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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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Gluteus medius muscle function in people with and without low back pain: a systematic review.
Sadler, S, Cassidy, S, Peterson, B, Spink, M, Chuter, V
BMC musculoskeletal disorders. 2019;(1):463
Abstract
INTRODUCTION Globally, low back pain (LBP) is one of the greatest causes of disability. In people with LBP, dysfunction of muscles such as the gluteus medius have been demonstrated to increase spinal loading and reduce spinal stability. Differences in gluteus medius function have been reported in those with LBP compared to those without, although this has only been reported in individual studies. The aim of this systematic review was to determine if adults with a history, or current LBP, demonstrate differences in measures of gluteus medius function when compared to adults without LBP. METHODS MEDLINE, EMBASE, AMED, PsycINFO, PubMED, Pro Quest Database, CINAHL and SPORTDiscus were searched from inception until December 2018 for published journal articles and conference abstracts. No language restrictions were applied. Only case-control studies with participants 18 years and over were included. Participants could have had any type and duration of LBP. Studies could have assessed gluteus medius function with any quantifiable clinical assessment or measurement tool, with the participant non-weight bearing or weight bearing, and during static or dynamic activity. Quality appraisal and data extraction were independently performed by two authors. RESULTS The 24 included articles involved 1088 participants with LBP and 998 without LBP. The gluteus medius muscle in participants with LBP tended to demonstrate reduced strength and more trigger points compared to the gluteus medius muscle of those without LBP. The level of activity, fatigability, time to activate, time to peak activation, cross sectional area, and muscle thickness showed unclear results. Meta-analysis was not performed due to the heterogeneity of included studies. CONCLUSION Clinically, the findings from this systematic review should be considered when assessing and managing patients with LBP. Future studies that clearly define the type and duration of LBP, and prospectively assess gluteus medius muscle function in those with and without LBP are needed. TRIAL REGISTRATION PROSPERO ( CRD42017076773 ).
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Effects of cholecalciferol supplementation on inflammatory markers and muscle damage indices of soccer players after a simulated soccer match.
Parsaie, N, Ghavamzadeh, S, Cheraghi, M
Nutrition (Burbank, Los Angeles County, Calif.). 2019;:37-43
Abstract
OBJECTIVES Soccer-induced muscle damage and inflammation lead to a reduction in athletic performance. The aim of this study was to determine whether supplementation with cholecalciferol would reduce inflammation and muscle damage in soccer players after a simulated soccer match. METHODS Twenty-two soccer players (median age 27 y, interquartile range 5 y) were divided randomly into two groups, as follows: a cholecalciferol group (n = 11) and a placebo group (n = 11). Cholecalciferol supplements (50 000 IU/wk) or placebos were administered to the groups by an independent co-worker. After 8 wk, the athletes participated in a simulated soccer match, and perceived exertion and heart rates were measured during the trial. Blood samples were obtained presupplementation, postsupplementation, immediately after, and 2- and 24-h postexercise for measurement of lactate dehydrogenase, creatine phosphokinase, C-reactive protein (CRP), and interleukin (IL)-6. RESULTS The intervention group demonstrated a significant increase in serum 25-hydroxyvitamin D levels (53.93, 10.68 ng/mL, P < 0.0001), which is the best indicator of vitamin D levels in the body, with no change in the circulating markers of muscle damage and CRP (P ˃ 0.05) but showed increased IL-6 (P = 0.034). In addition, the ratings of perceived exertion and heart rates were not altered by vitamin D compared with placebo ingestion (P = 0.155 versus P = 0.261; P = 0.600 versus P = 0.983). CONCLUSION The study showed that 50 000 IU/wk of cholecalciferol supplementation for 8 wk increased the 25-hydroxyvitamin D levels, with no effect on muscle damage indices or CRP. However, The IL-6 concentration was generally higher in the intervention group.
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Exercise and immune system as modulators of intestinal microbiome: implications for the gut-muscle axis hypothesis.
