Sympathetic neural adaptation to hypocaloric diet with or without exercise training in obese metabolic syndrome subjects

The impact of exercise training on muscle sympathetic nerve activity: a systematic review and meta-analysis

The purpose of this systematic review and meta-analysis was to examine the effects of exercise training on muscle sympathetic nerve activity (MSNA) in humans. Studies included exercise interventions [randomized controlled trials (RCTs), nonrandomized controlled trials (non-RCTs), or pre-to-post intervention] that reported on adults (≥18 yr) where MSNA was directly assessed using microneurography, and relevant outcomes were assessed [MSNA (total activity, burst frequency, burst incidence, amplitude), heart rate, blood pressure (systolic blood pressure, diastolic blood pressure, or mean blood pressure), and aerobic capacity (maximal or peak oxygen consumption)]. Forty intervention studies (n = 1,253 individuals) were included. RCTs of exercise compared with no exercise illustrated that those randomized to the exercise intervention had a significant reduction in MSNA burst frequency and incidence compared with controls. This reduction in burst frequency was not different between individuals with cardiovascular disease compared with those without. However, the reduction in burst incidence was greater in those with cardiovascular disease [9 RCTs studies, n = 234, mean difference (MD) -21.08 bursts/100 hbs; 95% confidence interval (CI) -16.51, -25.66; I2 = 63%] compared with those without (6 RCTs, n = 192, MD -10.92 bursts/100 hbs; 95% CI -4.12, -17.73; I2 = 76%). Meta-regression analyses demonstrated a dose-response relationship where individuals with higher burst frequency and incidence preintervention had a greater reduction in values post-intervention. These findings suggest that exercise training reduces muscle sympathetic nerve activity, which may be valuable for improving cardiovascular health.NEW & NOTEWORTHY This systematic review and meta-analysis suggests exercise training reduces muscle sympathetic nerve activity (MSNA), which may be valuable for improving cardiovascular health. The reduction in burst incidence was greater among individuals with cardiovascular disease when compared with those without; exercise training may be particularly beneficial for individuals with cardiovascular disease. Meta-regression analyses demonstrated a dose-response relationship, where individuals with higher sympathetic activity preintervention had greater reductions in sympathetic activity post-intervention.

The Impact on Autonomic Nervous System Activity during and Following Exercise in Adults: A Meta-Regression Study and Trial Sequential Analysis

Background and Objectives: Exercise enhances cardiovascular health through various mechanisms, including the modulation of autonomic nervous system activity. This study aimed to systematically examine the impact of exercise on heart rate variability (HRV) in adults during and within one hour after exercise (WHAE). Materials and Methods: A comprehensive literature review was conducted using the MEDLINE, Embase, Cochrane Library, Scopus, and PubMed databases to identify published studies that reported the impact of exercise on autonomic nervous system activity in adults. The studies measured the absolute power of the low-frequency band (0.04-0.15 Hz) to the absolute power of the high-frequency band (0.015-0.4 Hz) (LF/HF ratio) to assess sympathetic activity and the root mean square of successive differences between normal heartbeats (RMSSD) to assess parasympathetic activity. Results: A total of 3329 studies were screened for relevance, and finally, 10 articles that utilized methods for measuring autonomic nervous system activity, such as the LF/HF ratio and RMSSD, covering 292 adult patients, were included for meta-analysis. In the current meta-analysis, we observed a significant decrease in parasympathetic activity during and after exercise, as indicated by RMSSD, compared to pre-exercise levels (mean difference [MD] = -4.96, 95% confidence interval [CI]: -8.00 to -1.91, p = 0.003). However, sympathetic activity after exercise, represented by the LF/HF ratio, showed a borderline significant increase compared to pre-exercise levels (MD = 1.06, 95% CI: -0.01 to 2.12, p = 0.052). The meta-regression model found that factors associated with RMSSD included mean age, male gender, and duration post-exercise. Additionally, the factor associated with the LF/HF ratio was the healthy condition of participants. The trial sequential analysis provided robust evidence of a decrease in RMSSD and an increase in the LF/HF ratio during and WHAE. Conclusions: Given the limitations of the current study, the findings suggest that a significant decrease in parasympathetic activity and a borderline significant increase in sympathetic activity in adults during and WHAE, as confirmed by trial sequential analysis. Meta-regression analysis indicated that parasympathetic activity was negatively associated with participant age and male gender, but positively associated with duration post-exercise. Additionally, increased sympathetic activity was linked to the healthy conditions of participants. This study suggests that exercise might differentially affect autonomic balance in individuals with chronic conditions compared to healthy individuals. This highlights the potential need for tailored exercise interventions to improve autonomic function across different populations.

