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The Effect of 7 Days of Creatine Supplementation on 24-Hour Urinary Creatine Excretion
Abstract
Since the discovery that oral ingestion of creatine leads to an increase in intramuscular creatine, its supplementation has become widespread. However, the dosage necessary to maximize retention and create significant increases in intramuscular creatine is poorly understood. In this study, 24-hour urinary creatine and creatinine levels of 20 university men's football players and 20 university men's hockey players involved in a resistance-exercise program and supplementing with creatine were collected and analyzed. In a double-blind, randomized design, 10 football players and 10 hockey players were randomly assigned to either the supplement or placebo group. Subjects provided a 24-hour urine sample twice during the study: once prior to supplementation (baseline) and the second 7 days after daily supplementation and resistance exercise. Creatine dosage was 0.1 g x kg(-1) lean body mass. The quantity of creatine ingested was compared with the amount excreted in the urine of those subjects supplementing with creatine and with placebo. Creatinine levels were compared between the first and second urine collection and between groups. Creatine and creatinine concentrations were determined using high-performance liquid chromatography. In 24-hours, 46% of the ingested creatine was excreted. There was no change in creatine levels for placebo subjects. Creatinine levels remained the same within groups at the first and second collection times (p < 0.05). Our findings indicate that when supplementing with dosages of 0.1 g x kg(-1) lean body mass or between 6 and 8 g at a time, approximately half of the ingested creatine gets excreted. Because there was no change in urinary creatinine, it can be assumed that enhanced degradation of creatine did not occur.
... Previous data have shown that the absorption of creatine from the alimentary tract is complete, with no evidence of degradation or bacterial destruction (Chanutin, 1926; Deldicque et al., 2008; Rose & Dimmitt, 1916). Burke and colleagues (Burke, Smith-Palmer, Holt, Head, & Chilbeck, 2001) have shown that *46% of ingested creatine was excreted when supplementing with doses of 0.1 g Á kg 71 lean body mass (between 6 and 8 g of creatine monohydrate ). However, the proportion excreted rises with continued supplementation as less and less is retained in the muscle stores (Harris et al., 1992), with almost 100% of the dose administered excreted after several days of supplementation (Chanutin, 1926 ). ...
... Creatine excretion with 20 6 1 g Á day 71 was 49% of the ingested creatine monohydrate, which was significantly lower than the 62% excreted with 4 6 5 g Á day 71 . Previous studies have reported 24-h urinary creatine excretion to be 46% of the ingested creatine monohydrate (Burke et al., 2001). Although lower than that with the 4 6 5 g Á day 71 regime, it is, however, close to the value for the 20 6 1 g Á day 71 regime. ...
... The data from the present study are based on excretion over 5 days of supplementation . In addition, the participants in the study of Burke et al. (2001) participated in a resistance exercise-training programme during the period of supplementation, which might explain the slightly lower urinary creatine excretion than was observed in the present study. Steenge et al. (2000) also examined whole-body creatine retention following creatine monohydrate supplementation in 4 6 5 g Á day 71 doses. ...
In this study, we examined the effect of two creatine monohydrate supplementation regimes on 24-h urinary creatine and methylamine excretion. Nine male participants completed two trials, separated by 6 weeks. Participants ingested 4 x 5 g x day(-1) creatine monohydrate for 5 days in one trial and 20 x 1 g x day(-1) for 5 days in the other. We collected 24-h urine samples on 2 baseline days (days 1-2), during 5 days of supplementation (days 3-7), and for 2 days post-supplementation (days 8-9). Urine was assayed for creatine using high-performance liquid chromatography and methylamine using gas chromatography. Less creatine was excreted following the 20 x 1 g x day(-1) regime (49.25 +/- 10.53 g) than the 4 x 5 g x day(-1) regime (62.32 +/- 9.36 g) (mean +/- s; P < 0.05). Mean total excretion of methylamine (n = 6) over days 3-7 was 8.61 +/- 7.58 mg and 24.81 +/- 25.76 mg on the 20 x 1 g x day(-1) and 4 x 5 g x day(-1) regimes, respectively (P < 0.05). The lower excretion of creatine using 20 x 1 g x day(-1) doses suggests a greater retention in the body and most probably in the muscle. Lower and more frequent doses of creatine monohydrate appear to further attenuate formation of methylamine.
... After the initial screening of abstracts and titles, 408 articles were excluded. Two additional studies were identified through the manual search of retrieved fulltext articles (Bassit et al., 2010;Machado et al., 2009); overall, eighteen full-text articles were identified for further assessment Creatine and Exercise Recovery 3 (Bassit et al., 2008(Bassit et al., , 2010Basta et al., 2006;Boychuk et al., 2016;Burke et al., 2001;Cooke et al., 2009;Deminice et al., 2013;Machado et al., 2009;McKinnon et al., 2012;Rawson et al., 2001Rawson et al., , 2007Rosene et al., 2009;Santos et al., 2004;Silva et al., 2013;Taylor et al., 2018;Veggi et al., 2013;Volek et al., 2004;Wang et al., 2018). Of these, five were excluded (Burke et al., 2001;Deminice et al., 2013;Rosene et al., 2009;Silva et al., 2013;Volek et al., 2004) for various reasons (Figure 1), and thirteen were deemed eligible for the systematic review and meta-analysis ( Figure 1; Tables 1 and 2). ...
... Two additional studies were identified through the manual search of retrieved fulltext articles (Bassit et al., 2010;Machado et al., 2009); overall, eighteen full-text articles were identified for further assessment Creatine and Exercise Recovery 3 (Bassit et al., 2008(Bassit et al., , 2010Basta et al., 2006;Boychuk et al., 2016;Burke et al., 2001;Cooke et al., 2009;Deminice et al., 2013;Machado et al., 2009;McKinnon et al., 2012;Rawson et al., 2001Rawson et al., , 2007Rosene et al., 2009;Santos et al., 2004;Silva et al., 2013;Taylor et al., 2018;Veggi et al., 2013;Volek et al., 2004;Wang et al., 2018). Of these, five were excluded (Burke et al., 2001;Deminice et al., 2013;Rosene et al., 2009;Silva et al., 2013;Volek et al., 2004) for various reasons (Figure 1), and thirteen were deemed eligible for the systematic review and meta-analysis ( Figure 1; Tables 1 and 2). ...
