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A Creatine-Protein-Carbohydrate Supplement Enhances Responses to Resistance Training
Abstract
Studies attributing gains in strength and lean body mass (LBM) to creatine monohydrate (CrM) during resistance exercise (RE) training have not assessed these changes alongside cellular and subcellular adaptations. Additionally, CrM-treated groups have seldom been compared with a group receiving a placebo similar in nitrogen and energy. The purpose of this study was to examine the effects of a CrM-containing protein-carbohydrate (PRO-CHO) supplement in comparison with a supplement containing a similar amount of nitrogen and energy on body composition, muscle strength, fiber-specific hypertrophy, and contractile protein accrual during RE training.
In a double-blind, randomized protocol, resistance-trained males were matched for strength and placed into one of three groups: protein (PRO), PRO-CHO, or the same PRO-CHO supplement (1.5 g x kg(-1) body weight x d(-1)) containing CrM (Cr-PRO-CHO) (0.1 g x kg(-1) body weight x d(-1)). Assessments were completed the week before and after a 10-wk structured, supervised RE program: strength (1RM, three exercises), body composition (DEXA), and vastus lateralis muscle biopsies for determination of muscle fiber type (I, IIa, IIx), cross-sectional area (CSA), contractile protein, and creatine content.
Cr-PRO-CHO provided greater improvements in 1RM strength. At least 40% of the strength improvements could be attributed to hypertrophy of muscle involved in this exercise. Cr-PRO-CHO also resulted in greater increases in LBM, fiber CSA, and contractile protein compared with PRO and PRO-CHO.
In RE-trained participants, supplementation with Cr-PRO-CHO provided greater muscle hypertrophy than an equivalent dose of PRO-CHO, and this response was apparent at three levels of physiology (LBM, fiber CSA, and contractile protein content).
... Thirty-three studies assessed the effect of protein/aa supplementation compared with a control group on muscle mass with the use of dual-energy x-ray absorptiometry. 12,17,19,22,30,32,33,35,36,38,39,[41][42][43][45][46][47][48][49][51][52][53][54][55][56][57]59,60,[63][64][65][66] Six studies 29,31,34,44,62,67 used bioelectrical impedance analysis, 2 studies 50,58 used hydrostatic weighing, and 1 study 37 used anthropometric method to assess body composition. Protein/aa supplementation yielded a significant increase in muscle mass compared with the control group (WMD, 0.45 kg; 95% CI, 0.20-0.71 ...
... Lat Pull Strength Five studies (8 groups) with 141 participants were analyzed for the effects of protein supplementation on lat pull strength. 15,41,47,59,60 A significant difference was seen when strength was measured by lat pull (WMD, 8.42 kg; 95% CI, 5.58-11.26 kg; P < .001; Figure 3). ...
... Twenty-two studies (36 groups) with 959 participants assessed the effect of protein/aa supplementation on upper body strength, represented by bench press. 15,[17][18][19]30,35,[39][40][41][42]46,[48][49][50][55][56][57]59,60 Bench press strength tended to increase more in the protein/aa supplementation group compared with the placebo group (WMD, 4.29 kg; 95% CI, 1.05-7.54 kg; P = .01; ...
The objective of this study was to investigate the effect of protein and/or amino acid supplementation on muscle mass and strength in a healthy population. A structured literature search was conducted from database inception up to October 23, 2019, using PubMed and Scopus. Data were collected from randomized controlled trials and weighted mean difference, and its 95% confidence interval was calculated by using a random-effects model. Risk of bias was assessed using the Cochrane tool. Data were included from 46 randomized controlled trials, totaling 2049 participants. Protein but not amino acid supplementation resulted in significant positive effects on muscle mass (weighted mean difference, 0.47 kg; 95% confidence interval, 0.18-0.75 kg; P < .001) and upper body strength. The significant effect of protein supplementation on muscle mass persisted in the
... While insightful, there were limitations including: (a) some studies contained fewer than eight participants, (b) some studies included participants with diseases, (c) some studies were confounded by limb unloading prior to resistance training, or (d) some studies used biochemical methods to assess myofibrillar protein concentrations that may yield inaccurate results. Moreover, with the exception of three studies (Cribb and Hayes, 2006;Cribb et al., 2007;Haun et al., 2019a), all of the aforementioned studies examined untrained participants, and all of these studies examined intramuscular protein responses to moderate-to-higher-volume training regimens. Thus, it is currently unknown how high-load resistance training affects skeletal muscle protein composition adaptations. ...
... Concentration decrements in both contractile proteins were not nearly as robust as observed in Haun et al. (2019a) study and, in lieu of the 19% increases in type II fCSA herein, these data suggest appreciable myofibrillar protein accretion likely occurred with the implemented high-load training program. It is notable that data from two studies by Cribb et al. (2007) contradict the aforementioned paradigm. In the first study the authors reported that 10 weeks of resistance training with or without the timing of nutrient provision surrounding workouts increased contractile protein content from ∼65 mg/g wet muscle to ∼90 mg/g wet muscle (Cribb and Hayes, 2006). ...
... In the first study the authors reported that 10 weeks of resistance training with or without the timing of nutrient provision surrounding workouts increased contractile protein content from ∼65 mg/g wet muscle to ∼90 mg/g wet muscle (Cribb and Hayes, 2006). In the second study participants were examined prior to and following 10 weeks of resistance training while using different nutritional supplements (Cribb et al., 2007). Only change scores in myofibrillar protein content were reported, and similar to the first publication, the authors noted that PRE-to-POST intervention changes across groups were ∼20-30 mg/g wet muscle. ...
While high-load resistance training increases muscle hypertrophy, the intramuscular protein responses to this form of training remains largely unknown. In the current study, recreationally resistance-trained college-aged males (N = 15; mean ± SD: 23 ± 3 years old, 6 ± 5 years training) performed full-body, low-volume, high-load [68–90% of one repetition maximum (1RM)] resistance training over 10 weeks. Back squat strength testing, body composition testing, and a vastus lateralis biopsy were performed before (PRE) and 72 h after the 10-week training program (POST). Fiber type-specific cross-sectional area (fCSA), myofibrillar protein concentrations, sarcoplasmic protein concentrations, myosin heavy chain and actin protein abundances, and muscle tissue percent fluid were analyzed. The abundances of individual sarcoplasmic proteins in 10 of the 15 participants were also assessed using proteomics. Significant increases (p < 0.05) in type II fCSA and back squat strength occurred with training, although whole-body fat-free mass paradoxically decreased (p = 0.026). No changes in sarcoplasmic protein concentrations or muscle tissue percent fluid were observed. Myosin heavy chain protein abundance trended downward (−2.9 ± 5.8%, p = 0.069) and actin protein abundance decreased (−3.2 ± 5.3%, p = 0.034) with training. Proteomics indicated only 13 sarcoplasmic proteins were altered with training (12 up-regulated, 1 down-regulated, p < 0.05). Bioinformatics indicated no signaling pathways were affected, and proteins involved with metabolism (e.g., ATP-PCr, glycolysis, TCA cycle, or beta-oxidation) were not affected. These data comprehensively describe intramuscular protein adaptations that occur following 10 weeks of high-load resistance training. Although previous data from our laboratory suggests high-volume resistance training enhances the ATP-PCr and glycolytic pathways, we observed different changes in metabolism-related proteins in the current study with high-load training.
... Maintaining the momentum of muscle protein synthesis is related to the turnover and metabolism of protein resources in the body, which greatly affects the anabolic processes [16,17]. The recommended protein intake for athletes is 1.5-2 g/kg body mass (BM) and in specific cases even more than 3.0 g/kg BM [18,19,20,21]. ...
... In contrast to whey protein, supplements containing a predominance of casein protein, due to their slower rate of digestion and release kinetics allow for prolonged supply of amino acids for skeletal muscles [20,22,25]. Numerous studies have confirmed that the use of protein dietary supplements before and after exercise increases sports performance [23,28], affects muscle hypertrophy [19,21] and muscular power [18,19,28], and increases lean body mass [18,19,29]. Important supplements used immediately after and during the first 2 hours of recovery include carbohydrate-protein products that also affect the concentration of GH and I [8]. ...
... In contrast to whey protein, supplements containing a predominance of casein protein, due to their slower rate of digestion and release kinetics allow for prolonged supply of amino acids for skeletal muscles [20,22,25]. Numerous studies have confirmed that the use of protein dietary supplements before and after exercise increases sports performance [23,28], affects muscle hypertrophy [19,21] and muscular power [18,19,28], and increases lean body mass [18,19,29]. Important supplements used immediately after and during the first 2 hours of recovery include carbohydrate-protein products that also affect the concentration of GH and I [8]. ...
... Maintaining the momentum of muscle protein synthesis is related to the turnover and metabolism of protein resources in the body, which greatly affects the anabolic processes [16,17]. The recommended protein intake for athletes is 1.5-2 g/kg body mass (BM) and in specific cases even more than 3.0 g/kg BM [18,19,20,21]. ...
... In contrast to whey protein, supplements containing a predominance of casein protein, due to their slower rate of digestion and release kinetics allow for prolonged supply of amino acids for skeletal muscles [20,22,25]. Numerous studies have confirmed that the use of protein dietary supplements before and after exercise increases sports performance [23,28], affects muscle hypertrophy [19,21] and muscular power [18,19,28], and increases lean body mass [18,19,29]. Important supplements used immediately after and during the first 2 hours of recovery include carbohydrate-protein products that also affect the concentration of GH and I [8]. ...
... In contrast to whey protein, supplements containing a predominance of casein protein, due to their slower rate of digestion and release kinetics allow for prolonged supply of amino acids for skeletal muscles [20,22,25]. Numerous studies have confirmed that the use of protein dietary supplements before and after exercise increases sports performance [23,28], affects muscle hypertrophy [19,21] and muscular power [18,19,28], and increases lean body mass [18,19,29]. Important supplements used immediately after and during the first 2 hours of recovery include carbohydrate-protein products that also affect the concentration of GH and I [8]. ...
... 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. ...
... Research that focuses on protein turnover using tracer kinetic shows that WP supplementation results in a high blood amino acid peak as well as a transient rise in protein synthesis and leucine oxidation at rest [5][6]. When given in conjunction with resistance exercise, WP supplementation has been shown to increase strength and power as well as fat free mass (FFM) [1][2][3]7]. Such gains in strength and FFM during resistance training with WP were also greater compared with soy protein [7], casein [8], or carbohydrate [1]. ...
... In addition, results of these study were derived from a single exercise bout, so it remains unclear how fast such an increase in protein synthesis would result in a gain in muscle mass. Other studies did show increases in body weight and FFM as a result of WP supplementation [1][2][3]7]. However, these studies have used a much longer treatment period (i.e., > 10 weeks) and a much higher dose of WP (i.e., 1.5 g per kg body weight per day) [1][2][3]. ...
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.
... This meta-analysis also suggests that these muscular hypertrophic benefits are greater in young adults compared to older individuals. Another study discovers greater improvements in 1RM, lean body mass, fiber cross-sectional area and contractile protein in trained young males when supplemented with creatine monohydrate combined with a multi-nutrient supplement and resistance training [40]. This research found improvements in body composition at the cellular and sub cellular-levels in resistance-trained participants which was a novel finding. ...
... This research found improvements in body composition at the cellular and sub cellular-levels in resistance-trained participants which was a novel finding. It was conducted at a supplement loading dosage of 20g day-1 followed by a maintenance phase of 0.03g/kg/day [40]. The reduction of the serum levels of myostatin [37] also promotes muscle gain as myostatin isa muscle growth inhibitor and reduction of it allows skeletal muscle hypertrophy. ...
Creatine is popular as a supplement, especially for strength and power activities. Even though most of the studies performed on creatine, have been focused on its efficacy as an ergogenic aid, there have been multiple therapeutic benefits as well. Creatine supplementation has been reported as beneficial for a plethora of medical conditions such as diabetes, heart disease, and sarcopenia. Additionally, creatine is an antioxidant, reducing the risk of progression of some cancers, reducing liver fat accumulation, minimizing bone loss, and increasing cognitive function in the aging population. Creatine is essential in cellular metabolism and the body's phosphagen energy system leading to better endurance and increased levels of energy in short time intervals such as during a sprint or a fast set of weightlifting. Usage of creatine, short-term or over a long period is safe, with no effects of renal dysfunction, gastrointestinal issues, musculoskeletal injuries, or cognitive functioning. This review article explains the benefits of creatine primarily from an athletic standpoint and concludes that creatine supplementation is safe with little to no side effects. Nevertheless, the quality and purity of creatine supplements vary significantly due to variable regulation and manufacturing procedures, which pose possible health concerns to consumers.