Immunoneuroendocrine, Stress, Metabolic, and Behavioural Responses in High-Fat Diet-Induced Obesity

Obesity has reached global epidemic proportions, and even though its effects are well-documented, studying the interactions among all influencing factors is crucial for a better understanding of its physiopathology. In a high-fat-diet-induced obesity animal model using C57BL/6J mice, behavioural responses were assessed through a battery of tests, while stress biomarkers and systemic inflammatory cytokines were measured using an Enzyme-Linked ImmunoSorbent Assay and a Bio-Plex Multiplex System. The peritoneal macrophage microbicide capacity was analysed via flow cytometry, and crown-like structures (CLSs) in white adipose tissue (WAT) were evaluated through staining techniques. Results indicated that obese mice exhibited increased body weight, hyperglycaemia, and hyperlipidaemia after 18 weeks on a high-fat diet, as well as worse physical conditions, poorer coordination and balance, and anxiety-like behaviour. Differences in corticosterone and noradrenaline concentrations were also found in obese animals, revealing a stress response and noradrenergic dysregulation, along with a weakened innate immune response characterized by a lower microbicide capacity, and the presence of an underlying inflammation evidenced by more CLSs in WAT. Altogether, these findings indicate that obesity deteriorates the entire stress, inflammatory, metabolic, sensorimotor and anxiety-like behavioural axis. This demonstrates that jointly evaluating all these aspects allows for a deeper and better exploration of this disease and its associated comorbidities, emphasizing the need for individualized and context-specific strategies for its management.

Neurocirculatory regulation and adaptations to exercise in chronic kidney disease

Chronic kidney disease (CKD) is characterized by pronounced exercise intolerance and exaggerated blood pressure reactivity during exercise. Classic mechanisms of exercise intolerance in CKD have been extensively described previously and include uremic myopathy, chronic inflammation, malnutrition, and anemia. We contend that these classic mechanisms only partially explain the exercise intolerance experienced in CKD and that alterations in cardiovascular and autonomic regulation also play a key contributing role. The purpose of this review is to examine the physiological factors that contribute to neurocirculatory dysregulation during exercise and discuss the adaptations that result from regular exercise training in CKD. Key neurocirculatory mechanisms contributing to exercise intolerance in CKD include augmentation of the exercise pressor reflex, aberrations in neurocirculatory control, and increased neurovascular transduction. In addition, we highlight how some contributing factors may be improved through exercise training, with a specific focus on the sympathetic nervous system. Important areas for future work include understanding how the exercise prescription may best be optimized in CKD and how the beneficial effects of exercise training may extend to the brain.

Signaling pathways in vascular function and hypertension: molecular mechanisms and therapeutic interventions

Hypertension is a global public health issue and the leading cause of premature death in humans. Despite more than a century of research, hypertension remains difficult to cure due to its complex mechanisms involving multiple interactive factors and our limited understanding of it. Hypertension is a condition that is named after its clinical features. Vascular function is a factor that affects blood pressure directly, and it is a main strategy for clinically controlling BP to regulate constriction/relaxation function of blood vessels. Vascular elasticity, caliber, and reactivity are all characteristic indicators reflecting vascular function. Blood vessels are composed of three distinct layers, out of which the endothelial cells in intima and the smooth muscle cells in media are the main performers of vascular function. The alterations in signaling pathways in these cells are the key molecular mechanisms underlying vascular dysfunction and hypertension development. In this manuscript, we will comprehensively review the signaling pathways involved in vascular function regulation and hypertension progression, including calcium pathway, NO-NOsGC-cGMP pathway, various vascular remodeling pathways and some important upstream pathways such as renin-angiotensin-aldosterone system, oxidative stress-related signaling pathway, immunity/inflammation pathway, etc. Meanwhile, we will also summarize the treatment methods of hypertension that targets vascular function regulation and discuss the possibility of these signaling pathways being applied to clinical work.

