Article

Creatine-dextrose and protein-dextrose induce similar strength gains during training

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Abstract

Creatine supplementation during resistance exercise training has been reported to induce greater increases in fat-free mass (FFM), muscle fiber area, and strength when compared with a placebo. We have recently shown that timing of nutrient delivery in the postexercise period can have positive effects on whole body protein turnover (B. D. Roy et al., Med Sci Sports Exerc. 32(8):1412-1418, 2000). We tested the hypothesis that a postexercise protein-carbohydrate supplement would result in similar increases in FFM, muscle fiber area, and strength as compared with creatine monohydrate (CM), during a supervised 2-month resistance exercise training program in untrained men. Young healthy male subjects were randomized to receive either CM and glucose (N = 11; CM 10 g + glucose 75 g [CR-CHO] (CELL-Tech)) or protein and glucose (N = 8; casein 10 g + glucose 75 g [PRO+CHO]), using double-blinded allocation. Participants performed 8 wk of whole body split-routine straight set weight training, 1 h.d(-1), 6 d.wk(-1). Measurements, pre- and post-training were made of fat-free mass (FFM; DEXA), total body mass, muscle fiber area, isokinetic knee extension strength (45 and 240 degrees.s(-1)), and 1 repetition maximal (1RM) strength for 16 weight training exercises. Total body mass increased more for CR-CHO (+4.3 kg, 5.4%) as compared with PRO-CHO (+1.9 kg, 2.4%) (P < 0.05 for interaction) and FFM increased after training (P < 0.01) but was not significantly different between the groups (CR-CHO = +4.0 kg, 6.4%; PRO-CHO = +2.6 kg, 4.1%) (P = 0.11 for interaction). Muscle fiber area increased similarly after training for both groups (approximately 20%; P < 0.05). Training resulted in an increase in 1RM for each of the 16 activities (range = 14.2-39.9%) (P < 0.001), isokinetic knee extension torque (P < 0.01), with no treatment effects upon any of the variables. We concluded that postexercise supplementation with PRO-CHO resulted in similar increases in strength after a resistance exercise training program as compared with CR-CHO. However, the greater gains in total mass for the CR-CHO group may have implications for sport-specific performance.

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... Following this one-week loading regime, participants consumed 2 g creatine per day (maintenance dose) for the remainder of the study. Creatine appears to be more effective when carbohydrate (such as dextrose) is added to the supplement dose (Tarnopolsky, Parise et al. 2001). The addition of carbohydrate to creatine supplements potentiates muscle-building effects because of the insulinstimulating effect of the carbohydrate (Tarnopolsky, Parise et al. 2001). ...
... Creatine appears to be more effective when carbohydrate (such as dextrose) is added to the supplement dose (Tarnopolsky, Parise et al. 2001). The addition of carbohydrate to creatine supplements potentiates muscle-building effects because of the insulinstimulating effect of the carbohydrate (Tarnopolsky, Parise et al. 2001). Insulin secretion enhances nutrient uptake and inhibits protein breakdown within muscle (Tarnopolsky, Parise et al. 2001). ...
... The addition of carbohydrate to creatine supplements potentiates muscle-building effects because of the insulinstimulating effect of the carbohydrate (Tarnopolsky, Parise et al. 2001). Insulin secretion enhances nutrient uptake and inhibits protein breakdown within muscle (Tarnopolsky, Parise et al. 2001). Therefore carbohydrate (in the form of dextrose, as in the placebo group) was added to the creatine supplement group as well as acting as a control. ...
... Bibliografía: [108][109][110][111][112][113][114][115][116] Tópicos en nutrición y suplementación deportiva -Dr. Heber E. Andrada pág. ...
... Tópicos en nutrición y suplementación deportiva -Dr. Heber E. Andrada pág.114 ...
Book
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This book is intended for anyone passionate about nutrition and sports supplementation. It aims to introduce readers to what regards the subject, combining areas such as nutrition, biological chemistry, the physiology of the exercise, food science and pharmacology. It is by no means intended to replace a good book on each of these areas, just try to give a general snapshot of each of the substances that are currently being used in the world of supplementation sports, its functions, applications, benefits and doses that are usually used. Heber E. Andrada October 5, 2020
... Probably the most consistent finding regarding creatine supplementation is that when weight training is combined with creatine supplementation the improvements in strength performance and fat free mass are greater than those seen with strength training alone (Vandenberghe et al., 1997;Kreider et al., 1998;van Leemputte et al., 1999;Volek et al., 1999;Stout et al., 2000;Arciero et al., 2001;Chrusch et al., 2001;Jowko et al., 2001;Tarnopolsky et al., 2001;Willoughby & Rosene, 2001;Brose, Parise, & Tarnopolsky, 2003). Although there is some evidence that creatine supplementation can increase the force of single muscle contractions (Maganaris & Maughan, 1998;Vandenberghe et al., 1999;Tarnopolsky & MacLennan, 2000), it is likely that the increases come from a greater volume of work over time with a possible direct effect on muscle (see above). ...
... Although there is some evidence that creatine supplementation can increase the force of single muscle contractions (Maganaris & Maughan, 1998;Vandenberghe et al., 1999;Tarnopolsky & MacLennan, 2000), it is likely that the increases come from a greater volume of work over time with a possible direct effect on muscle (see above). An increase in total mass and fat free mass are the most consistent findings when creatine supplementation is combined with a period of weight training (Vandenberghe et al., 1997;Kreider et al., 1998;Volek et al., 1999;Stout et al., 2000;Arciero et al., 2001;Chrusch et al., 2001;Jowko et al., 2001;Tarnopolsky et al., 2001;Willoughby & Rosene, 2001;Brose et al., 2003). Some studies have also reported a concomittant increase in strength in some of the outcome measuements after weight training on creatine compared to placebo (Kreider et al., 1998;Volek et al., 1999;Stout et al., 2000;Arciero et al., 2001;Chrusch et al., 2001;Jowko et al., 2001;Willoughby & Rosene, 2001;Brose et al., 2003). ...
Article
Amino acids contribute between 2–8% of the energy needs during endurance exercise. Endurance exercise training leads to an adaptive reduction in the oxidation of amino acids at the same absolute exercise intensity, however, the capacity to oxidize amino acids goes up due to the increase in the total amount of the rate limiting enzyme, branched chain 2-oxo-acid dehydrogenase. There appears to be a modest increase (range = 12–95%) in protein requirements only for very well trained athletes who are actively training. Although the majority of athletes will have ample dietary protein to meet any increased need, those on a hypoenergetic diet or during extreme periods of physical stress may need dietary manipulation to accommodate the need. Caffeine is a trimethylxanthine derivative that is common in many foods and beverages. The consumption of caffeine (3–7 mg/kg) prior to endurance exercise improves performance for habitual and non-habitual consumers. The ergogenic effect is likely due to a direct effect on muscle contractility and not via an enhancement of fatty acid oxidation. Creatine is important in intra-cellular energy shuttling and in cellular fluid regulation. Creatine monohydrate supplementation (20 g/d X 3–5 days) increases fat-free mass, improves muscle strength during repetitive high intensity contractions and increases fat-free mass accumulation and strength during a period of weight training. Given the increase in weight, there are likely neutral or even performance reducing effects in sports that are influenced by body mass (i.e., running, hill climbing cycling).
... A study by Tarnopolsky et al. (65) utilized previously inactive participants and daily supplementation with either CrM (10 g) þ CHO (75 g) (1252 KJ or 300 kcal) or protein (10 g) þ CHO (75 g) (1420 KJ or 340 kcal) during 10 weeks of resistance training. Results indicated that CrM treatment provided no greater gains in strength, LBM, or muscle fiber hypertrophy (65). One explanation for the discrepancy between these results and those reported by Kreider et al. (18,19) and Cribb et al. (63,176) may have been the populations used. ...
... One explanation for the discrepancy between these results and those reported by Kreider et al. (18,19) and Cribb et al. (63,176) may have been the populations used. Whereas Kreider et al. (18,19) and Cribb et al. (63,175) utilized experienced (trained) participants, Tarnopolsky et al. (65) recruited participants who had been inactive prior to the study. Although the influence of training status on the effects of supplementation is unknown, it has been speculated that trained individuals might experience more efficient muscle Cr uptake, as exercise training is associated with improved insulin sensitivity (30). ...
Chapter
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Few supplement combinations that are marketed to athletes are supported by scientific evidence of their effectiveness. Quite often, under the rigor of scientific investigation, the patented combination fails to provide any greater benefit than a group given the active (generic) ingredient. The focus of this chapter is supplement combinations and dosing strategies that are effective at promoting an acute physiological response that may improve/enhance exercise performance or influence chronic adaptations desired from training. In recent years, there has been a particular focus on two nutritional ergogenic aids—creatine monohydrate and protein/amino acids—in combination with specific nutrients in an effort to augment or add to their already established independent ergogenic effects. These combinations and others are discussed in this chapter. Key wordsAcute–Chronic–Supplementation–Aerobic–Anaerobic–Exercise performance–Resistance training–Protein–Amino acids–Carbohydrate–Creatine monohydrate–Protein balance–Glycogen resynthesis–Sodium– d-Pinotol–HMβ–Sodium bicarbonate–Caffeine–Ephedrine
... As a result, the muscle becomes more resistant to fatigue compared with untreated control muscle. Thus, Cr can increase the training intensity during a single or repeated series of exercises, potentially stimulating functional adaptations (eg, power, strength, and speed) and muscular hypertrophy [4][5][6][7]. ...
... In addition, Willoughby and Rosene [9] have shown an increase in fatfree mass in untrained male subjects supplemented with Cr (6 g/d) during 12 weeks of weight-resistance training (3× per week using 3 sets of 6-8 repetitions at 85%-90% onerepetition maximum). Consistent with previous studies [6,7], these results indicate that Cr supplementation may be a suitable strategy for promoting an additional hypertrophic response during resistance training. However, the exact mechanisms by which Cr supplementation induces an increase in skeletal muscle mass remains poorly elucidated. ...
Article
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The purpose of this study was to test the hypothesis that creatine (Cr) supplementation may promote an additional hypertrophic effect on skeletal muscle independent of a higher workload on Cr-supplemented trained muscle compared with Cr-nonsupplemented trained muscle. Male Wistar rats (2-3 months old, 250-300 g) were divided randomly into 4 groups (n = 8 per group): nontrained without Cr supplementation (CO), nontrained with Cr supplementation (CR), trained without Cr supplementation (TR), and trained with Cr supplementation (TRCR). Creatine supplementation was given at 0.5 g/kg per day. Trained groups were submitted to a 5-week resistance training program (5 d/wk). The progressive workloads were similar between the Cr-supplemented (TRCR) and Cr-nonsupplemented (TR) trained groups; the only difference between groups was the Cr treatment. After the 5-week experiment, the soleus muscle was dissected to analyze the cross-sectional area (CSA) of the muscle fibers. Resistance training promoted a significant (P < .05) increase in the muscle fibers CSA in the TR group compared with the CO group. However, no additional hypertrophic effect was found when Cr supplementation was added to training (TRCR vs TR comparison, P > .05). In addition, Cr supplementation alone did not promote significant alterations in muscle fiber CSA (CR vs CO comparison, P > .05). We conclude that Cr supplementation does not promote any additional hypertrophic effect on skeletal muscle area when Cr-supplemented trained muscles are submitted to same training regimen than Cr-nonsupplemented trained muscles. Specifically, any benefits of Cr supplementation on hypertrophy gains during resistance training may not be attributed to a direct anabolic effect on the skeletal muscle.
... A suplementação de CR também está associada a um aumento inicial de peso, possivelmente devido à retenção de água relacionada à captação de CR pelo músculo. No entanto, esse ganho de peso inicial pode estar relacionado a um aumento subsequente na força muscular, que pode ser atribuído a um maior volume e intensidade de treinamento alcançado com a suplementação de CR (Tarnopolsky et al., 2001). Engelhardt et al. (1998) avaliaram os efeitos da suplementação de nas concentrações de creatina e creatinina em atletas. ...
