly emphasised the health risks of creatine supplementation and do not hesitate to draw broad conclusions from individual case reports. Exogenous creatine supplements are often consumed by athletes in amounts of up to 20 g/day for a few days, followed by 1 to 10 g/day for weeks, months and even years. Usually, consumers do not report any adverse effects, but body mass increases. There are few reports that creatine supplementation has protective effects in heart, muscle and neurological diseases. Gastrointestinal disturbances and muscle cramps have been reported occasionally in healthy individuals, but the effects are anecdotal. Liver and kidney dysfunction have also been suggested on the basis of small changes in markers of organ function and of occasional case reports, but well controlled studies on the adverse effects of exogenous creatine supplementation are almost nonexistent. We have investigated liver changes during medium term (4 weeks) creatine supplementation in young athletes. None showed any evidence of dysfunction on the basis of serum enzymes and urea production. Short term (5 days), medium term (9 weeks) and long term (up to 5 years) oral creatine supplementation has been studied in small cohorts of athletes whose kidney function was monitored by clearance methods and urine protein excretion rate. We did not find any adverse effects on renal function. The present review is not intended to reach conclusions on the effect of creatine supplementation on sport performance, but we believe that there is no evidence for deleterious effects in healthy individuals. Nevertheless, idiosyncratic effects may occur when large amounts of an exogenous substance containing an amino group are consumed, with the consequent increased load on the liver and kidneys. Regular monitoring is compulsory to avoid any abnormal reactions during oral creatine supplementation.
Article
The purpose of this study was to determine the effect of long-term Cr supplementation on blood parameters reflecting liver and kidney function. Twenty-three members of an NCAA Division 11 American football team (ages = 19-24 years) with at least 2 years of strength training experience were divided into a Cr monohydrate group (CrM, n = 10) in which they voluntarily and spontaneously ingested creatine, and a control group (n = 13) in which they took no supplements. Individuals in the CrM group averaged regular daily consumption of 5 to 20 g (mean +/- SD = 13.9 +/- 5.8 g) for 0.25 to 5.6 years (2.9 +/- 1.8 years). Venous blood analysis for serum albumin, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, urea, and creatinine produced no significant differences between groups. Creatinine clearance was estimated from serum creatinine and was not significantly different between groups. Within the CrM group, correlations between all blood parameters and either daily dosage or duration of supplementation were nonsignificant. Therefore, it appears that oral supplementation with CrM has no long-term detrimental effects on kidney or liver functions in highly trained college athletes in the absence of other nutritional supplements.
Conference Paper
The purpose of this study was to examine the effects of acute creatine-monohydrate supplementation on soccer-specific performance in young soccer players. Twenty young male soccer players (16.6 +/- 1.9 years) participated in the study and were matched and allocated to 2 randomly assigned trials: ingesting creatine-monohydrate supplement (3 x 10-g doses) or placebo for 7 days. Before and after the supplementation protocol, each subject underwent a series of soccer-specific skill tests: dribble test, sprint-power test, endurance test, and vertical jump test. Specific dribble test times improved significantly in the creatine group (13.0 +/- 1.5 vs. 10.2 +/- 1.8 s; p < .05) after supplementation protocol. Sprint-power test times were significantly improved after creatine-monohydrate supplementation (2.7 +/- 0.4 vs. 2.2 +/- 0.5 s; p < .05) as well as vertical jump height (49.2 +/- 5.9 vs. 55.1 +/- 6.3 cm; p < .05) in creatine trial. Furthermore, dribble and power test times, along with vertical jump height, were superior in creatine versus placebo trial (p < .05) at post-supplementation performance. There were no changes in specific endurance test results within or between trials (p > .05). There were no between-trial differences in the placebo trial (p > .05). The main finding of the present study indicates that supplementation with creatine in young soccer players improved soccer-specific skill performance compared with ingestion of placebo.
Article
Creatine phosphate allows high rates of adenosine triphosphate resynthesis to occur in muscle and therefore plays a vital role in the performance of high-intensity exercise. Recent studies have shown that feeding large amounts of creatine (typically 20 g per day for 5 days) increases muscle total creatine (and phosphocreatine) content. The extent of the increase that is normally observed is inversely related to the presupplementation level. Vegetarians, who have a very low dietary creatine intake, generally show the largest increases. Creatine supplementation has been shown to increase performance in situations where the availability of creatine phosphate is important; thus, performance is improved in very high-intensity exercise and especially where repeated sprints are performed with short recovery periods. Creatine supplementation is widely practiced by athletes in many sports and does not contravene current doping regulations. There are no reports of harmful side effects at the recommended dosage.
