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de Carvalho MR, Duarte EF, Mendonça MLM, de Morais CS, Ota GE, Gaspar-Junior JJ, de Oliveira Filiú WF, Damatto FC, Okoshi MP, Okoshi K, Oliveira RJ, Martinez PF, de Oliveira-Junior SA. Effects of Creatine Supplementation on the Myostatin Pathway and Myosin Heavy Chain Isoforms in Different Skeletal Muscles of Resistance-Trained Rats. Nutrients 2023; 15:2224. [PMID: 37432386 DOI: 10.3390/nu15092224] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 07/12/2023] Open
Abstract
Creatine has been used to maximize resistance training effects on skeletal muscles, including muscle hypertrophy and fiber type changes. This study aimed to evaluate the impact of creatine supplementation on the myostatin pathway and myosin heavy chain (MyHC) isoforms in the slow- and fast-twitch muscles of resistance-trained rats. Twenty-eight male Wistar rats were divided into four groups: a sedentary control (Cc), sedentary creatine supplementation (Cr), resistance training (Tc), and resistance training combined with creatine supplementation (Tcr). Cc and Tc received standard commercial chow; Cr and Tcr received a 2% creatine-supplemented diet. Tc and Tcr performed a resistance training protocol on a ladder for 12 weeks. Morphology, MyHC isoforms, myostatin, follistatin, and ActRIIB protein expressions were analyzed in soleus and white gastrocnemius portion samples. The results were analyzed using two-way ANOVA and Tukey's test. Tc and Tcr exhibited higher performance than their control counterparts. Resistance training increased the ratio between muscle and body weight, the cross-sectional area, as well as the interstitial collagen fraction. Resistance training alone increased MyHC IIx and follistatin while reducing myostatin (p < 0.001) and ActRIIB (p = 0.040) expressions in the gastrocnemius. Resistance training induced skeletal muscle hypertrophy and interstitial remodeling, which are more evident in the gastrocnemius muscle. The effects were not impacted by creatine supplementation.
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Affiliation(s)
- Marianna Rabelo de Carvalho
- Graduate Program in Health and Development in the Midwestern Region, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
| | - Ellen Fernandes Duarte
- Graduate Program in Health and Development in the Midwestern Region, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
| | - Maria Lua Marques Mendonça
- Graduate Program in Health and Development in the Midwestern Region, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
| | - Camila Souza de Morais
- Graduate Program in Health and Development in the Midwestern Region, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
| | - Gabriel Elias Ota
- Graduate Program in Health and Development in the Midwestern Region, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
| | - Jair José Gaspar-Junior
- Graduate Program in Health and Development in the Midwestern Region, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
| | - Wander Fernando de Oliveira Filiú
- Faculty of Pharmaceutical Sciences, Food and Nutrition, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
| | - Felipe Cesar Damatto
- Internal Medicine Department, Botucatu Medical School, Sao Paulo State University (UNESP), Botucatu 18618-687, SP, Brazil
| | - Marina Politi Okoshi
- Internal Medicine Department, Botucatu Medical School, Sao Paulo State University (UNESP), Botucatu 18618-687, SP, Brazil
| | - Katashi Okoshi
- Internal Medicine Department, Botucatu Medical School, Sao Paulo State University (UNESP), Botucatu 18618-687, SP, Brazil
| | - Rodrigo Juliano Oliveira
- Graduate Program in Health and Development in the Midwestern Region, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
| | - Paula Felippe Martinez
- Graduate Program in Health and Development in the Midwestern Region, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
- Graduate Program in Movement Sciences, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
| | - Silvio Assis de Oliveira-Junior
- Graduate Program in Health and Development in the Midwestern Region, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
- Graduate Program in Movement Sciences, Federal University of Mato Grosso do Sul (UFMS), Campo Grande 79070-900, MS, Brazil
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Cheng X, Li M, Leng X, Wen H, Wu F, Yu L, Jiang M, Lu X, Gao W, Zhang W, Tian J. Creatine improves the flesh quality of Pacific white shrimp (Litopenaeus vannamei) reared in freshwater. Food Chem 2021; 354:129498. [PMID: 33773482 DOI: 10.1016/j.foodchem.2021.129498] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/08/2021] [Accepted: 02/25/2021] [Indexed: 02/08/2023]
Abstract
Creatine improves flesh quality on mammalian but studies on crustaceans are scarce. In the present study, diets with six levels of creatine (1.23, 2.58, 5.12, 8.28, 14.12, 24.49 g kg-1 diet) were hand-fed to juvenile Litopenaeus vannamei (IBW: 1.50 ± 0.02 g) reared in freshwater for 46 days. Results showed creatine supplementation did not affect the growth performance (FBW: 17.04 ± 1.28 g) or the content of guanidinoacetic acid in muscle and hepatopancreas whereas significantly increased muscular creatine content. Diet with 8.28 g kg-1 creatine significantly increased muscular hardness and chewiness by decreasing myofiber diameter and increasing myofiber density. Additionally, creatine downregulated the mRNA expression of fast sMyHC1, sMyHC2, sMyHC6a and upregulated slow sMyHC5 and sMyHC15 mRNA expression. Muscular protein, collagen, total amino acid and flavor amino acid contents increased with creatine supplementation. In conclusion, the diet with 8.28 g kg-1 creatine improved the flesh quality of L. vannamei.