Article
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Nutritional supplements integrated with any physical or sports activity are substances aimed at increasing physical performance, improving physical effort efficiency, enhancing physical recovery processes after intense exertion, enhancing training quality, and facilitating physiological adaptations. Among the most commonly used supplements is creatine (CR), a non-essential nitrogenous compound formed by three amino acids: glycine, arginine, and methionine, whose main benefit lies in improving performance in high-intensity activities. The consumption of CR along with carbohydrate (CHO) sources promotes supplement absorption compared to isolated consumption due to increased plasma insulin levels. The human body can absorb approximately 25% more CR when ingested with a CHO source. This review aimed to provide an expanded outlook on the consumption of CR combined with CHO sources and its relationship with increased CR transport into muscle cells in individuals engaging in strength exercises. Studies have shown that the increase or improvement in CR absorption by muscle cells may be related to increased blood glucose levels and consequent insulin release, which acts in a co-dependent and direct manner on the membrane transporter that regulates the entry of CR together with sodium into the intracellular environment, demonstrating that CHO supplementation is not necessary every time CR is consumed, but instead that this improvement consists of increased serum glucose and insulin release.
... Whey protein (WP) and creatine monohydrate (CrM) are the two dietary supplements commonly used to promote muscle strength and hypertrophy [1][2][3][4]. WP is acid soluble and thus digested quickly. WP contain enriched essential amino acids, including branched chain amino acids (BCAA) that the body needs for tissue synthesis, energy, and health. ...
Article
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The present study examined the effect of simultaneous ingestion of whey protein (WP) and creating monohydrate (CrM) on body composition, selected measures of muscular strength and power, and risks for potential renal dysfunction. Fifteen professional athletes including nine males and six females specialized in track and field, Olympic weight lifting, and modern pentathlon volunteered to participate in the study. Subjects underwent a four-week treatment period during which they ingested both (WP) and CrM while maintaining their regular diet and training intensity and volume. Body composition and performance of one-min pull-up, one-min push up, one-min squat-to-stand, standing long jump, triple jump, and 30-s single leg lateral jumps were measured before and after the treatment. Urine samples were collected throughout the treatment to determine albumin and creatinine concentrations. No changes in body weight, muscle mass, and % body fat were noted following the treatment. The treatment, however, improved (p < 0.05) scores in one-min pull-up, one-min push up, one-min squat-to-stand, triple jump, 30-s single leg lateral jump tests. No differences in urinary albumin and creatinine were found throughout the treatment period. In conclusion, co-supplementation of WP and CrM for four weeks is an effective yet safe ergogenic strategy in enhancing strength and power in professional athletes.
... In support of this theory, Esmarck and coworkers [107] found that ingesting carbohydrate and protein immediately following exercise doubled training adaptations in comparison to waiting until 2-hours to ingest carbohydrate and protein. Additionally, Tarnopolsky and associates [430] reported that post-exercise ingestion of carbohydrate with protein promoted as much strength gains as ingesting creatine with carbohydrate during training. A recent study by Kreider and colleagues [431] found that protein and carbohydrate supplementation post workout was capable of positively supporting the post exercise anabolic response. ...
Article
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Abstract Sport nutrition is a constantly evolving field with literally thousands of research papers published annually. For this reason, keeping up to date with the literature is often difficult. This paper presents a well-referenced overview of the current state of the science related to how to optimize training through nutrition. More specifically, this article discusses: 1.) how to evaluate the scientific merit of nutritional supplements; 2.) general nutritional strategies to optimize performance and enhance recovery; and, 3.) our current understanding of the available science behind weight gain, weight loss, and performance enhancement supplements. Our hope is that ISSN members find this review useful in their daily practice and consultation with their clients.
... Numerous studies have indicated that oral creatine monohydrate supplementation (e.g., 20 grams/day for 5 days) increases muscle creatine and PC content typically by 15 -40% [1][2][3][4][5][6][7][8][9]. The increase in muscle creatine and PC allows an individual to increase work output during high intensity exercise leading to greater gains in strength and muscle mass during training [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The potential ergogenic value of creatine supplementation is contingent on the effectiveness of the supplementation protocol in increasing muscle total creatine and PC stores [5,9,[24][25][26][27]. ...
Article
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Muscle Marketing USA (Valencia, CA) has claimed that liquid ATP Advantage™ Creatine Serum (CS) more effectively transports creatine to muscle than creatine monohydrate powder (CM). To date, no independent university lab has been able to verify label claims of the creatine content in CS and prior studies have shown no effect of CS supplementation on blood. creatine levels. This study examined whether CS supplementation has any affect on muscle adenosine triphosphate (ATP), free creatine (FCr), phosphocreatine (PC), or total creatine (TCr) levels. 40 male subjects (83±13 kg) with no history of creatine use had percutaneous muscle biopsies obtained from the vastus lateralis using standard procedures prior to and following 5-days of supplementing their diet in a randomized and double blind manner with either 5 mL of CS purportedly providing 2.5 grams of CM equivalent (LD-CS), 5 mL of a placebo (LD-P), 8 x 5 mL of CS purportedly providing 20 grams of CM equivalent (HD-CS), or 8 x 5 mL of P (HD-P). One group ingested 4 x 5 grams of CM for 5 days as a non-blinded benchmark control. Results revealed that none of the supplementation protocols had a significant effect on ATP concentrations. CM supplementation significantly increased muscle FCr content while remaining groups had no effects (LD-CS -12.3±11.3; LD-P -8.6±24.7; HD-CS 3.8±14.7; HD-P -2.7±14.1; CM 30.8±27.7 %, p=0.001). No significant differences were observed among groups in PC concentrations (p=0.53). These findings indicate that CS (at doses equivalent to 1 and 8 times label claims) is not an effective form of creatine to promote muscle creatine and/or phosphagen retention. Therefore, claims that that CS is a more effective form of creatine than creatine monohydrate appear to be false.
... Impairments in PCr metabolism may therefore hinder muscle performance and reduce muscle mass [398,399], although it remains unclear whether or not creatine content is altered by the aging process, different to the marked reduction of PCr in muscle of metabolic myopathic patients [400]. Although some studies did not show a beneficial effect from CrM supplementation during resistance training for elderly individuals [401,402], many studies have reported that CrM supplementation during resistance training increases muscle mass and muscular strength, endurance, and power in older individuals [400,[403][404][405][406]. Rawson et al. [402] reported that 1 month of CrM supplementation (20 g/d × 10 d → 4 g/d × 20 d) did not enhance FFM, total body mass, or upper extremity strength gains, yet there was less leg fatigue in the CrM-supplemented group. ...
Article
The world's elderly population is expanding rapidly, and we are now faced with the significant challenge of maintaining or improving physical activity, independence, and quality of life in the elderly. Sarcopenia, the age-related loss of skeletal muscle mass, is characterized by a deterioration of muscle quantity and quality leading to a gradual slowing of movement, a decline in strength and power, increased risk of fall-related injury, and often, frailty. Since sarcopenia is largely attributed to various molecular mediators affecting fiber size, mitochondrial homeostatis, and apoptosis, the mechanisms responsible for these deleterious changes present numerous therapeutic targets for drug discovery. Muscle loss has been linked with several proteolytic systems, including the calpain, ubuiquitin-proteasome and lysosome-autophagy systems. In addition, reseachers have indicated defects of Akt-mTOR (mammalian target of rapamycin) and RhoA-SRF (Serum response factor) signaling in sarcopenic muscle. In this chapter, we summarize the current understanding of the mechanisms underlying the progressive loss of muscle mass and provide an update on therapeutic strategies (resistance training, myostatin inhibition, amino acids supplementation, calorie restriction, etc) for counteracting sarcopenia. Resistance training combined with amino acid-containing supplements would be the best way to prevent age-related muscle wasting and weakness. Myostatin inhibition seems to be the most interesting strategy for attenuating sarcopenia as well as muscular dystrophy in the near future. In contrast, muscle loss with age may not be influenced positively by treatment with a proteasome inhibitor or antioxidant.
... Studies that compared drink formulations that included protein as well as vitamins and herbal supplements against a placebo trial [30][31][32] were also excluded since it was not possible to isolate the effects attributed solely to protein supplementation. Studies that combined protein supplementation with creatine were excluded [33][34][35][36][37][38][39] except when they compared protein supplementation alone with placebo or carbohydrate. Papers that examined the effects of bovine colostrum [40][41][42][43][44][45][46][47], b-hydroxy-b-methylbutyrate [48], and the ingestion of single amino acids (e.g., arginine or ornithine) were not included in this review [49]. ...
Article
Background: Protein supplements are frequently consumed by athletes and recreationally active adults to achieve greater gains in muscle mass and strength and improve physical performance. Objective: This review provides a systematic and comprehensive analysis of the literature that tested the hypothesis that protein supplements accelerate gains in muscle mass and strength resulting in improvements in aerobic and anaerobic power. Evidence statements were created based on an accepted strength of recommendation taxonomy. Data sources: English language articles were searched through PubMed and Google Scholar using protein and supplements together with performance, exercise, strength, and muscle, alone or in combination as keywords. Additional articles were retrieved from reference lists found in these papers. Study selection: Studies recruiting healthy adults between 18 and 50 years of age that evaluated the effects of protein supplements alone or in combination with carbohydrate on a performance metric (e.g., one repetition maximum or isometric or isokinetic muscle strength), metrics of body composition, or measures of aerobic or anaerobic power were included in this review. The literature search identified 32 articles which incorporated test metrics that dealt exclusively with changes in muscle mass and strength, 5 articles that implemented combined resistance and aerobic training or followed participants during their normal sport training programs, and 1 article that evaluated changes in muscle oxidative enzymes and maximal aerobic power. Study appraisal and synthesis methods: All papers were read in detail, and examined for experimental design confounders such as dietary monitoring, history of physical training (i.e., trained and untrained), and the number of participants studied. Studies were also evaluated based on the intensity, frequency, and duration of training, the type and timing of protein supplementation, and the sensitivity of the test metrics. Results: For untrained individuals, consuming supplemental protein likely has no impact on lean mass and muscle strength during the initial weeks of resistance training. However, as the duration, frequency, and volume of resistance training increase, protein supplementation may promote muscle hypertrophy and enhance gains in muscle strength in both untrained and trained individuals. Evidence also suggests that protein supplementation may accelerate gains in both aerobic and anaerobic power. Limitations: To demonstrate measureable gains in strength and performance with exercise training and protein supplementation, many of the studies reviewed recruited untrained participants. Since skeletal muscle responses to exercise and protein supplementation differ between trained and untrained individuals, findings are not easily generalized for all consumers who may be considering the use of protein supplements. Conclusions: This review suggests that protein supplementation may enhance muscle mass and performance when the training stimulus is adequate (e.g., frequency, volume, duration), and dietary intake is consistent with recommendations for physically active individuals.
... Recovery: fasting data collected the following morning after exercise treatment supplemental strategy (12 g creatine/day for 15 days) was effective. The increase in body mass after creatine consumption was explained by increasing in fat-free-mass [32,33] and water retention in muscle [34,35]. The inadequacy in washout period, leading to the water (accumulated from the endurance trial with creatine supplementation) retained in the athletes of power trial without creatine supplementation, resulted in an increase in the body weight before sprint running. ...
Article
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Purpose: Few studies have focused on the metabolic changes induced by creatine supplementation. This study investigated the effects of creatine supplementation on plasma and urinary metabolite changes of athletes after endurance and sprint running. Methods: Twelve male athletes (20.3 ± 1.4 y) performed two identical (65-70 % maximum heart rate reserved) 60 min running exercises (endurance trial) before and after creatine supplementation (12 g creatine monohydrate/day for 15 days), followed by a 5-day washout period. Subsequently, they performed two identical 100 m sprint running exercises (power trial) before and after 15 days of creatine supplementation in accordance with the supplementary protocol of the endurance trial. Body composition measurements were performed during the entire study. Plasma samples were examined for the concentrations of glucose, lactate, branched-chain amino acids (BCAAs), free-tryptophan (f-TRP), glutamine, alanine, hypoxanthine, and uric acid. Urinary samples were examined for the concentrations of hydroxyproline, 3-methylhistidine, urea nitrogen, and creatinine. Results: Creatine supplementation significantly increased body weights of the athletes of endurance trial. Plasma lactate concentration and ratio of f-TRP/BCAAs after recovery from endurance running were significantly decreased with creatine supplementation. Plasma purine metabolites (the sum of hypoxanthine and uric acid), glutamine, urinary 3-methylhistidine, and urea nitrogen concentrations tended to decrease before running in trials with creatine supplements. After running, urinary hydroxyproline concentration significantly increased in the power trial with creatine supplements. Conclusions: The findings suggest that creatine supplementation tended to decrease muscle glycogen and protein degradation, especially after endurance exercise. However, creatine supplementation might induce collagen proteolysis in athletes after sprint running.