Article
This study aimed to compare the effects of oral creatine (Cr) supplementation with creatine supplementation in combination with caffeine (Cr+C) on muscle phosphocreatine (PCr) level and performance in healthy male volunteers (n = 9). Before and after 6 days of placebo, Cr (0.5 g x kg-1 x day-1), or Cr (0.5 g x kg-1 x day-1) + C (5 mg x kg-1 x day-1) supplementation, 31P-nuclear magnetic resonance spectroscopy of the gastrocnemius muscle and a maximal intermittent exercise fatigue test of the knee extensors on an isokinetic dynamometer were performed. The exercise consisted of three consecutive maximal isometric contractions and three interval series of 90, 80, and 50 maximal voluntary contractions performed with a rest interval of 2 min between the series. Muscle ATP concentration remained constant over the three experimental conditions. Cr and Cr+C increased (P < 0.05) muscle PCr concentration by 4-6%. Dynamic torque production, however, was increased by 10-23% (P < 0.05) by Cr but was not changed by Cr+C. Torque improvement during Cr was most prominent immediately after the 2-min rest between the exercise bouts. The data show that Cr supplementation elevates muscle PCr concentration and markedly improves performance during intense intermittent exercise. This ergogenic effect, however, is completely eliminated by caffeine intake.
Article
Creatine supplementation has become a common practice among competition athletes participating in different sports over the last few years. The mechanism by which supplementary creatine could have potential ergogenic effects would be an increased muscle creatine and phosphocreatine concentration, leading to a higher rate of ATP resynthesis, a delay in the onset of muscular fatigue and a facilitated recovery during repeated bouts of high-intensity exercise. A critical review of the literature reveals that these ergogenic effects, when found, have been generally shown in untrained subjects performing several exercise bouts under laboratory conditions. The limited body of scientific data available concerning highly trained athletes performing single competition-like exercise tasks indicates that this type of population does not benefit from creatine supplementation. Therefore, the widespread use of creatine ingestion to improve competition performance does not seem to be justified. The potential interest of creatine supplementation for elite athletes could be related to an increased ability to perform repeated high-intensity exercise bouts, either during training or during competition in sports in which repeated efforts are required (e.g. soccer, basketball), but this possibility needs scientific confirmation.
Article
To critically review the current data concerning potential safety concerns of oral creatine supplementation. Medline was searched using keywords to locate published works relating to creatine supplementation and adverse effects. Abstracts that specifically studied potential adverse effects of creatine were also utilized, as were human and animal studies of creatine metabolism in various organ systems. Specific data from studies that investigated creatine's side effects and metabolism were grouped by organ system to better describe potential safety issues. Creatine supplementation results in weight gain due to water retention, which may impede performance in mass-dependent activities such as running and swimming. Although short-term use (fewer than 28 days) at recommended does has not been shown to cause significant adverse effects, the studies on which this is based involved small numbers of subjects, and none of the studies provided a sample size calculation. Furthermore, despite the fact that creatine is normally found in cardiac muscle, brain, and testes, these areas remain essentially unstudied with respect to oral creatine supplementation. Future studies should include large randomized controlled trials evaluating the short and long term effects of oral creatine supplementation on the renal and hepatic systems, as well as the many other organ systems in which creatine plays a metabolic role.