... Foram utilizadas revisões dos últimos 10 anos, com exceção de artigos utilizados como base de referências conceituais sobre achados e definições de terminologias relevantes para a realização dessa revisão, sendo esses Hattori. (2009) ;Kreider, (2010) ;Cribb, (2007) ;Gualano, (2011);Hill, (2007). Para a montagem desta revisão de literatura, foram utilizadas 41 referências, sendo essas artigos científicos e livros publicados em português, inglês e espanhol. ...
... Na literatura científica somos contemplados com um estudo que analisa o efeito de um treinamento durante 4 semanas intervalado de alta intensidade e a suplementação de creatina analisando a potência crítica e capacidade anaeróbica, distribuindo 42 homens de forma aleatória entre 3 grupos: grupo CR (10g de creatina e 10g de dextrose), grupo placebo com apenas 10 grama de dextrose e um grupo controle sem tratamento. Dos grupos analisados, foram vistas melhorias na capacidade de potência máxima no grupo com tratamento de creatina e dextrose, sendo assim, sugere-se a possível contribuição da creatina nos exercícios que exijam de fatores de capacidade de potência crítica máxima e necessidades de vias anaeróbicas (Cribb, 2007). ...
O uso de recursos ergogênicos tem sido cada vez mais frequentes no âmbito esportivo e clínico, tanto com o objetivo de melhora de performance quanto com o objetivo de melhora da composição corporal de praticantes recreativos. A partir desses dados, é de suma importância um maior entendimento sobre os riscos e benefícios do uso de tais recursos. O presente trabalho tem como função investigar os riscos e benefícios associados ao uso da cafeína, creatina, beta-alanina e suplementação à base de carboidratos. Foram analisados 41 estudos, onde foram traçados a dimensão do aumento de performance e efeitos adversos designados a cada suplementação, levando em consideração o número amostral e o número de artigos analisados nas revisões sistemáticas que compõem a presente revisão de literatura. A partir dos dados analisados, foi constatado que a creatina, cafeína, beta-alanina e suplementos à base de carboidratos apresentam desfechos positivos significativos em relação à performance e composição corporal. Não foram observados graves efeitos adversos em todos os suplementos analisados, exceto na cafeína, com o uso de altas doses. Conclui-se então que o uso dos suplementos supracitados é seguro e apresenta boas evidências para uso.
... Este protocolo aplicado não foi eficaz em homens de meia-idade e mais velhos, no desenvolvimento de massa muscular e força (Buford, et al., 2007). Cribb, et al., (2007), relataram melhores resultados em 1RM, massa muscular, área da seção transversal da fibra e proteína contrátil em jovens treinados do sexo masculino, estes suplementados e treinando treinamento de resistência contendo 0,1 grama por peso corporal de creatina, 1,5 grama por peso corporal de proteína e carboidrato e comparado com a proteína ou um suplemento de carboidrato de proteína sem creatina. ...
... A quantidade de creatina suplementada em estudo por Cribb, et al., (2007), foi maior do que a quantidade normalmente relatada em estudos anteriores (uma dose de carga a cerca de 20 gramas por peso corporal ao dia, seguido por uma dose de manutenção de 3 a 5 gramas por peso corporal ao dia, é, geralmente equivalente a aproximadamente 0,3 gramas por peso corporal ao dia, e a duração do período de suplementação em estudos anteriores (Louis, et al., 2003). ...
O consumo de creatina pode potencializar os efeitos do treinamento resistido promovendo resultados fisiológicas que podem interferir de forma positiva, gerando o aumento de força muscular, hipertrofia muscular e resistência. Este artigo objetivou verificar os principais efeitos e os benefícios da suplementação de creatina em praticantes de treinamento resistido. Quanto aos métodos para a elaboração deste, buscou-se a revisão de literatura, qualitativa, de caráter descritivo, a partir de documentos secundários para o alcance do objetivo. Conclui-se que a suplementação de creatina por praticantes de treinamento resistido, poderá influenciar nos resultados fisiológicos de tal maneira a melhorar a força muscular, a hidratação celular, o aumento de massa muscular e a resistência muscular.
... Finally, the addition of carbohydrates, proteins and/or caffeine appears to be beneficial. On the one hand, the ingestion of carbohydrates and proteins in combination with creatine may create a greater insulin spike and, therefore, augment creatine uptake and glycogen storage in muscles [4,41,55]. On the other hand, the addition of caffeine may emphasize the primary ergogenic effect of creatine supplementation, which is an extra amount of energy, by delaying the onset of neuromuscular fatigue and, therefore, improve the ability to practice longer and/or perform at a higher level [49,56,57]. The addition of D-pinitol might also be considered as this supplement may negate the possible weight gain (possibly detrimental for soccer players) with creatine supplementation without affecting its advantageous benefits [58]. ...
... Light to moderate dose(s) of creatine (3 to 5 g -once or several times per week) during the season might also be beneficial in cases of fatigue, to sustain adequate levels of creatine, phosphocreatine and/or glycogen in the muscles, to improve the repair of muscles, or to give a physical (and mental) boost to soccer players. The addition of carbohydrates, proteins and/or caffeine may increase some of these advantageous effects [41,[55][56][57]. ...
This review article aimed to summarize the current state of understanding on creatine supplementation for soccer players. In other words, it investigated the beneficial (and potentially negative) effects of this supplementation on sport-specific skills and performance in soccer players. Furthermore, this article accordingly discussed the safest and most recommended protocols for the consumption of creatine by these athletes.
... Our preliminary data suggests that in times of metabolic stress when mTOR signaling is inhibited by AMPK and downstream activators drive mitochondrial biogenesis, AA uptake into cells is directed toward mitochondrial fission, growth and function. Indeed, our data in healthy trained humans also suggests an augmentative effect of WP on contractile protein accretion-independent force production [131]. While Cr supplementation demonstrably induced greater increases in fibre size, contractile protein content and strength gains, the force production gains observed following Cr + WP supplementation were independent of fibre size [131]. ...
... Indeed, our data in healthy trained humans also suggests an augmentative effect of WP on contractile protein accretion-independent force production [131]. While Cr supplementation demonstrably induced greater increases in fibre size, contractile protein content and strength gains, the force production gains observed following Cr + WP supplementation were independent of fibre size [131]. We speculate that WP modulates contractile function via direct effects on the sarcoplasmic reticular calcium-handling apparatus and/or mitochondrial ATP production, albeit we are yet to confirm this in healthy humans or DMD patients/animal models. ...
Duchenne Muscular Dystrophy (DMD) is a fatal genetic muscle wasting disease with no current cure. A prominent, yet poorly treated feature of dystrophic muscle is the dysregulation of energy homeostasis which may be associated with intrinsic defects in key energy systems and promote muscle wasting. As such, supplementative nutriceuticals that target and augment the bioenergetical expansion of the metabolic pathways involved in cellular energy production have been widely investigated for their therapeutic efficacy in the treatment of DMD. We describe the metabolic nuances of dystrophin-deficient skeletal muscle and review the potential of various metabogenic and nutriceutical compounds to ameliorate the pathological and clinical progression of the disease.
... In a study by Cribb et al. (2007), 10 recreational bodybuilders were given a total dose of 1.5 g$kg 21 $d 21 consisting of either whey isolate protein, protein + carbohydrate or protein + carbohydrate + creatine while participating in a high-intensity, 3-phase resistance training program for 10 weeks (18). Subjects consumed the prescribed supplement dose in 3 equal servings (0.5 g$kg 21 $d 21 ) throughout the day (i.e., midmorning, posttraining, and before sleep); total dietary intake ranged from 1.6 to 2.3 g$kg 21 $d 21 . ...
... In a study by Cribb et al. (2007), 10 recreational bodybuilders were given a total dose of 1.5 g$kg 21 $d 21 consisting of either whey isolate protein, protein + carbohydrate or protein + carbohydrate + creatine while participating in a high-intensity, 3-phase resistance training program for 10 weeks (18). Subjects consumed the prescribed supplement dose in 3 equal servings (0.5 g$kg 21 $d 21 ) throughout the day (i.e., midmorning, posttraining, and before sleep); total dietary intake ranged from 1.6 to 2.3 g$kg 21 $d 21 . ...
A NUMBER OF KEY CONSIDERATIONS EXIST REGARDING PROTEIN, INCLUDING OVERT REQUIREMENTS, QUALITY, AND DOSING. IN ADDITION, ATHLETES AND RESEARCHERS HAVE CLOSELY EXAMINED THE IMPACT OF PROTEIN AND NUTRIENT TIMING ON ACUTE AND PROLONGED ADAPTATIONS TO DIFFERENT TYPES OF EXERCISE WITH MIXED RESULTS. THE PATTERN OF MEAL AND PROTEIN CONSUMPTION SEEMS TO EXERT AN IMPACT ON CHANGES RELATED TO HEALTH, BODY COMPOSITION, AND MUSCLE PROTEIN SYNTHESIS. PROTEIN IS A KEY NUTRIENT FOR INDIVIDUALS LOOKING TO LOSE WEIGHT, REDUCE THEIR BODY FAT, AND IMPROVE THEIR HEALTH. FINALLY, PROTEIN INTAKE CONTINUES TO BE A KEY VARIABLE FOR ATHLETES LOOKING TO GAIN STRENGTH, POWER, AND FAT-FREE MASS.
... Without adequate intake of calories and essential proteins, individuals experience a situation where the assembly of muscle protein is exceeded by breakdown. Dangin et al. (2001) state that a concomitant nutrient intake is therefore necessary to produce a positive NPB in order to avoid a shift to this catabolic state (Cribb et al., 2007). ...
... Ultimately the addition of protein in the form of whey isolates has been shown to improve performance with chronic use before, during, and after resistance training (Rasmussen et al. 2000;Cribb et al. 2007;Hartman et al. 2007;Cockburn et al. 2008). Whey protein contains the essential amino acids necessary for regeneration of muscle cells damaged during strenuous lifting. ...
... Despite the possibilities for rigorous planning, programming at the start of a training block alone could lead to suboptimal progression and insufficient preparation for competition, particularly in multifaceted sports with long and congested competitive schedules (e.g., soccer, rugby, basketball, etc.). For example, an individual's strength capabilities can fluctuate in response to psychological and physiological stressors (Figure 1), and research has suggested that confounding variables, such as fatigue, poor sleep, high levels of stress, specific training phases, and improper nutrition, can all impact an athlete's ability to lift consistent loads continuously (7,18,23,66,76,95). Therefore, practitioners must find strategies to help circumvent some potential limiters to performance. ...
Velocity-based training (VBT) uses the measurement of velocity to help inform and influence testing, monitoring, programming, autoregulation, and feedback strategies within strength and conditioning (S&C) practice. This review focuses specifically on the definitions and underpinning principles of VBT, as well as load-velocity profiling, while undertaking an in-depth evaluation of the literature and translating this information into practical recommendations for S&C coaches. There is a detailed evaluation of the different ways to construct a load-velocity profile (LVP), providing examples of simplicity, time efficiency, increased accuracy, and optimizing training prescriptions and manipulations. New approaches, such as combining ballistic and nonballistic exercises, and methods of extrapolation have been explored. In addition, this review highlights practical considerations regarding data analysis, specific exercises, statistical modeling, number of loads, and extrapolation methods. A worked example of using LVP data within Excel has also been presented. Finally, there is a focus on 1 repetition maximum prediction, the benefits and challenges of implementing such an approach, and the most appropriate ways of collecting reliable and valid data.
... Also, creatine has been well established to preserve energy during strenuous exercise, and creatine supplementation in combination with heavy resistance exercise is known to improve physical performance, lean mass gain, and muscle function (Volek et al., 1997;Kreider, 2003;Brudnak, 2004). Accordingly, 10-week creatine-protein-carbohydrate supplementation resulted in greater improvements in 1 RM strength, lean body mass, muscle cross-sectional area, and contractile protein compared to protein-carbohydrate ingestion (Cribb et al., 2007). Typically, creatine is characterized by its ability to provide anabolic stimulation due to increased water retention (Antonio et al., 2021). ...