This systematic review and meta-analysis examined the effects of creatine supplementation on recovery from exercise-induced muscle damage, and is reported according to the PRISMA guidelines. MEDLINE and SPORTDiscus were searched for articles from inception until April 2020. Inclusion criteria were adult participants (≥18 years); creatine provided before and/or after exercise versus a noncreatine comparator; measurement of muscle function recovery, muscle soreness, inflammation, myocellular protein efflux, oxidative stress; range of motion; randomized controlled trials in humans. Thirteen studies (totaling 278 participants; 235 males and 43 females; age range 20–60 years) were deemed eligible for analysis. Data extraction was performed independently by both authors. The Cochrane Collaboration Risk of Bias Tool was used to critically appraise the studies; forest plots were generated with random-effects model and standardized mean differences. Creatine supplementation did not alter muscle strength, muscle soreness, range of motion, or inflammation at each of the five follow-up times after exercise (<30 min, 24, 48, 72, and 96 hr; p > .05). Creatine attenuated creatine kinase activity at 48-hr postexercise (standardized mean difference: −1.06; 95% confidence interval [−1.97, −0.14]; p = .02) but at no other time points. High (I ² ; >75%) and significant (Chi ² ; p < .01) heterogeneity was identified for all outcome measures at various follow-up times. In conclusion, creatine supplementation does not accelerate recovery following exercise-induced muscle damage; however, well-controlled studies with higher sample sizes are warranted to verify these conclusions. Systematic review registration (PROSPERO CRD42020178735).
... The calculated size of the creatine pools is likely an under-estimation because of loss/excretion of some of the bolus tracer creatine in the urine prior to mixing in the entire pool. This is particularly true following creatine supplementation (Harris et al. 1992;Burke et al. 2001;Rawson et al. 2004) when the concentration of creatine in the plasma was high. Previous data in the literature show that as much as 30-40 % of the creatine supplement is excreted in the urine (Harris et al. 1992;Burke et al. 2001). ...
... This is particularly true following creatine supplementation (Harris et al. 1992;Burke et al. 2001;Rawson et al. 2004) when the concentration of creatine in the plasma was high. Previous data in the literature show that as much as 30-40 % of the creatine supplement is excreted in the urine (Harris et al. 1992;Burke et al. 2001). We could not correct for this loss because we had not obtained timed urine collections. ...
Creatine kinetics were measured in young healthy subjects, eight males and seven females, age 20-30 years, after an overnight fast on creatine-free diet. Whole body turnover of glycine and its appearance in creatine was quantified using [1-(13)C] glycine and the rate of protein turnover was quantified using L-ring [(2)H5] phenylalanine. The creatine pool size was estimated by the dilution of a bolus [C(2)H3] creatine. Studies were repeated following a five days supplement creatine 21 g.day(-1) and following supplement amino acids 14.3 g day(-1). Creatine caused a ten-fold increase in the plasma concentration of creatine and a 50 % decrease in the concentration of guanidinoacetic acid. Plasma amino acids profile showed a significant decrease in glycine, glutamine, and taurine and a significant increase in citrulline, valine, lysine, and cysteine. There was a significant decrease in the rate of appearance of glycine, suggesting a decrease in de-novo synthesis (p = 0.006). The fractional and absolute rate of synthesis of creatine was significantly decreased by supplemental creatine. Amino acid supplement had no impact on any of the parameters. This is the first detailed analysis of creatine kinetics and the effects of creatine supplement in healthy young men and women. These methods can be applied for the analysis of creatine kinetics in different physiological states.
... Para a determinação das concentrações de creatinina foram feitas coletas de urina de 24 horas no momento pré e pós-suplementação. A coleta de urina de 24 horas foi iniciada a partir da segunda micção de um determinado dia, prolongando-se até a primeira do dia seguinte (Burke et al., 2001;Rawson et al., 2004). Após o volume urinário total ser registrado, uma alíquota de 5-10 mL foi separada em frascos coletores de urina de plástico e, em seguida, armazenada em congelador a -70º C. As amostras de urina foram analisadas 48 horas após as coletas. ...
... Assim, a maioria dos estudos tem utilizado coletas de urina de 24 horas para determinar as concentrações de creatinina urinária. Diferente dos nossos achados, esses estudos têm encontrado taxas de excreção de creatinina significativamente aumentadas após a suplementação com creatina Burke et al., 2001;Havenetidis et al., 2002;Rawson et al., 2002;Havenetidis, Bourdas, 2003;Mendes et al., 2004;Rawson et al., 2004). Esse efeito tem sido atribuído à maior oferta de creatina ao organismo. ...
Este estudo investigou o efeito de um longo período de suplementação com creatina monoidratada (Crm) sobre o trabalho total relativo (TTR) em esforços intermitentes máximos no cicloergômetro de homens treinados. Vinte seis indivíduos foram divididos aleatoriamente em grupo creatina (CR, n=13) e grupo placebo (PL, n=13). Os sujeitos receberam em sistema duplo-cego, doses de Crm ou placebo-maltodextrina (20 g.d-1 por 5 dias e 3 g.d-1 durante 51 dias subseqüentes). Os grupos tiveram seus hábitos alimentares e sua condição física previamente controlados. Para determinação do TTR os sujeitos foram submetidos a protocolo de exercício em cicloergômetro composto de três Testes de Wingate de 30s separados por dois minutos recuperação, antes e após o período de suplementação. ANOVA, seguido pelo teste post hoc de Tukey, quando p<0,05, foi usado para tratamento dos dados. Observou-se efeito significante do tempo para o TTR (F1,24=8,00; p<0,05), com o grupo Cr apresentando aumento significante na produção de TTR comparado ao grupo PL após o período de suplementação (690,54 ± 46,83 vs 655,71 ± 74,34 J.kg-1 respectivamente; p<0,05). Os resultados do presente estudo sugerem que a suplementação de Crm melhora o desempenho físico em esforços repetidos de alta intensidade e curta duração.