... Little investigation has been conducted into the effect of MIPS and RT on isokinetic strength. These results are surprising as single-supplement [29,36,424344 and training-alone [45,46] studies have demonstrated modest increases in isokinetic performance following RT. Results of the isometric tests are particularly puzzling, as the MIPS group made no improvements while the PLA group improved in several measures during flexion. ...
Article
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Unlabelled: Background: Resistance training (RT) enhances muscle protein synthesis and hypertrophy while increasing strength and power. Some multi-ingredient performance supplements (MIPS) have been shown to augment the physiological improvements associated with RT. The purpose of this study was to investigate the impact of specific pre- and post-workout MIPS on anabolic hormones, body composition, muscle strength, and power in resistance-trained men participating in a periodized RT program. Methods: Twenty-four ( mean ± SE; 24.0 ± 0.9 years; 180.5 ± 5.8 cm; 83.7 ± 0.5 kg) resistance-trained men completed 6 wks of periodized RT (3x/wk). Participants were assigned to one of two groups based upon maximal voluntary contraction of the quadriceps (Biodex) to lean mass (LM) ratio. Group 1 (n = 13; MIPS) consumed one serving of NO-Shotgun® (whey protein, casein protein, branched-chain amino acids, creatine, beta alanine, and caffeine) before each workout and one serving of NO-Synthesize® (whey protein, casein protein, branched-chain amino acids, creatine, and beta alanine; Vital Pharmaceuticals, Inc., Davie, FL) immediately after each workout and on non-RT days. Group 2 (n = 11; Placebo; PLA) consumed a flavor-matched isocaloric maltodextrin placebo. Serum insulin-like growth factor 1, human growth hormone, testosterone, body composition (DXA), circumferences, 1-repetition maximal strength (1RM) of the upper (chest press) and lower body (leg press), and anaerobic power (Wingate test) were assessed before and after the intervention. Statistical analysis included a 2 × 2 (group x time) ANOVA with repeated measures. Tukey LSD post hoc tests were used to examine pairwise differences. Significance was set at p < 0.05. Results: There was a main time effect (p = 0.035) for testosterone to increase, but no differences between groups were observed. There were no differences in the other blood hormones. Group x time interactions were observed for LM (MIPS: PRE, 62.9 ± 2.1 to POST, 65.7 ± 2.0 vs. PLA: PRE, 63.5 ± 2.3 to POST, 64.8 ± 2.5 kg; p = 0.017). Only a main effect of time was noted for circumference measures. Both groups increased upper and lower body 1RM strength to a similar degree. MIPS significantly increased peak anaerobic power (PRE, 932.7 ± 172.5 W vs. POST, 1119.2 ± 183.8 W, p = 0.002) while PLA remained unchanged (PRE, 974.4 ± 44.1 W vs. POST, 1033.7 ± 48.6 W, p = 0.166). Conclusion: Consumption of MIPS during the course of a periodized RT program facilitated training-induced improvement in LM in trained males, whereas the consumption of PLA did not. MIPS improved measures of anaerobic power while PLA did not.
... In muscle, brain and heart, creatine functions as a temporal energy buffer to re-phosphorylate ADP and also has a role in «energy sensing» and «shuttling» between the cytosol and the mitochondria through the creatine-phosphocreatine shuttle [64]. Creatine may also function to increase myofibrillar protein synthesis either directly [65], or indirectly by allowing a person to perform more muscle contractions over a period of time [65][66][67]. There has been much interest in the use of creatine as a nutraceutical agent following several reports that creatine monohydrate ingestion could enhance high intensity exercise performance [68,69]. ...
Article
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Females and males: should nutritional recommendations be gender specific? Summary Most exercise physiology research has shown that women oxidize proportionately more lipid and less carbohydrate and protein as compared to men during endurance exercise. To date, most of the sports nutrition literature has not considered the implications of gender differences in metabolism on nutritional recommendations. Consequently, most nutritional recommendations and exercise training prescriptions are based upon data collected with male subjects that were extrapolated to women. The three areas where there have been a few studies regarding gender differences in nutritional/supplement recommendations include carbohydrate (CHO) nutrition, protein requirements and creatine (CrM) supple-mentation. We have shown that women did not carbohydrate load in response to an increase in dietary carbohydrate intake (carbo-hydrate loading) when expressed as a percentage of total energy intake (i.e., 55 75%). However, if women consumed carbo-hydrate expressed relative to total (>8 g CHO·kg –1 ·d –1) or fat-free mass (>10 g CHO ·kg –1 FFM·d –1), they were able to increase their muscle glycogen content, but only to about 50% of the magnitude seen for men. In contrast, women are able to oxidize slightly more exogenous carbohydrate (i.e., glucose drinks) during endurance exercise as compared to men. The consumption of carbohydrate and protein shortly after exercise spares protein loss, enhances glycogen re-synthesis and enhances endurance exercise perfor-mance in women as well as men. Top sport male and female athletes require more dietary protein as compared to sedentary persons. The maximal requirement for elite male athletes is about 100%, and for elite female athletes is about 50–60%, above that for a sedentary person or recreational athlete. Women showed less of an increase in fat-free mass (~400 g) following acute CrM loading as compared to men (~1200 g) in spite of identical in-creases in intra-muscular creatine and phosphocreatine concen-tration. Women also did not show reductions in protein breakdown or amino acid oxidation in response to CrM loading, whereas men did. Conversely, women and men appear to derive similar improvements in high intensity exercise performance following CrM loading. Further research is needed in order to derive gender specific nutritional/supplement recommendations in all areas of sport. Schweizerische Zeitschrift für «Sportmedizin und Sporttraumatologie» 51 (1), 39–46, 2003 Zusammenfassung Die Forschung im Bereiche der Sportphysiologie hat mehrheitlich gezeigt, dass Frauen während Ausdauerbelastungen proportional gesehen mehr Fette und weniger Kohlenhydrate und Protein oxi-dieren als Männer. Bis zum jetzigen Zeitpunkt hat aber der Gross-teil der Sporternährungsliteratur die Stoffwechselunterschiede zwischen den Geschlechtern nicht berücksichtigt, und dement-sprechend basieren die meisten Empfehlungen für die Ernährung und das Training von Frauen auf aus Versuchen mit Männern ge-wonnenen und extrapolierten Daten. Geschlechtsspezifische Un-terschiede bezüglich Empfehlungen für die Ernährung bzw. Supplementzufuhr wurden bislang in drei Gebieten erforscht: Ein-fluss einer Ernährung reich an Kohlenhydraten (KH), Empfehlun-gen zur Proteinzufuhr und Creatinsupplementierung. Wir konnten zeigen, dass es bei Frauen als Reaktion auf eine kohlenhydratrei-che Ernährung nicht zu einer Überfüllung der Glycogenspeicher kam, wenn das Carboloading (die Kohlenhydratzufuhr) prozentual auf die Energiezufuhr bezogen war (d.h. von 55 auf 75 Energie-prozente erhöht wurde). Wurde das Carboloading auf die Körper-masse (d.h. mehr als 8 g KH·kg –1 ·d –1) oder auf die fettfreie Kör-permasse (FFM) bezogen (>10 g KH·kg –1 FFM·d –1), konnte zwar eine Überfüllung der Glycogenspeicher beobachtet werden, diese hatte aber nur ungefähr 50% des Ausmasses wie diejenige bei den Männern. Frauen konnten dafür während Ausdauerbelastungen etwas mehr exogene KH (d.h. Glucosegetränke) oxidieren als Männer. Der Konsum von KH und Protein unmittelbar nach Been-digung einer Belastung reduziert den Proteinverlust, erhöht die Glycogenresynthese und verbessert die Ausdauerleistungsfähig-keit sowohl bei Frauen als auch bei Männern. Eliteathletinnen und -athleten benötigen beide mehr Protein im Vergleich zu inaktiven Personen. Der höchste Bedarf für männliche Eliteathleten beträgt etwa 100% und derjenige für weibliche Eliteathletinnen 50 bis 60% mehr als der Bedarf für Personen mit ausgesprochener sitzen-der Tätigkeit. Nach akuter Creatinsupplementierung wiesen Frau-en einen geringeren Zuwachs an FFM (~400 g) auf als Männer (~1200 g), obwohl der intramuskuläre Gehalt an Creatin und Phos-phocreatin in beiden Geschlechtern auf identische Weise zunahm. Bei Frauen wurde auch keine Reduktion des Proteinabbaus oder der Aminosäurenoxidation nach Creatinsupplementierung beob-achtet, wogegen dies bei Männern der Fall war. Im Gegensatz dazu wurde eine ähnliche Leistungssteigerung bei Männern und Frauen nach hochintensiver Belastung und Creatinsupplementierung fest-gestellt. Es bedarf weiterer Forschung, um geschlechtsspezifische Empfehlungen für die Ernährung bzw. Supplementzufuhr in allen Sportarten ableiten zu können.
... Thus, it is compulsory to evaluate whether ''cycled'' Cr supplementation provides greater benefits than continuous classical regimen or not. Despite the large body of evidence indicating that Cr supplementation promotes increased strength and lean mass, a very interesting study showed that healthy subjects supplemented with Cr and submitted to 8-week resistance training had similar strength and lean mass gains as compared to those who underwent the same training and were supplemented with an isoenergetic and isonitrogenous diet (Tarnopolsky et al. 2001). These findings suggest that studies that include a carbohydrate as placebo could overestimate the effects of Cr supplementation on skeletal muscle. ...
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Creatine (Cr) plays a central role in energy provision through a reaction catalyzed by phosphorylcreatine kinase. Furthermore, this amine enhances both gene expression and satellite cell activation involved in hypertrophic response. Recent findings have indicated that Cr supplementation has a therapeutic role in several diseases characterized by atrophic conditions, weakness, and metabolic disturbances (i.e., in the muscle, bone, lung, and brain). Accordingly, there has been an evidence indicating that Cr supplementation is capable of attenuating the degenerative state in some muscle disorders (i.e., Duchenne and inflammatory myopathies), central nervous diseases (i.e., Parkinson’s, Huntington’s, and Alzheimer’s), and bone and metabolic disturbances (i.e., osteoporosis and type II diabetes). In light of this, Cr supplementation could be used as a therapeutic tool for the elderly. The aim of this review is to summarize the main studies conducted in this field and to highlight the scientific and clinical perspectives of this promising therapeutic supplement.
... Additionally, Tarnopolsky and associates [315] reported that post-exercise ingestion of carbohydrate with protein promoted as much strength gains as ingesting creatine with carbohydrate during training. These findings underscore the importance of post-exercise carbohydrate and protein ingestion. ...
... In fact, creatine supplements, in general, appear to have only minor or negligible effects on renal function in the majority [22,23] and may even offer some benefits during exercise [24]. Furthermore, there is some evidence, from one study, to suggest that its combination with carbohydrate supplements may increase body mass of 5.4% although there were no differences reported compared to carbohydrate and protein supplement in fat-free mass, muscle fibre area, and isokinetic strength (the features likely to be of interest to the military personnel taking them) [25]. Other studies have however suggested an increase in muscle hypertrophy and strength with creatine based supplements, particularly when taken in combination with additional protein and carbohydrate during resistance training programmes [26]. ...
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... In support of this theory, Esmarck and coworkers [107] found that ingesting carbohydrate and protein immediately following exercise doubled training adaptations in comparison to waiting until 2-hours to ingest carbohydrate and protein . Additionally, Tarnopolsky and associates [430] reported that post-exercise ingestion of carbohydrate with protein promoted as much strength gains as ingesting creatine with carbohydrate during training. A recent study by Kreider and colleagues [431] found that protein and carbohydrate supplementation post workout was capable of positively supporting the post exercise anabolic response. ...
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Sports nutrition is a constantly evolving field with hundreds of research papers published annually. For this reason, keeping up to date with the literature is often difficult. This paper is a five year update of the sports nutrition review article published as the lead paper to launch the JISSN in 2004 and presents a well-referenced overview of the current state of the science related to how to optimize training and athletic performance through nutrition. More specifically, this paper provides an overview of: 1.) The definitional category of ergogenic aids and dietary supplements; 2.) How dietary supplements are legally regulated; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of the ergogenic value of nutrition and dietary supplementation in regards to weight gain, weight loss, and performance enhancement. Our hope is that ISSN members and individuals interested in sports nutrition find this review useful in their daily practice and consultation with their clients.
