RESUMO
In recent years, there have been an increasing number of genetic variants associated with athletic phenotypes. Here, we selected a set of sports-relevant polymorphisms that have been previously suggested as genetic markers for human physical performance, and we examined their association with athletic status in a large cohort of Brazilians. We evaluated a sample of 1,622 individuals, in which 966 were nonathletes, and 656 were athletes: 328 endurance athletes and 328 power athletes. Only the AGT M268T minor allele was nominally associated with the endurance status. Conversely, we found that seven polymorphisms are more frequent in power athletes (MCT1 D490E, AGT M268T, PPARG P12A, PGC1A G482S, VEGFR2 Q472H, NOS3 C/T, and ACTN3 R577X). For all of these polymorphisms, power athletes were more likely than nonathletes or endurance athletes to carry the major allele or the homozygous genotype for the major allele. In particular, MCT1 D490E, AGT M268T, NOS3 C/T, and ACTN3 R577X showed stronger associations. Our findings support a role for these variants in the achievement of power athletic status in Brazilians: MCT1 D490E (T allele), AGT M268T (G allele), PPARG (C allele), PGC1A G482S (C allele), VEGFR2 Q472H (T allele), NOS3 C/T (T allele), and ACTN3 R577X (R allele).
Assuntos
Atletas , Marcadores Genéticos , Polimorfismo de Nucleotídeo Único , Esportes , Adolescente , Adulto , Alelos , Brasil , Estudos de Coortes , Feminino , Frequência do Gene , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Resistência Física , Adulto JovemRESUMO
Sodium citrate (SCit) supplementation has been studied for several years as a strategy to reduce the muscle fatigue induced by H+ ion accumulation within the skeletal muscle during high-intensity, short-duration exercise. Several investigations have been published on this matter, and appear to indicate that SCit is not effective as an ergogenic aid, despite its ability to increase extracellular buffering capacity. In this short report, we briefly discuss the SCit results previously published in the literature and consider them in light of new and promising findings, which appear to address issues associated with previous study designs. We also suggest possible reasons for the current lack of reported ergogenic effects from this nutritional strategy and make recommendations that may re-define research in this area.
Assuntos
Citratos/farmacologia , Suplementos Nutricionais , Fadiga Muscular/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Substâncias para Melhoria do Desempenho/farmacologia , Humanos , Músculo Esquelético/fisiologia , Citrato de SódioRESUMO
The main purpose of this study was to investigate if the rs11091046 (A>C) polymorphism in AGTR2 gene is associated with athletic status in top-level athletes from Brazil. Since the AGTR2 gene is located on the X chromosome, the case-control association study was done separately for women and men. The female cohort was composed of 205 athletes and 241 non-athletes, and the male cohort was composed of 419 athletes and 490 non-athletes. We did not identify an association between the C-allele and the endurance phenotype. However, power athletes had a higher frequency of the A-allele. In women, A/A genotype was overrepresented in international-level power group compared with non-athletes or international-level endurance athletes (23.2% vs. 16.6% or 8.8%, respectively; p < 0.05). In men, the A-allele frequency observed in power athletes or international-level power athletes was statistically different from that observed in non-athletes (51.6% or 57.8% vs. 40.4%; p < 0.009). Furthermore, men sprinters with the A-allele showed significantly faster personal best times for the 100 m than those with the C-allele (10.56 ± 0.32 s vs. 10.93 ± 0.49 s; p < 0.02). In conclusion, it was found that the AGTR2 A-allele is a candidate genetic marker for top-level power athletes.
Assuntos
Desempenho Atlético/fisiologia , Polimorfismo de Nucleotídeo Único , Receptor Tipo 2 de Angiotensina/genética , Adulto , Brasil , Estudos de Casos e Controles , Feminino , Frequência do Gene , Genótipo , Humanos , Masculino , Força Muscular/fisiologia , Resistência Física/fisiologiaRESUMO
Women of childbearing age have variations in substrate oxidation rates that can lead to overweight, type II diabetes, and other conditions that may be associated with metabolic inflexibility and the variations in estrogen concentrations observed during the monthly ovarian cycle. PURPOSE: This study aimed to verify and compare the influence of eight treadmill high-intensity interval training (HIT) sessions on carbohydrate and lipid oxidation rates (CHOox and LIPox, respectively) and intensities of ventilatory anaerobic thresholds (VATs) of women in different phases of the monthly ovarian cycle. METHODS: Eleven irregularly active women performed incremental treadmill exercise testing followed by submaximal work-rate running for 45 min to determine VATs, VO2peak, peak velocity (Vpeak), and substrate oxidation rates, before and after a training period, in different phases of their monthly ovarian cycle (follicular phase group, FL, n = 6; luteal phase group, LT, n = 5). The training period consisted of eight HIT sessions, composed each one of eight sets of 60 s running at 100%Vpeak interspersed by 75 s recovery every 48 h. RESULTS: Our results showed no significant differences in VATs intensities between groups. The comparison between groups showed significant differences in relative energy derived from CHO pre- and post-training of -61.42% and -59.26%, respectively, and LIP pre- and post-training of 27.46% and 34.41%, respectively. The relative energy derived from CHO after the training period was 18.89% and 25.50% higher for FL and LT, respectively; consequently, the relative energy derived from LIPox after the training period was 8,45% and 3.46% lower for FL and LT, respectively. Over the training period, Vpeak was ~13.5 km/h, which produced the relative intensities of ~89%VO2peak e ~93%HRpeak for both groups. CONCLUSION: The monthly ovarian cycle phases promote significant changes in substrate oxidation rates leading to a decrease in CHOox. High-intensity interval training can minimize the differences observed and constitute an alternative intervention.