Article
To review and summarize the current data on oral creatine supplementation regarding its potential efficacy in athletic performance, mechanism of action, and metabolism. Medline was searched using terms relating creatine supplementation to athletic performance. Studies that evaluated the effects of oral creatine supplementation on exercise performance in humans were selected for inclusion. Selected studies on muscle metabolism and exercise physiology were included if they provided useful information relative to creatine. Additional references were reviewed from the bibliographies of selected studies. To summarize efficacy, extracted data were listed in table format, grouping studies together by type of activity and efficacy on performance. Whenever possible, the effect of creatine supplementation was quantified. Proposed explanations for creatine's efficacy or lack thereof in a particular type of activity were formulated. In laboratory settings, creatine supplementation is ergogenic in repeated 6-30-second bouts of maxima stationary cycling sprints. The data on a single sprint or first-bout sprint of any kind are inconsistent. The data regarding creatine's ergogenic effects on mass-dependent activities, such as running and swimming, are not convincing, perhaps because of the side effect of weight gain from water retention. Studies on weight lifting suggest that creatine improves strength possibly by increasing myofibrillar protein synthesis however, more study is needed to prove this. No ergogenic effects on submaximal or endurance exercise are evident Individual response to creatine supplementation can vary greatly.
Article
To describe patterns of creatine use in select Division I collegiate athletes based on recommended dosages according to body weight. Further, to report the perceived effects noted with creatine supplementation. Anonymous open-ended self-report descriptive questionnaire. National Collegiate Athletic Association Division I institution. Two-hundred and nineteen male and female collegiate athletes representing eight varsity sports. An open-ended questionnaire was administered to determine patterns of creatine use during the loading and maintenance phases of this nutritional supplement. In addition, perceived positive, negative, and no effects associated with creatine usage patterns were determined from athlete responses on this self-report measure. Considering this select group of collegiate athletes, highly variable patterns of creatine supplementation were noted for loading/maintenance phases based on recommended dosages/days and body weight. Of the 219 athletes surveyed, 90 (41%) reported using creatine, while creatine supplementation was more prevalent among men than women. Creatine users (80 athletes, 89%) reporting perceived positive effects were primarily at or below recommended dosages for the loading phase but above recommended dosages in the maintenance phase. Creatine users (34 athletes, 38%) reporting perceived negative effects were primarily at or below recommended dosages in the loading phase but noticeably above recommended dosages in the maintenance phase. Ironically, all creatine users who reported negative side effects also reported positive effects. Creatine users (10 athletes, 11%) reporting no effects were below recommended loading dosages but above recommended maintenance dosages. The perceived positive effects noted support current research (strength/weight gains), while the perceived negative effects (cramping/gastrointestinal distress) were consistent with anecdotal reports surrounding creatine supplementation. Apparently, collegiate athletes in this study are in need of education regarding the proper use of creatine supplementation. Additional studies are needed to ascertain creatine supplementation patterns of collegiate athletes in various settings.
Article
Competitive athletes, including adolescents, seek ways to gain advantage over competitors. One ergogenic aid is creatine, a naturally occurring nitrogen compound found primarily in skeletal muscle. Increasing creatine levels may prolong skeletal muscle activity, enhancing work output. A questionnaire assessing awareness and use of creatine supplementation was completed by 674 athletes from 11 high schools. Data were statistically analyzed to determine variation among groups. Of those surveyed, 75% had knowledge of creatine supplements, and 16% used creatine to enhance athletic performance. Percentage of use increased with age and grade level. Awareness and use were greater among boys than girls. Adverse effects were reported by 26%. Most athletes consumed creatine using a method inconsistent with scientific recommendations. Use of creatine by adolescent athletes is significant and inconsistent with optimal dosing. Physicians, athletic trainers, and coaches should disseminate proper information and advise these adolescent athletes.
Article
Creatine is a nutritional supplement that is purported to be a safe ergogenic aid in adults. Although as many as 28% of collegiate athletes admit taking creatine, there is little information about creatine use or potential health risk in children and adolescents. Although the use of creatine is not recommended in people less than 18 years of age, numerous anecdotal reports indicate widespread use in young athletes. The purpose of this study was to determine the frequency, risk factors, and demographics of creatine use among middle and high school student athletes. Before their annual sports preparticipation physical examinations, middle and high school athletes aged 10 to 18 in Westchester County, a suburb north of New York City, were surveyed in a confidential manner. Information was collected regarding school grade, gender, specific sport participation, and creatine use. Overall, 62 of 1103 participants (5.6%) admitted taking creatine. Creatine use was reported in every grade, from 6 to 12. Forty-four percent of grade 12 athletes surveyed reported using creatine. Creatine use was significantly more common (P <.001) among boys (53/604, 8.8%) than girls (9/492, 1.8%). Although creatine was taken by participants in every sport, use was significantly more common among football players, wrestlers, hockey players, gymnasts, and lacrosse players (P <.001 for all). The most common reasons cited for taking creatine were enhanced performance (74.2% of users) and improved appearance (61.3%), and the most common reason cited for not taking creatine was safety (45.7% of nonusers). Despite current recommendations against use in adolescents less than 18 years old, creatine is being used by middle and high school athletes at all grade levels. The prevalence in grades 11 and 12 approaches levels reported among collegiate athletes. Until the safety of creatine can be established in adolescents, the use of this product should be discouraged.