The aim of this study was to investigate the combined effect of glutamine (GLU) and creatine (CRE) supplementation on body composition, body hydration levels, and selected performance parameters in football players. Eight volunteer licensed male football players aged 19 to 23 participated in this study. The study was randomized and single-blinded. In the study, athletes were administered 10 g of glutamine and creatine before and after training for seven days. Some tests, measurements, and analyses were performed in equal physical conditions with seven-day intervals using a pre-test/post-test experimental design. The research data were analyzed with a dependent sample t-test. In the comparison of the parameters pre- and post-supplementation, statistically significant differences were found in body mass, skeletal muscle mass, total body water, body mass index (BMI), metabolic rate, protein, and mineral values (p
... However, the increase in muscle size may be primarily due to intracellular water retention (Bemben & Lamont;Mesa et al., 2002). In addition, an increase in the cross-sectional area of muscle fibers as well as myogenic regulatory factors is achieved when a concurrent longer resistance training intervention is applied (Branch, 2003;Cribb et al., 2007;Deldicque et al., 2008). As participants in the current study underwent the reduced training regime throughout the post-season, based on soccer-skill and game practice, without muscle strength/power training, the increase in BW was most likely associated with increase in intracellular water. ...
BACKGROUNDː Several studies have examined the effects of creatine supplementation in adult athletes in season or pre-season preparation. However, few studies have examined the effects of creatine supplementation in adolescent soccer players during reduced training in an off-season. OBJECTIVE: The aim of the study was to examine the effects of short-term creatine monohydrate supplementation on the anaerobic performance and body composition in adolescent soccer players during reduced training in an off-season. METHODSː Using a double-blind experiment design, 16 soccer players (aged 18.0 ± 0.8 yr) were randomly assigned to 5 days of either 20 g . day-1 creatine monohydrate (Cr) or placebo supplementation. One day before and a day after the supplementation, participants completed squat and countermovement jumps (SJ, CMJ), 10-m running sprint, 6-s single cycling sprint (CST), an intermittent anaerobic test on a bicycle ergometer (10 x 6s, IAnTBE) and measurement of body composition. RESULTSː Cr supplementation had no significant effect (p > .05) on any performance test. However, effect size values indicated medium or small clinical significance in SJ (d = 0.59), CST (6-s power, d = 0.50; peak power, d = 0.48) and IAnTBE (best peak power, d = 0.44; post-exercise blood lactate concentration, d = - 0.59; fatigue index, d = - 0.28 ). Relative to the placebo, Cr supplementation resulted in a significant increase in body weight (BW) (p = .015). CONCLUSIONSː The results of the study suggest that short-term Cr supplementation administered to adolescent soccer players during their off-season significantly increase body weight and could have small/medium clinical significance effect on improve lower-body maximal anaerobic power output and power output recovery during maximal intermittent exercise. The study also confirms that Cr supplementation is safe and without side effects for adolescent athletes.
... It is known that, in modalities involving strength, carbohydrates play an important role. In the study by Cribb et al. (2007) conducted with 31 people, three groups were compared for 10 weeks, the first group used a supplement containing only protein, the second group used protein and carbohydrate and the third group a solution containing monohydrate creatine, protein and carbohydrate. It was found that the participants of the protein group associated with carbohydrate and creatine had higher body mass and muscle strength gain compared to the other groups. ...
Introdução: O crossfit é uma atividade de força física e condicionamento metabólico. Sabe-se que a alimentação e a suplementação nutricional podem interferir no desempenho físico dos praticantes. Objetivo: Quantificar o uso de suplementos nutricionais (proteicos, de carboidratos e de micronutrientes), bem como avaliar a adequação do momento do consumo do suplementos mais citado (pré, durante ou pós treino). Materiais e Métodos: Foram convidados 60 participantes da modalidade crossfit de três academias situadas na cidade de São Paulo. O instrumento da pesquisa foi um questionário elaborado pelos pesquisadores. Os dados foram analisados com estatística descritiva. Resultados: Dentre os participantes (48% homens e 52% mulheres), 70% faziam uso de suplemento. Os mais utilizados foram os proteicos, principalmente o whey protein. Apenas 4,8% utilizavam suplementos de carboidratos, e 3,2% de micronutrientes. A maioria dos consumidores de whey protein relatou uso de 1 (37,1%) ou 2 (34,3%) colheres-medida por dia. Um terço (34,3%) dos usuários relatou consumir este suplemento antes do treino, seguidos de 25,7% que o consumiam antes e após o treino, e 14,3% que faziam uso somente no pós treino. Discussão: Atividades de potência muscular anaeróbia envolvem maior turnover proteico, o que pode explicar a preferência por suplementos de proteína. Conclusão: A maioria dos participantes da pesquisa fazia uso de suplementos nutricionais, e o whey protein foi o mais citado. As doses estipuladas no rótulo dos produtos eram respeitadas pela maior parte dos entrevistados, no entanto, o momento de utilização e o tipo de suplemento escolhido em muitos casos não estavam adequados.
... Frequent maximum testing could therefore create unwanted fatigue, potentially impacting on performances throughout the year [5]. While this is unlikely to be problematic in settings where 1RMs are relatively stable (e.g., strength sports), maximum strength might fluctuate in athletes competing in these sports due to training priorities [5], sleep [6], nutrition [7], and/or fatigue [8]. As a result, alternative strategies such as 1RM prediction from load-velocity profile (LVP) data might be an effective strategy to manipulate load (i.e., autoregulation), which is thought to be vital to optimize athletic development [9]. ...
The study aim was to compare different predictive models in one repetition maximum (1RM) estimation from load-velocity profile (LVP) data. Fourteen strength-trained men underwent initial 1RMs in the free-weight back squat, followed by two LVPs, over three sessions. Profiles were constructed via a combined method (jump squat (0 load, 30–60% 1RM) + back squat (70–100% 1RM)) or back squat only (0 load, 30–100% 1RM) in 10% increments. Quadratic and linear regression modeling was applied to the data to estimate 80% 1RM (kg) using 80% 1RM mean velocity identified in LVP one as the reference point, with load (kg), then extrapolated to predict 1RM. The 1RM prediction was based on LVP two data and analyzed via analysis of variance, effect size (g/), Pearson correlation coefficients (r), paired t-tests, standard error of the estimate (SEE), and limits of agreement (LOA). p < 0.05. All models reported systematic bias < 10 kg, r > 0.97, and SEE < 5 kg, however, all linear models were significantly different from measured 1RM (p = 0.015 <0.001). Significant differences were observed between quadratic and linear models for combined (p < 0.001; = 0.90) and back squat (p = 0.004, = 0.35) methods. Significant differences were observed between exercises when applying linear modeling (p < 0.001, = 0.67–0.80), but not quadratic (p = 0.632–0.929, = 0.001–0.18). Quadratic modeling employing the combined method rendered the greatest predictive validity. Practitioners should therefore utilize this method when looking to predict daily 1RMs as a means of load autoregulation.
... Intake of about 60 grams of whey protein per day for 12 weeks proved effective in decreasing body fat and increasing lean body mass in overweight men following a calorie restricted diet and resistance training program (22). Resistance-trained men with whey protein supplement intake of 1.5g/kg of body per day for 11 weeks showed improvements in strength and doubling their lean body mass as compared to those groups which were using different carbohydrates, creatine or combination of creatine and whey protein supplements (23). ...
Whey nowadays considered as nutritional power house of future. Presently, whey mainly used as energy base drinks for sportsman and for therapeutic application in many countries. The two primary sources of protein in milk are the caseins and whey. After processing occurs, the caseins are the proteins responsible for making curds, while whey remains in an aqueous environment. Whey protein is a reliable source of amino acids and biologically active proteins which act as a nutritional supplement. The components of whey include beta lactoglobulin, alpha lactoalbumin, bovine serum albumin, lactoferrin, immunoglobluins, lactoperoxidase enzymes, glycomacropeptides, lactose, and minerals. Whey proteins have a high amount of branched chain amino acids such as leucine, isoleucine, and valine. These are also rich in the sulfur-containing amino acids cysteine and methionine, which enhance immune functions through their intracellular conversion to glutathione. The present review paper gives information about the potential beneficial properties of whey protein and focuses on using whey protein supplementation as an immuno-modulator, antioxidant, anti-inflammatory, anti-diabetic, anti-cancer. In this context, the current review presented that whey protein supplementation is shown to maintain a high concentration of cellular antioxidants and boost immune defenses that promote carcinogen detoxification. Due to the positive findings, whey protein supplementation is starting to be viewed as a non-pharmaceutical adjunct therapy in the treatment of cancer. Also, whey protein provides an abundant supply of essential amino acids to organs and tissues, which stimulate tissue regenerative mechanisms and help minimize immune suppression. J Pharm Care 2019; 7(4): 112-117.
... Creatine is one of the most popular sports supplement these days and it is consumed by 25-40% of young athletes [7,10,12,19]. A broad range of creatine use can be attributed to its greater representation in sports where strength and speed are imperious [24]. The use of vitamins and mineral complexes was reported by 37.4% of athletes, which is similar to 45.0% of Australian athletes [8] and 45-47% of UK athletes [7,21]. ...
Background:
The aim of this international study was to investigate the prevalence of the use of sports supplements among young athletes, as well as their knowledge and attitudes towards sports supplementation.
Methods:
Organized survey study testing the level of knowledge, attitudes, beliefs and practices concerning the use of sports supplements was administered to 348 athletes, 15-18 year olds from 4 countries competing in 18 sports at the international level.
Results:
The prevalence rate of the intake of sports supplements was 82.2%, with the protein supplements being predominant (54.5%). Coaches were identified as the primary source of information regarding supplementation (41.4%). The enhancement of athletic performance (35.4%) was the major motivation for the supplements intake. The majority of athletes (72.1%) were aware of associated health risks. The young athletes possess varying levels of knowledge regarding their own supplementation. The obtained data about the level of knowledge were statistically analyzed using the correspondence analysis. Less than 40% of athletes had the knowledge about the proper and intended use of protein, creatine, amino acids, beta alanine and glutamine, while they had greater understanding about vitamins and minerals, sports drinks and caffeine. The athletes in developed countries had greater access and utilization of professional resources such as dieticians. Young athletes are still unfamiliar with WADA regulations (55.5%), and the misuse of sports supplements represents an ethical dilemma for some.
Conclusion:
These findings indicate the necessity of a comprehensive education of all team members about sports supplements and careful supervision of the athletic development of young athletes.
... Willoughby and Rosene (2001) similarly reported ∼40% increases in myofibrillar protein concentration after 12 weeks of resistance training, and have also reported ∼85% increases in myofibrillar protein concentrations 6 h after a single session of resistance training . Cribb and Hayes (2006) and Cribb et al. (2007) have reported similar increases in myofibrillar protein concentration after 10 weeks of resistance training in two separate studies. However, a comparatively greater number of authors have reported no alteration in protein concentration or an apparent decrease in response to resistance training. ...
Skeletal muscle is highly adaptable and has consistently been shown to morphologically respond to exercise training. Skeletal muscle growth during periods of resistance training has traditionally been referred to as skeletal muscle hypertrophy, and this manifests as increases in muscle mass, muscle thickness, muscle area, muscle volume, and muscle fiber cross-sectional area (fCSA). Delicate electron microscopy and biochemical techniques have also been used to demonstrate that resistance exercise promotes ultrastructural adaptations within muscle fibers. Decades of research in this area of exercise physiology have promulgated a widespread hypothetical model of training-induced skeletal muscle hypertrophy; specifically, fCSA increases are accompanied by proportional increases in myofibrillar protein, leading to an expansion in the number of sarcomeres in parallel and/or an increase in myofibril number. However, there is ample evidence to suggest that myofibrillar protein concentration may be diluted through sarcoplasmic expansion as fCSA increases occur. Furthermore, and perhaps more problematic, are numerous investigations reporting that pre-to-post training change scores in macroscopic, microscopic, and molecular variables supporting this model are often poorly associated with one another. The current review first provides a brief description of skeletal muscle composition and structure. We then provide a historical overview of muscle hypertrophy assessment. Next, current-day methods commonly used to assess skeletal muscle hypertrophy at the biochemical, ultramicroscopic, microscopic, macroscopic, and whole-body levels in response to training are examined. Data from our laboratory, and others, demonstrating correlations (or the lack thereof) between these variables are also presented, and reasons for comparative discrepancies are discussed with particular attention directed to studies reporting ultrastructural and muscle protein concentration alterations. Finally, we critically evaluate the biological construct of skeletal muscle hypertrophy, propose potential operational definitions, and provide suggestions for consideration in hopes of guiding future research in this area.