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Affiliation(s)
- Xiaoli Cheng
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; College of Animal Science, Yangtze University, Jingzhou 434024, China
| | - Meifeng Li
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Xiangjun Leng
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China
| | - Hua Wen
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Fan Wu
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Lijuan Yu
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Ming Jiang
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Xing Lu
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Weihua Gao
- College of Animal Science, Yangtze University, Jingzhou 434024, China
| | - Wenbing Zhang
- College of Animal Science, Yangtze University, Jingzhou 434024, China
| | - Juan Tian
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China.
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Guedes JM, Pieri BLDS, Luciano TF, Marques SDO, Guglielmo LGA, Souza CTD. Muscular resistance, hypertrophy and strength training equally reduce adiposity, inflammation and insulin resistance in mice with diet-induced obesity. EINSTEIN-SAO PAULO 2019; 18:eAO4784. [PMID: 31553356 PMCID: PMC6905165 DOI: 10.31744/einstein_journal/2020ao4784] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 04/29/2019] [Indexed: 12/22/2022] Open
Abstract
Objective To evaluate the effect of three types of muscular resistance training on adiposity, inflammation levels and insulin activity in Swiss mice with fat-rich diet-induced obesity. Methods Lean and obese male Swiss mice were selected and allocated to one of eight groups comprising eight mice each, as follows: standard diet + no training; standard diet + muscular resistance training; standard diet + hypertrophy training; standard diet + strength training; high-fat diet + no training; high-fat diet + muscular resistance training; high-fat diet + hypertrophy training; high-fat diet + strength training. The training protocol consisted of stair climbing for a 10-week period. Blood samples were collected for lactate analysis, glucose level measurement and insulin tolerance test. After euthanasia, adipose tissues were removed and weighed for adiposity index determination. Fragments of epididymal adipose tissue were then embedded for histological analysis or homogenized for tumor necrosis factor alpha level determination using the ELISA method. Results Ausency of differences in total training volume and blood lactate levels overall emphasize the similarity between the different resistance training protocols. Body weight loss, reduced adipocyte area and lower adiposity index were observed in trained obese mice, regardless of training modality. Different training protocols also improved insulin sensitivity and reduced inflammation levels. Conclusion Resistance training protocols were equally effective in reducing body fat, inflammation levels and insulin resistance in obese mice.