Exercise modulates sympathetic and vascular function in chronic kidney disease

BACKGROUNDChronic kidney disease (CKD) is characterized by chronic overactivation of the sympathetic nervous system (SNS), which increases the risk of cardiovascular (CV) disease and mortality. SNS overactivity increases CV risk by multiple mechanisms, including vascular stiffness. We tested the hypothesis that aerobic exercise training would reduce resting SNS activity and vascular stiffness in patients with CKD.METHODSIn this randomized controlled trial, sedentary older adults with CKD underwent 12 weeks of exercise (cycling, n = 32) or stretching (an active control group, n = 26). Exercise and stretching interventions were performed 20-45 minutes/session at 3 days/week and were matched for duration. Primary endpoints include resting muscle sympathetic nerve activity (MSNA) via microneurography, arterial stiffness by central pulse wave velocity (PWV), and aortic wave reflection by augmentation index (AIx).RESULTSThere was a significant group × time interaction in MSNA and AIx with no change in the exercise group but with an increase in the stretching group after 12 weeks. The magnitude of change in MSNA was inversely associated with baseline MSNA in the exercise group. There was no change in PWV in either group over the study period.CONCLUSIONOur data demonstrate that 12 weeks of cycling exercise has beneficial neurovascular effects in patients with CKD. Specifically, exercise training safely and effectively ameliorated the increase in MSNA and AIx observed over time in the control group. This sympathoinhibitory effect of exercise training showed greater magnitude in patients with CKD with higher resting MSNA.TRIAL REGISTRATIONClinicalTrials.gov, NCT02947750.FUNDINGNIH R01HL135183; NIH R61AT10457; NIH NCATS KL2TR002381; and NIH T32 DK00756; NIH F32HL147547; and VA Merit I01CX001065.

The impact of exercise and dietary interventions on circulating leptin and adiponectin in individuals who are overweight and those with obesity: A systematic review and meta-analysis

The effects of exercise training (Ex), dietary interventions (DIs), and a combination of Ex and DI (Ex + DI) on leptin and adiponectin have been established. However, less is known regarding the comparisons of Ex with DI and of Ex + DI with either Ex or DI alone. The aim of the present meta-analysis is to compare the effects of Ex with those of DI and those of Ex + DI with those of either Ex or DI alone on circulating leptin and adiponectin in individuals who are overweight and those with obesity. PubMed, Web of Science, and MEDLINE were searched to identify original articles, published through June 2022, that compared the effects of Ex with those of DI and/or the effects of Ex + DI with those of Ex and/or DI on leptin and adiponectin in individuals with BMIs (in kg/m²) of ≥25 and aged 7-70 y. Standardized mean differences (SMDs), weighted mean differences, and 95% CIs were calculated using random-effect models for outcomes. Forty-seven studies, comprising 3872 participants who were overweight and those with obesity, were included in the current meta-analysis. DI reduced the concentration of leptin (SMD: -0.30; P = 0.001) and increased the concentration of adiponectin (SMD: 0.23; P = 0.001) compared with Ex, as did Ex + DI (leptin: SMD: -0.34; P = 0.001; adiponectin: SMD: 0.37; P = 0.004) compared with Ex alone. However, Ex + DI did not affect the concentration of adiponectin (SMD: 0.10; P = 0.11) and led to inconsistent and nonsignificant changes in the concentration of leptin (SMD: -0.13; P = 0.06) compared with DI alone. Subgroup analyses showed that age, BMI, duration of intervention, type of supervision, quality of the study, and magnitude of energy restriction are sources of heterogeneity. Our results suggest that Ex alone was not as effective as DI or Ex + DI for decreasing leptin and increasing adiponectin in individuals with overweight and obesity. However, Ex + DI was not more effective than DI alone, suggesting that diet plays a critical role in beneficially altering the concentrations of leptin and adiponectin. This review was registered at PROSPERO as CRD42021283532.