... Para a determinação das concentrações de creatinina foram feitas coletas de urina de 24 horas no momento pré e pós-suplementação. A coleta de urina de 24 horas foi iniciada a partir da segunda micção de um determinado dia, prolongando-se até a primeira do dia seguinte (Burke et al., 2001;Rawson et al., 2004). Após o volume urinário total ser registrado, uma alíquota de 5-10 mL foi separada em frascos coletores de urina de plástico e, em seguida, armazenada em congelador a-70º C. As amostras de urina foram analisadas 48 horas após as coletas. ...
... Assim, a maioria dos estudos tem utilizado coletas de urina de 24 horas para determinar as concentrações de creatinina urinária. Diferente dos nossos achados, esses estudos têm encontrado taxas de excreção de creatinina significativamente aumentadas após a suplementação com creatina Burke et al., 2001;Havenetidis et al., 2002;Rawson et al., 2002;Havenetidis, Bourdas, 2003;Mendes et al., 2004;Rawson et al., 2004). Esse efeito tem sido atribuído à maior oferta de creatina ao organismo. ...
This study investigated the effect of long-term supplementation with creatine monohydrate (Crm) on relative total work (RTW) in intermittent maximal efforts in the cycle ergometer of trained men. Twenty six individuals, were randomly divided in creatine group (CR, n=13) and placebo group (PL, n=13). The subjects received in a double-blind manner, doses of Crm or placebo-maltodextrin (20 g.d-1 for 5 days and 3 g.d-1 for 51 subsequent days). The groups had their alimentary habits and physical fitness controlled previously. For determination of the RTW the subjects were submitted to exercise protocol in cycle ergometer comprised three 30s Anaerobic Wingate Test interspersed with two minutes recovery, before and after the supplementation period. ANOVA, followed by the Tukey post hoc test, when p<0.05, were used for data treatment. There was a significant time effect for RTW (F1,24=8.00; p<0.05), with the CR group demonstrating significant greater (3%) on the RTW production compared to PL group after the supplementation period (690.54 46.83 vs 655.71 74.34 J.kg-1 respectively; p<0.05). The results of the present study suggest that Crm supplementation improve the performance in repeated efforts of high intensity and short duration.
... Outra consideração relativa à dosagem de creatina é basear a quantidade sobre a massa magra do corpo de um indivíduo. Burke et al. (2001) estudou este aspecto da suplementação de creatina ao ter sujeitos ingerem creatina na dosagem de 0,1 g/kg de massa magra (isto equivale a aproximadamente 8 g de creatina para um indivíduo de 200 libras a 15% de gordura corporal). Hultman et al. (1996) demonstraram outra abordagem interessante para a ingestão de creatina. ...
O jejum é a abstenção de consumir alimentos e bebidas por um determinado tempo. Tanto os sistemas de saúde tradicionais quanto os modernos usam jejuns como forma de ajudar a gerenciar doenças crônicas não infecciosas. Durante o jejum, a atividade aumenta a lipólise do tecido adiposo (queima de gordura na gordura adiposa) enquanto aumenta a oxidação de ácidos graxos nos órgãos periféricos, o que aumenta a queima de gordura e a perda de peso. A principal coisa que esta análise estava investigando é se o treinamento de resistência realizado em jejum induz adaptações específicas no treinamento, em que o aumento da oxidação de gordura melhora os níveis de treinamento de resistência a longo prazo. Alguns dados mostram que o jejum tem uma influência mais ampla no metabolismo corporal tanto em indivíduos não treinados quanto treinados, afetando o metabolismo de proteínas e glicose. Há informações conflitantes sobre como o jejum afeta o metabolismo da glicose em atletas altamente treinados, e o impacto no desempenho também não é claro (alguns dizem que tem um impacto negativo, outros dizem que não há efeito significativo). O jejum diminui o peso corporal de indivíduos treinados e não treinados, juntamente com o teor de gordura. Há pouca evidência de que o treinamento de resistência e o jejum juntos aumentam a oxidação da gordura, pois muitos estudos têm resultados conflitantes. Embora existam diferenças nos detalhes dos experimentos, como a gravidade da restrição calórica, quanto tempo durou o experimento e quem eram os participantes. Em nossa revisão da literatura, sugerimos que os atletas não devem fazer treinamento de alta intensidade em jejum.
... Outra consideração relativa à dosagem de creatina é basear a quantidade sobre a massa magra do corpo de um indivíduo. Burke et al. (2001) estudou este aspecto da suplementação de creatina ao ter sujeitos ingerem creatina na dosagem de 0,1 g/kg de massa magra (isto equivale a aproximadamente 8 g de creatina para um indivíduo de 200 libras a 15% de gordura corporal). Hultman et al. (1996) demonstraram outra abordagem interessante para a ingestão de creatina. ...
O jejum é a abstenção de consumir alimentos e bebidas por um determinado tempo. Tanto os sistemas de saúde tradicionais quanto os modernos usam jejuns como forma de ajudar a gerenciar doenças crônicas não infecciosas. Durante o jejum, a atividade aumenta a lipólise do tecido adiposo (queima de gordura na gordura adiposa) enquanto aumenta a oxidação de ácidos graxos nos órgãos periféricos, o que aumenta a queima de gordura e a perda de peso. A principal coisa que esta análise estava investigando é se o treinamento de resistência realizado em jejum induz adaptações específicas no treinamento, em que o aumento da oxidação de gordura melhora os níveis de treinamento de resistência a longo prazo. Alguns dados mostram que o jejum tem uma influência mais ampla no metabolismo corporal tanto em indivíduos não treinados quanto treinados, afetando o metabolismo de proteínas e glicose. Há informações conflitantes sobre como o jejum afeta o metabolismo da glicose em atletas altamente treinados, e o impacto no desempenho também não é claro (alguns dizem que tem um impacto negativo, outros dizem que não há efeito significativo). O jejum diminui o peso corporal de indivíduos treinados e não treinados, juntamente com o teor de gordura. Há pouca evidência de que o treinamento de resistência e o jejum juntos aumentam a oxidação da gordura, pois muitos estudos têm resultados conflitantes. Embora existam diferenças nos detalhes dos experimentos, como a gravidade da restrição calórica, quanto tempo durou o experimento e quem eram os participantes. Em nossa revisão da literatura, sugerimos que os atletas não devem fazer treinamento de alta intensidade em jejum.