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Guzzoni V, Briet L, Costa R, Souza RWA, Carani FR, Dal-Pai-Silva M, Silva KAS, Cunha TS, Marcondes FK. Intense resistance training induces pronounced metabolic stress and impairs hypertrophic response in hind-limb muscles of rats. Stress 2019; 22:377-386. [PMID: 30857457 DOI: 10.1080/10253890.2019.1573364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Skeletal muscle hypertrophy is an exercise-induced adaptation, particularly in resistance training (RT) programs that use large volumes and low loads. However, evidence regarding the role of rest intervals on metabolic stress and muscular adaptations is inconclusive. Thus, we aimed to investigate the effects of a strenuous RT model (jump-training) on skeletal muscle adaptations and metabolic stress, considering the scarce information about RT models for rats. We hypothesized that jump-training induces metabolic stress and influences negatively the growth of soleus (SOL) and extensor digitorum longus (EDL) muscles of rats. Male Wistar rats (aged 60 days) were randomly assigned to non-trained or trained groups (n = 8/group). Trained rats performed jump-training during 5 days a week for 1, 3, or 5 weeks with 30 s of inter-set rest intervals. Forty-eight hours after the experimental period, rats were euthanized and blood samples immediately drawn to measure creatine kinase activity, lactate and corticosterone concentrations. Muscle weight-to-body weight ratio (MW/BW), cross-sectional area (CSA) and myosin heavy chain (MHC) isoform expression were determined. Higher lactate levels occurred after 20 min of training in weeks 1 and 3. Corticosterone levels were higher after 5 weeks of training. Jump-training had negative effects on hypertrophy of types-I and II muscle fibers after 5 weeks of training, as evidenced by decreased CSA and reduced muscle weight. Our results demonstrated that pronounced metabolic stress and impairment of muscle growth might take place when variables of exercise training are not appropriately manipulated. Lay summary Resistance training (RT) has been used to increase muscle mass. In this regard, training variables (intensity, volume, and frequency) must be strictly controlled in order to evoke substantial muscular fitness. This study shows that rats submitted to 5 weeks of intensive resistance jump-training - high intensity, large volume, and short rest intervals - present high levels of blood corticosterone associated with negative effects on hypertrophy of types-I and II muscle fibers.
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Affiliation(s)
- Vinicius Guzzoni
- a Department of Physiological Sciences , Piracicaba Dental School, University of Campinas , Piracicaba , Brazil
- b Department of Cellular and Molecular Biology , Federal University of Paraíba , João Pessoa , Brazil
| | - Larissa Briet
- c Institute of Biology , University of Campinas , Campinas , Brazil
| | - Rafaela Costa
- a Department of Physiological Sciences , Piracicaba Dental School, University of Campinas , Piracicaba , Brazil
| | - Rodrigo W A Souza
- d Department of Morphology, Institute of Biosciences , São Paulo State University , Botucatu , Brazil
| | - Fernanda R Carani
- d Department of Morphology, Institute of Biosciences , São Paulo State University , Botucatu , Brazil
| | - Maeli Dal-Pai-Silva
- d Department of Morphology, Institute of Biosciences , São Paulo State University , Botucatu , Brazil
| | - Kleiton A S Silva
- e Department of Medicine , University of Missouri School of Medicine , Columbia , MO, USA
| | - Tatiana S Cunha
- f Science and Technology Institute , Federal University of São Paulo , São José dos Campos , Brazil
| | - Fernanda K Marcondes
- a Department of Physiological Sciences , Piracicaba Dental School, University of Campinas , Piracicaba , Brazil
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Myoprotective Potential of Creatine Is Greater than Whey Protein after Chemically-Induced Damage in Rat Skeletal Muscle. Nutrients 2018; 10:nu10050553. [PMID: 29710855 PMCID: PMC5986433 DOI: 10.3390/nu10050553] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 04/26/2018] [Accepted: 04/27/2018] [Indexed: 12/28/2022] Open
Abstract
The myoprotective effects of creatine monohydrate (CR) and whey protein (WP) are equivocal, with the use of proxy measures of muscle damage making interpretation of their effectiveness limited. The purpose of the study was to determine the effects of CR and WP supplementation on muscle damage and recovery following controlled, chemically-induced muscle damage. Degeneration of the extensor digitorum longus (EDL) muscle was induced by bupivacaine in rats supplemented with either CR, WP, or standard rat chow (CON). At day 7 and 14 post-myotoxic injury, injured EDL muscles were surgically removed and tested for isometric contractile properties, followed by the contralateral, non-injured EDL muscle. At the completion of testing, muscles were snap-frozen in liquid nitrogen and stored for later analysis. Data were analyzed using analysis of variance. Creatine-supplemented muscles displayed a greater proportion of non-damaged (intact) fibers (p = 0.002) and larger cross-sectional areas of regenerating and non-damaged fibers (p = 0.024) compared to CON muscles at day 7 post-injury. At day 14 post-injury, CR-supplemented muscles generated higher absolute forces concomitant with greater contractile protein levels compared to CON (p = 0.001, p = 0.008) and WP-supplemented muscles (p = 0.003, p = 0.006). Creatine supplementation appears to offer an element of myoprotection which was not observed following whey protein supplementation.