İnsülin Duyarlılığı ve Vücut Kitle İndeksinin Ortostatik İntolerans Üzerine Etkileri

Amaç: Çalışmanın amacı insülin duyarlılığı ve antropometrik ölçümlerin ortostatik intolerans sendromları üzerindeki etkilerini değerlendirmektir. Yöntem: Retrospektif bir çalışmadır. 7-18 yaş arası senkop öyküsü ile başvuran hastalarda insülin duyarlılık indeksleri hesaplandı ve antropometrik ölçümlerine değerlendirildi. Hastalar head-up tilt test sonuçlarına göre test pozitif ve test negatif olarak gruplandırıldı. Ayrıca tilt testi pozitif olan hastalar vazodepresör vazovagal senkop (VVS), kardiyoinhibitör VVS, mikst VVS ve postural ortostatik taşikardi sendromu olmak üzere dört alt gruba ayrıldı. Bulgular: Çalışmaya toplam 509 hasta dahil edildi. Yaş ortalaması 13,45 ± 2,82 yıldı ve %64,4'ü kızdı. Tilt testi 214 hastada pozitif, 295 hastada negatifti. Tilt testi sonuçları ile 173 hastaya VVS ve 41 hastaya (%19) POTS tanısı konuldu. İnsülin duyarlılık indekslerine göre gruplar arasında istatistiksel olarak anlamlı fark yoktu. Antropometrik ölçümlerde boy, boy standart deviasyonu, vücut kitle indeksi (VKİ) standart deviasyonu ve VKİ persentili (sırasıyla p=0,008, p=0,02, p=0,036, p=0,03) açısından iki grup arasında anlamlı farklılık gözlendi. Sonuç: Çalışmamızda özellikle genç kızlarda düşük VKİ ve uzun boylu olmak vazovagal senkop ataklarına zemin hazırlayan faktörler iken, insülin duyarlılık indeksleri ile pozitif head-up tilt test sonucu arasında ilişki bulunmadı. Tekrarlayan senkoplara neden olan faktörlere ışık tutarak uygun tedavinin sağlanması hastaların yaşam kalitelerine katkı sağlayabilir.

A comparison of the impact of exercise training with dietary intervention versus dietary intervention alone on insulin resistance and glucose regulation in individual with overweight or obesity: a systemic review and meta-analysis

PURPOSE

Obesity is associated with the development of insulin resistance (IR) and type 2 diabetes for which exercise training (Ex) and dietary interventions (DI) are effective interventions that can improve IR. We therefore performed a systematic meta-analysis to compare the effect of Ex + DI compared with DI on IR and glucose homeostasis.

METHODS

PubMed and Cochrane Library were conducted up to May 2021. Meta-analyses were conducted to compare the effect of Ex + DI compared with DI on fasting glucose and insulin, IR and body weight. Standardized mean differences (SMDs), weighted mean differences (WMD) and 95% confidence intervals (95% CIs) were computed using random or fixed effect models.

RESULTS

Fifty studies involving 2864 participants with overweight or obesity were included in the meta-analysis. Ex + DI caused a larger decrease in fasting glucose (p = 0.001, 62 trials) and IR (p = 0.01, 29 trials) when compared with DI alone. There was no significant evidence, however, for a greater effect of Ex + DI on fasting insulin (p = 0.07, 48 trials) and body weight (p = 0.12, 58 trials), compared with DI alone.

CONCLUSION

Our results suggest that a combination of Ex and DI may be more effective than DI alone at improving IR and fasting glucose in individuals with overweight and obesity.

Understanding diabetes-induced cardiomyopathy from the perspective of renin angiotensin aldosterone system

Experimental and clinical evidence suggests that diabetic subjects are predisposed to a distinct cardiovascular dysfunction, known as diabetic cardiomyopathy (DCM), which could be an autonomous disease independent of concomitant micro and macrovascular disorders. DCM is one of the prominent causes of global morbidity and mortality and is on a rising trend with the increase in the prevalence of diabetes mellitus (DM). DCM is characterized by an early left ventricle diastolic dysfunction associated with the slow progression of cardiomyocyte hypertrophy leading to heart failure, which still has no effective therapy. Although the well-known "Renin Angiotensin Aldosterone System (RAAS)" inhibition is considered a gold-standard treatment in heart failure, its role in DCM is still unclear. At the cellular level of DCM, RAAS induces various secondary mechanisms, adding complications to poor prognosis and treatment of DCM. This review highlights the importance of RAAS signaling and its major secondary mechanisms involving inflammation, oxidative stress, mitochondrial dysfunction, and autophagy, their role in establishing DCM. In addition, studies lacking in the specific area of DCM are also highlighted. Therefore, understanding the complex role of RAAS in DCM may lead to the identification of better prognosis and therapeutic strategies in treating DCM.