... (5) (16) (48) Une étude menée chez des culturistes montre un gain de puissance et masse musculaires plus important dans le groupe prenant de la créatine en plus des glucides et des protéines. (58) Toutefois, environ un tiers des sportifs ne réagissent pas à la créatine, qu'il s'agisse du développement musculaire ou de l'amélioration des performances. (22) La prise quotidienne de moins de 3 g de créatine par jour est considérée comme non pourvoyeuse d'effets indésirables par l'EFSA. ...
Le marché de la nutrition sportive est en plein essor. Les sportifs, voulant mettre toutes les chances de leur côté afin d’optimiser leurs performances, sont souvent prêts à effectuer des dépenses pour tester ces produits présentés comme miracles par leurs fabricants. Car les produits et compléments alimentaires destinés aux sportifs sont coûteux. Mais sont-ils pour autant efficaces ? Et surtout sans risques pour le consommateur ? Nous avons, à travers une enquête menée auprès d’athlètes, essayé d’en savoir davantage sur la consommation des compléments et produits alimentaires. A partir des résultats obtenus, nous avons fait le point sur les produits et compléments alimentaires les plus consommés, et surtout nous avons mis en évidence les risques qu’ils peuvent occasionner pour la santé. En effet, au-delà d’une efficacité contestable pour la plupart des compléments alimentaires, certains d’entre eux sont pourvoyeurs d’effets indésirables, et peuvent de ce fait aggraver des pathologies voire en induire. Ainsi, les sportifs devraient faire preuve de prudence, d’autant que dans la majorité des cas une alimentation variée et équilibrée suffit à couvrir leurs besoins et offre le meilleur garant de bonnes performances sportives.
... Comparable to studies examining strength gains following resistance training for 7-16 weeks [34][35][36][37], the subjects in the present study increased leg and bench press 1 RM muscle strength by 10-24% from pre to post. This is in line with most similar studies on protein supplementation and resistance training for 8-12 weeks, which report strength gains in 1 RM between 12% and 44% [29,30,32,33,[38][39][40]; however, a few outliers [26,27,41] appear with strength gains over 100% in 1 RM. The discrepancy between strength gains in the present study and the outliers may be due to subject characteristics and training status. ...
During prolonged resistance training, protein supplementation is known to promote morphological changes; however, no previous training studies have tested the effect of insect protein isolate in a human trial. The aim of this study was to investigate the potential effect of insect protein as a dietary supplement to increase muscle hypertrophy and strength gains during prolonged resistance training in young men. Eighteen healthy young men performed resistance training four day/week for eight weeks. Subjects were block randomized into two groups consuming either an insect protein isolate or isocaloric carbohydrate supplementation within 1 h after training and pre-sleep on training days. Strength and body composition were measured before and after intervention to detect adaptions to the resistance training. Three-day weighed dietary records were completed before and during intervention. Fat- and bone- free mass (FBFM) improved significantly in both groups (Mean (95% confidence interval (CI))), control group (Con): (2.5 kg (1.5, 3.5)p <0.01), protein group (Pro): (2.7 kg (1.6, 3.8)p <0.01) from pre- to post-. Leg and bench press one repetition maximum (1 RM) improved by Con: (42.0 kg (32.0, 52.0)p <0.01) and (13.8 kg (10.3, 17.2)p <0.01), Pro: (36.6 kg (27.3, 45.8)p <0.01) and (8.1 kg (4.5, 11.8)p <0.01), respectively. No significant differences in body composition and muscle strength improvements were found between groups. In young healthy men, insect protein supplementation did not improve adaptations to eight weeks of resistance training in comparison to carbohydrate supplementation. A high habitual protein intake in both Con and Pro may partly explain our observation of no superior effect of insect protein supplementation.
... Staples et al. (78) showed that except for postresistance exercise phosphorylation of Akt, after ingestion of 25 g of whey protein and 50 g of maltodextrin, there were no differences in muscle protein degradation or acetyl-CoA carboxylase-β, a surrogate marker for AMPK, v. 25 g of whey protein alone. Reports of enhanced hypertrophy while co-ingesting CHO and protein post-resistance exercise (91)(92)(93) are likely then attributed to amino acid content rather than a combinatory effect of amino acids and CHO and that the resultant insulinogenic response appears to be superfluous in the presence of an adequate provision of amino acids (77,78) . ...
Substantial research has been completed examining the impact of carbohydrate (CHO) intake on endurance exercise, whereas its role in resistance-based exercise performance, adaptation and cell signalling has yet to be fully characterised. This empirical shortcoming has precluded the ability to establish specific CHO recommendations for resistance exercise. This results in recommendations largely stemming from findings based on endurance exercise and/or anecdotal evidence despite the distinct energetic demands and molecular responses mediating adaptation from endurance- and resistance-based exercise. Moreover, the topic of CHO and exercise has become one of polarising nature with divergent views – some substantiated, others lacking evidence. Current literature suggests a moderately high daily CHO intake (3–7 g/kg per d) for resistance training, which is thought to prevent glycogen depletion and facilitate performance and adaptation. However, contemporary investigation, along with an emerging understanding of the molecular underpinnings of resistance exercise adaptation, may suggest that such an intake may not be necessary. In addition to the low likelihood of true glycogen depletion occurring in response to resistance exercise, a diet restrictive in CHO may not be detrimental to acute resistance exercise performance or the cellular signalling activity responsible for adaptation, even when muscle glycogen stores are reduced. Current evidence suggests that signalling of the mammalian target of rapamycin complex 1, the key regulatory kinase for gene translation (protein synthesis), is unaffected by CHO restriction or low muscular glycogen concentrations. Such findings may call into question the current view and subsequent recommendations of CHO intake with regard to resistance-based exercise.
... Regardless of which protocol is chosen, Cr should be administered close to exercise session (60 minutes prior to and/or immediately after) [111]. The reason for this is to provide a higher degree of Cr accumulation and therefore promote better gains in strength, body composition (increase lean mass with no increase in fat mass), training adaptations and muscle mass [70,112,113]. ...
Creatine is one of the best-known and most studied ergogenic supplements among athletes. Besides its performance-enhancing power, creatine has significant clinical potential in patients with neurological and neuromuscular diseases. The most frequently used form of creatine is creatine monohydrate. The utilization of creatine monohydrate seems to be somewhat limited due to its physico-chemical characteristics such as poor water solubility, instability in aqueous solutions (because of its tendency to cyclize into biologically inactive creatinine), and finite capacity of creatine transporters. Therefore, the pharmaceutical industry strives to develop novel forms of creatine that will diminishor overcome aforementioned limitations. New formulations of creatine seem to appear inthe market on a daily basis while no sufficient research is conducted regarding their physico-chemical characteristics and safety in humans. In this chapter, authors reviewed recent literature on advanced creatine formulations (e.g., creatine salts, chelates, estersand alkaline buffered forms). The purpose and goal for the use of new creatine formulations have been discussed as well as their advantages and disadvantages compared to creatine monohydrate
... But, to our knowledge, changes in CSA have not yet been found to correlate with changes in strength over the course of RET (237). Of the ;70 studies we examined, there were very few reports of this relation and only 1 laboratory to our knowledge, showed a robust association with changes in muscle strength and fiber CSA during protein supplementation and RET with all treatment groups combined (206,239,240). Both muscle size and strength increase with RET, and a common idea persists that increases in lean/muscle mass are coupled to changes in strength, yet the scientific evidence to support such a claim is limited. ...
The goal of this critical review is to comprehensively assess the evidence for the molecular, physiologic, and phenotypic skeletal muscle responses to resistance exercise (RE) combined with the nutritional intervention of protein and/or amino acid (AA) ingestion in young adults. We gathered the literature regarding the translational response in human skeletal muscle to acute exposure to RE and protein/AA supplements and the literature describing the phenotypic skeletal muscle adaptation to RE and nutritional interventions. Supplementation of protein/AAs with RE exhibited clear protein dose-dependent effects on translational regulation (protein synthesis) through mammalian target of rapamycin complex 1 (mTORC1) signaling, which was most apparent through increases in p70 ribosomal protein S6 kinase 1 (S6K1) phosphorylation, compared with postexercise recovery in the fasted or carbohydrate-fed state. These acute findings were critically tested via long-term exposure to RE training (RET) and protein/AA supplementation, and it was determined that a diminishing protein/AA supplement effect occurs over a prolonged exposure stimulus after exercise training. Furthermore, we found that protein/AA supplements, combined with RET, produced a positive, albeit minor, effect on the promotion of lean mass growth (when assessed in >20 participants/treatment); a negligible effect on muscle mass; and a negligible to no additional effect on strength. A potential concern we discovered was that the majority of the exercise training studies were underpowered in their ability to discern effects of protein/AA supplementation. Regardless, even when using optimal methodology and large sample sizes, it is clear that the effect size for protein/AA supplementation is low and likely limited to a subset of individuals because the individual variability is high. With regard to nutritional intakes, total protein intake per day, rather than protein timing or quality, appears to be more of a factor on this effect during long-term exercise interventions. There were no differences in strength or mass/muscle mass on RET outcomes between protein types when a leucine threshold (>2 g/dose) was reached. Future research with larger sample sizes and more homogeneity in design is necessary to understand the underlying adaptations and to better evaluate the individual variability in the muscle-adaptive response to protein/AA supplementation during RET.
... A estimativa energética e de macronutrientes subestimada, ocasionada pela não quantificação dos suplementos alimentares, parece ser o fator responsável pela correlação inversa e moderada entre Kcal/kg x IMC e Kcal/kg x somatório de dobras cutâneas já que os atletas de massa corporal mais elevada apresentam menor consumo relativo de energia e proteínas via alimentação, porém possuem IFMR = maior peso levantado na competição (kg) massa corporal do atleta (kg) Dentre os suplementos alimentares utilizados pelos paratletas estudados, destacaram-se os proteicos à base de proteínas do soro do leite (whey protein), mostrando provável interesse dos atletas em melhorar a qualidade proteica da sua dieta. Segundo Cribb et al. 11 , dentre os suplementos proteicos existentes, o whey protein apresenta vantagens devido ao seu perfil de aminoácidos, que têm rápida absorção e promovem maior hipertrofia muscular. ...
Introdução:
Atletas de halterofilismo buscam aumentar sua força em relação ao peso corporal utilizando treinamento resistido e a nutrição como ferramentas para melhorar o desempenho. Apesar dos benefícios proporcionados por um adequado planejamento alimentar, muitos atletas utilizam estratégias inadequadas, manifestadas pela piora na composição corporal e no desempenho esportivo.
Objetivo:
Analisar o consumo energético e proteico e o uso de suplementos alimentares de paratletas a fim de avaliar a influência da estratégia dietética no desempenho.
Métodos:
Foram coletados dados pessoais, medidas antropométricas, informações referentes ao comportamento alimentar e da competição de 24 paratletas halterofilistas do sexo masculino.
Resultados:
A quantidade de calorias e as porções de macronutrientes consumidas pela alimentação foram em média 2.235,8 ± 694,92 kcal, 27 ± 11,55% proteínas, 46 ± 8,17% carboidratos e 27 ± 8,57% lipídeos. Dos atletas estudados, 87,5% relataram utilizar suplementos alimentares. Os atletas com maior índice de massa corporal (IMC) apresentaram menor ingestão energética e proteica relativa, maior somatório de dobras cutâneas e desempenho similar a dos demais estudados.
Conclusão:
A estratégia utilizada pelos atletas de maior massa corporal não propiciou melhoria direta no desempenho e influen-ciou negativamente na composição corporal. Este fato deve-se provavelmente à falta de adequação entre dieta e suplementação.