... Phosphocreatine (PCr) plays an important role in supporting metabolism during high-intensity exercise and impairments in PCr metabolism may therefore hinder muscle performance and reduce muscle mass [160,161]. Although some studies did not show a beneficial effect from creatine supplementation during resistance training for elderly individuals [162,163], many studies have reported that creatine supplementation during resistance training increases muscle mass and muscular strength, endurance, and power in older individuals [164][165][166][167][168]. There are several effects of creatine monophosphate administration that may enhance resistance exercise-induced strength gains in elderly including activation of myogenic determination factors [169], enhancement of satellite cell activation and recruitment [170], and reduction of amino acid oxidation and protein breakdown [171]. ...
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In 2011, we published a paper providing an overview about the bioavailability, efficacy, and regulatory status of creatine monohydrate (CrM), as well as other “novel forms” of creatine that were being marketed at the time. This paper concluded that no other purported form of creatine had been shown to be a more effective source of creatine than CrM, and that CrM was recognized by international regulatory authorities as safe for use in dietary supplements. Moreover, that most purported “forms” of creatine that were being marketed at the time were either less bioavailable, less effective, more expensive, and/or not sufficiently studied in terms of safety and/or efficacy. We also provided examples of several “forms” of creatine that were being marketed that were not bioavailable sources of creatine or less effective than CrM in comparative effectiveness trials. We had hoped that this paper would encourage supplement manufacturers to use CrM in dietary supplements given the overwhelming efficacy and safety profile. Alternatively, encourage them to conduct research to show their purported “form” of creatine was a bioavailable, effective, and safe source of creatine before making unsubstantiated claims of greater efficacy and/or safety than CrM. Unfortunately, unsupported misrepresentations about the effectiveness and safety of various “forms” of creatine have continued. The purpose of this critical review is to: (1) provide an overview of the physiochemical properties, bioavailability, and safety of CrM; (2) describe the data needed to substantiate claims that a “novel form” of creatine is a bioavailable, effective, and safe source of creatine; (3) examine whether other marketed sources of creatine are more effective sources of creatine than CrM; (4) provide an update about the regulatory status of CrM and other purported sources of creatine sold as dietary supplements; and (5) provide guidance regarding the type of research needed to validate that a purported “new form” of creatine is a bioavailable, effective and safe source of creatine for dietary supplements. Based on this analysis, we categorized forms of creatine that are being sold as dietary supplements as either having strong, some, or no evidence of bioavailability and safety. As will be seen, CrM continues to be the only source of creatine that has substantial evidence to support bioavailability, efficacy, and safety. Additionally, CrM is the source of creatine recommended explicitly by professional societies and organizations and approved for use in global markets as a dietary ingredient or food additive.
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Context The impact of timing the consumption of protein supplements in relation to meals on resistance training–induced changes in body composition has not been evaluated systematically. Objective The aim of this systematic review was to assess the effect of consuming protein supplements with meals, vs between meals, on resistance training–induced body composition changes in adults. Data Sources Studies published up to 2017 were identified with the PubMed, Scopus, Cochrane, and CINAHL databases. Data Extraction Two researchers independently screened 2077 abstracts for eligible randomized controlled trials of parallel design that prescribed a protein supplement and measured changes in body composition for a period of 6 weeks or more. Results In total, 34 randomized controlled trials with 59 intervention groups were included and qualitatively assessed. Of the intervention groups designated as consuming protein supplements with meals (n = 16) vs between meals (n = 43), 56% vs 72% showed an increase in body mass, 94% vs 90% showed an increase in lean mass, 87% vs 59% showed a reduction in fat mass, and 100% vs 84% showed an increase in the ratio of lean mass to fat mass over time, respectively. Conclusions Concurrently with resistance training, consuming protein supplements with meals, rather than between meals, may more effectively promote weight control and reduce fat mass without influencing improvements in lean mass.
Chapter
Few supplement combinations that are marketed to athletes are supported by scientific evidence of their effectiveness. Under the rigor of scientific investigation, we often see that the patented combination fails to provide any greater benefit when compared to an active (generic) ingredient. The focus of this chapter is supplement combinations and dosing strategies that are effective at promoting an acute physiological response that may improve/enhance exercise performance and/or influence chronic adaptations desired from training. In recent years, there has been a particular focus on two nutrition ergogenic aids—creatine monohydrate and protein/amino acids—in combination with specific nutrients in an effort to augment or add to their already established independent ergogenic effects. These combinations and others are discussed in this chapter.
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A high proportion of athletes consume dietary supplements in the belief that they will enhance performance or alter body composition. Therefore, research into dietary supplements should accurately evaluate alterations in body composition, specifically muscle and fat mass (FM). A number of factors need to be considered in the selection of anthropometric methodologies to evaluate body composition changes due to dietary supplementation. These factors include measurement details (reliability, validity, accuracy and sensitivity), ethical factors such as invasiveness, statistical effect size and practical considerations such as time, cost and equipment availability. Researchers should first consider the statistical effect size of the supplement under study. Does previous research indicate a marked effect of the supplement on body composition? If so, then a less sensitive methodology can be utilised. Where previous research indicates only a small or negligible effect on body composition, the more sensitive anthropometric methodologies should be employed. The validity and reliability of the anthropometric technique is important. However, there is a lack of research into the reliability and validity of various anthropometric methodologies when assessed in conjunction with dietary supplementation. Examination of recent research into the most popular dietary supplements including creatine monohydrate, β-hydroxy-β-methyl butyrate (HMB), chromium picolinate, Tribulus Terrestris, ephedrine and L-carnitine, reveals utilisation of a wide variety of anthropometric methodologies with no particular methodology associated with detecting significant effects on body composition. Ephedrine, when combined with caffeine, and creatine are amongst the few dietary supplements consistently reported to alter body composition. Changes in hydration status can lead to confounding errors when assessing body composition and researchers should aim to minimise or control alterations in hydration status. Future research is needed in the area of anthropometry and dietary supplementation, particularly investigating the validity and reliability of various anthropometric techniques to detect change in body composition as a result of dietary supplementation. A greater availability of this information would assist researchers to choose appropriate anthropometric methodology to assess the effects of dietary supplements on muscle and FM.
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History Identifying Characteristics Exposure Dose Effect Toxicokinetics Histopathology and Pathophysiology Clinical Response Diagnostic Testing Treatment References
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Creatine supplementation has been widely used to increase both muscle strength and lean mass in healthy individuals and athletes. Furthermore, several studies have investigated the mechanisms responsible for such adaptations. Thus, this review aimed at 1) examining the major studies investigating the effects of creatine supplementation on strength and hypertrophy, and 2) exploring the mechanisms underlying these responses, stressing the most recent findings and perspectives regarding creatine supplementation. There is strong evidence demonstrating that creatine supplementation is able to enhance strength and hypertrophy. The effects of creatine on water retention, protein balance, genes/proteins related to hypertrophy, and satellite cells activation may explain the creatine-mediated muscle skeletal adaptations. In light of these findings, the potential therapeutic effects of creatine supplementation might be considered as a promising clinical and research field.
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Introduction: Ageing is associated with decreased muscle mass, strength, power and function, and reduction in bone density and mineral content, leading to reduced independence and increased risk of falls. Creatine supplementation is reported to improve muscular strength and performance with training in younger athletes, and therefore could benefit older individuals. Aims: This review critically appraises the current literature on whether creatine supplementation enhances muscular performance and function, body composition, bone mineral density and content in older adults without the addition of resistance training, and thus determines whether creatine supplementation can lead to an improved lifestyle for the sedentary elderly population. Results: There is conflicting evidence regarding the usefulness of creatine supplementation in older subjects. Generally, however, creatine supplementation, without associated resistance training, seems to enhance muscular strength, power and endurance, increase lean body mass (LBM) and improve the functional capacity of the elderly. Furthermore, it has been demonstrated that increased muscle mass due to creatine supplementation can result in increased local bone density. It appears that the effect of creatine supplementation is more beneficial in larger muscles and less effective in smaller muscles, however there are exceptions. The mechanism by which creatine supplementation works requires further research, however it is likely that the effects of creatine are related to creatine kinase activity, providing enhanced energy production for greater muscular contraction. Conclusions: These data indicate that creatine supplementation without associated training in the elderly could potentially delay atrophy of muscle mass, improve endurance and strength, and increase bone strength, and thus may be a safe therapeutic strategy to help decrease loss in functional performance of everyday tasks.
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Creatine monohydrate is a dietary supplement that increases muscle performance in short-duration, high-intensity resistance exercises, which rely on the phosphocreatine shuttle for adenosine triphosphate. The effective dosing for creatine supplementation includes loading with 0.3 g·kg·d for 5 to 7 days, followed by maintenance dosing at 0.03 g·kg·d most commonly for 4 to 6 wk. However loading doses are not necessary to increase the intramuscular stores of creatine. Creatine monohydrate is the most studied; other forms such as creatine ethyl ester have not shown added benefits. Creatine is a relatively safe supplement with few adverse effects reported. The most common adverse effect is transient water retention in the early stages of supplementation. When combined with other supplements or taken at higher than recommended doses for several months, there have been cases of liver and renal complications with creatine. Further studies are needed to evaluate the remote and potential future adverse effects from prolonged creatine supplementation.
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The exogenous ingestion of creatine (Cr) is typically used as a performance enhancing (ergogenic) supplement because it is known to improve performance in muscular strength and power activities, enhance short bursts of muscular endurance, and allow for greater muscular overload in order to improve training effectiveness. Creatine has become one of the most popular ingested nutritional supplements due to its potential enhancement of athletic performance. Creatine is primarily located in skeletal muscle and plays a pivotal role in cellular bioenergetics, specifically towards the reformation of a molecule essential for muscular contraction, adenosine triphosphate (ATP). The vast majority of research indicates that high-intensity, short duration, and repeated exercise bouts are the most effective modes of exercise that can be enhanced by creatine supplementation. Oral creatine supplementation has been shown to provide numerous benefits, including increases in lean muscle mass, muscular strength, and enhanced performance in various athletic capacities. The creatine transporter is a protein that mediates the entry of creatine from the circulation into the muscle cell.
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Concerns about the deleterious consequences of oral creatine (Cr) supplementation were initiated in Spring 1998. Two British nephrologists published a paper in “The Lancet” suggesting that there is “strong circumstantial evidence that Cr was responsible for the deterioration in renal function” (1) (details given in Section 3.3.2). Three days after this publication a French sport newspaper “L’Equipe” (28th April 1998) stressed that Cr is dangerous for the kidneys, in any condition. This news was handed over to several European newspapers. Cr became the champion’s viagra with eventual death! Indeed, Pritchard and Kalra commented on the case of three American college wrestlers who died (1). This later turned out to be false and the Food and Drug Administration (FDA) ruled out Cr supplementation as a primary cause of the deaths of these young athletes (2).
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Dietary creatine supplementation is associated with increases in muscle mass, but the mechanism is unknown. We tested the hypothesis that creatine supplementation enhanced myofibrillar protein synthesis (MPS) and diminished muscle protein breakdown (MPB) in the fed state. Six healthy men (26 +/- 7 yr, body mass index 22 +/- 4 kg/m(2)) were studied twice, 2-4 wk apart, before and after ingestion of creatine (21 g/day, 5 days). We carried out two sets of measurements within 5.5 h of both MPS (by incorporation of [1-(13)C]leucine in quadriceps muscle) and MPB (as dilution of [1-(13)C]leucine or [(2)H(5)]phenylalanine across the forearm); for the first 3 h, the subjects were postabsorptive but thereafter were fed orally (0.3 g maltodextrin and 0.083 g protein. kg body wt(-1) x h(-1)). Creatine supplementation increased muscle total creatine by approximately 30% (P < 0.01). Feeding had significant effects, doubling MPS (P < 0.001) and depressing MPB by approximately 40% (P < 0.026), but creatine had no effect on turnover in the postabsorptive or fed states. Thus any increase in muscle mass accompanying creatine supplementation must be associated with increased physical activity.
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Muscle hypertrophy during resistance training is reportedly increased by creatine supplementation. Having previously failed to find an anabolic effect on muscle protein turnover at rest, either fed or fasted, we have now examined the possibility of a stimulatory effect of creatine in conjunction with acute resistance exercise. Seven healthy men (body mass index, 23 +/- 2 kg/m2, 21 +/- 1 yr, means +/- SE) performed 20 x 10 repetitions of leg extension-flexion at 75% one-repetition maximum in one leg, on two occasions, 4 wk apart, before and after ingesting 21 g/day creatine for 5 days. The subjects ate approximately 21 g maltodextrin + 6 g protein/h for 3 h postexercise. We measured incorporation of [1-13C]leucine into quadriceps muscle proteins in the rested and exercised legs. Leg protein breakdown (as dilution of [2H5]phenylalanine) was also assessed in the exercised and rested leg postexercise. Creatine supplementation increased muscle total creatine by approximately 21% (P < 0.01). Exercise increased the synthetic rates of myofibrillar and sarcoplasmic proteins by two- to threefold (P < 0.05), and leg phenylalanine balance became more positive, but creatine was without any anabolic effect.