Assuntos
Diabetes Mellitus Tipo 2 , Treinamento Intervalado de Alta Intensidade , Feminino , Humanos , Bezafibrato , Metabolismo Energético , Ciclo Menstrual , Consumo de Oxigênio , Projetos PilotoRESUMO
We aimed to investigate the role of betaine supplementation on muscle phosphorylcreatine (PCr) content and strength performance in untrained subjects. Additionally, we compared the ergogenic and physiological responses to betaine versus creatine supplementation. Finally, we also tested the possible additive effects of creatine and betaine supplementation. This was a double-blind, randomized, placebo-controlled study. Subjects were assigned to receive betaine (BET; 2 g/day), creatine (CR; 20 g/day), betaine plus creatine (BET+CR; 2+20 g/day, respectively) or placebo (PL). At baseline and after 10 days of supplementation, we assessed muscle strength and power, muscle PCr content, and body composition. The CR and BET+CR groups presented greater increase in muscle PCr content than PL (p=0.004 and p=0.006, respectively). PCr content was comparable between BET versus PL (p=0.78) and CR versus BET+CR (p=0.99). CR and BET+CR presented greater muscle power output than PL in the squat exercise following supplementation (p=0.003 and p=0.041, respectively). Similarly, bench press average power was significantly greater for the CR-supplemented groups. CR and BET+CR groups also showed significant pre- to post-test increase in 1-RM squat and bench press (CR: p=0.027 and p<0.0001; BET+CR: p=0.03 and p<0.0001 for upper- and lower-body assessments, respectively) No significant differences for 1-RM strength and power were observed between BET versus PL and CR versus BET+CR. Body composition did not differ between the groups. In conclusion, we reported that betaine supplementation does not augment muscle PCr content. Furthermore, we showed that betaine supplementation combined or not with creatine supplementation does not affect strength and power performance in untrained subjects.
Assuntos
Betaína/administração & dosagem , Creatina/administração & dosagem , Força Muscular/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Adolescente , Adulto , Composição Corporal/efeitos dos fármacos , Suplementos Nutricionais , Método Duplo-Cego , Humanos , Espectroscopia de Ressonância Magnética , Masculino , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Fosfocreatina/análise , PlacebosRESUMO
The aim of this study was to investigate the effects of beta-alanine supplementation on exercise capacity and the muscle carnosine content in elderly subjects. Eighteen healthy elderly subjects (60-80 years, 10 female and 4 male) were randomly assigned to receive either beta-alanine (BA, n=12) or placebo (PL, n=6) for 12 weeks. The BA group received 3.2 g of beta-alanine per day (2×800 mg sustained-release Carnosyn™ tablets, given 2 times per day). The PL group received 2× (2×800 mg) of a matched placebo. At baseline (PRE) and after 12 weeks (POST-12) of supplementation, assessments were made of the muscle carnosine content, anaerobic exercise capacity, muscle function, quality of life, physical activity and food intake. A significant increase in the muscle carnosine content of the gastrocnemius muscle was shown in the BA group (+85.4%) when compared with the PL group (+7.2%) (p=0.004; ES: 1.21). The time-to-exhaustion in the constant-load submaximal test (i.e., TLIM) was significantly improved (p=0.05; ES: 1.71) in the BA group (+36.5%) versus the PL group (+8.6%). Similarly, time-to-exhaustion in the incremental test was also significantly increased (p=0.04; ES 1.03) following beta-alanine supplementation (+12.2%) when compared with placebo (+0.1%). Significant positive correlations were also shown between the relative change in the muscle carnosine content and the relative change in the time-to-exhaustion in the TLIM test (r=0.62; p=0.01) and in the incremental test (r=0.48; p=0.02). In summary, the current data indicate for the first time, that beta-alanine supplementation is effective in increasing the muscle carnosine content in healthy elderly subjects, with subsequent improvement in their exercise capacity.