Calorie Restriction With Exercise Intervention Improves Inflammatory Response in Overweight and Obese Adults: A Systematic Review and Meta-Analysis

Background/Purpose: In this systematic review and meta-analysis, we assessed the effects of exercise (EX) combined with calorie restriction (CR) intervention on inflammatory biomarkers, and correlations between biomarkers and participants' characteristics were calculated in overweight and obese adults. Methods: An article search was conducted through PubMed, Web of Science, EMBASE, the Cochrane database, Scopus, and Google Scholar to identify articles published up to April 2021. Studies that examined the effect of EX + CR intervention on inflammatory biomarkers, including C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), and compared them with a CR trial in overweight and obese adults were included. We calculated the pooled effect by meta-analysis, identified the correlations (between inflammatory biomarkers and participants' characteristics) through meta-regression, and explored the beneficial variable through subgroup analysis. The Cochrane risk of bias tool and Methodological Index for Non-randomized Studies were used to assess the risk of bias for the included trials. Results: A total of 23 trials, including 1196 overweight and obese adults, were included in the meta-analysis. The pooled effect showed that EX + CR intervention significantly decreased CRP levels (P = 0.02), but had no effect on IL-6 (P = 0.62) and TNF-α (P = 0.11). Meta-regression analysis showed that the effect of EX + CR on CRP, IL-6, and TNF-α changes was correlated with lifestyle behavior of adults (Coef. = -0.380, P = 0.018; Coef. = -0.359, P = 0.031; Coef. = -0.424, P = 0.041, respectively), but not with age and BMI. The subgroup analysis results revealed that participants with sedentary lifestyle behavior did not respond to EX + CR intervention, as we found no changes in CRP, IL-6, and TNF-α concentrations (P = 0.84, P = 0.16, P = 0.92, respectively). However, EX + CR intervention significantly decreased CRP (P = 0.0003; SMD = -0.39; 95%CI: -0.60 to -0.18), IL-6 (P = 0.04; SMD = -0.21; 95%CI: -0.40 to -0.01) and TNF-α (P = 0.006; SMD = -0.40, 95%CI: -0.68 to -0.12) in adults without a sedentary lifestyle or with a normal lifestyle. Furthermore, the values between sedentary and normal lifestyle subgroups were statistically significant for CRP, IL-6, and TNF-α. Conclusion: Our findings showed that combination EX + CR intervention effectively decreased CRP, IL-6, and TNF-α in overweight and obese adults with active lifestyles, but not with sedentary lifestyle behavior. We suggest that 'lifestyle behavior' is a considerable factor when designing new intervention programs for overweight or obese adults to improve their inflammatory response.

The addition of exercise to a weight loss diet on inflammatory markers: a systematic review and Meta-analysis of controlled clinical trials

This systematic review and meta-analysis of controlled clinical trials was performed to evaluate the effects of weight-loss diets plus exercise compared with weight-loss diets alone on inflammatory biomarkers in adults. PubMed, Scopus, EMBASE, Web of Science (ISI), and Google Scholar were searched up to April 2021. Overall effects were derived using a random effects model. The overall quality of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Twenty-nine trials were included in this systematic review and meta-analysis. The meta-analysis showed no significant difference in serum high sensitivity C-reactive protein (hs-CRP) [weighted mean difference (WMD) = -0.004 mg/l, 95% CI: -0.140, 0.132, P = 0.954], interleukin-6 (IL-6) (WMD = -0.039 pg/ml, 95% CI: -0.233 to 0.156, P = 0.696), and tumor necrosis factor-α (TNF-α) (WMD = 0.405 ng/ml, 95% CI: -1.036 to 0.226, P = 0.209) after adding exercise to a weight-loss diet compared with a weight-loss diet alone. Subgroup analysis revealed that exercise plus a weight-loss diet significantly reduced TNF-α in studies greater than 16 weeks in duration (WMD = -0.742 ng/ml, 95% CI: -1.384 to -0.1, P = 0.024). This systematic review and meta-analysis indicate that exercise in addition to a weight-loss diet does not have a significant effect on further reducing inflammatory markers compared to a weight loss diet alone.