Article
The purpose of this study was to examine the effects of acute creatine-monohydrate supplementation on soccer-specific performance in young soccer players. Twenty young male soccer players (16.6 +/- 1.9 years) participated in the study and were matched and allocated to 2 randomly assigned trials: ingesting creatine-monohydrate supplement (3 x 10-g doses) or placebo for 7 days. Before and after the supplementation protocol, each subject underwent a series of soccer-specific skill tests: dribble test, sprint-power test, endurance test, and vertical jump test. Specific dribble test times improved significantly in the creatine group (13.0 +/- 1.5 vs. 10.2 +/- 1.8 s; p < .05) after supplementation protocol. Sprint-power test times were significantly improved after creatine-monohydrate supplementation (2.7 +/- 0.4 vs. 2.2 +/- 0.5 s; p < .05) as well as vertical jump height (49.2 +/- 5.9 vs. 55.1 +/- 6.3 cm; p < .05) in creatine trial. Furthermore, dribble and power test times, along with vertical jump height, were superior in creatine versus placebo trial (p < .05) at post-supplementation performance. There were no changes in specific endurance test results within or between trials (p > .05). There were no between-trial differences in the placebo trial (p > .05). The main finding of the present study indicates that supplementation with creatine in young soccer players improved soccer-specific skill performance compared with ingestion of placebo.
Article
This review focuses on the potential side effects caused by oral creatine supplementation on gastrointestinal, cardiovascular, musculoskeletal, renal and liver functions. No strong evidence linking creatine supplementation to deterioration of these functions has been found. In fact, most reports on side effects, such as muscle cramping, gastrointestinal symptoms, changes in renal and hepatic laboratory values, remain anecdotal because the case studies do not represent well-controlled trials, so no causal relationship between creatine supplementation and these side-effects has yet been established. The only documented side effect is an increase in body mass. Furthermore, a possibly unexpected outcome related to creatine monohydrate ingestion is the amount of contaminants present that may be generated during the industrial production. Recently, controlled studies made to integrate the existing knowledge based on anecdotal reports on the side effects of creatine have indicated that, in healthy subjects, oral supplementation with creatine, even with long-term dosage, may be considered an effective and safe ergogenic aid. However, athletes should be educated as to proper dosing or to take creatine under medical supervision.
Article
The purpose of this study was to determine the effect of long-term Cr supplementation on blood parameters reflecting liver and kidney function. Twenty-three members of an NCAA Division II American football team (ages = 19-24 years) with at least 2 years of strength training experience were divided into a Cr monohydrate group (CrM, n = 10) in which they voluntarily and spontaneously ingested creatine, and a control group (n = 13) in which they took no supplements. Individuals in the CrM group averaged regular daily consumption of 5 to 20 g (mean SD = 13.9 5.8 g) for 0.25 to 5.6 years (2.9 1.8 years). Venous blood analysis for serum albumin, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, urea, and creatinine produced no significant differences between groups. Creatinine clearance was estimated from serum creatinine and was not significantly different between groups. Within the CrM group, correlations between all blood parameters and either daily dosage or duration of supplementation were nonsignificant. Therefore, it appears that oral supplementation with CrM has no long-term detrimental effects on kidney or liver functions in highly trained college athletes in the absence of other nutritional supplements.
Oral creatine supplementation in male collegiate athletes: A survey of dosing habits and side effects
  • Ms Juhn
  • O Kane
  • Dm Vinci
Oral creatine supplementation and athletic performance: A critical review
  • M Juhn
  • M Tarnopolsky
Juhn M, Tarnopolsky M (1998a) Oral creatine supplementation and athletic performance: A critical review. Clinical Journal of Sports Medicine 8: 286-297.