RESUMO
The aim of this research was to investigate the existence of associations between habitual physical activity and cardiovascular risk in people living with HIV; and to identify self-perceived barriers to physical activity. The sample of 104 subjects was composed of people living with HIV and treatment for at least 6 months in a Specialized Care Service. Baeck's survey, a self-perceived barrier questionnaire, medical records, and equations from Framingham's Cardiovascular Disease were used. Linear regression models were used to investigate the association between Habitual Physical Activity score (HPA) and predicted cardiovascular risk, and descriptive statistics to investigate prevalence of self-perceived barriers. In the first model (r² = 0.212, F = 4.34, p < 0.001), increasing 1 point in the HPA score predicts the decrease by 1.04 percentage points (p.p.) Cardiovascular risk for the next 10 years. In the second model (r2 = 0. 244, F = 4. 99, p < 0.001), increase one point the HPA score decreases by 3.729 p.p. Predicted cardiovascular risk for the next 30 years. The results confirmed an inverse association between HPA and predicted cardiovascular risk in PLHIV.
Assuntos
Doenças Cardiovasculares , Infecções por HIV , Humanos , Doenças Cardiovasculares/epidemiologia , Infecções por HIV/epidemiologia , Fatores de Risco , Brasil/epidemiologia , Exercício Físico , Fatores de Risco de Doenças CardíacasRESUMO
Branched-chain amino acids (BCAA) (especially leucine) have been shown to activate protein synthesis pathways, decrease proteolysis and increase insulin sensitivity. Furthermore, it appears that leucine can be used as a nutritional therapy to avoid sarcopenia and skeletal muscle atrophy due to immobilization or glucocorticoid treatment. However, it is of note that all of these conditions are related to insulin resistance to varying degrees and affect different tissues, particularly skeletal muscle. Additionally, evidence from recent studies demonstrate that a combination of protein containing high levels of leucine with nutrients containing saturated fatty acids or an excess of leucine are capable of inducing insulin resistance. From this discussion, a few major questions arise. First, what is the role of a combination of macronutrients in inducing insulin resistance? Second, in insulin resistance, does leucine supplementation follow the same path observed under healthy conditions? Finally, what are the dose-dependent outcome and the latency of leucine effect under such conditions? The present article discusses these questions based on data from the literature and experiments performed by our group.
Assuntos
Glucose/metabolismo , Homeostase , Leucina/metabolismo , Dexametasona/administração & dosagem , Proteínas Alimentares/administração & dosagem , Humanos , Resistência à Insulina , Modelos TeóricosRESUMO
Physical inactivity leads to the accumulation of visceral fat and, consequently, to the activation of a network of inflammatory pathways which may promote development of insulin resistance, atherosclerosis, neurodegeneration, and tumour growth. These conditions belong to the "diseasome of physical inactivity". In contrast, the protective effect of regular exercise against diseases associated with chronic inflammation may to some extent be ascribed to an anti-inflammatory effect. The so called "acute exercise threshold", the complex mixture of several variables involved in exercise, such as type, volume, frequency, and intensity range is capable of inducing positive physiological adaptations and has been specifically addressed in the recent literature. The major concern is related to the level of the threshold: "exercise training shifts from a therapeutic adaptive intervention to one with potential pathological consequences". Nonetheless, if the mechanical stimulus is too weak to disrupt cellular homeostasis, training adaptations will not occur. Answering these questions could present practical applications, especially during inflammatory diseases associated with detrimental muscle effects and could theoretically constitute a "new" therapeutic approach to treat/improve an inflammatory state. This paper aims to describe specific data from the literature regarding the effects of exercise on inflammatory diseases in order to promote a more sophisticated perspective on the anti-inflammatory effects of exercise.
Assuntos
Terapia por Exercício/métodos , Exercício Físico , Contração Muscular/imunologia , Músculo Esquelético/fisiopatologia , Miosite/imunologia , Miosite/prevenção & controle , Humanos , Modelos ImunológicosRESUMO
This study focused on understanding the signaling mechanisms leading to GLUT-4 translocation and increased skeletal-muscle glucose uptake that follow creatine (Cr) supplementation in type 2 diabetes (n = 10). AMPK-α protein content presented a tendency to be higher (p = 0.06) after Cr supplementation (5 g/d for 12w). The changes in AMPK-α protein content significantly related (p < 0.001) to the changes in GLUT-4 translocation (r = 0.78) and Hb1Ac levels (r = -0.68), suggesting that AMPK signaling may be implicated in the effects of supplementation on glucose uptake in type 2 diabetes.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Creatina/farmacologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Glucose/metabolismo , Músculo Esquelético/efeitos dos fármacos , Proteínas Quinases Ativadas por AMP/genética , Antígenos CD/genética , Antígenos CD/metabolismo , Biópsia , Creatina/uso terapêutico , Diabetes Mellitus Tipo 2/metabolismo , Método Duplo-Cego , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Músculo Esquelético/metabolismo , Transporte Proteico/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Dexamethasone (DEXA) is a potent immunosupressant and anti-inflammatory agent whose main side effects are muscle atrophy and insulin resistance in skeletal muscles. In this context, leucine supplementation may represent a way to limit the DEXA side effects. In this study, we have investigated the effects of a low and a high dose of leucine supplementation (via a bolus) on glucose homeostasis, muscle mass and muscle strength in energy-restricted and DEXA-treated rats. Since the leucine response may also be linked to the administration of this amino acid, we performed a second set of experiments with leucine given in bolus (via gavage) versus leucine given via drinking water. Leucine supplementation was found to produce positive effects (e.g., reduced insulin levels) only when administrated in low dosage, both via the bolus or via drinking water. However, under DEXA treatment, leucine administration was found to significantly influence this response, since leucine supplementation via drinking water clearly induced a diabetic state, whereas the same effect was not observed when supplied via the gavage.