... After 6 days of loading, Cr stores in the muscles seems to be filled up. Afterwards, it is necessary to take only 2-5 g of CrMH daily as a single dose (or 0.03 g/kg) in order to maintain higher Cr stores levels[87,89](Figure 4). This mode of supplementation may promote fast ergogenic effect. ...
Creatine is one of the best-known and most studied ergogenic supplements among athletes. Besides its performance-enhancing power, creatine has significant clinical potential in patients with neurological and neuromuscular diseases. The most frequently used form of creatine is creatine monohydrate. The utilization of creatine monohydrate seems to be somewhat limited due to its physico-chemical characteristics such as poor water solubility, instability in aqueous solutions (because of its tendency to cyclize into biologically inactive creatinine), and finite capacity of creatine transporters. Therefore, the pharmaceutical industry strives to develop novel forms of creatine that will diminishor overcome aforementioned limitations. New formulations of creatine seem to appear inthe market on a daily basis while no sufficient research is conducted regarding their physico-chemical characteristics and safety in humans. In this chapter, authors reviewed recent literature on advanced creatine formulations (e.g., creatine salts, chelates, estersand alkaline buffered forms). The purpose and goal for the use of new creatine formulations have been discussed as well as their advantages and disadvantages compared to creatine monohydrate
... However, this absolute dosing may not be the best method since creatine uptake will most likely vary in regards to differences in muscle mass. Instead, a relative amount should be employed, based on either total body mass or fat-free mass, and adjusted accordingly throughout creatine supplementation (Burke et al., 2001;Hultman, Soderlund, Timmons, Cederblad & Greenhaff, 1996). ...
Thesis Chairperson: Darryn S. Willoughby, Ph.D. Creatine monohydrate has become one of the most popular ingested nutritional supplements used for its potential to enhance athletic performance. Numerous creatine formulations have been developed to maximize creatine absorption, and may also provide a means to either partially bypass or up-regulate the function of creatine transporter-1 (CreaT1). Cinnamon extract (Cinnulin TM) has been observed to mimic the effects of insulin, thereby up-regulating glucose uptake and insulin signaling. This study examined how a seven-week supplementation regimen with creatine monohydrate combined with Cinnulin TM (CCI), creatine monohydrate (CR), or placebo (PLA) affected physiological and molecular adaptations in nonresistance-trained males following a prescribed resistance-training program. Results demonstrated that Cinnulin TM combined with creatine monohydrate elicited greater mean increases in relative 1-RM leg press, thigh lean mass, body water, and total Akt protein content when compared to creatine monohydrate alone, or placebo; however, intramuscular creatine increases between the CCI and CR groups demonstrated no significant differences.
... It was proved that supplementation of CR increases the quantity of CR in muscle cells (Walker, 1979). Therefore, in accordance with literature findings (e.g., Burke, Smith-Palmer, Holt, Head, & Chilibeck, 2001), we can suppose that supplemented CR is partly metabolized in another way and not via CR dehydration and creatinine formation. Nevertheless, it is not possible to increase the amount of CR in the body over a certain limit. ...
Simple voltammetric determination of thiodiglycolic acid (TDGA) offers the possibility to follow individual deviations in metabolism of thiocompounds and one-carbon (1c) and two-carbon (2c) units, which take part in endogenous synthesis of creatine (CR). In three groups of young men the levels of TDGA in urine were followed after application of CR given as food supplement in 5 g daily doses. In the first group (7 men) it was found that the level of TDGA increased independently of the day time of application of CR. In the second group (9 men) the level of TDGA increased within an interval of 3–8.5 h after CR application and then dropped during 2 h to the normal level (20 mg L−1). In the third group (11 men), in 4 days’ study the effects of CR were compared in alternation to vitamin B12. Vitamin B12 was given in the evening of the 1st and 3rd day and CR in the morning of the 3rd and 4th day. CR increased the excretion of TDGA in all men, while B12 only in four men independently of CR application.
... Creatinuria is seen during CR supplementation and is a direct reflection of elevated CR levels in the plasma. It is well documented that a major fraction of ingested CR is excreted shortly after ingestion (Burke et al., 2001). The plasma was sampled on the morning of the sixth day of the study, approximately 12 hours after the last dose of CR was ingested. ...
The purpose of this study was to examine the effect of a 5-day creatine (CR) supplementation period on red blood cell (RBC) CR uptake in vegetarian and nonvegetarian young women. Blood samples were collected from lacto-ovo vegetarians (VG, n = 6, age 21.8 +/- 1.9 yrs) and nonvegetarians (NV, n = 6, age 21.7 +/- 1.9 yrs) before and after a 5-day CR loading period (0. 3g CR/kg lean body mass/day), and from a control group of nonvegetarians (NV, n = 5, age 22.0 +/- 0.7 yrs) who did not supplement with creatine. RBC and plasma samples were analyzed for the presence of creatine. Significant increases (p < .05) in RBC and plasma CR levels were found for vegetarians and nonvegetarians following supplementation. The initial RBC CR content was significantly lower (p < .05) in the vegetarian group. There was no significant difference between vegetarians and nonvegetarians in final RBC CR content, suggesting that a ceiling had been reached. As the uptake into both muscle and RBC is moderated by creatine transporter proteins, analysis of the uptake of CR into RBC may reflect the uptake of CR into muscle, offering an alternative to biopsies.