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This chapter focuses on creatine monohydrate, its history and therapeutic aspects, its formulae, synthesis, physical properties, analytical methods, stability, degradation, pharmacokinetics, metabolism, and toxicity. Creatine in its free or phosphorylated form plays an important role in the regulation and homeostasis of muscle energy metabolism. Creatine is synthesized in the liver and kidneys and released into the blood stream to be taken up into muscle cells via a protein-based transport system. Creatine is stable under ordinary conditions of use and storage. Solid creatine monohydrate dehydrates to anhydrous creatine after the evolution of 1 mol of water by heating at 97–125oC. Anhydrous creatine undergoes an intramolecular cyclization accompanied by a loss of 1 molecule of water to form creatinine, which undergoes melting with decomposition around 280–310oC. In presence of water, creatine forms creatine monohydrate, which crystallizes out from solution on long term storage because of its poor solubility relative to that of soluble di-creatine citrate. Creatine supplementation has been investigated as a possible therapeutic approach for the treatment of muscular, neurological, and neuromuscular diseases. The success of creatine in the treatment of various diseases is dependent on the understanding of its pharmacokinetic—volume of distribution, clearance, bioavailability, mean residence time, absorption rate, and half-life—behavior. Creatine monohydrate outsells all other forms of creatine.
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Many of the neuromuscular (e.g., muscular dystrophy) and neurometabolic (e.g., mitochondrial cytopathies) disorders share similar final common pathways of cellular dysfunction that may be favorably influenced by creatine monohydrate (CrM) supplementation. Studies using the mdx model of Duchenne muscular dystrophy have found evidence of enhanced mitochondrial function, reduced intra-cellular calcium and improved performance with CrM supplementation. Clinical trials in patients with Duchenne and Becker's muscular dystrophy have shown improved function, fat-free mass, and some evidence of improved bone health with CrM supplementation. In contrast, the improvements in function in myotonic dystrophy and inherited neuropathies (e.g., Charcot-Marie-Tooth) have not been significant. Some studies in patients with mitochondrial cytopathies have shown improved muscle endurance and body composition, yet other studies did not find significant improvements in patients with mitochondrial cytopathy. Lower-dose CrM supplementation in patients with McArdle's disease (myophosphorylase deficiency) improved exercise capacity, yet higher doses actually showed some indication of worsened function. Based upon known cellular pathologies, there are potential benefits from CrM supplementation in patients with steroid myopathy, inflammatory myopathy, myoadenylate deaminase deficiency, and fatty acid oxidation defects. Larger randomized control trials (RCT) using homogeneous patient groups and objective and clinically relevant outcome variables are needed to determine whether creatine supplementation will be of therapeutic benefit to patients with neuromuscular or neurometabolic disorders. Given the relatively low prevalence of some of the neuromuscular and neurometabolic disorders, it will be necessary to use surrogate markers of potential clinical efficacy including markers of oxidative stress, cellular energy charge, and gene expression patterns.
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Myopathies are genetic or acquired disorders of skeletal muscle that lead to varying degrees of weakness, atrophy, and exercise intolerance. In theory, creatine supplementation could have a number of beneficial effects that could enhance function in myopathy patients, including muscle mass, strength and endurance enhancement, lower calcium levels, anti-oxidant effects, and reduced apoptosis. Patients with muscular dystrophy respond to several months of creatine monohydrate supplementation (~0.075-0.1 g/kg/day) with greater strength (~9%) and fat-free mass (~0.63 kg). Patients with myotonic dystrophy do not show as consistent an effect, possibly due to creatine transport issues. Creatine monohydrate supplementation shows modest benefits only at lower doses and possibly negative effects (cramping) at higher doses in McArdle's disease patients. Patients with MELAS syndrome show some evidence of benefit from creatine supplementation in exercise capacity, with the effects in patients with CPEO being less robust, again, possibly due to limited muscle creatine uptake. The evidence for side effects or negative impact upon serological metrics from creatine supplementation in all groups of myopathy patients is almost non-existent and pale in comparison to the very substantial and well-known side effects from our current chemotherapeutic interventions for some myopathies (i.e., corticosteroids).
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The purpose of this study was to examine the effect of a commercially available energy drink on time to exhaustion during treadmill exercise. In addition, subjective measures of energy, focus, and fatigue were examined Fifteen subjects (9 men and 6 women; 20.9 +/- 1.0 y; 172.1 +/- 9.1 cm; 71.0 +/- 9.4 kg; 16.9 +/- 9.7% body fat) underwent two testing sessions administered in a randomized, double-blind fashion. Subjects reported to the laboratory in a 3-hr post-absorptive state and were provided either the supplement (SUP; commercially marketed as Amino Impact) or placebo (P). During each laboratory visit subjects performed a treadmill run (70% VO2 max) to exhaustion. Mean VO2 was measured during each endurance exercise protocol. Subjects were required to complete visual analog scales for subjective measures of energy, focus and fatigue at the onset of exercise (PRE), 10-mins into their run (EX10) and immediately post-exercise (IP). Time to exhaustion was significantly greater (p = 0.012) during SUP than P. Subjects consuming the supplement were able to run 12.5% longer than during the placebo treatment. Subjects consuming SUP reported significantly greater focus (p = 0.031), energy (p = 0.016), and less fatigue (p = 0.005) at PRE. Significant differences between groups were seen at EX10 for focus (p = 0.026) and energy (p = 0.004), but not fatigue (p = 0.123). No differences were seen at IP for either focus (p = 0.215), energy (p = 0.717) or fatigue (p = 0.430). Results of this study indicate that the supplement Amino Impact can significantly increase time to exhaustion during a moderate intensity endurance run and improve subjective feelings of focus, energy and fatigue.
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Creatine and protein supplementation can enhance the training outcomes of young subjects, but it is not clear if there are benefits for older individuals. Therefore, the purpose of this study was to determine the effects of creatine and protein supplementation on strength gains following a traditional resistance training program for middle-aged and older men. This study assessed changes in strength of men aged 48-72 years following 14 weeks of resistance training supplemented with creatine and/or protein. A double-blind, randomized, placebo-controlled design placed 42 males into one of four groups: Resistance Trained Placebo (RTP, n=10); Resistance Trained Creatine (RTCr, 5g Cr, n=10); Resistance Trained Protein (RTPr, 35g whey Pr, n=11); or Resistance Trained Creatine and Protein (RTCrPr, 5g Cr and 35g Pr, n=11). All groups trained 3 days per week for 14 weeks. The resistance training program was based on progressive overload. Training loads corresponded to 80% 1 RM (one repetition maximum strength), 3 sets of 8 repetitions for the following exercises: knee extension/knee flexion; bicep curl/tricep extension; military press; lat pull down; seated leg press; and bench press. 1 RM for each exercise and measures of lean body mass were assessed prior to and following the 14 week program. Each group significantly (p < 0.05) increased strength and lean body mass, however, there were no significant group effects or group X trial interactions. Resistance training in middle-aged and older men significantly increased muscular strength and added muscle mass with no additional benefits from creatine and/or protein supplementation.
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Creatine (Cr), one of the most popular nutritional supplements among athletes, has been recently shown to prevent the cytotoxicity caused by different oxidative stressors in various mammalian cell lines, including C2C12 myoblasts, via a direct antioxidant activity. Here, the effect of Cr on the differentiating capacity of C2C12 cells exposed to H(2)O(2) has been investigated. Differentiation into myotubes was monitored using morphological, ultrastructural, and molecular techniques. Treatment with H(2)O(2) (1 h) not only caused a significant (30%) loss of cell viability, but also abrogated the myogenic ability of surviving C2C12. Cr-supplementation (24 h prior to H(2)O(2) treatment) was found to prevent these effects. Interestingly, H(2)O(2)-challenged cells preconditioned with the established antioxidants trolox or N-acetyl-cysteine, although cytoprotected, did not display the same differentiating ability characterizing oxidatively-injured, Cr-supplemented cells. Besides acting as an antioxidant, Cr increased the level of muscle regulatory factors and IGF1 (an effect partly refractory to oxidative stress), the cellular availability of phosphocreatine and seemed to exert some mitochondrially-targeted protective activity. It is concluded that Cr preserves the myogenic ability of oxidatively injured C2C12 via a pleiotropic mechanism involving not only its antioxidant capacity, but also the contribution to cell energy charge and effects at the transcriptional level which common bona fide antioxidants lack.
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To investigate the effect of acute changes of extracellular osmolality on whole body protein and glucose metabolism, we studied 10 male subjects during three conditions: hyperosmolality was induced by fluid restriction and intravenous infusion of hypertonic NaCl [2-5%; (wt/vol)] during 17 h; hypoosmolality was produced by intravenous administration of desmopressin, liberal water drinking, and infusion of hypotonic saline (0.4%); and the isoosmolality study consisted of ad libitum oral water intake by the subjects. Leucine flux ([1-13C]leucine infusion technique), a parameter of whole body protein breakdown, decreased during the hypoosmolality study ( P < 0.02 vs. isoosmolality). The leucine oxidation rate decreased during the hypoosmolality study ( P < 0.005 vs. isoosmolality). Metabolic clearance rate of glucose during hyperinsulinemic-euglycemic clamping increased less during the hypoosmolality study than during the isoosmolality study ( P < 0.04). Plasma insulin decreased, and plasma nonesterified fatty acids, glycerol, and ketone body concentrations and lipid oxidation increased during the hypoosmolality study. It is concluded that acute alterations of plasma osmolality influence whole body protein, glucose, and lipid metabolism; hypoosmolality results in protein sparing associated with increased lipolysis and lipid oxidation and impaired insulin sensitivity.
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This randomized double-blind cross-over study assessed protein (PRO) requirements during the early stages of intensive bodybuilding training and determined whether supplemental PRO intake (PROIN) enhanced muscle mass/strength gains. Twelve men [22.4 +/- 2.4 (SD) yr] received an isoenergetic PRO (total PROIN 2.62 g.kg-1.day-1) or carbohydrate (CHO; total PROIN 1.35 g.kg-1.day-1) supplement for 1 mo each during intensive (1.5 h/day, 6 days/wk) weight training. On the basis of 3-day nitrogen balance (NBAL) measurements after 3.5 wk on each treatment (8.9 +/- 4.2 and -3.4 +/- 1.9 g N/day, respectively), the PROIN necessary for zero NBAL (requirement) was 1.4-1.5 g.kg-1.day-1. The recommended intake (requirement + 2 SD) was 1.6-1.7 g.kg-1.day-1. However, strength (voluntary and electrically evoked) and muscle mass [density, creatinine excretion, muscle area (computer axial tomography scan), and biceps N content] gains were not different between diet treatments. These data indicate that, during the early stages of intensive bodybuilding training, PRO needs are approximately 100% greater than current recommendations but that PROIN increases from 1.35 to 2.62 g.kg-1.day-1 do not enhance muscle mass/strength gains, at least during the 1st mo of training. Whether differential gains would occur with longer training remains to be determined.
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This study provides additional evidence that creatine, an end product of contraction unique to muscle, is involved in the control of muscle protein synthesis. Creatine is shown to stimulate selectively the rate of synthesis of two major contractile proteins, actin and myosin heavy chain, in cultures of differentiating skeletal muscle. Creatine affects only the rate of synthesis and not the rate of degradation. Several creatine analogs are as effective as creatine in stimulating muscle protein synthesis, creatinine and amino acids such as arginine and glycine are not. Creatine stimulates myosin heavy chain synthesis twofold in cultures of embryonic muscle grown in either normal or dialyzed media.
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A cDNA has been cloned from rabbit brain that is a new member of the emerging family of Na(+)-dependent plasma membrane transporters for several neurotransmitters and structurally related compounds. Functional expression of this cDNA in COS-7 cells identifies its product as a Na(+)- and Cl(-)-dependent creatine transporter with a Km of approximately 35 microM. Its creatine transporter activity is efficiently antagonized by 3-guanidinopropionate, a well characterized alternative substrate of creatine transport in several tissues, and by 4-guanidinobutyrate. More distant structural analogues of creatine are much less efficient or inactive as antagonists, indicating a high substrate specificity of the transporter. Northern blot hybridization detects the expression of its mRNA in most tissues tested, most prominently in kidney, heart, and muscle, but not in liver and intestine. A full-length cDNA clone was also isolated from a muscle cDNA library and found to contain the same coding sequence. Substrate affinity and specificity of the cloned transporter are very similar to the endogenous creatine transporter of the COS-7 cells and to the creatine transport activities of several cell types described in the literature. Moreover, its mRNA is most abundant in the tissues known to possess high creatine uptake capacity.