... The current results suggest that untrained men will experience significant muscle hypertrophy and strength adaptations following resistance training regardless of postexercise protein supplementation. Although a number of researchers report positive effects (i.e., augmented training adaptations) of protein supplementation with resistance training, it should be noted that ingestion occurred both pre-and post-training (Coburn et al. 2006;Cribb et al. 2007), suggesting that additional supplementation proximal to training may be necessary for optimal hypertrophic adaptations to occur. While postexercise protein supplementation appears to enhance the acute anabolic response, recent research has observed no correlation between the acute effects of milk protein supplementation and the training-induced muscle hypertrophy seen after chronic resistance training (Mitchell et al. 2015). ...
Short-term resistance training has consistently demonstrated gains in muscular strength, but not hypertrophy. Post-resistance training protein ingestion is posited to augment the acute anabolic stimulus, thus potentially accelerating changes in muscle size and strength. The purpose of this investigation was to examine the effects of 4 weeks of resistance training with protein supplementation on strength and muscle morphology changes in untrained men. Participants (mean ± SD; N = 18; age, 22.0 ± 2.5 years; body mass index, 25.1 ± 5.4 kg·m⁻²) were randomly assigned to a resistance training + protein group (n = 9; whey (17 g) + colostrum (3 g) + leucine (2 g)) or a resistance training + placebo group (n = 9). One-repetition maximum (1RM) strength in the leg press (LP) and leg extension (LE) exercises, maximal isometric knee extensor strength (MVIC), and muscle morphology (thickness (MT), cross-sectional area (CSA), pennation angle) of the dominant rectus femoris (RF) and vastus lateralis (VL) was assessed before and after training. Participants performed LP and LE exercises (3 × 8–10; at 80% 1RM) 3 days/week for 4 weeks. Data were analyzed using 2-way ANOVA with repeated measures. Four weeks of resistance training resulted in significant increases in LP (p < 0.001), LE (p < 0.001), MVIC (p < 0.001), RF MT (p < 0.001), RF CSA (p < 0.001), VL MT (p < 0.001), and VL CSA (p < 0.001). No between-group differences were observed. Although nutrition can significantly affect training adaptations, these results suggest that short-term resistance training augments muscle strength and size in previously untrained men with no additive benefit from postexercise protein supplementation.
... Higher initial CP availability and resynthesis 16 Greater dynamic strength and endurance 17 Increased ATP resynthesis 12 More efficient muscle damage attenuation 18 More efficient antioxidant activity 19 Faster and higher power production 20 Increased muscle protein kinetics 21 Accelerated muscle hypertrophy 22 Increased hormonal proliferation 22 Decreased recovery time during anaerobic activity 23 Enhanced fatigue resistance 8 Searches were performed using the terms: 'military personnel', 'creatine'. CP, creatine phosphate. ...
Introduction: Creatine is considered an effective nutritional ergogenic aid to enhance exercise performance. In spite of the publication of several reviews in the last decade on the topic of exercise performance/sports and creatine there is a need for an update related to the military given the lack of information in this area. The aim of this study was to critically assess original research addressing the use of creatine supplements in the military.
Methods: A search of the electronic databases PubMed and SPORTDiscus, for the following key words: military personnel, trainees, recruit, soldier, physical fitness, physical conditioning, creatine supplementation, creatine ingestion, nutritional supplements to identify surveys and randomised clinical trials from journal articles and technical reports investigating the effect of creatine supplementation on military populations.
Results: Thirty-three out of 90 articles examined the use of creatine as a dietary supplement in military
personnel. Twenty-one studies were finally selected on the basis of stated inclusion criteria for military surveys and randomised clinical trials. Most of the surveys (15/17) in the military indicate a high popularity of creatine (average 27%) among supplement users. In contrast, in most of the exercise protocols used (6/9) during randomised clinical trials creatine has produced a nonsignificant
performance-enhancing effect.
Conclusions: Creatine is one of the most widely used supplemental compounds in the military. It is not considered a doping infraction or related to any adverse health effects but its long-term usage needs further investigation.Experimental research suggests that creatine supplementation does not enhance physical performance in the military. However, limitations in creatine dosage, military fitness testing and sample group selection might have underestimated the ergogenic properties of creatine. Recent studies also indicate positive effects on various aspects of total force fitness such as cognitive-psychomotor performance, bone health, musculoskeletal damage and neuromuscular function.
... Moreover, prolonged resistance-type exercise training has been shown to represent the most effective strategy to increase muscle mass and strength, as well as functional capacity in the elderly. Various long-term intervention studies have confirmed the paradigm that protein feeding in close temporal proximity to each bout of exercise augments training-induced gains in muscle mass and strength [20][21][22][23][24][115][116][117][118][119][120]. However, many other studies have been unable to confirm these surplus benefits of protein supplementation above and beyond those afforded by exercise training only [121][122][123][124][125][126][127][128][129]. ...
Given our rapidly aging world-wide population, the loss of skeletal muscle mass with healthy aging (sarcopenia) represents an important societal and public health concern. Maintaining or adopting an active lifestyle alleviates age-related muscle loss to a certain extent. Over time, even small losses of muscle tissue can hinder the ability to maintain an active lifestyle and, as such, contribute to the development of frailty and metabolic disease. Considerable research focus has addressed the application of dietary protein supplementation to support exercise-induced gains in muscle mass in younger individuals. In contrast, the role of dietary protein in supporting the maintenance (or gain) of skeletal muscle mass in active older persons has received less attention. Older individuals display a blunted muscle protein synthetic response to dietary protein ingestion. However, this reduced anabolic response can largely be overcome when physical activity is performed in close temporal proximity to protein consumption. Moreover, recent evidence has helped elucidate the optimal type and amount of dietary protein that should be ingested by the older adult throughout the day in order to maximize the skeletal muscle adaptive response to physical activity. Evidence demonstrates that when these principles are adhered to, muscle maintenance or hypertrophy over prolonged periods can be further augmented in active older persons. The present review outlines the current understanding of the role that dietary protein occupies in the lifestyle of active older adults as a means to increase skeletal muscle mass, strength and function, and thus support healthier aging.
Resistance training (RT) triggers diverse morphological and physiological adaptations that are broadly considered beneficial for performance enhancement as well as injury risk reduction. Some athletes and coaches therefore engage in, or prescribe, substantial amounts of RT under the assumption that continued increments in maximal strength capacity and/or muscle mass will lead to improved sports performance. In contrast, others employ minimal or no RT under the assumption that RT may impair endurance or sprint performances. However, the morphological and physiological adaptations by which RT might impair physical performance, the likelihood of these being evoked, and the training program specifications that might promote such impairments, remain largely undefined. Here, we discuss how selected adaptations to RT may enhance or impair speed and endurance performances while also addressing the RT program variables under which these adaptations are likely to occur. Specifically, we argue that while some myofibrillar (muscle) hypertrophy can be beneficial for increasing maximum strength, substantial hypertrophy can lead to macro- and microscopic adaptations such as increases in body (or limb) mass and internal moment arms that might, under some conditions, impair both sprint and endurance performances. Further, we discuss how changes in muscle architecture, fiber typology, microscopic muscle structure, and intra- and intermuscular coordination with RT may maximize speed at the expense of endurance, or maximize strength at the expense of speed. The beneficial effect of RT for sprint and endurance sports can be further improved by considering the adaptive trade-offs and practical implications discussed in this review.
Graphical abstract
Background
Despite the robust evidence demonstrating positive effects from creatine supplementation (primarily when associated with resistance training) on measures of body composition, there is a lack of a comprehensive evaluation regarding the influence of creatine protocol parameters (including dose and form) on body mass and estimates of fat-free and fat mass.
Methods
Randomized controlled trials (RCTs) evaluating the effect of creatine supplementation on body composition were included. Electronic databases, including PubMed, Web of Science, and Scopus were searched up to July 2023. Heterogeneity tests were performed. Random effect models were assessed based on the heterogeneity tests, and pooled data were examined to determine the weighted mean difference (WMD) with a 95% confidence interval (CI).
Results
From 4831 initial records, a total of 143 studies met the inclusion criteria. Creatine supplementation increased body mass (WMD: 0.86 kg; 95% CI: 0.76 to 0.96, I² = 0%) and fat-free mass (WMD: 0.82 kg; 95% CI: 0.57 to 1.06, I² = 0%) while reducing body fat percentage (WMD: −0.28 %; 95% CI: −0.47 to −0.09; I² = 0%). Studies that incorporated a maintenance dose of creatine or performed resistance training in conjunction with supplementation had greater effects on body composition.
Conclusion
Creatine supplementation has a small effect on body mass and estimates of fat-free mass and body fat percentage. These findings were more robust when combined with resistance training.
It is a common belief amongst strength and power athletes that nutritional supplementation strategies aid recovery by shifting the anabolic/catabolic profile toward anabolism. Factors such as nutrient quantity, nutrient quality, and nutrient timing significantly impact upon the effectiveness of nutritional strategies in optimizing the acute responses to resistance exercise and the adaptive response to resistance training (i.e., muscle growth and strength expression). Specifically, the aim of this review is to address carbohydrates (CHOs), protein (PRO), and/or amino acids (AAs) supplementation strategies, as there is growing evidence suggesting a link between nutrient signaling and the initiation of protein synthesis, muscle glycogen resynthesis, and the attenuation of myofibrillar protein degradation following resistance exercise. Collectively, the current scientific literature indicates that nutritional supplementation strategies utilizing CHO, PRO, and/or AA represents an important approach aimed at enhancing muscular responses for strength and power athletes, primarily increased muscular hypertrophy and enhanced strength expression. There appears to be a critical interaction between resistance exercise and nutrient–cell signaling associated with the principle of nutrient timing (i.e., pre-exercise, during, and post-exercise). Recommendations for nutritional supplementation strategies to promote muscular responses for strength and athletes are provided.
Peynir altı suyu proteini (whey proteini), peynir üretim prosesi sonucunda açığa çıkan, peynir altı suyunun en önemli bileşenidir. Peynir altı suyu; peynir üretimi sırasında pıhtının ayrılması işleminden sonra geriye kalan sarımsı yeşil renkli sıvı maddedir. Bu ürünün emülsifikasyon, jel oluşturma, köpürme, yağ bağlama, kıvam artırma gibi gelişmiş özellikleri vardır ve gıda endüstrisinde kullanımı yaygındır. Peynir altı suyu proteini, besinsel nitrojen ve amino asit sağlar ve bu sebeple her bireyin sağlığını iyileştirmesi ve koruması için kullanılabilir. Bu yazımızda, PubMed, Science Direct ve Google Scholar gibi farklı veri tabanlarında arama yaparak peynir altı suyu proteininin sağlık üzerindeki potansiyel etkilerini değerlendirmek amaçlanmıştır. Literatürün gözden geçirilmesi ile birlikte, peynir altı suyu proteininin yeni avantajlar yaratttığı ve fonksiyonel, besleyici ve tedavi edici özellikleri olduğu sonucuna varıldı. Yara iyileşmesi, hücre büyümesi kontrolü, antioksidan ve antiinflamatuar özellikleri farklı çalışmalarda belirtilmiştir. Ayrıca kanser, diyabet, obezite, kardiyovasküler hastalıklar, insan bağışıklık yetmezliği ve hepatit tedavisinde umut verici olumlu etkilere neden olabilir. Bebek, yaşlı ve sporcu beslenmesinde önemli bir gıda katkı maddesi olarak kullanılabileceği düşünülmektedir. Yüksek besin değeri, spesifik fonksiyonel özellikleri ve üretim sırasındaki sürdürülebilirliği göz önüne alındığında peynir altı suyu proteininin, gıda ve sağlık endüstrisinde birçok uygulama alanı olabilir.
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.