... The body breaks down about 1 – 2% of the creatine pool per day (about 1–2 grams/day) into creatinine in the skeletal muscle [13]. The creatinine is then excreted in urine [13,16]. Creatine stores can be replenished by obtaining creatine in the diet or through endogenous synthesis of creatine from glycine, arginine, and methionine [17,18]. ...
Position Statement: The following nine points related to the use of creatine as a nutritional supplement constitute the Position Statement of the Society. They have been approved by the Research Committee of the Society .
One of the most common-sought after goals in athletic performance is attaining and maintaining muscle mass. From protein to creatine, arginine to human growth hormone, how is one to determine what really works, what is legitimate, and what is merely another gimmick in the supplement industry? Coupling the array of supplements with the unique performance needs of an athlete creates an infinite amount of possible combinations. How do you know what is the right combination for successfully building the desired amount of muscle mass, maintaining an “optimal” body composition, and (during periods when additional body mass is desired) ensuring lean mass is gained over fat mass? It is with great time, research, and a foundation laid for us by our predecessors in the field of sports nutrition that we write this chapter on muscle building and optimizing lean body mass. By the end of this chapter you should be able to:
Describe the muscle building process
Define and determine net protein balance
Describe how genetics play a role in muscle growth
Know the recommended amounts of protein for gaining muscle
Know the suggested protein: carbohydrate ratio for optimal muscle hypertrophy
Define nutrient timing and its role in muscle hypertrophy
Explain the difference between whey, casein, egg, soy, and vegan protein supplements
Explain why and when supplementing with BCAAs are important to muscle growth
Explain the major hormones that play a role in muscle growth
Explain the potential benefits and drawbacks of anabolic steroids
Define the role of IGF in muscle growth
Describe the creatine-phosphate system and why creatine is used for muscle hypertrophy
Explain why supplements that promote the production of nitric oxide are used by athletes
Explain how resistance training stimulates muscle hypertrophy
The intake of supplements with creatin monohydrate in high performance athletes has been used to stimulate or increase ergogenic capacity in high-intensity, short-duration exercise. However, the increase in performance has not been sufficiently demonstrated and its use has been the source of undesirable effects. Material and methods. Twenty-eight high performance rugby players, with an average age of 26.31 ± 3.48, were studied. Of these, 22 (Group A) ingested doily, for one week, 20 gr. of creatin, followed by a maintenance dosis of 5 to 10 gr./day for 30-60 days. The remaining 6 players (Group B) did not receive any supplement. The modified Anthropometric Fractioning method was used to make the evaluation, which allows for the classification of the organism in 5 components: Fat Mass (FM), Skeletal Mass (SM), Muscular Mass (MM), Visceral Mass (VM) and Residual Mass (RM). Twenty-five body surface measurements were taken (7 fat folds, 8 bone diameters, 7 girths, standing and seated measurements and body weight). The data was then processed with the ENFA™ program. Body mass and caloricproteic reserve (CR and PR) were evaluated (NV = 0.85-1.47 and 2.15-2.72, respectively), and muscular mass was correlated with skeletal mass in the total of the studied population (r) and (p). The remaining data was treated statistically by a "t" test, with a p ≤ 0.05 taken as significant. Results: The comparative values for both groups (A vs. B) are: MM (41.03 ± 5.23 vs. 40.42 ± 5.15 Kg.)(p = 0.80); SM (16.67 ± 2.09 vs. 16.96 ± 2.14 Kg.) (p = 0.76); FM (10.78 ± 3.21 vs. 10.34 ± 2.92 Kg.) (p = 0.76); VM (19.73 ± 3.23 vs. 19.83 ± 2.05 Kg.)(p = 0.94); RM (8.52 ± 2.3 vs. 3.52 ± 1.27 Kg.) (p = 0.000); CR (0.64 ± 0.18 vs. 0.61 ± 0.17) (p = 0.71); PR (2.46 ± 0.18 vs. 2.39 ±0.21)(p = 0.42). There was a good correlation (r = 0.83) between muscular mass and skeletal mass (n = 28). Conclusion: The intake of regular doses of creatin monohydrate in high performance athletes for a period of 30-60 days causes a significant increase in residual mass (hydric retention) in the extra-cellular space. This adverse effect should be taken into consideration at the time of its indication.
Creatine remains one of the most extensively studied nutritional ergogenic aids available for athletes. Hundreds of studies have reported that increasing muscle creatine stores through creatine supplementation can augment muscle creatine content, improve exercise and training adaptations, and/or provide some therapeutic benefit to some clinical populations. Consequently, creatine represents one of the most effective and popular nutritional ergogenic aids available for athletes. The future of creatine research is very promising. Researchers are attempting to determine ways to maximize creatine storage in the muscle, which types of exercise may obtain the greatest benefit from creatine supplementation, the potential medical uses of creatine, and the long-term safety and efficacy of creatine supplementation. Among these, the most promising area of research is determining the potential medical uses of creatine, particularly in patients with creatine synthesis deficiencies and neuromuscular diseases. Nevertheless, in regard to athletes, creatine has continually proved itself to be one of the most effective and safe nutritional supplements to increase strength, muscle mass, and performance. This is despite oftentimes inaccurate and misleading information that has been written about creatine in the popular media over the last several years.
Creatine (CR) (methyl guanidine acetic acid), is recommended for application as food (dietary) supplement. It is supposed that human organism uses it for formation of CR phosphate, which is necessary as a source of energy for muscular work. The fate of supplemented CR is not as simple as that. Its molecule is decomposed and reused again in each recipient individually. In our short-term study we have observed changes in the metabolism of two-carbon (2C) units and of thiolic substances 4 to 6 hours after CR supplementation. The level of thiodiglycolic acid (TDGA) in urine increased rapidly and then decreased again to the original level. At the same time the pH values of urine increased by 1.5 units. The level of TDGA in urine is a marker of disturbance in metabolic pathways of 2C units and of thiolic compounds. Our long-term CR study, with quantitative evaluation of more than 30 parameters of potential metabolic products revealed that the biochemical pathways, affected by CR application included intrinsic participation of vitamin B12 and folates. The levels of those two vitamins changed in a mutually reverse way. The men under study can be divided into 4 different groups according to changes of CR levels found in urine, and of levels of folates and vitamin B12, determined in blood before and after CR administration. The probands of each group utilized CR as donor of 1C and 2C units derived from CR in different metabolic pathways. Differences between initial and terminal TDGA levels indicated that CR disturbed the equilibria of redox processes, catalyzed by folates and vitamin B12. The levels of homocysteine increased in all but one probands. The amount of creatinine excreted into urine depended on the extent of metabolic disturbances. The observed changes indicated that exogenous application of CR affected metabolic pathways connected with endogenous synthesis as well as with decomposition of CR.
