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Hypoxia and exercise interactions on skeletal muscle insulin sensitivity in obese subjects with metabolic syndrome: results of a randomized controlled trial.
Mai, K, Klug, L, Rakova, N, Piper, SK, Mähler, A, Bobbert, T, Schulz-Menger, J, Spranger, J, Boschmann, M, Luft, FC
International journal of obesity (2005). 2020;(5):1119-1128
Abstract
BACKGROUND Physical activity improves insulin sensitivity in obesity. Hypoxia training is claimed to augment this effect. We tested the hypothesis that normobaric hypoxia training would improve insulin sensitivity in obese patients with metabolic syndrome. METHODS In a randomized controlled trial, 23 obese men with metabolic syndrome who were not informed of the FiO2 conditions underwent a 6-week physical exercise intervention under ambient (n = 11; FiO2 21%) conditions or hypoxia (n = 12; FiO2 15%) using a normobaric hypoxic chamber. Three 60-min sessions of interval training were performed each week at 60% of individual V̇O2max. Assessment of myocellular insulin sensitivity by euglycemic hyperinsulinemic clamp was performed in 21 of these subjects before and after 6 weeks of training. Comprehensive phenotyping also included biopsies of subcutaneous adipose tissues. RESULTS The intermittent moderate physical exercise protocol did not substantially change the myocellular insulin sensitivity within 6 weeks under normoxic conditions (ISIClamp: 0.035 (IQR 0.016-0.075) vs. 0.037 (IQR 0.026-0.056) mg* kg-1 *min-1/(mU* l-1); p = 0.767). In contrast, ISIClamp improved during hypoxia training (0.028 (IQR 0.018-0.035) vs. 0.038 (IQR 0.024-0.060) mg * kg-1 *min-1/(mU *l-1); p < 0.05). Between group comparison of ISIClamp change revealed a small difference between groups (Cohen's d = 0.26). Within the hypoxic group, improvement of ISIClamp during training was associated with individual increase of circulating vascular endothelial growth factor (VEGF) levels (r = 0.678, p = 0.015), even if mean VEGF levels were not modified by any training condition. Atrial natriuretic peptide (ANP) system components were not associated with increased ISIClamp during hypoxic training. CONCLUSIONS Physical training under hypoxic conditions could partially augment the favorable effects of exercise alone on myocellular insulin sensitivity in obese men with metabolic syndrome. Concomitant changes in VEGF might represent an underlying pathophysiological mechanism.
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Muscular Fitness and Cardiovascular Risk Factors in Children and Adolescents: A Systematic Review.
Rodrigues de Lima, T, Custódio Martins, P, Henrique Guerra, P, Augusto Santos Silva, D
Journal of strength and conditioning research. 2020;(8):2394-2406
Abstract
Rodrigues de Lima, T, Custódio Martins, P, Henrique Guerra, P, and Augusto Santos Silva, D. Muscular fitness and cardiovascular risk factors in children and adolescents: A systematic review. J Strength Cond Res 34(8): 2394-2406, 2020-The purpose of this study was to identify and summarize the relationships between muscular fitness (MF) and individual components of metabolic syndrome (high waist circumference [WC], high blood pressure [BP], high systolic BP [SBP], high diastolic BP [DBP], high triglycerides [TG], fasting blood glucose [FG], and low HDL cholesterol levels [HDL-C]) in children and adolescents. A systematic review was conducted in 5 electronic databases, with complementary searches in reference lists, and the inclusion criteria were children and adolescents (age group up to 19 years of age) with no special clinical conditions. In all articles, risk of bias was analyzed by a standardized instrument. Of the 5,973 articles initially identified, 21 were included, with data on 22,261 children and adolescents. Higher MF values were associated with lower TG (n = 07) and WC values (n = 15). Different results in relation to the relationship between MF and SBP (n = 10) and MF and DBP (n = 07) were verified. In addition, there was no relationship between MF and FG (n = 06). In addition, inconclusive results were verified in the relationship between MF and HDL-C (n = 07). Concluded higher MF values were related to lower WC values and lower TG concentrations.
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Sympathetic Neural Overdrive in the Obese and Overweight State.
Grassi, G, Biffi, A, Seravalle, G, Trevano, FQ, Dell'Oro, R, Corrao, G, Mancia, G
Hypertension (Dallas, Tex. : 1979). 2019;(2):349-358
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Abstract
Nerve traffic recordings (muscle sympathetic nerve traffic [MSNA]) have shown that sympathetic activation may occur in obesity. However, the small sample size of the available studies, presence of comorbidities, heterogeneity of the subjects examined represented major weaknesses not allowing to draw definite conclusions. This is the case for the overweight state. The present meta-analysis evaluated 1438 obese or overweight subjects recruited in 45 microneurographic studies. The analysis was primarily based on MSNA quantification in obesity and overweight, excluding as concomitant conditions hypertension, metabolic syndrome, and other comorbidities. Assessment was extended to the relationships of MSNA with other neuroadrenergic markers, such as plasma norepinephrine and heart rate, anthropometric variables, as body mass index, waist-to-hip ratio, presence/absence of obstructive sleep apnea, and metabolic profile. Compared with normoweights MSNA was significantly greater in overweight and more in obese individuals (37.0±4.1 versus 43.2±3.5 and 50.4±5.0 burts/100 heartbeats, P<0.01). This was the case even in the absence of obstructive sleep apnea. MSNA was significantly directly related to body mass index and waist-to-hip ratio ( r=0.41 and r=0.64, P<0.04 and <0.01, respectively), clinic blood pressure ( r=0.68, P<0.01), total cholesterol, LDL (low-density lipoprotein) cholesterol, and triglycerides ( r=0.91, r=0.94, and r=0.80, respectively, P<0.01) but unrelated to plasma insulin, glucose, and homeostatic model assessment for insulin resistance. No significant correlation was found between MSNA, heart rate, and norepinephrine. Thus, obesity and overweight are characterized by sympathetic overactivity which mirrors the severity of the clinical condition and reflects metabolic alterations, with the exclusion of glucose/insulin profile. Neither heart rate nor norepinephrine appear to represent faithful markers of the muscle sympathetic overdrive.