Comparison of Resveratrol Supplementation and Energy Restriction Effects on Sympathetic Nervous System Activity and Vascular Reactivity: A Randomized Clinical Trial

Background: Chronic sympathetic nervous system activation is associated with endothelial dysfunction and cardiometabolic disease, which may be modulated by resveratrol (RSV) and energy restriction (ER). This study aimed to examine the effects of RSV and ER on plasma noradrenaline (NA), flow-mediated vasodilation (ed-FMD), and endothelium-independent nitrate-mediated vasodilation (ei-NMD). Methods: The study included 48 healthy adults randomized to 30-days intervention of RSV or ER. Results: Waist circumference, total cholesterol, HDL-c, LDL-c, apoA-I, and plasma NA decreased in the ER group, whilst RSV increased apoB and total cholesterol, without changing plasma NA. No effects on vascular reactivity were observed in both groups. Plasma NA change was positively correlated with total cholesterol (r = 0.443; p = 0.002), triglycerides (r = 0.438; p = 0.002), apoA-I (r = 0.467; p = 0.001), apoB (r = 0.318; p = 0.032) changes, and ei-NMD (OR = 1.294; 95%CI: 1.021–1.640). Conclusions: RSV does not improve cardiometabolic risk factors, sympathetic activity, and endothelial function. ER decreases plasma NA and waist circumference as well as improves blood lipids, but does not modify endothelial function. Finally, plasma NA was associated with ei-NMD, which could be attributed to a higher response to nitrate in patients with greater resting sympathetic vasoconstriction.

Plasma lipocalin-2/NGAL is stable over 12 weeks and is not modulated by exercise or dieting

Amongst other immune cells, neutrophils play a key role in systemic inflammation leading to cardiovascular disease and can release inflammatory factors, including lipocalin-2 (LCN2). LCN2 drives cardiac hypertrophy and plays a role in maladaptive remodelling of the heart and has been associated with renal injury. While lifestyle factors such as diet and exercise are known to attenuate low-grade inflammation, their ability to modulate plasma LCN2 levels is unknown. Forty-eight endurance athletes and 52 controls (18–55 years) underwent measurement for various cardiovascular health indicators, along with plasma LCN2 concentration. No significant difference in LCN2 concentration was seen between the two groups. LCN2 was a very weak predictor or absent from models describing blood pressures or predicting athlete status. In another cohort, 57 non-diabetic overweight or obese men and post-menopausal women who fulfilled Adult Treatment Panel III metabolic syndrome criteria were randomly allocated into either a control, modified Dietary Approaches to Stop Hypertension (DASH) diet, or DASH and exercise group. Pre- and post-intervention demographic, cardiovascular health indicators, and plasma LCN2 expression were measured in each individual. While BMI fell in intervention groups, LCN2 levels remained unchanged within and between all groups, as illustrated by strong correlations between LCN2 concentrations pre- and 12 weeks post-intervention (r = 0.743, P < 0.0001). This suggests that circulating LCN2 expression are stable over a period of at least 12 weeks and is not modifiable by diet and exercise.

The impact of exercise training versus caloric restriction on inflammation markers: a systemic review and meta-analysis

Obesity is associated with an increased risk of chronic, low-grade systematic inflammation for which exercise training (EX) and caloric restriction (CR) are potential treatments. We therefore performed a systematic meta-analysis to compare the effect of EX vs. CR and EX + CR vs. CR on inflammation markers in overweight and obese individuals. PubMed, Scopus, Web of Science and the Cochrane were searched up to April 2020 for EX vs. CR or EX + CR vs. CR interventions studies on inflammatory makers i.e. CRP, IL-6 and TNF-α in overweight and obese individuals. Standardized mean differences and 95% confidence intervals were calculated. Thirty two articles (reporting 38 trials) involving 2108 participants were included in the meta-analysis. Based on studies that directly compared EX and CR, there were no evidence for an effect of EX on IL-6 (p = 0.20) and TNF-α (p = 0.58), when compared with a CR. However, when compared to EX, CR has a statistically greater benefit on CRP (p = 0.01). In those studies, directly comparing EX + CR and CR, EX + CR caused a larger decrease in TNF-α (p = 0.002) and IL-6 (p = 0.02) and tended to decrease CRP (p = 0.06) when compared with CR. These results suggest that a combination of EX and CR may be more effective than CR alone at reducing inflammatory cytokines and CRP in overweight and obese individuals.