Strength-power athletes improve exercise performance primarily by improving their sport-specific skills. in addition, exercise performance can be enhanced by improving strength, lean muscle mass, and anaerobic exercise performance. several sports supplements have been documented to enhance these attributes, including creatine monohydrate, betaalanine, β-hydroxy β- methylbutyrate, and protein.
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There are numerous sports supplements available that claim to increase lean body mass. However, for these sports supplements
to exert any favorable changes in lean body mass, they must influence those factors regulating skeletal muscle hypertrophy
(i.e., satellite cell activity, gene transcription, protein translation). If a given sports supplement does favorably influence
one of these regulatory factors, the result is a positive net protein balance (in which protein synthesis exceeds protein
breakdown). Sports supplement categories aimed at eliciting a positive net protein balance include anabolic hormone enhancers,
nutrient timing pre- and postexercise workout supplements, anticatabolic supplements, and nitric oxide boosters. Of all the
sports supplements available, only a few have been subject to multiple clinical trials with repeated favorable outcomes relative
to increasing lean body mass. This chapter focuses on these supplements and others that have a sound theoretical rationale
in relation to increasing lean body mass.
Key wordsSports nutrition–Lean body mass–Creatine–Protein supplements–HMB–Nitric oxide–Anabolic–Anticatabolic–Nutrient timing
Urinary creatinine has been analyzed for many years as an indicator of glomerular filtration rate. More recently, interest in studying the uptake of creatine as a result of creatine supplementation, a practice increasingly common among bodybuilders and athletes, has lead to a need to measure urinary creatine concentrations. Creatine levels are of the same order of magnitude as creatinine levels when subjects have recently ingested creatine, while somewhat elevated urinary creatine concentrations in non-supplementing subjects can be an indication of a degenerative disease of the muscle. Urinary creatine and creatinine can be analyzed by HPLC using a variety of columns. Detection methods include absorption, fluorescence after post-column derivatization, and mass spectrometry, and some methods have been automated. Capillary zone electrophoresis and micellar electrokinetic capillary chromatography have also been used to analyze urinary creatine and creatinine. Creatine and creatinine have also been analyzed in serum and tissue using HPLC and CE, and many of these separations could also be applicable to urinary analysis.
Creatine is the object of growing interest in the scientific literature. This is because of the widespread use of creatine by athletes, on the one hand, and to some promising results regarding its therapeutic potential in neuromuscular disease on the other. In fact, since the late 1900s, many studies have examined the effects of creatine supplementation on exercise performance. This article reviews the literature on creatine supplementation as an ergogenic aid, including some basic aspects relating to its metabolism, pharmacokinetics and side effects. The use of creatine supplements to increase muscle creatine content above approximately 20 mmol/kg dry muscle mass leads to improvements in high-intensity, intermittent high-intensity and even endurance exercise (mainly in nonweightbearing endurance activities). An effective supplementation scheme is a dosage of 20 g/day for 4-6 days, and 5 g/day thereafter. Based on recent pharmacokinetic data, new regimens of creatine supplementation could be used. Although there are opinion statements suggesting that creatine supplementation may be implicated in carcinogenesis, data to prove this effect are lacking, and indeed, several studies showing anticarcinogenic effects of creatine and its analogues have been published. There is a shortage of scientific evidence concerning the adverse effects following creatine supplementation in healthy individuals even with long-term dosage. Therefore, creatine may be considered as a widespread, effective and safe ergogenic aid.
Creatine monohydrate (creatine) has become an increasingly popular ingredient in dietary supplements, especially sports nutrition products. A large body of human and animal research suggests that creatine does have a consistent ergogenic effect, particularly with exercises or activities requiring high intensity short bursts of energy. Human data are primarily derived from three types of studies: acute studies, involving high doses (20 g/d) with short duration (< or = 1 week), chronic studies involving lower doses (3-5 g/d) and longer duration (1 year), or a combination of both. Systematic evaluation of the research designs and data do not provide a basis for risk assessment and the usual safe Upper Level of Intake (UL) derived from it unless the newer methods described as the Observed Safe Level (OSL) or Highest Observed Intake (HOI) are utilized. The OSL risk assessment method indicates that the evidence of safety is strong at intakes up to 5 g/d for chronic supplementation, and this level is identified as the OSL. Although much higher levels have been tested under acute conditions without adverse effects and may be safe, the data for intakes above 5 g/d are not sufficient for a confident conclusion of long-term safety.
The purpose of this study was to examine 10 weeks of creatine monohydrate (Cr) supplementation coupled with resistance training on body composition and strength in women trainees. Twenty-six subjects ingested Cr (n = 13) or a placebo (Pl) (n = 13) at a dose of 0.3 g.kg(-1) and 0.03 g.kg(-1) body mass for the initial 7 days and subsequent 9 weeks, respectively, while performing a resistance training program 4 days per week. Significant increases (p < 0.05) occurred in both groups for lean body mass and 1 repetition maximum (1RM) bench press and incline leg press. There was a significant main effect for training, but there was no significant difference in the total number of repetitions completed after 5 sets of multiple repetitions to exhaustion at 70% of 1RM for bench press and incline leg press for both groups or in the ability to perform a greater training volume (sets x repetitions x load) in the Cr vs. Pl groups over the 10 weeks. The results indicate that Cr supplementation combined with 10 weeks of concurrent resistance training may not improve strength or lean body mass greater than training only. These findings may be a result of nonresponders due to gender differences or a varying biological potential to uptake Cr within the muscle.