Ticinesi, A, Lauretani, F, Tana, C, Nouvenne, A, Ridolo, E, Meschi, T
Exercise immunology review. 2019;:84-95
Abstract
Exercise is a possible modulator of intestinal microbiome composition, since some investigations have shown that it is associated with increased biodiversity and representation of taxa with beneficial metabolic functions. Conversely, training to exhaustion can be associated with dysbiosis of the intestinal microbiome, promoting inflammation and negative metabolic consequences. Gut microbiota can, in turn, influence the pathophysiology of several distant organs, including the skeletal muscle. A gut-muscle axis may in fact regulate muscle protein deposition and muscle function. In older individuals, this axis may be involved in the pathogenesis of muscle wasting disorders through multiple mechanisms, involving transduction of pro-anabolic stimuli from dietary nutrients, modulation of inflammation and insulin sensitivity. The immune system plays a fundamental role in these processes, being influenced by microbiome composition and at the same time contributing to shape microbial communities. In this review, we summarize the most recent literature acquisitions in this field, disentangling the complex relationships between exercise, microbiome, immune system and skeletal muscle function and proposing an interpretative framework that will need verification in future studies.
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Skeletal muscle mass in acute coronary syndrome prognosis: Gender-based analysis from Hellenic Heart Failure cohort.
Kouvari, M, Chrysohoou, C, Dilaveris, P, Georgiopoulos, G, Magkas, N, Aggelopoulos, P, Panagiotakos, DB, Tousoulis, D
Nutrition, metabolism, and cardiovascular diseases : NMCD. 2019;(7):718-727
Abstract
BACKGROUND AND AIMS Predictive and prognostic ability of muscle mass in CVD settings is increasingly discussed. The gender-specific effect of skeletal muscle mass index (SMI) on 10-year recurrent fatal/non fatal cardiovascular disease (CVD) event of acute coronary syndrome (ACS) patients was evaluated. METHODS AND RESULTS In 2006-2009, n = 1000 consecutive patients (n = 222 women), hospitalized at the First Cardiology Clinic of Athens with ACS diagnosis and with symptoms and left ventricular function indicative of heart failure were selected. SMI was created to reflect skeletal muscle mass through appendicular skeletal muscle mass (indirectly calculated through population formulas) divided by body mass index (BMI). In the 10-year follow-up (2016), 55% of ACS patients experienced recurrent fatal/non fatal CVD events (53% in women vs.62% in men, p = 0.04). Patients in the 2nd SMI tertile (mostly overweight) had 10% lower risk for CVD recurrence (women:men rate ratio = 0.87) over their counterparts in the 1st (mostly normalweight) and 3rd tertile (mostly obese). Multivariate analysis revealed that ACS patients in the 2nd SMI tertile presented 46% and 85% lower CVD event risk over their counterparts in the 1st tertile (Hazard Ratio (HR) = 0.54, 95% Confidence Interval (95% CI) 0.30, 0.96, p = 0.002) and 3rd tertile (HR = 1.85, 95%CI 1.05, 2.94, p = 0.03). Gender-based analysis revealed that this trend remained significant only in women. Inflammatory markers had strong confounding effect. CONCLUSION A U-shape association between SMI and 10-year CVD event especially in women was highlighted. This work reveals gender-specific remarks for "obesity-lean paradox" in secondary prevention, implying that high muscle mass accompanied by obesity and excess adiposity may not guarantee better prognosis.
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The Physiological Roles of Carnosine and β-Alanine in Exercising Human Skeletal Muscle.