A controlled creatine-release system has been developed from whey protein-based gels. Their functionalization was carried out by aeration and sodium ions induced “cold gelation” processes. The effect of protein concentration in the aerated whey protein gels at pH 7.0 and 8.0 was analyzed. Physicochemical properties of the aerated gels were evaluated. It was possible to obtain the ions induced whey protein aerated gel with well distributed creatine and different microstructure as well as rheological properties. Different protein concentrations and pH enabled obtaining gels with different rheological properties, texture, air fraction, diameter of air bubbles, microstructure and surface roughness. An increase in the protein concentration enhanced the hardness of the samples, regardless of their pH. The mechanical strength of gels prepared at pH 8 were higher than those obtained at pH 7, as was manifested by the smaller storage modulus of the latter. The former gel exhibited a microstructure between particulate and fine-stranded. A stronger gel matrix produced smaller air bubbles. Aerated gels produced at pH 7.0 had higher roughness than those obtained at pH 8.0. Optimal conditions for inclusion of air bubbles into the gel matrix were: 9% protein concentration at pH 8.0 and this aerated gel was selected for digestion in the artificial stomach. There is a small conversion of creatine to creatinine in the artificial stomach digestion process (9.6% after 6 h). The diffusion of creatine crystals from the aerated gel matrix was the mechanism responsible for the release process. Aerated whey protein gels can be used as matrices for time extended releasing of creatine in the stomach.
A creatina é uma substância produzida naturalmente pelo corpo e encontrada em alimentos de origem animal. É considerada um recurso ergogênico nutricional efetivo para aumento do desempenho e ganho de massa muscular. O presente estudo teve como objetivo descrever os principais mecanismos de ação da creatina, apresentando as doses recomendadas de suplementação, tempo de uso, possíveis efeitos colaterais e para quais tipos de exercícios a suplementação é recomendada. Trata-se de uma revisão narrativa da literatura que foi realizado a partir de publicações científicas em português e inglês oriundas das bases de dados PubMed®, SciElo® e Google Acadêmico®. Os estudos selecionados apontaram que a suplementação de creatina entre 3 a 5 gramas por dia pode proporcionar um aumento no volume de água nas células musculares, aumento de síntese proteica, aumento na expressão gênica de IGF-1 e o aumento de fatores miogênicos regulatórios, além de atuar em uma das vias metabólicas de fornecimento e reposição de energia, possibilitando aumento do rendimento no treino (principalmente naqueles de alta intensidade e curta duração) e aumento do ganho de massa muscular. A suplementação de creatina demonstra-se segura para indivíduos saudáveis, sendo válido ressaltar a importância do acompanhamento profissional para adequação das dosagens de acordo com as necessidades.
Objective
To determine the effects of multi-ingredient protein (MIP) supplements on resistance exercise training (RT)-induced gains in muscle mass and strength compared with protein-only (PRO) or placebo supplementation.
Data sources
Systematic search of MEDLINE, Embase, CINAHL and SPORTDiscus.
Eligibility criteria
Randomised controlled trials with interventions including RT ≥6 weeks in duration and a MIP supplement.
Design
Random effects meta-analyses were conducted to determine the effect of supplementation on fat-free mass (FFM), fat mass, one-repetition maximum (1RM) upper body and 1RM lower body muscular strength. Subgroup analyses compared the efficacy of MIP supplementation relative to training status and chronological age.
Results
The most common MIP supplements included protein with creatine (n=17) or vitamin D (n=10). Data from 35 trials with 1387 participants showed significant (p<0.05) increases in FFM (0.80 kg (95% CI 0.44 to 1.15)), 1RM lower body (4.22 kg (95% CI 0.79 to 7.64)) and 1RM upper body (2.56 kg (95% CI 0.79 to 4.33)) where a supplement was compared with all non-MIP supplemented conditions (means (95% CI)). Subgroup analyses indicated a greater effect of MIP supplements compared with all non-MIP supplements on FFM in untrained (0.95 kg (95% CI 0.51 to 1.39), p<0.0001) and older participants (0.77 kg (95% CI 0.11 to 1.43), p=0.02); taking MIP supplements was also associated with gains in 1RM upper body (1.56 kg (95% CI 0.80 to 2.33), p=0.01) in older adults.
Summary/conclusions
When MIP supplements were combined with resistance exercise training, there were greater gains in FFM and strength in healthy adults than in counterparts who were supplemented with non-MIP. MIP supplements were not superior when directly compared with PRO supplements. The magnitude of effect of MIP supplements was greater (in absolute values) in untrained and elderly individuals undertaking RT than it was in trained individuals and in younger people.
Trial registration number
CRD42017081970.
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.
Female athletes tend to choose their supplements for different reasons than their male counterparts. Collegiate female athletes report taking supplements “for their health,” to make up for an inadequate diet, or to have more energy. Multivitamins, herbal substances, protein supplements, amino acids, creatine, fat burners/weight-loss products, caffeine, iron, and calcium are the most frequently used products reported by female athletes. Many female athletes are unclear on when to use a protein supplement, how to use it, and different sources of protein (whey, casein, and soy). This chapter addresses essential amino acid and branched chain amino acid supplementation. Along with recommendations for protein supplementation, creatine supplementation is discussed. Not all female athletes are concerned with building muscle. Burning fat is also a major concern for the female athlete. This may result in the athlete turning to products marketed for weight control (i.e., ginseng or ephedra). A product legal for over-the-counter (OTC) sales, however, can be illegal for athletic competition (i.e., ephedra).competitive athletes should be aware of the banned substance list for their governing body and that OTC products are not currently regulated by the FDA. This lack of regulation can lead to OTC products that are contaminated with banned substances.
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.
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.
BACKGROUND: Research shows that creatine supplementation is a safe and effective method to diminish age-related declines in muscle mass and strength. OBJECTIVE: To summarize studies about the effects of creatine supplementation on skeletal muscle energy metabolism, exercise capacity and life quality in old adults. METHODS: An online search of PubMed database and CNKI was performed using key words of "creatine; old adults; skeletal muscle; phosphocreatine; strength" for articles published before March 2011, both in English and Chinese. Papers about effects of creatine supplementation on skeletal muscle energy metabolism and exercise capacity in old adults were included, and repetitive researches were excluded. RESULTS AND CONCLUSION: A total of 72 documents were retrieved, and 38 articles were retained after depleting unrelated and repetitive ones. The recent researches concerning the effects of creatine supplementation on intramuscular energy metabolism, skeletal muscle morphology and life quality in old adults were summarized. Creatine can increase muscle strength, induce muscle hypertrophy and improve the exercise capacity of old adults. Creatine supplementation is a safe, inexpensive and effective nutritional intervention. It can slow the muscle wasting rate associated with aging, especially when consumed in conjunction with resistance training.
Testosterone is a steroid hormone with powerful androgenic and anabolic effects. It is generally known that testosterone can help to build muscle mass and change body composition in favor of fat-free mass. Additionally those effects can be enhanced if combined with strength training. Testosterone exerts its hypertrophic effects on muscles in an anabolic as well as an anti-catabolic manner, leading to increased protein synthesis and decreased protein breakdown; and furthermore leading to an activation of resting myogenic stem cells supporting hypertrophy. In sports the use of testosterone as an illegal drug to enhance physical performance is not limited to competitive athletes. The misuse has already infiltrated recreational sports, especially the fitness and bodybuilding area, bringing up diverse health-related side effects. The reasons for testosterone abuse are mainly its mentioned effects on strength and muscle mass, and in many cases the desire to be attractive. Of course, the benefits are expected to be inferior to those from an exogenous testosterone abuse; but the main goal has to be to maximize muscle growth in a natural, legal and healthy way. The aim of this chapter is to shed some light on optimizing muscle growth. The authors discuss the role of food on testosterone level(s) and the hormonal changes that occur in response to resistance training combined with immediate post-exercise food intake, while emphasizing testosterone.
The aim of this study was to investigate the effects of the short-term (5g. kg -1 for 1 week) and long-term (1g. kg -1 for 8 weeks) creatine supplementation on ponderal adaptation of anterior tibial and soleus muscles of sedentary and exercised (swimming to 80% of the tolerated maximum load) rats.72 Wistar males rats (240 ± 10g) were divided in 4 groups: sedentary rats without supplementation (CON; n = 18); exercised rats without supplementation (NAT; n = 18); sedentary rats with supplementation (CRE; n = 18); exercised rats with supplementation (CRE+NAT; n = 18). At the end of the first, fourth and eighth weeks six animals of each group were sacrificed. There were obtained the following results (p
Our purpose was to assess muscular adaptations during 6 weeks of resistance training in 36 males randomly assigned to supplementation with whey protein (W; 1.2 g/kg/day), whey protein and creatine monohydrate (WC; 0.1 g/kg/day), or placebo (P; 1.2 g/kg/day maltodextrin). Measures included lean tissue mass by dual energy x-ray absorptiometry, bench press and squat strength (1-repetition maximum), and knee extension/flexion peak torque. Lean tissue mass increased to a greater extent with training in WC compared to the other groups, and in the W compared to the P group (p < .05). Bench press strength increased to a greater extent for WC compared to W and P (p < .05). Knee extension peak torque increased with training for WC and W (p < .05), but not for P. All other measures increased to a similar extent across groups. Continued training without supplementation for an additional 6 weeks resulted in maintenance of strength and lean tissue mass in all groups. Males that supplemented with whey protein while resistance training demonstrated greater improvement in knee extension peak torque and lean tissue mass than males engaged in training alone. Males that supplemented with a combination of whey protein and creatine had greater increases in lean tissue mass and bench press than those who supplemented with only whey protein or placebo. However, not all strength measures were improved with supplementation, since subjects who supplemented with creatine and/or whey protein had similar increases in squat strength and knee flexion peak torque compared to subjects who received placebo.
We validated whole body composition estimates from dual-energy X-ray absorptiometry (DEXA) against estimates from a four-component model to determine whether accuracy is affected by gender, race, athletic status, or musculoskeletal development in young adults. Measurements of body density by hydrostatic weighing, body water by deuterium dilution, and bone mineral by whole body DEXA were obtained in 172 young men (n = 91) and women (n = 81). Estimates of body fat (%Fat) from DEXA (%FatDEXA) were highly correlated with estimates of body fat from the four-component model [body density, total body water, and total body mineral (%Fatd,w,m); r = 0.94, standard error of the estimante (SEE) = 2.8% body mass (BM)] with no significant difference between methods [mean of the difference +/- SD of the difference = -0.4 +/- 2.9 (SD) % BM, P = 0.10] in women and men. On the basis of the comparison with %Fatd,w,m, estimates of %FatDEXA were slightly more accurate than those from body density (r = 0.91, SEE = 3.4%; mean of the difference +/- SD of the difference = -1.2 +/- 3.4% BM). Differences between %FatDEXA and %Fatd,w,m were weakly related to body thickness, as reflected by BMI (r = -0.34), and to the percentage of water in the fat-free mass (r = -0.51), but were not affected by race, athletic status, or musculoskeletal development. We conclude that body composition estimates from DEXA are accurate compared with those from a four-component model in young adults who vary in gender, race, athletic status, body size, musculoskeletal development, and body fatness.
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.
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.
We examined the effect of glycogen-depleting exercise on subsequent muscle total creatine (TCr) accumulation and glycogen resynthesis during postexercise periods when the diet was supplemented with carbohydrate (CHO) or creatine (Cr) + CHO. Fourteen subjects performed one-legged cycling exercise to exhaustion. Muscle biopsies were taken from the exhausted (Ex) and nonexhausted (Nex) limbs after exercise and after 6 h and 5 days of recovery, during which CHO (CHO group, n = 7) or Cr + CHO (Cr+CHO group, n = 7) supplements were ingested. Muscle TCr concentration ([TCr]) was unchanged in both groups 6 h after supplementation commenced but had increased in the Ex (P < 0.001) and Nex limbs (P < 0.05) of the Cr+CHO group after 5 days. Greater TCr accumulation was achieved in the Ex limbs (P < 0.01) of this group. Glycogen was increased above nonexercised concentrations in the Ex limbs of both groups after 5 days, with the concentration being greater in the Cr+CHO group (P = 0.06). Thus a single bout of exercise enhanced muscle Cr accumulation, and this effect was restricted to the exercised muscle. However, exercise also diminished CHO-mediated insulin release, which may have attenuated insulin-mediated muscle Cr accumulation. Ingesting Cr with CHO also augmented glycogen supercompensation in the exercised muscle.