In studies in vitro, creatine-1-14C entered the extensor digitorum longus of young rats by a saturable process which had an apparent Vmax of 0.6 mmole per liter of intracellular water per hour and an apparent Km of 5 x 10-4 M. Creatine entry by nonsaturable processes was negligible at physiologic external creatine concentrations. Anaerobiosis, 1
x 10-3 M 2,4-dinitrophenol, and cooling each reduced the intracellular accumulation of creatine-14C. The apparent Q10o for entry was 2.7. Loss of creatine from the muscle accelerated rapidly during incubation at 37° and exceeded the rate of
creatine entry, but no connection between entry and loss was apparent. The large creatine loss in vitro was considered to be an artifact because it accelerated so rapidly during incubation and because it is inconsistent with
observations from earlier experiments in vivo which indicate that much of the creatine in skeletal muscle is trapped there.
A special mechanism for entry, the saturable process, and intracellular trapping of creatine provide a plausible explanation
for the high creatine content of skeletal muscle.
A classic body-composition method is estimation of total-body skeletal muscle mass (SM, in kg) from 24-h urinary creatinine excretion (in g). Two approaches of unknown validity have been used to calculate SM from creatinine: one assumes a constant ratio of SM to creatinine, the so-called creatinine equivalence (k), and that SM = k x creatinine; the other suggests a highly variable ratio of SM to creatinine and is based on regression equations of the form SM = b + a x creatinine. We explored these two extreme possibilities by measuring SM with whole-body computerized axial tomography and collecting urinary creatinine during meat-free dietary conditions in 12 healthy adult men. Prediction equations were developed in the men that fit these two models: SM = 21.8 x creatinine (SD and CV of the ratio of SM to creatinine: 1.3 kg and 6.0%, respectively) and SM = 18.9 x creatinine + 4.1 (r = 0.92, P = 2.55 x 10(-5), SEE = 1.89 kg). The validity of each model is reviewed in the context of theoretical aspects of creatine-creatinine metabolism. This first investigation of the method of measuring urinary creatinine excretion to determine SM by using modern techniques raises important practical and basic questions related to SM prediction.
1. The present study was undertaken to test whether creatine given as a supplement to normal subjects was absorbed, and if continued resulted in an increase in the total creatine pool in muscle. An additional effect of exercise upon uptake into muscle was also investigated.
2. Low doses (1 g of creatine monohydrate or less in water) produced only a modest rise in the plasma creatine concentration, whereas 5 g resulted in a mean peak after 1 h of 795 (sd 104) μmol/l in three subjects weighing 76–87 kg. Repeated dosing with 5 g every 2 h sustained the plasma concentration at around 1000 μmol/l. A single 5 g dose corresponds to the creatine content of 1.1 kg of fresh, uncooked steak.
3. Supplementation with 5 g of creatine monohydrate, four or six times a day for 2 or more days resulted in a significant increase in the total creatine content of the quadriceps femoris muscle measured in 17 subjects. This was greatest in subjects with a low initial total creatine content and the effect was to raise the content in these subjects closer to the upper limit of the normal range. In some the increase was as much as 50%.
4. Uptake into muscle was greatest during the first 2 days of supplementation accounting for 32% of the dose administered in three subjects receiving 6 × 5 g of creatine monohydrate/day. In these subjects renal excretion was 40, 61 and 68% of the creatine dose over the first 3 days. Approximately 20% or more of the creatine taken up was measured as phosphocreatine. No changes were apparent in the muscle ATP content.
5. No side effects of creatine supplementation were noted.
6. One hour of hard exercise per day using one leg augmented the increase in the total creatine content of the exercised leg, but had no effect in the collateral. In these subjects the mean total creatine content increased from 118.1 (sd 3.0) mmol/kg dry muscle before supplementation to 148.5 (sd 5.2) in the control leg, and to 162.2 (sd 12.5) in the exercised leg. Supplementation and exercise resulted in a total creatine content in one subject of 182.8 mmol/kg dry muscle, of which 112.0 mmol/kg dry muscle was in the form of phosphocreatine.
A simple, robust and reproducible analytical method for the determination of phosphocreatine (PCr), creatine (Cr) and creatinine (Cn) in equine skeletal muscle is presented. The technique used isocratic reverse-phase ion-pairing high-performance liquid chromatography. Neutralized perchloric acid extracts of equine muscle biopsies were analysed and the values obtained were compared with determinations from an established enzymic procedure. Good resolution of all three metabolites was achieved within a retention time of less than 11 min. Linearity for each metabolite within the concentration range in the samples was demonstrated. Peak purity was specifically addressed. The abolition of each creatine in a pooled extract by enzymic incubation showed no underlying peaks. It was concluded that peaks were free of co-eluents which would otherwise lead to an overestimation of PCr, Cr and Cn concentrations.
Percutaneous muscle biopsies were obtained from the vastus lateralis of physically active men (n = 12) 1) at rest, 2) immediately after an exercise bout consisting of 30 maximal voluntary knee extensions of constant angular velocity (3.14 rad/s), and 3) 60 s after termination of exercise. Creatine phosphate (CP) content was analyzed in pools of freeze-dried fast-twitch (FT) and slow-twitch (ST) muscle fiber fragments, and ATP, CP, creatine, and lactate content were assayed in mixed pools of FT and ST fibers. CP content at rest was 82.7 +/- 11.2 and 73.1 +/- 9.5 (SD) mmol/kg dry wt in FT and ST fibers (P less than 0.05). After exercise the corresponding values were 25.4 +/- 19.8 and 29.7 +/- 14.4 mmol/kg dry wt. After 60 s of recovery CP increased (P less than 0.01) to 41.3 +/- 12.6 and 49.6 +/- 11.7 mmol/kg dry wt in FT and ST fibers, respectively. CP content after recovery, relative to initial level, was higher in ST compared with FT fibers (P less than 0.05). ATP content decreased (P less than 0.05) and lactate content rose to 67.4 +/- 28.3 mmol/kg dry wt (P less than 0.001) in response to exercise. It is concluded that basal CP content is higher in FT fibers than in ST fibers. CP content also appears to be higher in ST fibers after a 60-s recovery period after maximal short-term exercise. These data are consistent with the different metabolic profiles of FT and ST fibers.