Assuntos
Carnosina/metabolismo , Suplementos Nutricionais , Músculo Esquelético/fisiologia , Resistência Física/efeitos dos fármacos , beta-Alanina/administração & dosagem , Idoso , Idoso de 80 Anos ou mais , Envelhecimento , Método Duplo-Cego , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismoRESUMO
The purpose of this study was to determine the physiological, anthropometric, performance, and nutritional characteristics of the Brazil Canoe Polo National Team. Ten male canoe polo athletes (age 26.7 ± 4.1 years) performed a battery of tests including assessments of anthropometric parameters, upper-body anaerobic power (Wingate), muscular strength, aerobic power, and nutritional profile. In addition, we characterized heart rate and plasma lactate responses and the temporal pattern of the effort/recovery during a simulated canoe polo match. The main results are as follows: body fat, 12.3 ± 4.0%; upper-body peak and mean power, 6.8 ± 0.5 and 4.7 ± 0.4 W · kg(-1), respectively; 1-RM bench press, 99.1 ± 11.7 kg; peak oxygen uptake, 44.3 ± 5.8 mL · kg(-1) · min(-1); total energy intake, 42.8 ± 8.6 kcal · kg(-1); protein, carbohydrate, and fat intakes, 1.9 ± 0.1, 5.0 ± 1.5, and 1.7 ± 0.4 g · kg(-1), respectively; mean heart rate, 146 ± 11 beats · min(-1); plasma lactate, 5.7 ± 3.8 mmol · L(-1) at half-time and 4.6 ± 2.2 mmol · L(-1) at the end of the match; effort time (relative to total match time), 93.1 ± 3.0%; number of sprints, 9.6 ± 4.4. The results of this study will assist coaches, trainers, and nutritionists in developing more adequate training programmes and dietary interventions for canoe polo athletes.
Assuntos
Antropometria , Atletas , Desempenho Atlético/fisiologia , Estado Nutricional , Tecido Adiposo , Adolescente , Adulto , Composição Corporal/fisiologia , Brasil , Alimentos , Frequência Cardíaca/fisiologia , Humanos , Ácido Láctico/sangue , Masculino , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Consumo de Oxigênio/fisiologia , Navios , Adulto JovemRESUMO
Creatine supplementation may have a therapeutic role in diabetes, but it is uncertain whether this supplement is safe for kidney function. The aim of this study was to investigate the effects of creatine supplementation on kidney function in type 2 diabetic patients. A randomized, double-blind, placebo-controlled trial was performed. The patients were randomly allocated to receive either creatine or placebo for 12 weeks. All the patients underwent exercise training throughout the trial. Subjects were assessed at baseline and after the intervention. Blood samples and 24-h urine samples were obtained for kidney function assessments. Additionally, (51)Cr-EDTA clearance was performed. To ensure the compliance with creatine intake, we also assessed muscle phosphorylcreatine content. The creatine group presented higher muscle phosphorylcreatine content when compared to placebo group (CR Pre 44 ± 10, Post 70 ± 18 mmol/kg/wt; PL Pre 52 ± 13, Post 46 ± 13 mmol/kg/wt; p = 0.03; estimated difference between means 23.6; 95% confidence interval 1.42-45.8). No significant differences were observed for (51)Cr-EDTA clearance (CR Pre 90.4 ± 16.9, Post 96.1 ± 15.0 mL/min/1.73 m(2); PL Pre 97.9 ± 21.6, Post 96.4 ± 26.8 mL/min/1.73 m(2); p = 0.58; estimated difference between means -0.3; 95% confidence interval -24.9 to 24.2). Creatinine clearance, serum and urinary urea, electrolytes, proteinuria, and albuminuria were unchanged. CR supplementation does not affect kidney function in type 2 diabetic patients, opening a window of opportunities to explore its promising therapeutic role in this population. ClinicalTrials.gov registration number: NCT00992043.