This study investigated the effect of creatine supplementation in conjunction with protein and/or carbohydrate (CHO) ingestion on plasma creatine and serum insulin concentrations and whole body creatine retention. Twelve men consumed 4 x 5 g of creatine on four occasions in combination with 1) 5 g of CHO, 2) 50 g of protein and 47 g of CHO, 3) 96 g of CHO, or 4) 50 g of CHO. The increase in serum insulin was no different when the protein-CHO and high-CHO treatments were compared, but both were greater than the response recorded for the low-CHO treatment (both P < 0.05). As a consequence, body creatine retention was augmented by approximately 25% for protein-CHO and high-CHO treatments compared with placebo treatment. The areas under creatine- and insulin-time curves were related during the first oral challenge (r = -0.920, P < 0.05) but not after the fourth (r = -0.342). It is concluded, first, that the ingestion of creatine in conjunction with approximately 50 g of protein and CHO is as effective at potentiating insulin release and creatine retention as ingesting creatine in combination with almost 100 g of CHO. Second, the stimulatory effect of insulin on creatine disposal was diminished within the initial 24 h of supplementation.
The composition of the preexercise food intake is known to affect substrate utilization during exercise and thus can affect long-term changes in body weight and composition. These parameters were measured in male rats exercised 2 h daily over 5 wk, either in the fasting state or 1 h after they ingested a meal enriched with glucose (Glc), whole milk protein (WMP), or alpha-lactalbumin-enriched whey protein (CPalphaL). Compared with fasting, the Glc meal increased glucose oxidation and decreased lipid oxidation during and after exercise. In contrast, the WMP and CPalphaL meals preserved lipid oxidation and increased protein oxidation, the CPalphaL meal increasing protein oxidation more than the WMP meal. At the end of the study, body weight was larger in the WMP-, Glc-, and CPalphaL-fed rats than in the fasted ones. This resulted from an increased fat mass in the WMP and Glc rats and to an increased lean body mass, particularly muscles, in the CPalphaL rats. We conclude that the potential of the CPalphaL meal to preserve lipid oxidation and to rapidly deliver amino acids for use during exercise improved the efficiency of exercise training to decrease adiposity.
Most research on creatine has focused on short-term creatine loading and its effect on high-intensity performance capacity. Some studies have investigated the effect of prolonged creatine use during strength training. However, studies on the effects of prolonged creatine supplementation are lacking. In the present study, we have assessed the effects of both creatine loading and prolonged supplementation on muscle creatine content, body composition, muscle and whole-body oxidative capacity, substrate utilization during submaximal exercise, and on repeated supramaximal sprint, as well as endurance-type time-trial performance on a cycle ergometer. Twenty subjects ingested creatine or a placebo during a 5-day loading period (20 g.day(-1)) after which supplementation was continued for up to 6 weeks (2 g.day(-1)). Creatine loading increased muscle free creatine, creatine phosphate (CrP) and total creatine content ( P <0.05). The subsequent use of a 2 g.day(-1) maintenance dose, as suggested by an American College of Sports Medicine Roundtable, resulted in a decline in both the elevated CrP and total creatine content and maintenance of the free creatine concentration. Both short- and long-term creatine supplementation improved performance during repeated supramaximal sprints on a cycle ergometer. However, whole-body and muscle oxidative capacity, substrate utilization and time-trial performance were not affected. The increase in body mass following creatine loading was maintained after 6 weeks of continued supplementation and accounted for by a corresponding increase in fat-free mass. This study provides definite evidence that prolonged creatine supplementation in humans does not increase muscle or whole-body oxidative capacity and, as such, does not influence substrate utilization or performance during endurance cycling exercise. In addition, our findings suggest that prolonged creatine ingestion induces an increase in fat-free mass.
Beta(2)-adrenoceptor agonists such as fenoterol are anabolic in skeletal muscle, and because they promote hypertrophy and improve force-producing capacity, they have potential application for enhancing muscle repair after injury. No previous studies have measured the beta(2)-adrenoceptor population in regenerating skeletal muscle or determined whether fenoterol can improve functional recovery in regenerating muscle after myotoxic injury. In the present study, the extensor digitorum longus (EDL) muscle of the right hindlimb of deeply anesthetized rats was injected with bupivacaine hydrochloride, which caused complete degeneration of all muscle fibers. The EDL muscle of the left hindlimb served as the uninjured control. Rats received either fenoterol (1.4 mg x kg(-1) x day(-1)) or an equal volume of saline for 2, 7, 14, or 21 days. Radioligand binding assays identified a approximately 3.5-fold increase in beta(2)-adrenoceptor density in regenerating muscle at 2 days postinjury. Isometric contractile properties of rat EDL muscles were measured in vitro. At 14 and 21 days postinjury, maximum force production (P(o)) of injured muscles from fenoterol-treated rats was 19 and 18% greater than from saline-treated rats, respectively, indicating more rapid restoration of function after injury. The increase in P(o) in fenoterol-treated rats was due to increases in muscle mass, fiber cross-sectional area, and protein content. These findings suggest a physiological role for beta(2)-adrenoceptor-mediated mechanisms in muscle regeneration and show clearly that fenoterol hastens recovery after injury, indicating its potential therapeutic application.
Reliability, the consistency of a test or measurement, is frequently quantified in the movement sciences literature. A common metric is the intraclass correlation coefficient (ICC). In addition, the SEM, which can be calculated from the ICC, is also frequently reported in reliability studies. However, there are several versions of the ICC, and confusion exists in the movement sciences regarding which ICC to use. Further, the utility of the SEM is not fully appreciated. In this review, the basics of classic reliability theory are addressed in the context of choosing and interpreting an ICC. The primary distinction between ICC equations is argued to be one concerning the inclusion (equations 2,1 and 2,k) or exclusion (equations 3,1 and 3,k) of systematic error in the denominator of the ICC equation. Inferential tests of mean differences, which are performed in the process of deriving the necessary variance components for the calculation of ICC values, are useful to determine if systematic error is present. If so, the measurement schedule should be modified (removing trials where learning and/or fatigue effects are present) to remove systematic error, and ICC equations that only consider random error may be safely used. The use of ICC values is discussed in the context of estimating the effects of measurement error on sample size, statistical power, and correlation attenuation. Finally, calculation and application of the SEM are discussed. It is shown how the SEM and its variants can be used to construct confidence intervals for individual scores and to determine the minimal difference needed to be exhibited for one to be confident that a true change in performance of an individual has occurred.
The present study investigated the influence of creatine and protein supplementation on satellite cell frequency and number of myonuclei in human skeletal muscle during 16 weeks of heavy-resistance training. In a double-blinded design 32 healthy, male subjects (19-26 years) were assigned to strength training (STR) while receiving a timed intake of creatine (STR-CRE) (n=9), protein (STR-PRO) (n=8) or placebo (STR-CON) (n=8), or serving as a non-training control group (CON) (n=7). Supplementation was given daily (STR-CRE: 6-24 g creatine monohydrate, STR-PRO: 20 g protein, STR-CON: placebo). Furthermore, timed protein/placebo intake were administered at all training sessions. Muscle biopsies were obtained at week 0, 4, 8 (week 8 not CON) and 16 of resistance training (3 days per week). Satellite cells were identified by immunohistochemistry. Muscle mean fibre (MFA) area was determined after histochemical analysis. All training regimes were found to increase the proportion of satellite cells, but significantly greater enhancements were observed with creatine supplementation at week 4 (compared to STR-CON) and at week 8 (compared to STR-PRO and STR-CON) (P<0.01-0.05). At week 16, satellite cell number was no longer elevated in STR-CRE, while it remained elevated in STR-PRO and STR-CON. Furthermore, creatine supplementation resulted in an increased number of myonuclei per fibre and increases of 14-17% in MFA at week 4, 8 and 16 (P<0.01). In contrast, STR-PRO showed increase in MFA only in the later (16 week, +8%) and STR-CON only in the early (week 4, +14%) phases of training, respectively (P<0.05). In STR-CRE a positive relationship was found between the percentage increases in MFA and myonuclei from baseline to week 16, respectively (r=0.67, P<0.05). No changes were observed in the control group (CON). In conclusion, the present study demonstrates for the first time that creatine supplementation in combination with strength training amplifies the training-induced increase in satellite cell number and myonuclei concentration in human skeletal muscle fibres, thereby allowing an enhanced muscle fibre growth in response to strength training.
Some studies report greater muscle hypertrophy during resistance exercise (RE) training from supplement timing (i.e., the strategic consumption of protein and carbohydrate before and/or after each workout). However, no studies have examined whether this strategy provides greater muscle hypertrophy or strength development compared with supplementation at other times during the day. The purpose of this study was to examine the effects of supplement timing compared with supplementation in the hours not close to the workout on muscle-fiber hypertrophy, strength, and body composition during a 10-wk RE program.
In a single-blind, randomized protocol, resistance-trained males were matched for strength and placed into one of two groups; the PRE-POST group consumed a supplement (1 g x kg(-1) body weight) containing protein/creatine/glucose immediately before and after RE. The MOR-EVE group consumed the same dose of the same supplement in the morning and late evening. All assessments were completed the week before and after 10 wk of structured, supervised RE training. Assessments included strength (1RM, three exercises), body composition (DEXA), and vastus lateralis muscle biopsies for determination of muscle fiber type (I, IIa, IIx), cross-sectional area (CSA), contractile protein, creatine (Cr), and glycogen content.
PRE-POST demonstrated a greater (P < 0.05) increase in lean body mass and 1RM strength in two of three assessments. The changes in body composition were supported by a greater (P < 0.05) increase in CSA of the type II fibers and contractile protein content. PRE-POST supplementation also resulted in higher muscle Cr and glycogen values after the training program (P < 0.05).
Supplement timing represents a simple but effective strategy that enhances the adaptations desired from RE-training.
Different dietary proteins affect whole body protein anabolism and accretion and therefore, have the potential to influence results obtained from resistance training. This study examined the effects of supplementation with two proteins, hydrolyzed whey isolate (WI) and casein (C), on strength, body composition, and plasma glutamine levels during a 10 wk, supervised resistance training program. In a double-blind protocol, 13 male, recreational bodybuilders supplemented their normal diet with either WI or C (1.5 gm/kg body wt/d) for the duration of the program. Strength was assessed by 1-RM in three exercises (barbell bench press, squat, and cable pull-down). Body composition was assessed by dual energy X-ray absorptiometry. Plasma glutamine levels were determined by the enzymatic method with spectrophotometric detection. All assessments occurred in the week before and the week following 10 wk of training. Plasma glutamine levels did not change in either supplement group following the intervention. The WI group achieved a significantly greater gain (P < 0.01) in lean mass than the C group (5.0 +/- 0.3 vs. 0.8 +/- 0.4 kg for WI and C, respectively) and a significant (P < 0.05) change in fat mass (-1.5 +/- 0.5 kg) compared to the C group (+0.2 +/- 0.3 kg). The WI group also achieved significantly greater (P < 0.05) improvements in strength compared to the C group in each assessment of strength. When the strength changes were expressed relative to body weight, the WI group still achieved significantly greater (P < 0.05) improvements in strength compared to the C group.
Different dietary proteins affect whole body protein anabolism and accretion and therefore, have the potential to influence results obtained from resistance training. This study examined the effects of supplementation with two proteins, hydrolyzed whey isolate (WI) and casein (C), on strength, body composition, and plasma glutamine levels during a 10 wk, supervised resistance training program. In a double-blind protocol, 13 male, recreational bodybuilders supplemented their normal diet with either WI or C (1.5 gm/kg body wt/d) for the duration of the program. Strength was assessed by 1-RM in three exercises (barbell bench press, squat, and cable pull-down). Body composition was assessed by dual energy X-ray absorptiometry. Plasma glutamine levels were determined by the enzymatic method with spectrophotometric detection. All assessments occurred in the week before and the week following 10 wk of training. Plasma glutamine levels did not change in either supplement group following the intervention. The WI group achieved a significantly greater gain (P < 0.01) in lean mass than the C group (5.0 +/- 0.3 vs. 0.8 +/- 0.4 kg for WI and C, respectively) and a significant (P < 0.05) change in fat mass (-1.5 +/- 0.5 kg) compared to the C group (+0.2 +/- 0.3 kg). The WI group also achieved significantly greater (P < 0.05) improvements in strength compared to the C group in each assessment of strength. When the strength changes were expressed relative to body weight, the WI group still achieved significantly greater (P < 0.05) improvements in strength compared to the C group.
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.
1. The present study was undertaken to test whether creatine given as a supplement to normal subjects was absorbed, and if continued resulted in an increase in the total creatine pool in muscle. An additional effect of exercise upon uptake into muscle was also investigated.