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Smith MA, Fronk GE, Abel JM, Lacy RT, Bills SE, Lynch WJ. Resistance exercise decreases heroin self-administration and alters gene expression in the nucleus accumbens of heroin-exposed rats. Psychopharmacology (Berl) 2018; 235:1245-1255. [PMID: 29396617 PMCID: PMC5871570 DOI: 10.1007/s00213-018-4840-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 01/21/2018] [Indexed: 12/11/2022]
Abstract
RATIONALE Preclinical studies consistently report that aerobic exercise decreases drug self-administration and other forms of drug-seeking behavior; however, relatively few studies have examined other types of physical activity. OBJECTIVES The purpose of the present study was to examine the effects of resistance exercise (i.e., strength training) on heroin self-administration and mRNA expression of genes known to mediate opioid reinforcement and addictive behavior in the nucleus accumbens (NAc) of heroin-exposed rats. METHODS Female rats were obtained during late adolescence and divided into two groups. Resistance exercise rats were trained to climb a vertical ladder wearing a weighted vest; sedentary control rats were placed repeatedly on the ladder oriented horizontally on its side. All rats were implanted with intravenous catheters and trained to self-administer heroin on a fixed ratio (FR1) schedule of reinforcement. mRNA expression in the NAc core and shell was examined following behavioral testing. RESULTS Resistance exercise significantly decreased heroin self-administration, resulting in a downward shift in the dose-effect curve. Resistance exercise also reduced mRNA expression for mu opioid receptors and dopamine D1, D2, and D3 receptors in the NAc core. Resistance exercise increased mRNA expression of dopamine D5 receptors in the NAc shell and increased mRNA expression of brain-derived neurotrophic factor (exons I, IIB, IIC, IV, VI, IX) in the NAc core. CONCLUSIONS These data indicate that resistance exercise decreases the positive reinforcing effects of heroin and produces changes in opioid and dopamine systems in the NAc of heroin-exposed rats.
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Affiliation(s)
- Mark A Smith
- Department of Psychology, Davidson College, Davidson, NC, 28035, USA.
- Program in Neuroscience, Davidson College, Davidson, NC, USA.
| | - Gaylen E Fronk
- Department of Psychology, Davidson College, Davidson, NC, 28035, USA
| | - Jean M Abel
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, USA
| | - Ryan T Lacy
- Department of Psychology, Franklin and Marshall College, Lancaster, PA, USA
| | - Sarah E Bills
- Department of Psychology, Davidson College, Davidson, NC, 28035, USA
| | - Wendy J Lynch
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, USA
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The effects of resistance exercise on cocaine self-administration, muscle hypertrophy, and BDNF expression in the nucleus accumbens. Drug Alcohol Depend 2016; 163:186-94. [PMID: 27137405 PMCID: PMC4880539 DOI: 10.1016/j.drugalcdep.2016.04.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Revised: 04/07/2016] [Accepted: 04/14/2016] [Indexed: 11/21/2022]
Abstract
BACKGROUND Exercise is associated with positive outcomes in drug abusing populations and reduces drug self-administration in laboratory animals. To date, most research has focused on aerobic exercise, and other types of exercise have not been examined. This study examined the effects of resistance exercise (strength training) on cocaine self-administration and BDNF expression, a marker of neuronal activation regulated by aerobic exercise. METHODS Female rats were assigned to either exercising or sedentary conditions. Exercising rats climbed a ladder wearing a weighted vest and trained six days/week. Training consisted of a three-set "pyramid" in which the number of repetitions and resistance varied across three sets: eight climbs carrying 70% body weight (BW), six climbs carrying 85% BW, and four climbs carrying 100% BW. Rats were implanted with intravenous catheters and cocaine self-administration was examined. Behavioral economic measures of demand intensity and demand elasticity were derived from the behavioral data. BDNF mRNA expression was measured via qRT-PCR in the nucleus accumbens following behavioral testing. RESULTS Exercising rats self-administered significantly less cocaine than sedentary rats. A behavioral economic analysis revealed that exercise increased demand elasticity for cocaine, reducing consumption at higher unit prices. Exercising rats had lower BDNF expression in the nucleus accumbens core than sedentary rats. CONCLUSIONS These data indicate that resistance exercise decreases cocaine self-administration and reduces BDNF expression in the nucleus accumbens after a history of cocaine exposure. Collectively, these findings suggest that strength training reduces the positive reinforcing effects of cocaine and may decrease cocaine use in human populations.