Assuntos
Creatina/administração & dosagem , Diabetes Mellitus Tipo 2/metabolismo , Suplementos Nutricionais , Creatina/sangue , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/urina , Método Duplo-Cego , Feminino , Humanos , Rim/fisiologia , Testes de Função Renal , Masculino , Pessoa de Meia-IdadeRESUMO
Creatine (Cr) plays a central role in energy provision through a reaction catalyzed by phosphorylcreatine kinase. Furthermore, this amine enhances both gene expression and satellite cell activation involved in hypertrophic response. Recent findings have indicated that Cr supplementation has a therapeutic role in several diseases characterized by atrophic conditions, weakness, and metabolic disturbances (i.e., in the muscle, bone, lung, and brain). Accordingly, there has been an evidence indicating that Cr supplementation is capable of attenuating the degenerative state in some muscle disorders (i.e., Duchenne and inflammatory myopathies), central nervous diseases (i.e., Parkinson's, Huntington's, and Alzheimer's), and bone and metabolic disturbances (i.e., osteoporosis and type II diabetes). In light of this, Cr supplementation could be used as a therapeutic tool for the elderly. The aim of this review is to summarize the main studies conducted in this field and to highlight the scientific and clinical perspectives of this promising therapeutic supplement.
Assuntos
Doenças do Sistema Nervoso Central/tratamento farmacológico , Creatina/uso terapêutico , Suplementos Nutricionais , Doenças Metabólicas/tratamento farmacológico , Doenças Musculares/tratamento farmacológico , Doenças do Sistema Nervoso Central/metabolismo , Creatina/metabolismo , Humanos , Doenças Metabólicas/metabolismo , Doenças Musculares/metabolismo , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Intramuscular acidosis is a contributing factor to fatigue during high-intensity exercise. Many nutritional strategies aiming to increase intra- and extracellular buffering capacity have been investigated. Among these, supplementation of beta-alanine (~3-6.4 g/day for 4 weeks or longer), the rate-limiting factor to the intramuscular synthesis of carnosine (i.e. an intracellular buffer), has been shown to result in positive effects on exercise performance in which acidosis is a contributing factor to fatigue. Furthermore, sodium bicarbonate, sodium citrate and sodium/calcium lactate supplementation have been employed in an attempt to increase the extracellular buffering capacity. Although all attempts have increased blood bicarbonate concentrations, evidence indicates that sodium bicarbonate (0.3 g/kg body mass) is the most effective in improving high-intensity exercise performance. The evidence supporting the ergogenic effects of sodium citrate and lactate remain weak. These nutritional strategies are not without side effects, as gastrointestinal distress is often associated with the effective doses of sodium bicarbonate, sodium citrate and calcium lactate. Similarly, paresthesia (i.e. tingling sensation of the skin) is currently the only known side effect associated with beta-alanine supplementation, and it is caused by the acute elevation in plasma beta-alanine concentration after a single dose of beta-alanine. Finally, the co-supplementation of beta-alanine and sodium bicarbonate may result in additive ergogenic gains during high-intensity exercise, although studies are required to investigate this combination in a wide range of sports.
Assuntos
Acidose/prevenção & controle , Suplementos Nutricionais , Exercício Físico/fisiologia , Músculo Esquelético/metabolismo , Compostos de Cálcio/administração & dosagem , Compostos de Cálcio/efeitos adversos , Compostos de Cálcio/metabolismo , Citratos/administração & dosagem , Citratos/efeitos adversos , Citratos/metabolismo , Suplementos Nutricionais/efeitos adversos , Metabolismo Energético , Líquido Extracelular/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Líquido Intracelular/metabolismo , Lactatos/administração & dosagem , Lactatos/efeitos adversos , Lactatos/metabolismo , Fadiga Muscular , Bicarbonato de Sódio/administração & dosagem , Bicarbonato de Sódio/efeitos adversos , Bicarbonato de Sódio/sangue , Citrato de Sódio , Lactato de Sódio/administração & dosagem , Lactato de Sódio/efeitos adversos , Lactato de Sódio/metabolismo , beta-Alanina/administração & dosagem , beta-Alanina/efeitos adversos , beta-Alanina/metabolismoRESUMO
The current investigation aimed to develop a valid specific field test to evaluate anaerobic physical performance in Aerobic Gymnastics athletes. We first designed the Specific Aerobic Gymnast Anaerobic Test (SAGAT), which included gymnastics-specific elements performed in maximal repeated sprint fashion, with a total duration of 80-90 s. In order to validate the SAGAT, three independent sub-studies were performed to evaluate the concurrent validity (Study I, n=8), the reliability (Study II, n=10) and the sensitivity (Study III, n=30) of the test in elite female athletes. In Study I, a positive correlation was shown between lower-body Wingate test and SAGAT performance (Mean power: p = 0.03, r = -0.69, CI: -0.94 to 0.03 and Peak power: p = 0.02, r = -0.72, CI: -0.95 to -0.04) and between upper-body Wingate test and SAGAT performance (Mean power: p = 0.03, r = -0.67, CI: -0.94 to 0.02 and Peak power: p = 0.03, r = -0.69, CI: -0.94 to 0.03). Additionally, plasma lactate was similarly increased in response to SAGAT (p = 0.002), lower-body Wingate Test (p = 0.021) and a simulated competition (p = 0.007). In Study II, no differences were found between the time to complete the SAGAT in repeated trials (p = 0.84; Cohen's d effect size = 0.09; ICC = 0.97, CI: 0.89 to 0.99; MDC95 = 0.12 s). Finally, in Study III the time to complete the SAGAT was significantly lower during the competition cycle when compared to the period before the preparatory cycle (p < 0.001), showing an improvement in SAGAT performance after a specific Aerobic Gymnastics training period. Taken together, these data have demonstrated that SAGAT is a specific, reliable and sensitive measurement of specific anaerobic performance in elite female Aerobic Gymnastics, presenting great potential to be largely applied in training settings.