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Nine male subjects performed two bouts of 30-s maximal isokinetic cycling before and after ingestion of 20 g creatine (Cr) monohydrate/day for 5 days. Cr ingestion produced a 23.1 +/- 4.7 mmol/kg dry matter increase in the muscle total creatine (TCr) concentration. Total work production during bouts 1 and 2 increased by approximately 4%, and the cumulative increases in both peak and total work production over the two exercise bouts were positively correlated with the increase in muscle TCr. Cumulative loss of ATP was 30.7 +/- 12.2% less after Cr ingestion, despite the increase in work production. Resting phosphocreatine (PCr) increased in type I and II fibers. Changes in PCr before exercise bouts 1 and 2 in type II fibers were positively correlated with changes in PCr degradation during exercise in this fiber type and changes in total work production. The results suggest that improvements in performance were mediated via improved ATP resynthesis as a consequence of increased PCr availability in type II fibers.
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We determined the effect of the timing of glucose supplementation on fractional muscle protein synthetic rate (FSR), urinary urea excretion, and whole body and myofibrillar protein degradation after resistance exercise. Eight healthy men performed unilateral knee extensor exercise (8 sets/approximately 10 repetitions/approximately 85% of 1 single maximal repetition). They received a carbohydrate (CHO) supplement (1 g/kg) or placebo (Pl) immediately (t = 0 h) and 1 h (t = +1 h) postexercise. FSR was determined for exercised (Ex) and control (Con) limbs by incremental L-[1-13C]leucine enrichment into the vastus lateralis over approximately 10 h postexercise. Insulin was greater (P < 0.01) at 0.5, 0.75, 1.25, 1.5, 1.75, and 2 h, and glucose was greater (P < 0.05) at 0.5 and 0.75 h for CHO compared with Pl condition. FSR was 36.1% greater in the CHO/Ex leg than in the CHO/Con leg (P = not significant) and 6.3% greater in the Pl/Ex leg than in the Pl/Con leg (P = not significant). 3-Methylhistidine excretion was lower in the CHO (110.43 +/- 3.62 mumol/g creatinine) than P1 condition (120.14 +/- 5.82, P < 0.05) as was urinary urea nitrogen (8.60 +/- 0.66 vs. 12.28 +/- 1.84 g/g creatinine, P < 0.05). This suggests that CHO supplementation (1 g/kg) immediately and 1 h after resistance exercise can decrease myofibrillar protein breakdown and urinary urea excretion, resulting in a more positive body protein balance.
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The effects of oral creatine supplementation on muscle phosphocreatine (PCr) concentration, muscle strength, and body composition were investigated in young female volunteers (n = 19) during 10 wk of resistance training (3 h/wk). Compared with placebo, 4 days of high-dose creatine intake (20 g/day) increased (P < 0.05) muscle PCr concentration by 6%. Thereafter, this increase was maintained during 10 wk of training associated with low-dose creatine intake (5 g/day). Compared with placebo, maximal strength of the muscle groups trained, maximal intermittent exercise capacity of the arm flexors, and fat-free mass were increased 20-25, 10-25, and 60% more (P < 0. 05), respectively, during creatine supplementation. Muscle PCr and strength, intermittent exercise capacity, and fat-free mass subsequently remained at a higher level in the creatine group than in the placebo group during 10 wk of detraining while low-dose creatine was continued. Finally, on cessation of creatine intake, muscle PCr in the creatine group returned to normal within 4 wk. It is concluded that long-term creatine supplementation enhances the progress of muscle strength during resistance training in sedentary females.
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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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The provision of additional protein (Pro) to a carbohydrate (CHO) supplement resulted in an enhanced rate of muscle glycogen resynthesis after endurance exercise (Zawadzki et al., J. Appl. Physiol. 72: 1854-1859, 1992). A comparison of isoenergetic CHO and CHO/Pro formula drinks on muscle glycogen resynthesis has not been examined after either endurance or resistance exercise. We studied the effect of isoenergetic CHO (1 g/kg) and CHO/Pro/fat (66% CHO, 23% Pro, 11% fat) defined formula drinks and placebo (Pl) given immediately (t = 0 h) and 1 h (t = +1 h) after resistance exercise in 10 healthy young men. They performed a whole body workout (9 exercises/3 sets at 80% 1 repetition maximum) with unilateral knee extension exercise [exercise (Ex) and control (Con) leg]. The CHO/Pro/fat and CHO trials resulted in significantly greater (P < 0. 05) plasma insulin and glucose concentration compared with Pl. Muscle glycogen was significantly lower (P < 0.05) for the Ex vs. Con leg immediately postexercise for all three conditions. The rate of glycogen resynthesis was significantly greater (P < 0.05) for both CHO/Pro/fat and CHO (23.0 +/- 4.5 and 19.3 +/- 6.1 mmol . kg dry muscle-1 . h-1, respectively) vs. Pl (Ex = 2.8 +/- 2.3 and Con = 1.4 +/- 3.6 mmol . kg dry muscle-1 . h-1). These results demonstrated that a bout of resistance exercise resulted in a significant decrease in muscle glycogen and that consumption of an isoenergetic CHO or CHO/Pro/fat formula drink resulted in similar rates of muscle glycogen resynthesis after resistance exercise. This suggests that total energy content and CHO content are important in the resynthesis of muscle glycogen.
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To investigate the effect of acute changes of extracellular osmolality on whole body protein and glucose metabolism, we studied 10 male subjects during three conditions: hyperosmolality was induced by fluid restriction and intravenous infusion of hypertonic NaCl [2-5%; (wt/vol)] during 17 h; hypoosmolality was produced by intravenous administration of desmopressin, liberal water drinking, and infusion of hypotonic saline (0.4%); and the isoosmolality study consisted of ad libitum oral water intake by the subjects. Leucine flux ([1-13C]leucine infusion technique), a parameter of whole body protein breakdown, decreased during the hypoosmolality study (P < 0. 02 vs. isoosmolality). The leucine oxidation rate decreased during the hypoosmolality study (P < 0.005 vs. isoosmolality). Metabolic clearance rate of glucose during hyperinsulinemic-euglycemic clamping increased less during the hypoosmolality study than during the isoosmolality study (P < 0.04). Plasma insulin decreased, and plasma nonesterified fatty acids, glycerol, and ketone body concentrations and lipid oxidation increased during the hypoosmolality study. It is concluded that acute alterations of plasma osmolality influence whole body protein, glucose, and lipid metabolism; hypoosmolality results in protein sparing associated with increased lipolysis and lipid oxidation and impaired insulin sensitivity.
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The purpose of this study was to test the effect of creatine supplement on the size of the extra- and intracellular compartments and on the increase of isokinetic force during a strength training-program. Twenty-five healthy male subjects (age 22.0+/-2.9 years) participated in this experiment. Seven subjects formed the control-group. They did not complete any training and did not have any dietary supplement. The eighteen other subjects were randomly divided into a creatine- (n = 8) and a placebo-group (n = 10). They were submitted to a controlled strength-training program for 42 days followed by a detraining period of 21 days. Creatine and placebo were given over a period of 9 weeks. The size of the body water compartments was assessed by bioimpedance spectroscopy and the isokinetic force was determined during a single squat by means of an isokinetic dynamometer. These measurements were completed beforehand, at the end of the training period, and after the determining period. Both placebo- and creatine-group increased the isokinetic force by about 6% after the training period, showing that creatine ingestion does not induce a higher increase of the force measured during a single movement. No change in body mass was observed in the control- and placebo-groups during the entire experiment period while the body mass of the creatine-group was increased by 2 kg (P < 0.001). This change can be attributed partially to an increase (P = 0.039) in the body water content (+1.11), and more specifically, to an increase (P < 0.001) in the volume of the inter-cellular compartment (+0.61). Nevertheless, the relative volumes of the body water compartments remained constant and therefore the gain in body mass cannot be attributed to water retention, but probably to dry matter growth accompanied with a normal water volume.
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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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The purpose of this investigation was to determine the effect of creatine (Cr) loading on the onset of neuromuscular fatigue by monitoring electromyographic fatigue curves from the vastus lateralis muscle using the physical working capacity at the fatigue threshold (PWC(FT)) test. Using a double-blind random design, 15 women athletes [mean age 19.0 +/- 2.0 (SD) yr] from the university crew team received a placebo (n = 8; 20 g glucose) or Cr (n = 7; 5 g Cr monohydrate + 20 g glucose) four times per day for 5 consecutive days. Analysis of covariance was used to analyze the data (covaried for presupplementation PWC(FT) values). The adjusted mean postsupplementation PWC(FT) value for the Cr group (mean = 186 W) was significantly (P < 0.05) higher than that of the placebo group (mean = 155 W). These findings suggest that Cr loading may delay the onset of neuromuscular fatigue.
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Purpose: The purpose of this study was to examine the effect of creatine supplementation in conjunction with resistance training on physiological adaptations including muscle fiber hypertrophy and muscle creatine accumulation. Methods: Nineteen healthy resistance-trained men were matched and then randomly assigned in a double-blind fashion to either a creatine (N = 10) or placebo (N = 9) group. Periodized heavy resistance training was performed for 12 wk. Creatine or placebo capsules were consumed (25 g x d(-1)) for 1 wk followed by a maintenance dose (5 g x d(-1)) for the remainder of the training. Results: After 12 wk, significant (P < or = 0.05) increases in body mass and fat-free mass were greater in creatine (6.3% and 6.3%, respectively) than placebo (3.6% and 3.1%, respectively) subjects. After 12 wk, increases in bench press and squat were greater in creatine (24% and 32%, respectively) than placebo (16% and 24%, respectively) subjects. Compared with placebo subjects, creatine subjects demonstrated significantly greater increases in Type I (35% vs 11%), IIA (36% vs 15%), and IIAB (35% vs 6%) muscle fiber cross-sectional areas. Muscle total creatine concentrations were unchanged in placebo subjects. Muscle creatine was significantly elevated after 1 wk in creatine subjects (22%), and values remained significantly greater than placebo subjects after 12 wk. Average volume lifted in the bench press during training was significantly greater in creatine subjects during weeks 5-8. No negative side effects to the supplementation were reported. Conclusion: Creatine supplementation enhanced fat-free mass, physical performance, and muscle morphology in response to heavy resistance training, presumably mediated via higher quality training sessions.
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Several neuromuscular disorders are associated with reductions in intramuscular adenosine triphosphate (ATP) and/or phosphocreatine (PCr). These alterations have been primarily characterized using 31P–magnetic resonance spectroscopy (31P-MRS). We prospectively measured total creatine, PCr, and ATP in muscle biopsies from 81 patients: normal controls (n = 33), mitochondrial cytopathy (n = 8), neuropathic (n = 3), dystrophy/congenital myopathies (n = 7), inflammatory myopathy (n = 12), and miscellaneous myopathies (n = 18) using direct biochemical analysis. Intramuscular concentrations of PCr and ATP were lower for the dystrophy/congenital myopathy, inflammatory myopathy, and mitochondrial disease patients with ragged red fiber (RRF) as compared with normal controls (P < 0.05). Total creatine was lower for the dystrophy/congenital myopathy group as compared with the normal control group (P < 0.05). These values compare favorably to results from other studies using 31P-MRS and provide external validation for the values obtained using that method. Given the reductions in high-energy phosphate compounds in these patients, there is the potential for therapeutic intervention with creatine monohydrate supplementation. © 1999 John Wiley & Sons, Inc. Muscle Nerve 22: 1228–1233, 1999.
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Creatine and creatine phosphate act as a buffer system for the regeneration of ATP in tissues with fluctuating energy demands. Following reports of the cloning of a creatine transporter in rat, rabbit, and human, we cloned and sequenced a creatine transporter from a human intestinal cDNA library. PCR amplification of genomic DNAs from somatic cell hybrid panels localized two creatine transporter (CT) genes: CT1 to Xq26-q28 and CT2 to 16p11.2. Refinement of CT1 to Xq28 was confirmed by FISH. Identification of CT2 sequences in YACs and cosmid contigs that had been ordered on human chromosome 16 enabled its assignment to the proximal end of 16p11.2. Sequencing of the CT2 gene identified sequence differences between CT1 and CT2 transcripts that were utilized to determine that CT2 is expressed in testis only. CT2 is the most proximally identified gene on chromosome 16p to date. The existence of an autosomal, testis-specific form of the human creatine transporter gene suggests that creatine transporter activity is critical for normal function of spermatazoa following meiosis.