Matthews, JJ, Artioli, GG, Turner, MD, Sale, C
Medicine and science in sports and exercise. 2019;(10):2098-2108
Abstract
Carnosine (β-alanyl-L-histidine) plays an important role in exercise performance and skeletal muscle homeostasis. Dietary supplementation with the rate-limiting precursor β-alanine leads to an increase in skeletal muscle carnosine content, which further potentiates its effects. There is significant interest in carnosine and β-alanine across athletic and clinical populations. Traditionally, attention has been given to performance outcomes with less focus on the underlying mechanism(s). Putative physiological roles in human skeletal muscle include acting as an intracellular pH buffer, modulating energy metabolism, regulating Ca handling and myofilament sensitivity, and scavenging of reactive species. Emerging evidence shows that carnosine could also act as a cytoplasmic Ca-H exchanger and form stable conjugates with exercise-induced reactive aldehydes. The enigmatic nature of carnosine means there is still much to learn regarding its actions and applications in exercise, health, and disease. In this review, we examine the research relating to each physiological role attributed to carnosine, and its precursor β-alanine, in exercising human skeletal muscle.
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Negligible Effects of β-Hydroxy-β-Methylbutyrate Free Acid and Calcium Salt on Strength and Hypertrophic Responses to Resistance Training: A Randomized, Placebo-Controlled Study.
Tritto, AC, Bueno, S, Rodrigues, RMP, Gualano, B, Roschel, H, Artioli, GG
International journal of sport nutrition and exercise metabolism. 2019;(5):505-511
Abstract
This study evaluated the effects of β-hydroxy-β-methylbutyrate free acid (HMB-FA) and calcium salt (HMB-Ca) on strength, hypertrophy, and markers of muscle damage. In this randomized, double-blind, placebo-controlled study, 44 resistance-trained men (age: 26 ± 4 years; body mass: 84.9 ± 12.0 kg) consuming ≥1.7 g·kg-1·day-1 of protein received HMB-FA (3 g/day; n = 14), HMB-Ca (3 g/day; n = 15), or placebo (PL; cornstarch, 3 g/day; n = 15) for 12 weeks, while performing a periodized resistance training program. Before and after intervention, lean body mass (measured with dual X-ray absorptiometry), maximal dynamic strength (one-repetition maximum), knee extension maximal isometric strength (maximal voluntary isometric contraction [MVIC]), cross-sectional area (measured with ultrasound), and muscle soreness were assessed. MVIC was also measured 48 hr after the first and the last training sessions. All groups increased lean body mass (main time effect: p < .0001; HMB-FA: 1.8 ± 1.8 kg; HMB-Ca: 0.8 ± 1.4 kg; PL: 0.9 ± 1.4 kg), cross-sectional area (main time effect: p < .0001; HMB-FA: 6.6 ± 3.8%; HMB-Ca: 4.7 ± 4.4%; PL: 6.9 ± 3.8%), one-repetition maximum bench press (main time effect: p < .0001; HMB-FA: 14.8 ± 8.4 kg; HMB-Ca: 11.8 ± 7.4 kg; PL: 11.2 ± 6.6 kg), MVIC (main time effect: p < .0001; HMB-FA: 34.4 ± 39.3%; HMB-Ca: 32.3 ± 27.4%; PL: 17.7 ± 20.9%) after the intervention, but no differences between groups were shown. HMB-FA group showed greater leg press strength after the intervention than HMB-Ca and PL groups (Group × Time interaction: p < .05; HMB-FA: 47.7 ± 31.2 kg; HMB-Ca: 43.8 ± 31.7 kg; PL: 30.2 ± 20.9 kg). MVIC measured 48 hr after the first and the last sessions showed no attenuation of force decline with supplementation. Muscle soreness following the first and last sessions was not different between groups. The authors concluded that neither HMB-Ca nor HMB-FA improved hypertrophy or reduced muscle damage in resistance-trained men undergoing resistance training ingesting optimal amounts of protein. HMB-FA but not HMB-Ca resulted in a statistically significant yet minor improvement on leg press one-repetition maximum.
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Regulation of Amino Acid Transporters and Sensors in Response to a High protein Diet: A Randomized Controlled Trial in Elderly Men.