Assuntos
Limiar Anaeróbio/fisiologia , Atletas , Desempenho Atlético/fisiologia , Teste de Esforço/métodos , Ginástica/fisiologia , Corrida/fisiologia , Adolescente , Feminino , Humanos , Consumo de Oxigênio , Reprodutibilidade dos TestesRESUMO
De acordo com o último relatório da Vigitel 2017 as Doenças Crônicas Não Transmissíveis (DCNT) são responsáveis por 68% de um total de 38 milhões de mortes ocorridas no mundo em 2012. No Brasil, esse cenário não é diferente: em 2011 as DCNT foram responsáveis por 68,3% do total de mortes. Milhares de dólares são gastos hoje com políticas que estimulam hábitos de vida mais saudável, mas essa estratégia, por si só, tem continuamente falhado em produzir resultados consistentes e duradouros. É necessário uma nova abordagem, que promova mudanças no estilo de vida, possibilitando a melhora dos parâmetros de saúde das pessoas. O processo de coaching apoia o desenvolvimento de um relacionamento de ajuda, incentivando o paciente a identificar sua visão, necessidades e objetivos. Além disso, o coaching visa ajudar na organização de rotinas e prioridades, enquanto coloca o paciente no controle de seu destino de saúde.
According to the latest Vigitel 2017 report, non-communicable chronic diseases accounted for 68% of a total of 38 million deaths worldwide in 2012. In Brazil, the scenario is no different; in 2011 the non communicable diseases were responsible for 68.3% of all deaths. Thousands of dollars are spent today on policies that encourage healthier living habits, but this strategy, by itself, has continually failed to produce consistent and long-lasting results. A new approach is needed that promotes lifestyle changes, making it possible to improve people's health parameters. The process of coaching supports the development of a helporiented relationship, encouraging patients to identify their vision, needs and goals. In addition, coaching aims to assist in the organization of routines and priorities, while putting patients in control of their health endgoal.
Assuntos
Humanos , Masculino , Feminino , Processo Saúde-Doença , Doença Crônica , Sistemas Públicos de Saúde , Estilo de VidaRESUMO
It has been suggested that the abrupt liposuction-induced decrease in adipose tissue could affect adipokine secretion pattern. We hypothesized that exercise training could positively impact adipokine metabolism following liposuction. The aim of this study was to investigate the effects of liposuction on inflammation-related adipokines in women who were either exercise-trained or remained sedentary after surgery. Thirty-six healthy normal-weight women underwent an abdominal liposuction and two months after surgery were randomly allocated into two groups: trained (TR, n = 18, four-month exercise program) and nontrained (NT, n = 18). Inflammation-related adipokine serum levels (TNF- α , IL-6, IL-10, and adiponectin) and abdominal and thigh subcutaneous adipose tissue (scAT) mRNA levels were assessed before (PRE) and six months after surgery (POST6). TNF- α , IL-6, and IL-10 serum levels were unchanged in both groups. In contrast, TNF- α , IL-6, and IL-10 mRNA levels in scAT were increased, whereas adiponectin scAT mRNA and serum levels were decreased at POST6 (P < 0.05, main effect for time). No changes were observed in mRNA levels of MCP-1, CD14, and CD68 in any of the groups. In conclusion, liposuction downregulates adiponectin scAT gene expression and serum levels and upregulates scAT gene expression of inflammation-related genes six months after surgery in normal-weight women, irrespective of exercise training.