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Ghrelin forms in the modulation of energy balance and metabolism.
Gortan Cappellari, G, Barazzoni, R
Eating and weight disorders : EWD. 2019;(6):997-1013
Abstract
Ghrelin is a gastric hormone circulating in acylated (AG) and unacylated (UnAG) forms. This narrative review aims at presenting current emerging knowledge on the impact of ghrelin forms on energy balance and metabolism. AG represents ~ 10% of total plasma ghrelin, has an appetite-stimulating effect and is the only form for which a receptor has been identified. Moreover, other metabolic AG-induced effects have been reported, including the modulation of glucose homeostasis with stimulation of liver gluconeogenesis, the increase of fat mass and the improvement of skeletal muscle mitochondrial function. On the other hand, UnAG has no orexigenic effects, however recent reports have shown that it is directly involved in the modulation of skeletal muscle energy metabolism by improving a cluster of interlinked functions including mitochondrial redox activities, tissue inflammation and insulin signalling and action. These findings are in agreement with human studies which show that UnAG circulating levels are positively associated with insulin sensitivity both in metabolic syndrome patients and in a large cohort from the general population. Moreover, ghrelin acylation is regulated by a nutrient sensor mechanism, specifically set on fatty acids availability. These recent findings consistently point towards a novel independent role of UnAG as a regulator of muscle metabolic pathways maintaining energy status and tissue anabolism. While a specific receptor for UnAG still needs to be identified, recent evidence strongly supports the hypothesis that the modulation of ghrelin-related molecular pathways, including those involved in its acylation, may be a potential novel target in the treatment of metabolic derangements in disease states characterized by metabolic and nutritional complications.Level of evidence Level V, narrative review.
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Modulating Metabolism to Improve Cancer-Induced Muscle Wasting.
Penna, F, Ballarò, R, Beltrá, M, De Lucia, S, Costelli, P
Oxidative medicine and cellular longevity. 2018;:7153610
Abstract
Muscle wasting is one of the main features of cancer cachexia, a multifactorial syndrome frequently occurring in oncologic patients. The onset of cachexia is associated with reduced tolerance and response to antineoplastic treatments, eventually leading to clinical conditions that are not compatible with survival. Among the mechanisms underlying cachexia, protein and energy dysmetabolism play a major role. In this regard, several potential treatments have been proposed, mainly on the basis of promising results obtained in preclinical models. However, at present, no treatment yet reached validation to be used in the clinical practice, although several drugs are currently tested in clinical trials for their ability to improve muscle metabolism in cancer patients. Along this line, the results obtained in both experimental and clinical studies clearly show that cachexia can be effectively approached by a multidirectional strategy targeting nutrition, inflammation, catabolism, and inactivity at the same time. In the present study, approaches aimed to modulate muscle metabolism in cachexia will be reviewed.
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Irisin Serum Levels in Metabolic Syndrome Patients Treated with Three Different Diets: A Post-Hoc Analysis from a Randomized Controlled Clinical Trial.
Osella, AR, Colaianni, G, Correale, M, Pesole, PL, Bruno, I, Buongiorno, C, Deflorio, V, Leone, CM, Colucci, SC, Grano, M, et al
Nutrients. 2018;(7)
Abstract
BACKGROUND Irisin, a hormone-like myokine, regulates energy homeostasis and mediates the benefits of physical activity on health. METHODS To estimate the effect of different diets on irisin concentrations in subjects with the Metabolic Syndrome (MetS). METHODS Subjects with MetS were derived from a population survey; 163 subjects were enrolled and randomized to a: Low Glycaemic Index (LGID), Mediterranean (MD) or Low Glycaemic Index Mediterranean (LGIMD) Diet, and the groups were compared, also with 80 controls without MetS. Sociodemographic, medical and nutritional data were collected and fasting blood samples drawn. Subjects underwent LUS and bioimpedentiometry. Generalized Estimating Equations were performed. RESULTS At baseline, lower irisin concentrations were observed in MetS subjects. Mean irisin levels increased in all diet groups but only the LGID group reached statistical significance, as well as showing an interaction between LGID and time at the sixth month examination (4.57, 95% CI −1.27, 7.87). There was a positive effect of Vegetable Proteins (0.03, 95% CI −0.01,0.06) and Saturated Fatty Acids (0.04, 95% CI 0.01, 0.07) on irisin concentrations. In the LGIMD, a positive effect on Fat-Free Mass (0.38, 95% CI 0.19, 0.57) and a negative effect on the Body Mass Index (−0.75, 95% CI −1.30, −0.19) were observed. CONCLUSIONS There seems to be a link between diet and muscle physiology. We showed that patients following a LGID had higher levels of irisin, a promising biomarker of muscle activity.