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The microelectrode technique of intracellular constant current application and intracellular transmembrane voltage recording was used to study the effects of procaine amide (PA) on cardiac excitability. We measured the effect of PA in a concentration equivalent to clinically effective antiarrhythmic plasma levels (5 mug/ml), on nonnormalized and normalized strength-duration and charge-duration curves, membrane characteristics, and cable properties in long sheep Purkinje fibers in normal Tyrode's solution with [K+]0 = 4.0 mM. PA exerted a complex action and influenced passive resistance-capacitance (RC) and active generator properties by decreasing membrane conductance, primarily membrane sodium conductance. Whether PA increased or decreased excitability depended on the relative contribution of the drug-induced alterations in passive and active membrane properties. These findings may explain, in part, the conflicting results of studies on cardiac excitability in the whole animal, as well as the clinical observation that PA may exert both artiarrhythmic and arrhythmogenic effects. The primary mechanism by which PA modifies excitability would seem to differ considerably from that of the structurally similar local anesthetic agent lidocaine.
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The observation that increased muscular activity leads to muscle hypertrophy is well known, but identification of the biochemical and physiological mechanisms by which this occurs remains an important problem. The hypothesis has been proposed that creatine, an end product of contraction, may be the chemical signal coupling increased muscular activity and increased contractile mass. Two muscle models have been used in experimental tests of this hypothesis: differentiating skeletal muscle cells in culture and the fetal mouse heart in organ culture. Using these culture models, it is possible to alter the intracellular creatine concentration and to measure the effect of increased creatine concentrations on the rates of synthesis and accumulation of both muscle-specific and nonspecific proteins. The results show that muscle-specific protein synthesis in both skeletal and cardiac muscle is selectively stimulated by creatine.
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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.
Article
The concentrations of ATP, phosphocreatine (PCr), creatine, and lactate were determined in muscle biopsy samples frozen immediately or after a delay of 1-6 min. During the delay the samples were exposed to normal air or a gas mixture of 6.5% CO2-93.5% O2. The ATP content was unchanged, but PCr increased significantly from 72 mmol after rapid freezing to 85 mmol X kg dry muscle-1 during the 1st min in air. The lactate concentration increased (2.8 to 5.2 mmol X kg-1). If muscles were made anoxic by circulatory occlusion for 4-6 min before sampling, no increase in PCr was observed. Direct homogenization of fresh tissue in perchloric acid gave the same ATP, PCr, and lactate contents as frozen samples. It is concluded that the ATP and PCr contents in muscle are unaffected by freezing but that the biopsy procedure activates the energy utilization processes resulting in PCr decrease. It is suggested that the muscle PCr content after a 1-min delay in tissue freezing corresponds to the level in resting fresh muscle.
Article
Embryonic-chick muscle cells reach a steady state with respect to protein metabolism after approx. 1 week in cell culture. To determine if this steady state could be altered by the administration of agents that have been reported to stimulate myosin heavy-chain synthesis, 7-day muscle-cell cultures were treated with 0-1 mM-creatine. Incorporation of [3H]leucine into myosin heavy chain was stimulated by 30-40% at the optimum creatine concentration (0.2 mM), but this stimulation was blocked when actinomycin D (10 micrograms/ml) was also present. However, the quantity of myosin-heavy-chain mRNA as measured by hybridization in vitro was only 15% higher in creatine-treated cultures, and was therefore not entirely responsible for the observed effect. It is important to note that creatine only exerted its action on myosin-heavy-chain synthesis rate in steady-state cultures; creatine was ineffective in altering this rate in rapidly differentiating 3-day muscle cultures. Finally, muscle-cell cultures that had been grown for the entire 7-day culture period in the presence of 0.2 mM-creatine were assayed for quantity of myosin heavy chain. Control and creatine-treated cultures contained 12.7 +/- 1.5 and 20.5 +/- 1.8 micrograms/dish respectively. In conclusion, creatine apparently enhances the quantity of myosin heavy chain in steady-state embryonic muscle-cell cultures, but it probably does not mediate regulation of myosin content in adult skeletal muscle.
Article
The purpose of this investigation was to determine the short-term reproducibility of measurements of whole-body and subregion bone mass and density, as well as body composition, made by dual energy x-ray absorptiometry. Bone mineral content, bone mineral density and body composition were measured on two occasions, 1 to 2 weeks apart, in 21 women (average age, 20.9 [standard deviation 1.6] years). The method errors of the duplicate measurements, expressed as a percentage of the combined mean values from the two sets of measurements (i.e., as a coefficient of variation), for whole-body bone mineral content, bone mineral density, lean tissue mass and fat mass were 1.6%, 1.1%, 1.4% and 1.8% respectively. The method errors for bone mineral density in the hip were 2.2%, 1.1% and 2.5% for the neck, trochanter and Ward's triangle respectively. On the basis of the method errors and the expected treatment effects, the sample sizes needed for intervention trials (e.g., exercise training) were calculated. All of the whole-body and most of the subregion bone mineral density and lean tissue mass measurements made by dual-energy x-ray absorptiometry were sufficient for detecting the small changes (about 2%) expected in trials with 20 subjects, whereas measurements of subregion bone mineral content and fat mass were less precise.
Article
Biopsy samples were obtained from the vastus lateralis muscle of eight subjects after 0, 20, 60, and 120 s of recovery from intense electrically evoked isometric contraction. Later (10 days), the same procedures were performed using the other leg, but subjects ingested 20 g creatine (Cr)/day for the preceding 5 days. Muscle ATP, phosphocreatine (PCr), free Cr, and lactate concentrations were measured, and total Cr was calculated as the sum of PCr and free Cr concentrations. In five of the eight subjects, Cr ingestion substantially increased muscle total Cr concentration (mean 29 +/- 3 mmol/kg dry matter, 25 +/- 3%; range 19-35 mmol/kg dry matter, 15-32%) and PCr resynthesis during recovery (mean 19 +/- 4 mmol/kg dry matter, 35 +/- 6%; range 11-28 mmol/kg dry matter, 23-53%). In the remaining three subjects, Cr ingestion had little effect on muscle total Cr concentration, producing increases of 8-9 mmol/kg dry matter (5-7%), and did not increase PCr resynthesis. The data suggest that a dietary-induced increase in muscle total Cr concentration can increase PCr resynthesis during the 2nd min of recovery from intense contraction.
Article
A rabbit homolog of the putative rat choline transporter CHOT1 has recently been shown to mediate creatine transport (Guimbal and Kilimann, J. Biol. Chem., 1993). Here, the functional properties of the CHOT1 cDNA were studied by heterologous expression in HEK-293 cells. After transfection, the cells displayed a 7-8fold stimulation of [14C]creatine uptake with a Km of 46.2 microM. This transport was inhibited by the creatine uptake inhibitor beta-guanidinopropionate (Ki of 23 microM). Northern blot analysis revealed a major transcript of 4.8 kb in brain, heart, skeletal muscle and kidney. In situ hybridization showed high transcript levels in the cerebellum, hippocampus and other brain regions. High expression was also seen in the rat embryo along the entire neuraxis and in some non-neuronal tissues. These data establish CHOT1 as a widely expressed rat creatine transporter.
Article
The effect of dietary creatine and supplementation on skeletal muscle creatine accumulation and subsequent degradation and on urinary creatinine excretion was investigated in 31 male subjects who ingested creatine in different quantities over varying time periods. Muscle total creatine concentration increased by approximately 20% after 6 days of creatine supplementation at a rate of 20 g/day. This elevated concentration was maintained when supplementation was continued at a rate of 2 g/day for a further 30 days. In the absence of 2 g/day supplementation, total creatine concentration gradually declined, such that 30 days after the cessation of supplementation the concentration was no different from the presupplementation value. During this period, urinary creatinine excretion was correspondingly increased. A similar, but more gradual, 20% increase in muscle total creatine concentration was observed over a period of 28 days when supplementation was undertaken at a rate of 3 g/day. In conclusion, a rapid way to "creatine load" human skeletal muscle is to ingest 20 g of creatine for 6 days. This elevated tissue concentration can then be maintained by ingestion of 2 g/day thereafter. The ingestion of 3 g creatine/day is in the long term likely to be as effective at raising tissue levels as this higher dose.
Article
This study examined the effects of ingesting nutritional supplements designed to promote lean tissue accretion on body composition alterations during resistance training. Twenty-eight resistance-trained males blindly supplemented their diets with maltodextrin (M), Gainers Fuel 1000 (GF), or Phosphagain (P). No significant differences were observed in absolute or relative total body water among groups. Energy intake and body weight significantly increased in all groups combined throughout the study with no group or interaction differences observed. Dual energy x-ray absorptiometry-determined body mass significantly increased in each group throughout the study with significantly greater gains observed in the GF and P groups. Lean tissue mass (excluding bone) gain was significantly greater in the P group, while fat mass and percent body fat were significantly increased in the GF group. Results indicate that total body weight significantly increased in each group and that P supplementation resulted in significantly greater gains in lean tissue mass during resistance training.
Article
This study was undertaken to investigate the influence of oral supplementation with creatine monohydrate on muscular performance during repeated sets of high-intensity resistance exercise. Fourteen active men were randomly assigned in a double-blind fashion to either a creatine group (n = 7) or a placebo group (n = 7). Both groups performed a bench press exercise protocol (5 sets to failure using each subject's predetermined 10-repetition maximum) and a jump squat exercise protocol (5 sets of 10 repetitions using 30% of each subject's 1-repetition maximum squat) on three different occasions (T1, T2, and T3) separated by 6 days. Before T1, both groups received no supplementation. From T1 to T2, both groups ingested placebo capsules. From T2 to T3, the creatine group ingested 25 g creatine monohydrate per day, and the placebo group ingested an equivalent amount of placebo. Total repetitions for each set of bench presses and peak power output for each set of jump squats were determined. Other measures included assessment of diet, body mass, skinfold thickness, and preexercise and 5-minute postexercise lactate concentrations. Lifting performance was not altered for either exercise protocol after ingestion of the placebos. Creatine supplementation resulted in a significant improvement in peak power output during all 5 sets of jump squats and a significant improvement in repetitions during all 5 sets of bench presses. After creatine supplementation, postexercise lactate concentrations were significantly higher after the bench press but not the jump squat. A significant increase in body mass of 1.4 kg (range = 0.0 to 2.7 kg) was observed after creatine ingestion. One week of creatine supplementation (25 g/day) enhances muscular performance during repeated sets of bench press and jump squat exercise.
Article
Mixed muscle protein fractional synthesis rate (FSR) and fractional breakdown rate (FBR) were examined after an isolated bout of either concentric or eccentric resistance exercise. Subjects were eight untrained volunteers (4 males, 4 females). Mixed muscle protein FSR and FBR were determined using primed constant infusions of [2H5]phenylalanine and 15N-phenylalanine, respectively. Subjects were studied in the fasted state on four occasions: at rest and 3, 24, and 48 h after a resistance exercise bout. Exercise was eight sets of eight concentric or eccentric repetitions at 80% of each subject's concentric 1 repetition maximum. There was no significant difference between contraction types for either FSR, FBR, or net balance (FSR minus FBR). Exercise resulted in significant increases above rest in muscle FSR at all times: 3 h = 112%, 24 h = 65%, 48 h = 34% (P < 0.01). Muscle FBR was also increased by exercise at 3 h (31%; P < 0.05) and 24 h (18%; P < 0.05) postexercise but returned to resting levels by 48 h. Muscle net balance was significantly increased after exercise at all time points [(in %/h) rest = -0.0573 +/- 0.003 (SE), 3 h = -0.0298 +/- 0.003, 24 h = -0.0413 +/- 0.004, and 48 h = -0.0440 +/- 0.005], and was significantly different from zero at all time points (P < 0.05). There was also a significant correlation between FSR and FBR (r = 0.88, P < 0.001). We conclude that exercise resulted in an increase in muscle net protein balance that persisted for up to 48 h after the exercise bout and was unrelated to the type of muscle contraction performed.