RESUMO
BACKGROUND: The aim of this study was to determine the effects of creatine supplementation on kidney function in resistance-trained individuals ingesting a high-protein diet. METHODS: A randomized, double-blind, placebo-controlled trial was performed. The participants were randomly allocated to receive either creatine (20 g/d for 5 d followed by 5 g/d throughout the trial) or placebo for 12 weeks. All of the participants were engaged in resistance training and consumed a high-protein diet (i.e., ≥ 1.2 g/Kg/d). Subjects were assessed at baseline (Pre) and after 12 weeks (Post). Glomerular filtration rate was measured by 51Cr-EDTA clearance. Additionally, blood samples and a 24-h urine collection were obtained for other kidney function assessments. RESULTS: No significant differences were observed for 51Cr-EDTA clearance throughout the trial (Creatine: Pre 101.42 ± 13.11, Post 108.78 ± 14.41 mL/min/1.73m2; Placebo: Pre 103.29 ± 17.64, Post 106.68 ± 16.05 mL/min/1.73m2; group x time interaction: F = 0.21, p = 0.64). Creatinine clearance, serum and urinary urea, electrolytes, proteinuria, and albuminuria remained virtually unchanged. CONCLUSIONS: A 12-week creatine supplementation protocol did not affect kidney function in resistance-trained healthy individuals consuming a high-protein diet; thus reinforcing the safety of this dietary supplement. TRIAL REGISTRATION: ClinicalTrials.gov NCT01817673.
RESUMO
The colonic epithelial cells represent a border between the colon luminal content, containing notably bacteria and a complex mixture of compounds, and the"milieu interieur"as defined by the French physiologist Claude Bernard.The physical-chemical composition of the luminal content, including luminal pH and bacterial metabolite, that obviousl y is not constant, is modified for instance according to the diet. Data obtained recently indicate that physical exercise may also modify the colonic luminal content. Evidence has indicated that modification of the luminal content characteristics has, indeed, consequences for the colonic epithelial cells, notably in terms of energy metabolism and DNA integrity. Although such alterations impact presumably the homeostatic process of the colonic epithelium renewal and the epithelial barrier function, their contribution to pathological processes like mucosal inflammation, pre-neoplasia, and neoplasia remains partly elusive. Open questions remain regarding the individual and collective roles of luminal changes, particularly in a long-term perspective. These questions are related particularly to the capacity of the bacterial metabolites to cross the mucus layer before entering the colonocytes, to the concentrations of metabolites in proximity of the colonic crypt stem cells, and to the capacity of colonocytes to detoxicate deleterious compounds, to take up and utilize beneficial compounds.
Assuntos
Humanos , Masculino , Feminino , Colo/anatomia & histologia , Colo/fisiopatologia , Microbioma Gastrointestinal/fisiologia , Proteínas Alimentares , Exercício FísicoRESUMO
INTRODUCTION: Recent evidence has suggested that creatine supplementation (Cr) can increase the bone mineral density (BMD) of the femur in healthy growing rats. Nevertheless, studies assessing the efficacy of the Cr supplementation in conditions characterized by bone mass loss are scarce. OBJECTIVE: To investigate the effect of Cr supplementation on BMD and bone mineral content (BMC) in spontaneously hypertensive rats (SHRs), an experimental model of osteoporosis. MATERIALS AND METHODS: Sixteen 8-month-old male SHRs were randomly allocated into two groups matched by body weight: 1) Pl group: SHRs treated with placebo (distilled water; n = 8); and 2) Cr group: SHRs treated with Cr (n = 8). After nine weeks of supplementation, the animals were euthanized and their femur and spine (L1-L4) were analyzed by use of densitometry (Dual Energy X-Ray Absorptiometry). RESULTS: No significant difference was observed between the groups regarding either the spine or the total femur measures as follows: spine - BMD (Pl = 0.249 ± 0.003 g/cm² vs. Cr = 0.249 ± 0.004 g/cm²; P = 0.95) and BMC (Pl = 0.509 ± 0.150 g vs. Cr = 0.509 ± 0.017 g; P > 0.99); and total femur - BMD (Pl = 0.210 ± 0.004 g/cm² vs. Cr = 0.206 ± 0.004 g/cm²; P > 0.49) and BMC (Pl = 0.407 ± 0.021 g vs. Cr = 0.385 ± 0.021 g; P > 0.46). CONCLUSION: In this study, using the experimental model of osteoporosis, Cr supplementation had no effect on bone mass.