Zeng, N, Prodhan, U, D'Souza, RF, Ramzan, F, Mitchell, SM, Sharma, P, Knowles, SO, Roy, NC, Sjödin, A, Wagner, KH, et al
The journal of nutrition, health & aging. 2019;(4):354-363
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Abstract
BACKGROUND The mammalian target of rapamycin complex 1 (mTORC1) is fundamental for many cellular processes, yet it is often dysregulated with aging. Increased amino acid (AA) availability is correlated with the expression of AA transporters (AAT) and mTORC1 activity. Although many AA sensors and mediators have been proposed to relay the AA signal to mTORC1, it has not yet been determined if chronic dietary intervention affects the expression of AAT, sensors and mediators and their relationships with mTORC1 activity. OBJECTIVE AND DESIGN This study investigated whether the consumption of a diet containing either the current recommended daily allowance (RDA) of protein intake (0.8 g/kg/d) or twice the RDA (2RDA) for ten weeks affected the expression of targets associated with AA transport, sensing and mTORC1 regulation in 26 older men (70-81 years). METHOD Muscle biopsies were collected before and after the intervention under fasting conditions. Diets were controlled by providing fully prepared meals and snacks. Western blot and quantitative polymerase chain reaction were used to measure protein and gene expression respectively. RESULTS Consumption of 2RDA reduced the protein expression of L-type amino acid transporter 1 (LAT1). However, plasma leucine concentration and basal mTORC1 activity were unaltered. The downregulation of LAT1 did not affect the expression of AA sensors and mediators, including leucyl tRNA synthetase (LRS), cytosolic arginine sensor for mTORC1 (CASTOR1), Sestrin2 and Rag proteins. Instead, total ribosomal protein S6 (RPS6) was upregulated with 2RDA. CONCLUSION Ten weeks of 2RDA diet did not affect the fasting mTORC1 signaling, but increased total RPS6 might suggest improved muscular translational capacity to maintain muscular mass.
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A double-blind placebo controlled trial into the impacts of HMB supplementation and exercise on free-living muscle protein synthesis, muscle mass and function, in older adults.
Din, USU, Brook, MS, Selby, A, Quinlan, J, Boereboom, C, Abdulla, H, Franchi, M, Narici, MV, Phillips, BE, Williams, JW, et al
Clinical nutrition (Edinburgh, Scotland). 2019;(5):2071-2078
Abstract
Age-related sarcopenia and dynapenia are associated with frailty and metabolic diseases. Resistance exercise training (RET) adjuvant to evidence-based nutritional intervention(s) have been shown as mitigating strategies. Given that β-hydroxy-β-methyl-butyrate (HMB) supplementation during RET improves lean body mass in younger humans, and that we have shown that HMB acutely stimulates muscle protein synthesis (MPS) and inhibits breakdown; we hypothesized that chronic supplementation of HMB free acid (HMB-FA) would enhance MPS and muscle mass/function in response to RET in older people. We recruited 16 healthy older men (Placebo (PLA): 68.5 ± 1.0 y, HMB-FA: 67.8 ± 1.15 y) for a randomised double-blind-placebo controlled trial (HMB-FA 3 × 1 g/day vs. PLA) involving a 6-week unilateral progressive RET regime (6 × 8 repetitions, 75% 1-RM, 3 · wk-1). Deuterium oxide (D2O) dosing was performed over the first two weeks (0-2 wk) and last two weeks (4-6 wk) with bilateral vastus lateralis (VL) biopsies at 0-2 and 4-6 wk (each time 75 ± 2 min after a single bout of resistance exercise (RE)) for quantification of early and later MPS responses and post-RE myogenic gene expression. Thigh lean mass (TLM) was measured by DXA, VL thickness and architecture (fibre length and pennation angle) by ultrasound at 0/3/6 wk, and strength by knee extensor 1-RM testing and MVC by isokinetic dynamometry (approx. every 10 days). RET induced strength increases (1-RM) in the exercised leg of both groups (398 ± 22N to 499 ± 30N HMB-FA vs. 396 ± 29N to 510 ± 43N PLA (both P < 0.05)). In addition, maximal voluntary contraction (MVC) also increased (179 ± 12 Nm to 203 ± 12 Nm HMB-FA vs. 185 ± 10 Nm to 217 ± 11 Nm PLA (both P < 0.05); with no group differences. VL muscle thickness increased significantly in the exercised leg in both groups, with no group differences. TLM (by DXA) rose to significance only in the HMB-FA group (by 5.8%-5734 ± 245 g p = 0.015 vs. 3.0% to 5644 ± 323 g P = 0.06 in PLA). MPS remained unchanged in the untrained legs (UT) 0-2 weeks being 1.06 ± 0.08%.d-1 (HMB-FA) and 1.14 ± 0.09%.d-1 (PLA), the trained legs (T) exhibited increased MPS in the HMB-FA group only at 0-2-weeks (1.39 ± 0.10%.d-1, P < 0.05) compared with UT: but was not different at 4-6-weeks: 1.26 ± 0.05%.d-1. However, there were no significant differences in MPS between the HMB-FA and PLA groups at any given time point and no significant treatment interaction observed. We also observed significant inductions of c-Myc gene expression following each acute RE bout, with no group differences. Further, there were no changes in any other muscle atrophy/hypertrophy or myogenic transcription factor genes we measured. RET with adjuvant HMB-FA supplements in free-living healthy older men did not enhance muscle strength or mass greater than that of RET alone (PLA). That said, only HMB-FA increased TLM, supported by early increases in chronic MPS. As such, chronic HMB-FA supplementation may result in long term benefits in older males, however longer and larger studies may be needed to fully determine the potential effects of HMB-FA supplementation; translating to any functional benefit.
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High-intensity exercise training enhances mitochondrial oxidative phosphorylation efficiency in a temperature-dependent manner in human skeletal muscle: implications for exercise performance.
Fiorenza, M, Lemminger, AK, Marker, M, Eibye, K, Iaia, FM, Bangsbo, J, Hostrup, M
FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 2019;(8):8976-8989
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Abstract
The purpose of the present study was to investigate whether exercise training-induced adaptations in human skeletal muscle mitochondrial bioenergetics are magnified under thermal conditions resembling sustained intense contractile activity and whether training-induced changes in mitochondrial oxidative phosphorylation (OXPHOS) efficiency influence exercise efficiency. Twenty healthy men performed 6 wk of high-intensity exercise training [i.e., speed endurance training (SET; n = 10)], or maintained their usual lifestyle (n = 10). Before and after the intervention, mitochondrial respiratory function was determined ex vivo in permeabilized muscle fibers under experimentally-induced normothermia (35°C) and hyperthermia (40°C) mimicking in vivo muscle temperature at rest and during intense exercise, respectively. In addition, activity and content of muscle mitochondrial enzymes and proteins were quantified. Exercising muscle efficiency was determined in vivo by measurements of leg hemodynamics and blood parameters during one-legged knee-extensor exercise. SET enhanced maximal OXPHOS capacity and OXPHOS efficiency at 40°C, but not at 35°C, and attenuated hyperthermia-induced decline in OXPHOS efficiency. Furthermore, SET increased expression of markers of mitochondrial content and up-regulated content of MFN2, DRP1, and ANT1. Also, SET improved exercise efficiency and capacity. These findings indicate that muscle mitochondrial bioenergetics adapts to high-intensity exercise training in a temperature-dependent manner and that enhancements in mitochondrial OXPHOS efficiency may contribute to improving exercise performance.-Fiorenza, M., Lemminger, A. K., Marker, M., Eibye, K., Iaia, F. M., Bangsbo, J., Hostrup, M. High-intensity exercise training enhances mitochondrial oxidative phosphorylation efficiency in a temperature-dependent manner in human skeletal muscle: implications for exercise performance.