Article
There is an increasing utilisation of oral creatine (Cr) supplementation among athletes who hope to enhance their performance but it is not known if this ingestion has any detrimental effect on the kidney. Five healthy men ingested either a placebo or 20 g of creatine monohydrate per day for 5 consecutive days. Blood samples and urine collections were analysed for Cr and creatinine (Crn) determination after each experimental session. Total protein and albumin urine excretion rates were also determined. Oral Cr supplementation had a significant incremental impact on arterial content (3.7 fold) and urine excretion rate (90 fold) of this compound. In contrast, arterial and urine Crn values were not affected by the Cr ingestion. The glomerular filtration rate (Crn clearance) and the total protein and albumin excretion rates remained within the normal range. In conclusion, this investigation showed that short-term oral Cr supplementation does not appear to have any detrimental effect on the renal responses of healthy men.
Article
This study investigated the effect of insulin on plasma and muscle creatine accumulation and limb blood flow in humans after creatine administration. Seven men underwent a 300-min euglycemic insulin clamp combined with creatine administration on four separate occasions. Insulin was infused at rates of 5, 30, 55, or 105 mU. m-2. min-1, and on each occasion 12.4 g creatine was administered. During infusion of insulin at rates of 55 and 105 mU. m-2. min-1, muscle total creatine concentration increased by 4.5 +/- 1.4 (P < 0. 05) and 8.3 +/- 1.0 mmol/kg dry mass (P < 0.05), and plasma creatine concentrations were lower at specific time points compared with the 5 mU. m-2. min-1 infusion rate. The magnitude of increase in calf blood flow (plethysmography) was the same irrespective of the rate of insulin infusion, and forearm blood flow increased to the same extent as the three highest infusion rates. These findings demonstrate that insulin can enhance muscle creatine accumulation in humans but only when present at physiologically high or supraphysiological concentrations. This response is likely to be the result of an insulin-mediated increase in muscle creatine transport rather than creatine delivery.
Article
The purpose of this study was to compare pure eccentric and concentric isokinetic training with respect to their possible specificity in the adaptation of strength and morphology of the knee extensor muscles. Ten moderately trained male physical education students were divided into groups undertaking eccentric (ETG) and concentric (CTG) training. They performed 10 weeks of maximal isokinetic (90 degrees x s(-1)) training of the left leg, 4x10 repetitions - three times a week, followed by a second 10-week period of similar training of the right-leg. Mean eccentric and concentric peak torques increased by 18% and 2% for ETG and by 10% and 14% for CTG, respectively. The highest increase in peak torque occurred in the eccentric 90 degrees x s(-1) test for ETG (35%) whereas in CTG strength gains ranged 8%-15% at velocities equal or lower than the training velocity. Significant increases in strength were observed in the untrained contra-lateral leg only at the velocity and mode used in ipsilateral training. Cross-sectional area of the quadriceps muscle increased 3%-4% with training in both groups, reaching statistical significance only in ETG. No major changes in muscle fibre composition or areas were detected in biopsies from the vastus lateralis muscle for either leg or training group. In conclusion, effects of eccentric training on muscle strength appeared to be more mode and speed specific than corresponding concentric training. Only minor adaptations in gross muscle morphology indicated that other factors, such as changes in neural activation patterns, were causing the specific training-induced gains in muscle strength.
Article
Oral creatine supplementation has been shown to improve power output during high intensity intermittent muscle contractions. Facilitated muscle phosphocreatine (PCr) resynthesis, by virtue of elevated intracellular PCr concentration, might contribute to this ergogenic action. Therefore, the effect of creatine loading (C: 25 g X d(-1) for 5 d) on muscle PCr breakdown and resynthesis and muscle performance during high intensity intermittent muscle contractions was investigated. A double-blind randomized cross-over study was performed in young healthy male volunteers (N = 9). 31P-NMR spectroscopy of the m. gastrocnemius and isokinetic dynamometry of knee-extension torque were performed before and after 2 and 5 d of either placebo (P) or C administration. Compared with P, 2 and 5 d of C increased (P < 0.05) resting muscle PCr concentration by 11% and 16%, respectively. Furthermore, torque production during maximal intermittent knee extensions, including the first bout of contractions, was increased (P < 0.05) by 5-13% by either 2 or 5 d of C. However, compared with P, the rate of PCr breakdown and resynthesis during intermittent isometric contractions of the calf was not significantly affected by C. Creatine loading raises muscle PCr concentration and improves performance during rapid and dynamic intermittent muscle contractions. Creatine loading does not facilitate muscle PCr resynthesis during intermittent isometric muscle contractions.
Article
Electrophoretic analyses of muscle proteins in whole muscle homogenates and single muscle fiber segments were used to examine myosin heavy chain (MHC) and myosin light chain 2 (MLC2) isoform composition and fiber type populations in soleus muscles from spontaneously hypertensive rats (SHRs) and their age-matched normotensive controls [Wistar-Kyoto (WKY) rats], at three stages in the development of high blood pressure (4 wk, 16 wk, and 24 wk of age). Demembranated (chemically skinned with 2% Triton X-100), single fiber preparations were used to determine the maximum Ca2+-activated force per cross-sectional area, calcium sensitivity, and degree of cooperativity of the contractile apparatus and Ca2+-regulatory system with respect to Ca2+. The results show that, at all ages examined, 1) SHR soleus contained a lower proportion of MHCI and MLC2 slow (MLC2s) and a higher proportion of MHCIIa, MHCIId/x, and MLC2 fast (MLC2f ) isoforms than the age-matched controls; 2) random dissection of single fibers from SHR and WKY soleus produced four populations of fibers: type I (expressing MHCI), type IIA (expressing MHCIIa), hybrid type I+IIA (coexpressing MHCI and MHCIIa), and hybrid type IIA+IID (coexpressing MHCIIa and MHCIId/x); and 3) single fiber dissection from SHR soleus yielded a lower proportion of type I fibers, a higher proportion of fast-twitch fibers (types IIA and IIA+IID), and a higher proportion of hybrid fibers (types I+IIA and IIA+IID) than the homologous muscles from the age-matched WKY rats. Because the presence of hybrid fibers is viewed as a marker of muscle transformation, these data suggest that SHR soleus undergoes transformation well into adulthood. Our data show also that, for a given fiber type, there are no significant differences between SHR and WKY soleus muscles with respect to any of the Ca2+-activation properties examined. This finding indicates that the lower specific tensions reported in the literature for SHR soleus muscles are not due to strain- or hypertension-related differences in the function of the contractile apparatus or regulatory system.
Article
We examined the response of net muscle protein synthesis to ingestion of amino acids after a bout of resistance exercise. A primed, constant infusion of L-[ring-2H5]phenylalanine was used to measure net muscle protein balance in three male and three female volunteers on three occasions. Subjects consumed in random order 1 liter of 1) a mixed amino acid (40 g) solution (MAA), 2) an essential amino acid (40 g) solution (EAA), and 3) a placebo solution (PLA). Arterial amino acid concentrations increased approximately 150-640% above baseline during ingestion of MAA and EAA. Net muscle protein balance was significantly increased from negative during PLA ingestion (-50 +/- 23 nmol. min-1. 100 ml leg volume-1) to positive during MAA ingestion (17 +/- 13 nmol. min-1. 100 ml leg volume-1) and EAA (29 +/- 14 nmol. min-1. 100 ml leg volume-1; P < 0.05). Because net balance was similar for MAA and EAA, it does not appear necessary to include nonessential amino acids in a formulation designed to elicit an anabolic response from muscle after exercise. We concluded that ingestion of oral essential amino acids results in a change from net muscle protein degradation to net muscle protein synthesis after heavy resistance exercise in humans similar to that seen when the amino acids were infused.
Article
The purpose of this study was to examine the effect of creatine supplementation in conjunction with resistance training on physiological adaptations including muscle fiber hypertrophy and muscle creatine accumulation. Nineteen healthy resistance-trained men were matched and then randomly assigned in a double-blind fashion to either a creatine (N = 10) or placebo (N = 9) group. Periodized heavy resistance training was performed for 12 wk. Creatine or placebo capsules were consumed (25 g x d(-1)) for 1 wk followed by a maintenance dose (5 g x d(-1)) for the remainder of the training. After 12 wk, significant (P < or = 0.05) increases in body mass and fat-free mass were greater in creatine (6.3% and 6.3%, respectively) than placebo (3.6% and 3.1%, respectively) subjects. After 12 wk, increases in bench press and squat were greater in creatine (24% and 32%, respectively) than placebo (16% and 24%, respectively) subjects. Compared with placebo subjects, creatine subjects demonstrated significantly greater increases in Type I (35% vs 11%), IIA (36% vs 15%), and IIAB (35% vs 6%) muscle fiber cross-sectional areas. Muscle total creatine concentrations were unchanged in placebo subjects. Muscle creatine was significantly elevated after 1 wk in creatine subjects (22%), and values remained significantly greater than placebo subjects after 12 wk. Average volume lifted in the bench press during training was significantly greater in creatine subjects during weeks 5-8. No negative side effects to the supplementation were reported. Creatine supplementation enhanced fat-free mass, physical performance, and muscle morphology in response to heavy resistance training, presumably mediated via higher quality training sessions.
Article
Several neuromuscular disorders are associated with reductions in intramuscular adenosine triphosphate (ATP) and/or phosphocreatine (PCr). These alterations have been primarily characterized using (31)P-magnetic resonance spectroscopy ((31)P-MRS). We prospectively measured total creatine, PCr, and ATP in muscle biopsies from 81 patients: normal controls (n = 33), mitochondrial cytopathy (n = 8), neuropathic (n = 3), dystrophy/congenital myopathies (n = 7), inflammatory myopathy (n = 12), and miscellaneous myopathies (n = 18) using direct biochemical analysis. Intramuscular concentrations of PCr and ATP were lower for the dystrophy/congenital myopathy, inflammatory myopathy, and mitochondrial disease patients with ragged red fiber (RRF) as compared with normal controls (P < 0.05). Total creatine was lower for the dystrophy/congenital myopathy group as compared with the normal control group (P < 0.05). These values compare favorably to results from other studies using (31)P-MRS and provide external validation for the values obtained using that method. Given the reductions in high-energy phosphate compounds in these patients, there is the potential for therapeutic intervention with creatine monohydrate supplementation.
Article
The purpose of this study was to investigate the time course of skeletal muscle adaptations resulting from high-intensity, upper and lower body dynamic resistance training (WT). A group of 17 men and 20 women were recruited for WT, and 6 men and 7 women served as a control group. The WT group performed six dynamic resistance exercises to fatigue using 8-12 repetition maximum (RM). The subjects trained 3 days a week for 12 weeks. One-RM knee extension (KE) and chest press (CP) exercises were measured at baseline and at weeks 2, 4, 6, 8, and 12 for the WT group. Muscle thickness (MTH) was measured by ultrasound at eight anatomical sites. One-RM CP and KE strength had increased significantly at week 4 for the female WT group. For the men in the WT group, 1 RM had increased significantly at week 2 for KE and at week 6 for CP. The mean relative increases in KE and CP strength were 19% and 19% for the men and 19% and 27% for the women, respectively, after 12 weeks of WT. Resistance training elicited a significant increase in MTH of the chest and triceps muscles at week 6 in both sexes. There were non-significant trends for increases in quadriceps MTH for the WT groups. The relative increases in upper and lower body MTH were 12%-21% and 7%-9% in the men and 10%-31% and 7%-8% in the women respectively, after 12 weeks of WT. These results would suggest that increases in MTH in the upper body are greater and occur earlier compared to the lower extremity, during the first 12 weeks of a total body WT programme. The time-course and proportions of the increase in strength and MTH were similar for both the men and the women.
Article
This study was designed to determine the response of muscle protein to the bolus ingestion of a drink containing essential amino acids and carbohydrate after resistance exercise. Six subjects (3 men, 3 women) randomly consumed a treatment drink (6 g essential amino acids, 35 g sucrose) or a flavored placebo drink 1 h or 3 h after a bout of resistance exercise on two separate occasions. We used a three-compartment model for determination of leg muscle protein kinetics. The model involves the infusion of ring-(2)H(5)-phenylalanine, femoral arterial and venous blood sampling, and muscle biopsies. Phenylalanine net balance and muscle protein synthesis were significantly increased above the predrink and corresponding placebo value (P < 0.05) when the drink was taken 1 or 3 h after exercise but not when the placebo was ingested at 1 or 3 h. The response to the amino acid-carbohydrate drink produced similar anabolic responses at 1 and 3 h. Muscle protein breakdown did not change in response to the drink. We conclude that essential amino acids with carbohydrates stimulate muscle protein anabolism by increasing muscle protein synthesis when ingested 1 or 3 h after resistance exercise.