Biopsy samples were obtained from vastus lateralis of eight female subjects before and after a maximal 30-s sprint on a nonmotorized treadmill and were analyzed for glycogen, phosphagens, and glycolytic intermediates. Peak power output averaged 534.4 +/- 85.0 W and was decreased by 50 +/- 10% at the end of the sprint. Glycogen, phosphocreatine, and ATP were decreased by 25, 64, and 37%, respectively. The glycolytic intermediates above phosphofructokinase increased approximately 13-fold, whereas fructose 1,6-diphosphate and triose phosphates only increased 4- and 2-fold. Muscle pyruvate and lactate were increased 19 and 29 times. After 3 min recovery, blood pH was decreased by 0.24 units and plasma epinephrine and norepinephrine increased from 0.3 +/- 0.2 nmol/l and 2.7 +/- 0.8 nmol/l at rest to 1.3 +/- 0.8 nmol/l and 11.7 +/- 6.6 nmol/l. A significant correlation was found between the changes in plasma catecholamines and estimated ATP production from glycolysis (norepinephrine, glycolysis r = 0.78, P less than 0.05; epinephrine, glycolysis r = 0.75, P less than 0.05) and between postexercise capillary lactate and muscle lactate concentrations (r = 0.82, P less than 0.05). The study demonstrated that a significant reduction in ATP occurs during maximal dynamic exercise in humans. The marked metabolic changes caused by the treadmill sprint and its close simulation of free running makes it a valuable test for examining the factors that limit performance and the etiology of fatigue during brief maximal exercise.
This study examined the effect of (a) creatine supplementation on exercise metabolism and performance and (b) changes in intramuscular total creatine stores following a 5 day supplementation period and a 28 day wash-out period. Six men performed four exercise trials, each consisting of four 1 min cycling bouts, punctuated by 1 min of rest followed by a fifth bout to fatigue, all at a workload estimated to require 115 or 125% VO2,max. After three familiarization trials, one trial was conducted following a creatine monohydrate supplementation protocol (CREAT); the other after 28 d without creatine supplementation, in which the last 5 d involved placebo ingestion (CON). Intramuscular TCr was elevated (P < 0.05) in CREAT compared with the final familiarization trial (FAM 3) and CON. Concentrations of this metabolite in these latter trials were not different. In addition, a main effect (P < 0.05) for treatment was observed for PCr when the data from CREAT were compared with CON. In contrast, no differences were observed in the total adenine nucleotide pool (ATP+ADP+AMP), inosine 5'-monophosphate, ammonia, lactate or glycogen when comparing CREAT with CON. Despite the differences in TCr and PCr concentrations when comparing CREAT with other trials, no difference was observed in exercise duration in the fifth work bout. These data demonstrate that creatine supplementation results in an increase in TCr but this has no effect on performance during exercise of this nature, where the creatine kinase system is not the principal energy supplier. In addition 28 d without supplementation is a sufficient time to return intramuscular TCr stores to basal levels.
This study investigated the effect of carbohydrate (CHO) ingestion on skeletal muscle creatine (Cr) accumulation during Cr supplementation in humans. Muscle biopsy, urine, and plasma samples were obtained from 24 males before and after ingesting 5 g Cr in solution (group A) or 5 g Cr followed, 30 min later, by 93 g simple CHO in solution (group B) four times each day for 5 days. Supplementation resulted in an increase in muscle phosphocreatine (PCr), Cr, and total creatine (TCr; sum of PCr and Cr) concentration in groups A and B, but the increase in TCr in group B was 60% greater than in group A (P < 0.01). There was also a corresponding decrease in urinary Cr excretion in group B (P < 0.001). Creatine supplementation had no effect on serum insulin concentration, but Cr and CHO ingestion dramatically elevated insulin concentration (P < 0.001). These findings demonstrate that CHO ingestion substantially augments muscle Cr accumulation during Cr feeding in humans, which appears to be insulin mediated.
Our purpose was to determine the effect of creatine supplementation on power output during a 30-s maximal cycling (Wingate) test. Nine males underwent 3 randomly ordered tests following ingestion of a creatine supplementation (CRE), placebo (PLA), and control (CON) CRE was ingested as creatine monohydrate (CrH2O) dissolved in a flavored drink (20g.d-1 for 3 d), while PLA consisted of the drink only. Tests were performed 14 d apart on a Monarch ergometer modified for immediate resistance loading. Needle biopsies were taken from the vastus lateralis at the end of each treatment period and before the exercise test. No difference was found between conditions for peak, mean 10-s, and mean 30-s power output, percent fatigue, or post-exercise blood lactate concentration. Similarly, no difference between conditions was observed for ATP, phosphocreatine (PCr), or total creatine (TCr); however, the TCr/ATP was higher in the CRE condition (P < 0.05) than in the CON and PLA conditions. Findings suggest that 3 d of oral Cr supplementation does not increase resting muscle PCr concentration and has no effect on performance during a single short-term maximal cycling task.
Creatine is found in the urine of subjects ingesting creatine monohydrate as an ergogenic aid. Creatinine, the catabolic breakdown product of creatine, is a major constituent of normal urine. It is of interest to follow the excretion of creatine and creatinine in urine as a function of time after creatine ingestion. In this study, creatine and creatinine were analyzed in urine by capillary electrophoresis. The optimization of the method was discussed, with the best results being obtained using a 30 mM phosphate-150 mM sodium dodecyl sulfate buffer at pH 6, with the detector set at 214 nm and an applied voltage of 15 kV across a 45 cm capillary. Verification of the method was provided by HPLC analysis and spiking. The application of the method was demonstrated by analysis of creatine and creatinine in urine samples collected in a 24-h period following creatine ingestion.