2. Low doses (1 g of creatine monohydrate or less in water) produced only a modest rise in the plasma creatine concentration, whereas 5 g resulted in a mean peak after 1 h of 795 (sd 104) μmol/l in three subjects weighing 76–87 kg. Repeated dosing with 5 g every 2 h sustained the plasma concentration at around 1000 μmol/l. A single 5 g dose corresponds to the creatine content of 1.1 kg of fresh, uncooked steak.
3. Supplementation with 5 g of creatine monohydrate, four or six times a day for 2 or more days resulted in a significant increase in the total creatine content of the quadriceps femoris muscle measured in 17 subjects. This was greatest in subjects with a low initial total creatine content and the effect was to raise the content in these subjects closer to the upper limit of the normal range. In some the increase was as much as 50%.
4. Uptake into muscle was greatest during the first 2 days of supplementation accounting for 32% of the dose administered in three subjects receiving 6 × 5 g of creatine monohydrate/day. In these subjects renal excretion was 40, 61 and 68% of the creatine dose over the first 3 days. Approximately 20% or more of the creatine taken up was measured as phosphocreatine. No changes were apparent in the muscle ATP content.
5. No side effects of creatine supplementation were noted.
6. One hour of hard exercise per day using one leg augmented the increase in the total creatine content of the exercised leg, but had no effect in the collateral. In these subjects the mean total creatine content increased from 118.1 (sd 3.0) mmol/kg dry muscle before supplementation to 148.5 (sd 5.2) in the control leg, and to 162.2 (sd 12.5) in the exercised leg. Supplementation and exercise resulted in a total creatine content in one subject of 182.8 mmol/kg dry muscle, of which 112.0 mmol/kg dry muscle was in the form of phosphocreatine.
A method for increasing the size of a percutaneous needle biopsy specimen of skeletal muscle is described. Suction (700 TORR) is applied to the inner bore of the biopsy needle after the needle has been inserted into the subject's muscle. The suction pulls the surrounding muscle tissue into the needle, thus insuring the taking of a larger piece (X = 78.5 mg). In most cases, this technique will eliminate the need for repeated biopsies because of inadequate muscle sample size and enhance the validity of subsequent analysis procedures.
In this brief review we examine the effects of resistance training on energy expenditure. The components of daily energy expenditure are described, and methods of measuring daily energy expenditure are discussed. Cross-sectional and exercise intervention studies are examined with respect to their effects on resting metabolic rate, physical activity energy expenditure, postexercise oxygen consumption, and substrate oxidation in younger and older individuals. Evidence is presented to suggest that although resistance training may elevate resting metabolic rate, it does not substantially enhance daily energy expenditure in free-living individuals. Several studies indicate that intense resistance exercise increases postexercise oxygen consumption and shifts substrate oxidation toward a greater reliance on fat oxidation. Preliminary evidence suggests that although resistance training increases muscular strength and endurance, its effects on energy balance and regulation of body weight appear to be primarily mediated by its effects on body composition (e.g., increasing fat-free mass) rather than by the direct energy costs of the resistance exercise.
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.
The purpose of this study was to compare changes in maximal strength, power, and muscular endurance after 12 wk of periodized heavy-resistance training directly supervised by a personal trainer (SUP) versus unsupervised training (UNSUP).
Twenty moderately trained men aged 24.6 +/- 1.0 yr (mean +/- SE) were randomly assigned to either the SUP group (N = 10) or the UNSUP group (N = 8). Both groups performed identical linear periodized resistance training programs consisting of preparatory (10-12 repetitions maximum (RM)), hypertrophy (8 to 10-RM), strength (5 to 8-RM), and peaking phases (3 to 6-RM) using free-weight and variable-resistance machine exercises. Subjects were tested for maximal squat and bench press strength (1-RM), squat jump power output, bench press muscular endurance, and body composition at week 0 and after 12 wk of training.
Mean training loads (kg per set) per week were significantly (P < 0.05) greater in the SUP group than the UNSUP group at weeks 7 through 11 for the squat, and weeks 3 and 7 through 12 for the bench press exercises. The rates of increase (slope) of squat and bench press kg per set were significantly greater in the SUP group. Maximal squat and bench press strength were significantly greater at week 12 in the SUP group. Squat and bench press 1-RM, and mean and peak power output increased significantly after training in both groups. Relative local muscular endurance (80% of 1-RM) was not compromised in either group despite significantly greater loads utilized in bench press muscular endurance testing after training. Body mass, fat mass, and fat-free mass increased significantly after training in the SUP group.
Directly supervised, heavy-resistance training in moderately trained men resulted in a greater rate of training load increase and magnitude which resulted in greater maximal strength gains compared with unsupervised training.
Chronic resistance training induces increases in muscle fibre cross-sectional area (CSA), otherwise known as hypertrophy. This is due to an increased volume percentage of myofibrillarproteins within a given fibre. The exact time-course for muscle fibre hypertrophy is not well-documented but appears to require at least 6-7 weeks of regular resistive training at reasonably high intensity before increases in fibre CSA are deemed significant. Proposed training-induced changes in neural drive are hypothesized to increase strength due to increased synchrony of motor unit firing, reducedant agonist muscle activity, and/or a reduction in any bilateral strength deficit. Nonetheless, increases in muscle protein synthesis were observed following an isolated bout of resistance exercise. In addition, muscle balance was positive, following resistance exercise when amino acids were infused/ingested. This showed that protein accretion occurred during the postexercise period. The implications of this hypothesis for training-induced increases in strength are discussed.
This study examined 12 wk of creatine (Cr) supplementation and heavy resistance training on muscle strength and myosin heavy chain (MHC) isoform mRNA and protein expression.
Twenty-two untrained male subjects were randomly assigned to either a control (CON), placebo (PLC), or Cr (CRT) group in a double-blind fashion. Muscle biopsies were obtained before and after 12 wk of heavy resistance training. PLC and CRT trained thrice weekly using three sets of 6-8 repetitions at 85-90% 1-RM on the leg press, knee extension, and knee curl exercises. CRT ingested 6 g.d-1 of Cr for 12 wk, whereas PLC consumed the equal concentration of placebo.
There were no significant differences for percent body fat (P > 0.05). However, for total body mass, fat-free mass, thigh volume, muscle strength, and myofibrillar protein, CRT and PLC exhibited significant increases after training when compared to CON (P < 0.05), whereas CRT was also significantly greater than PLC (P < 0.05). For Type I, IIa, and IIx MHC mRNA expression, CRT was significantly greater than CON and PLC, whereas PLC was greater than CON (P < 0.05). For MHC protein expression, CRT was significantly greater than CON and PLC for Type I and IIx (P < 0.05) but was equal to PLC for IIa.
Long-term Cr supplementation increases muscle strength and size, possibly as a result of increased MHC synthesis.
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.
The influence of creatine supplementation on substrate utilization during rest was investigated using a double-blind crossover design. Ten active men participated in 12 wk of weight training and were given creatine and placebo (20 g/day for 4 days, then 2 g/day for 17 days) in two trials separated by a 4-wk washout. Body composition, substrate utilization, and strength were assessed after weeks 2, 5, 9, and 12. Maximal isometric contraction [1 repetition maximum (RM)] leg press increased significantly (P < 0.05) after both treatments, but 1-RM bench press was increased (33 +/- 8 kg, P < 0.05) only after creatine. Total body mass increased (1.6 +/- 0.5 kg, P < 0.05) after creatine but not after placebo. Significant (P < 0.05) increases in fat-free mass were found after creatine and placebo supplementation (1.9 +/- 0.8 and 2.2 +/- 0.7 kg, respectively). Fat mass did not change significantly with creatine but decreased after the placebo trial (-2.4 +/- 0.8 kg, P < 0.05). Carbohydrate oxidation was increased by creatine (8.9 +/- 4.0%, P < 0.05), whereas there was a trend for increased respiratory exchange ratio after creatine supplementation (0.03 +/- 0.01, P = 0.07). Changes in substrate oxidation may influence the inhibition of fat mass loss associated with creatine after weight training.
We sought to determine whether creatine monohydrate (CrM) supplementation would enhance the increases in strength and fat-free mass that develop during resistance exercise training in older adults. Twenty-eight healthy men and women over the age of 65 years participated in a whole-body resistance exercise program 3 days per week for 14 weeks. The study participants were randomly allocated, in a double-blind fashion, to receive either CrM (5 g/d + 2 g of dextrose; n = 14) or placebo (7 g of dextrose; n = 14). The primary outcome measurements included the following: total body mass, fat-free mass, one-repetition maximum strength for each body part, isometric knee extension, handgrip, and dorsiflexion strength, chair stand performance, 30-m walk test, 14-stair climb performance, muscle fiber type and area, and intramuscular total creatine. Fourteen weeks of resistance exercise training resulted in significant increases in all measurements of strength and functional tasks and muscle fiber area for both groups (p <.05). CrM supplementation resulted in significantly greater increases in fat-free mass and total body mass, as compared with placebo (p <.05). The CrM group also showed a greater increase in isometric knee extension strength in men and women, as compared with placebo (p <.05), and also greater gains in isometric dorsiflexion strength (p <.05), but in men only. There was a significant increase in intramuscular total creatine in the CrM group (p <.05). Finally, there were no significant side effects of treatment or exercise training. This study confirms that supervised heavy resistance exercise training can safely increase muscle strength and functional capacity in older adults. The addition of CrM supplementation to the exercise stimulus enhanced the increase in total and fat-free mass, and gains in several indices of isometric muscle strength.
We compared the functional properties of muscle fibers from two groups of subjects that differed widely in their training history to investigate whether long-term resistance exercise alters the intrinsic contractile properties of skeletal muscle fibers.
Vastus lateralis muscle biopsies were obtained from six sedentary males (NT group, age = 23 +/- 1 yr) and six males who had participated in regular resistance exercise training over the preceding 7.6 +/- 1.6 yr (RT group, 22 +/- 1 yr). Chemically skinned muscle fiber segments were activated with a saturating free [Ca2+] to quantify fiber peak Ca2+-activated force (P(o)), unloaded shortening velocity (V(o)), and peak power. Fiber segment myosin heavy chain (MHC) isoform content was identified by gel electrophoresis.
Slow and fast fibers from the RT group were larger in CSA and produced greater absolute P(o) and absolute peak power in comparison with fibers from the NT group. However, these differences were no longer evident after P(o) and peak power were normalized to fiber CSA and fiber volume, respectively. V(o)/fiber length was dependent on fiber MHC content but independent of training status.
Fiber hypertrophy was sufficient to account for intergroup differences in P(o) and peak power of slow and fast fibers. There was no evidence that the intrinsic contractility of slow or fast fibers, as evaluated by force, shortening velocity, and power normalized to the appropriate fiber dimensions, differed between RT and NT groups.
Creatine monohydrate has become the supplement of choice for many athletes striving to improve sports performance. Recent data indicate that athletes may not be using creatine as a sports performance booster per se but instead use creatine chronically as a training aid to augment intense resistance training workouts. Although several studies have evaluated the combined effects of creatine supplementation and resistance training on muscle strength and weightlifting performance, these data have not been analyzed collectively. The purpose of this review is to evaluate the effects of creatine supplementation on muscle strength and weightlifting performance when ingested concomitant with resistance training. The effects of gender, interindividual variability, training status, and possible mechanisms of action are discussed. Of the 22 studies reviewed, the average increase in muscle strength (1, 3, or 10 repetition maximum [RM]) following creatine supplementation plus resistance training was 8% greater than the average increase in muscle strength following placebo ingestion during resistance training (20 vs. 12%). Similarly, the average increase in weightlifting performance (maximal repetitions at a given percent of maximal strength) following creatine supplementation plus resistance training was 14% greater than the average increase in weightlifting performance following placebo ingestion during resistance training (26 vs. 12%). The increase in bench press 1RM ranged from 3 to 45%, and the improvement in weightlifting performance in the bench press ranged from 16 to 43%. Thus there is substantial evidence to indicate that creatine supplementation during resistance training is more effective at increasing muscle strength and weightlifting performance than resistance training alone, although the response is highly variable.
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Beta 2-adrenoceptor agonist fenoterol enhances functional repair of regenerating rat skeletal muscle after injury.
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