Assuntos
Glicemia/metabolismo , Dexametasona/efeitos adversos , Glucocorticoides/efeitos adversos , Resistência à Insulina , Insulina/sangue , Leucina/administração & dosagem , Músculo Esquelético/efeitos dos fármacos , Animais , Suplementos Nutricionais , Relação Dose-Resposta a Droga , Vias de Administração de Medicamentos , Homeostase/efeitos dos fármacos , Leucina/farmacologia , Leucina/uso terapêutico , Masculino , Força Muscular/efeitos dos fármacos , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Atrofia Muscular/induzido quimicamente , Atrofia Muscular/tratamento farmacológico , Ratos , Ratos WistarRESUMO
Amino acids such as leucine and its metabolite α-ketoisocaproate (KIC), are returning to be the focus of studies, mainly because of their anti-catabolic properties, through inhibition of muscle proteolysis and enhancement of protein synthesis. It is clear that these effects may counteract catabolic conditions, as well as enhance skeletal muscle mass and strength in athletes. Moreover, beta-hydroxy-beta-methylbutyrate (HMB) has been shown to produce an important effect in reducing muscle damage induced by mechanical stimuli of skeletal muscle. This review aims to describe the general scientific evidence of KIC and HMB supplementation clinical relevance, as well as their effects (e.g., increases in skeletal muscle mass and/or strength), associated with resistance training or other sports. Moreover, the possible mechanisms of cell signaling regulation leading to increases and/or sparing (during catabolic conditions) of skeletal muscle mass are discussed in detail based on the recent literature.
Assuntos
Cetoácidos/administração & dosagem , Leucina/administração & dosagem , Força Muscular/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Valeratos/administração & dosagem , Administração Oral , Adulto , Desempenho Atlético , Composição Corporal , Suplementos Nutricionais , Humanos , Cetoácidos/metabolismo , Leucina/metabolismo , Masculino , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Treinamento Resistido , Transdução de Sinais/efeitos dos fármacos , Valeratos/metabolismoRESUMO
Skeletal muscle is the source of pro- and anti-inflammatory cytokines, and recently, it has been recognized as an important source of interleukin 6 (IL-6), a cytokine that exerts inhibitory effects on several pro-inflammatory cytokines. Although dynamic chronic resistance training has been shown to produce the known "repeated bout effect", which abolishes the acute muscle damage, performing of high-intensity resistance training has been regarded highly advisable, at least from the hypertrophy perspective. On the other hand, a more therapeutic, "non-damaging" resistance training program, mainly composed of concentric forces, low frequency/low volume of training, and the same exercise, could theoretically benefit the muscle when the main issue is to avoid muscle inflammation (as in the treatment of several "low-grade" inflammatory diseases) because the acute effect of each resistance exercise session could be diminished/avoided, at the same time that the muscle is still being overloaded in a concentric manner. However, the benefits of such "less demanding" resistance training schedule on the muscle inflammatory profile have never been investigated. Therefore, we assessed the protein expression of IL-6, TNF-alpha, IL-10, IL-10/TNF-alpha ratio, and HSP70 levels and mRNA expression of SCF(beta-TrCP), IL-15, and TLR-4 in the skeletal muscle of rats submitted to resistance training. Briefly, animals were randomly assigned to either a control group (S, n = 8) or a resistance-trained group (T, n = 7). Trained rats were exercised over a duration of 12 weeks (two times per day, two times per week). Detection of IL-6, TNF-alpha, IL-10, and HSP70 protein expression was carried out by western blotting and SCF(beta-TrCP) (SKP Cullin F-Box Protein Ligases), a class of enzymes involved in the ubiquitination of protein substrates to proteasomal degradation, IL-15, and TLR-4 by RT-PCR. Our results show a decreased expression of TNF-alpha and TLR4 mRNA (40 and 60%, respectively; p < 0.05) in the plantar muscle from trained, when compared with control rats. In conclusion, exercise training induced decreased TNF-alpha and TLR-4 expressions, resulting in a modified IL-10/TNF-alpha ratio in the skeletal muscle. These data show that, in healthy rats, 12-week resistance training, predominantly composed of concentric stimuli and low frequency/low volume schedule, down regulates skeletal muscle production of cytokines involved in the onset, maintenance, and regulation of inflammation.
Assuntos
Citocinas/imunologia , Músculo Esquelético/fisiopatologia , Miosite/imunologia , Miosite/prevenção & controle , Condicionamento Físico Animal/métodos , Receptor 4 Toll-Like/imunologia , Animais , Feminino , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptor 4 Toll-Like/genéticaRESUMO
Long-term adaptation to resistance training is probably due to the cumulative molecular effects of each exercise session. Therefore, we studied in female Wistar rats the molecular effects of a chronic resistance training regimen (3 months) leading to skeletal muscle hypertrophy in the plantaris muscle. Our results demonstrated that muscle proteolytic genes MuRF-1 and Atrogin-1 were significantly decreased in the exercised group measured 24 h after the last resistance exercise session (41.64 and 61.19%, respectively; P < 0.05). Nonetheless, when measured at the same time point, 4EBP-1, GSK-3beta and eIF2Bepsilon mRNA levels and Akt, GSK-3beta and p70S6K protein levels (regulators of translation initiation) were not modified. Such data suggests that if gene transcription constitutes a control point in the protein synthesis pathway this regulation probably occurs in early adaptation periods or during extreme situations leading to skeletal muscle remodeling. However, proteolytic gene expression is modified even after a prolonged resistance training regimen leading to moderate skeletal muscle hypertrophy.