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Seo DY, Lee SR, Kim N, Ko KS, Rhee BD, Han J. Humanized animal exercise model for clinical implication. Pflugers Arch 2014; 466:1673-87. [PMID: 24647666 DOI: 10.1007/s00424-014-1496-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/03/2014] [Accepted: 03/05/2014] [Indexed: 01/20/2023]
Abstract
Exercise and physical activity function as a patho-physiological process that can prevent, manage, and regulate numerous chronic conditions, including metabolic syndrome and age-related sarcopenia. Because of research ethics and technical difficulties in humans, exercise models using animals are requisite for the future development of exercise mimetics to treat such abnormalities. Moreover, the beneficial or adverse outcomes of a new regime or exercise intervention in the treatment of a specific condition should be tested prior to implementation in a clinical setting. In rodents, treadmill running (or swimming) and ladder climbing are widely used as aerobic and anaerobic exercise models, respectively. However, exercise models are not limited to these types. Indeed, there are no golden standard exercise modes or protocols for managing or improving health status since the types (aerobic vs. anaerobic), time (morning vs. evening), and duration (continuous vs. acute bouts) of exercise are the critical determinants for achieving expected beneficial effects. To provide insight into the understanding of exercise and exercise physiology, we have summarized current animal exercise models largely based on aerobic and anaerobic criteria. Additionally, specialized exercise models that have been developed for testing the effect of exercise on specific physiological conditions are presented. Finally, we provide suggestions and/or considerations for developing a new regime for an exercise model.
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Affiliation(s)
- Dae Yun Seo
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Department of Health Sciences and Technology, Cardiovascular and Metabolic Disease Center, Inje University, Bok Ji-Ro 75, Busanjin-Gu, Busan, 613-735, Republic of Korea
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Aguiar AF, de Souza RWA, Aguiar DH, Aguiar RCM, Vechetti IJ, Dal-Pai-Silva M. Creatine does not promote hypertrophy in skeletal muscle in supplemented compared with nonsupplemented rats subjected to a similar workload. Nutr Res 2012; 31:652-7. [PMID: 21925351 DOI: 10.1016/j.nutres.2011.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 08/05/2011] [Accepted: 08/08/2011] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to test the hypothesis that creatine (Cr) supplementation may promote an additional hypertrophic effect on skeletal muscle independent of a higher workload on Cr-supplemented trained muscle compared with Cr-nonsupplemented trained muscle. Male Wistar rats (2-3 months old, 250-300 g) were divided randomly into 4 groups (n = 8 per group): nontrained without Cr supplementation (CO), nontrained with Cr supplementation (CR), trained without Cr supplementation (TR), and trained with Cr supplementation (TRCR). Creatine supplementation was given at 0.5 g/kg per day. Trained groups were submitted to a 5-week resistance training program (5 d/wk). The progressive workloads were similar between the Cr-supplemented (TRCR) and Cr-nonsupplemented (TR) trained groups; the only difference between groups was the Cr treatment. After the 5-week experiment, the soleus muscle was dissected to analyze the cross-sectional area (CSA) of the muscle fibers. Resistance training promoted a significant (P < .05) increase in the muscle fibers CSA in the TR group compared with the CO group. However, no additional hypertrophic effect was found when Cr supplementation was added to training (TRCR vs TR comparison, P > .05). In addition, Cr supplementation alone did not promote significant alterations in muscle fiber CSA (CR vs CO comparison, P > .05). We conclude that Cr supplementation does not promote any additional hypertrophic effect on skeletal muscle area when Cr-supplemented trained muscles are submitted to same training regimen than Cr-nonsupplemented trained muscles. Specifically, any benefits of Cr supplementation on hypertrophy gains during resistance training may not be attributed to a direct anabolic effect on the skeletal muscle.
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Affiliation(s)
- Andreo Fernando Aguiar
- UNESP-Univ Estadual Paulista, Institute of Biosciences, Department of Morphology, Botucatu, 18618-970, São Paulo, Brazil.
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