Assuntos
Densidade Óssea/efeitos dos fármacos , Creatina/farmacologia , Animais , Masculino , Ratos , Ratos Endogâmicos SHRRESUMO
Sarcopenia is defined as a multifactor syndrome that induces age-related loss of skeletal muscle mass. The causes of sarcopenia include altered endocrine function, inflammation, disuse, insulin resistance, chronic diseases, and protein-energy deficiency. Different strategies are under investigation to counteract this loss and promote muscle anabolism in the elderly population, including increased intake of protein and amino acids. Objective: The purpose of present review is to compare and analyze studies related to muscle preservation or gain and the supplementation of whey or soy protein isolates in elderly healthy subjects. Data source: The present review analyzed original articles published in English between 2005 and 2013 tracked by the following key words: whey protein, soy protein, aging, elderly, supplementation, sarcopenia, and muscle wasting. Data synthesis: The content of essential amino acids in milk proteins has been described to be significantly higher than in soy proteins. Soy protein supplementation causeshigher liver deamination and nitrogen retention in the splanchnic tissue, causing weaker synthesis signaling in the muscle tissue. Conclusion: Supplementation with protein and amino acids may be beneficial; however, more studies are needed to establish proper type, dose and distribution, and to quantify improvement in the muscle function and quality of life in the elderly population.
A sarcopenia é uma síndrome complexa, relativa à idade e, em última instância, resulta em perda de massa muscular. Suas causas são multifatoriais e podem incluir alterações endócrinas, inflamações, desuso, resistência à insulina, doenças crônicas e deficiências nutricionais, em especial deficiência proteico-calórica. Diversas estratégias têm sido propostas a fim de preservar ou promover ganho de massa muscular do idoso, comoaumento da ingestão de proteína, aminoácidos essenciais associadas ou não à prática regular de exercício físico. Objetivo: A presente revisão tem como objetivo analisar estudos com a suplementação de proteína derivada da soja ou do leite, com relação ao ganho de massa muscular em idosos saudáveis. Fonte de dados: Foram utilizados artigos originais em inglês, realizados entre os anos 2005 e 2013. O critério para seleção dos artigos foram as palavras-chave: whey protein, soy protein, aging, elderly, supplementation,sarcopenia, muscle wasting. Síntese dos dados: A quantidade de aminoácidos essenciais encontrada na proteína derivada do leite é maior que na proteína derivada da soja. A desaminação de aminoácidos pelo fígado e retenção de nitrogênio no pool de aminoácidos esplâncnicos é maior com a suplementação de proteína de soja, causando assim menorsinalização anabólica no músculo esquelético. Conclusão: A suplementação de proteína e aminoácidos parece ser benéfica, porém mais estudos são necessários a fim de se estabelecer o melhor tipo, dose e distribuição, além de quantificar a real melhora na qualidade de vida de idosos sarcopênicos.
Assuntos
Idoso , Fenômenos Fisiológicos da Nutrição do Lactente , Envelhecimento/fisiologia , Sarcopenia/classificaçãoRESUMO
Abstract Currently, there has been new expectations in studying strategies with the potential to mitigate the skeletal muscle atrophy that characterizes conditions such as aging, disuse, cancer, and the use of certain medications. Among them, amino acid leucine has received special attention due to its potential to stimulate specific pathways of protein synthesis in skeletal muscle. Due to the wide spread use of this amino acid by the media, several studies have been aimed at investigating the possible effectiveness of leucine against skeletal muscle atrophy. As a result, this literature review was aimed to analyze recent studies that investigated the effects of leucine supplementation on skeletal muscle atrophy in both humans and animals. Overall, the wide variations in the experimental designs developed, models studied, leucine dose, treatment duration and sample healthiness make it difficult for professionals and researchers to establish guidelines about possible therapeutic effectiveness of this nutritional strategy.
Resumo Atualmente, surgem novas expectativas em estudar estratégias com o potencial de atenuar a atrofia muscular esquelética que caracteriza condições como o envelhecimento, o desuso, o câncer, assim como o uso de determinadas medicações. Dentre elas, o aminoácido leucina vem recebendo especial destaque devido ao seu potencial em estimular vias específicas de síntese proteica no músculo esquelético. Devido à grande disseminação do uso deste aminoácido pela mídia, diversas pesquisas vêm sendo desenvolvidas com foco na investigação de possível efetividade da leucina contra a atrofia muscular esquelética. Em virtude disso, essa revisão bibliográfica teve por objetivo analisar os estudos recentes que investigaram os efeitos da suplementação isolada de leucina sobre a atrofia muscular, tanto em humanos quanto em animais. De forma geral, as grandes variações nos desenhos experimentais desenvolvidos, nos modelos estudados, na dose de leucina empregada, na duração do protocolo de suplementação e na saudabilidade da amostra, fazem com que profissionais da área e pesquisadores sofram em poder estabelecer maiores diretrizes acerca da possível eficácia terapêutica desta estratégia nutricional.
RESUMO
Fatores que melhoram as adaptações ao treino de força, especialmente os nutricionais, têm sido alvo de interesse de praticantes de treino de força. Devido aos já conhecidos mecanismos de ação da cafeína, pesquisas vêm sendo desenvolvidas com o intuito de investigar o potencial ergogênico da cafeína sobre o desempenho de força. Tais estudos, entretanto, são escassos, e seus resultados, controversos. Assim, o objetivo desta revisão foi trazer à tona os potenciais mecanismos de ação pelos quais a cafeína poderia exercer seu efeito ergogênico sobre o desempenho de força, avaliando o possível papel ergogênico da suplementação de cafeína sobre esta atividade. De forma geral, devido à grande heterogeneidade existente nos desenhos experimentais, ao variado nível de habituação ao consumo de cafeína, às divergências dos testes físicos empregados e na dieta precedente ao teste físico, não podemos atestar a favor da eficácia ergogênica deste suplemento nutricional sobre o desempenho de força.
Factors that improve the adaptations to strength training, especially the nutritional, have been the subject of interest from individuals practicing strength training. Due to known mechanisms of action of caffeine, studies have been undertaken in order to investigate the ergogenic potential of caffeine on strength performance. Such studies, however, are scarce, and their results controversial. Thus, the aim of this review was to bring out the potential mechanisms of action by which caffeine could exert its ergogenic effect on strength performance, evaluating the possible ergogenic role of caffeine on this activity. In general, due to the heterogeneity in experimental designs, to the varied level of habituation to the consumption of caffeine, to the differences in the physical test employed and diet preceding the physical test, we cannot attest the ergogenic effectiveness of this nutritional supplement on strength performance.
RESUMO
Durante anos, pesquisadores inseridos na área de fisiologia do exercício apontaram para o lactato como o principal causador da fadiga durante exercícios de alta intensidade. Hoje, por outro lado, já existem diversos estudos demonstrando que o lactato per se não possui qualquer efeito sobre a fadiga neste tipo de exercício, mas que a acidose muscular, ocasionada pelo acúmulo de íons hidrogênio no interior da célula muscular, seria o fator limitante para o desempenho físico durante exercícios físicos de alta intensidade. Assim, estratégias com o objetivo de atenuar a queda do pH intramuscular, como a suplementação de beta-alanina e bicarbonato de sódio, têm se destacado no cenário esportivo. Embora anteriormente destacado como vilão durante esforços intensos, a suplementação de lactato vem recebendo especial atenção em anos recentes. A suplementação com este composto teoricamente pode aumentar os níveis sanguíneos de pH e bicarbonato, aumentando a capacidade de tamponamento extracelular, e por consequência, o desempenho físico. A suplementação com lactato também pode aumentar os níveis sanguíneos deste composto, aumentando sua disponibilidade como substrato para a gliconeogênese. Assim, estudos tem surgido com o intuito de avaliar a eficácia do lactato como tamponante e como substrato energético. Os poucos estudos até agora conduzidos, entretanto, não nos permitem atestar a eficácia ergogênica desta estratégia nutricional. A falta de estudos dose-resposta sobre as variáveis sanguíneas que caracterizam o mecanismo de ação do lactato, bem como de aplicação de testes físicos com baixo coeficiente de variação e boa validade externa exemplificam a necessidade de mais estudos investigando a eficácia ergogênica desta estratégia nutricional.
For years, researchers from the exercise physiology field pointed to lactate as the main cause of fatigue during high-intensity exercises. Today, however, there are several studies demonstrating that lactate per se does not have any effect on fatigue during this type of exercise, but muscle acidosis occasioned by hydrogen ions accumulation inside the muscle cell would be the limiting factor for performance during high-intensity exercises. Therefore strategies aiming to attenuate the decrease of intramuscular pH levels, like beta-alanine and sodium bicarbonate supplementation, have been prominent in the sports scenario. Although previously highlighted as a villain during high-intensity exercises, lactate supplementation has received special attention in recent years. Supplementation with this compound can theoretically increase blood pH and bicarbonate levels, increasing the extracellular buffering capacity, and hence, performance. Lactate supplementation can also increase lactate blood levels, increasing its availability as a substrate for gluconeogenesis. Thus, studies have arisen aiming to assess the effectiveness of lactate as a buffering agent and as an energy substrate. The few studies so far conducted, however, do not allow us to attest the ergogenic effectiveness of this nutritional strategy. The lack of dose-response studies on blood variables that characterize lactate mechanism of action, as well as the application of physical tests with a low coefficient of variation and good external validity exemplifies the need for further studies investigating the ergogenic effectiveness of this nutritional strategy.