Lifestyle interventions for the prevention and treatment of hypertension

Hypertension affects approximately one third of the world's adult population and is a major cause of premature death despite considerable advances in pharmacological treatments. Growing evidence supports the use of lifestyle interventions for the prevention and adjuvant treatment of hypertension. In this Review, we provide a summary of the epidemiological research supporting the preventive and antihypertensive effects of major lifestyle interventions (regular physical exercise, body weight management and healthy dietary patterns), as well as other less traditional recommendations such as stress management and the promotion of adequate sleep patterns coupled with circadian entrainment. We also discuss the physiological mechanisms underlying the beneficial effects of these lifestyle interventions on hypertension, which include not only the prevention of traditional risk factors (such as obesity and insulin resistance) and improvements in vascular health through an improved redox and inflammatory status, but also reduced sympathetic overactivation and non-traditional mechanisms such as increased secretion of myokines.

High-Intensity Interval Training Decreases Muscle Sympathetic Nerve Activity in Men With Essential Hypertension and in Normotensive Controls

Exercise training is a cornerstone in reducing blood pressure (BP) and muscle sympathetic nerve activity (MSNA) in individuals with essential hypertension. High-intensity interval training (HIIT) has been shown to be a time efficient alternative to classical continuous training in lowering BP in essential hypertension, but the effect of HIIT on MSNA levels has never been investigated. Leg MSNA responsiveness to 6 weeks of HIIT was examined in 14 hypertensive men (HYP; age: 62 ± 7 years, night time BP: 136 ± 12/83 ± 8 mmHg, BMI: 28 ± 3 kg/m²), and 10 age-matched normotensive controls (NORM; age: 60 ± 8 years, night time BP: 116 ± 2/68 ± 4 mmHg and BMI: 27 ± 3 kg/m²). Before training, MSNA levels were not different between HYP and NORM (burst frequency (BF): 41.0 ± 10.3 vs. 33.6 ± 10.6 bursts/min and burst incidence (BI): 67.5 ± 19.7 vs. 64.2 ± 17.0 bursts/100 heart beats, respectively). BF decreased (P < 0.05) with training by 13 and 5% in HYP and NORM, respectively, whereas BI decreased by 7% in NORM only, with no difference between groups. Training lowered (P < 0.05) night-time mean arterial- and diastolic BP in HYP only (100 ± 8 vs. 97 ± 5, and 82 ± 6 vs. 79 ± 5 mmHg, respectively). The change in HYP was greater (P < 0.05) compared to NORM. Training reduced (P < 0.05) body mass, visceral fat mass, and fat percentage similarly within- and between groups, with no change in fat free mass. Training increased (P < 0.05) V̇O₂-max in NORM only. Six weeks of HIIT lowered resting MSNA levels in age-matched hyper- and normotensive men, which was paralleled by a significant reduction in BP in the hypertensive men.

EpiMetal: an open-source graphical web browser tool for easy statistical analyses in epidemiology and metabolomics

MOTIVATION

An intuitive graphical interface that allows statistical analyses and visualizations of extensive data without any knowledge of dedicated statistical software or programming.

IMPLEMENTATION

EpiMetal is a single-page web application written in JavaScript, to be used via a modern desktop web browser.

GENERAL FEATURES

Standard epidemiological analyses and self-organizing maps for data-driven metabolic profiling are included. Multiple extensive datasets with an arbitrary number of continuous and category variables can be integrated with the software. Any snapshot of the analyses can be saved and shared with others via a www-link. We demonstrate the usage of EpiMetal using pilot data with over 500 quantitative molecular measures for each sample as well as in two large-scale epidemiological cohorts (N >10 000).

AVAILABILITY

The software usage exemplar and the pilot data are open access online at [http://EpiMetal.computationalmedicine.fi]. MIT licensed source code is available at the Github repository at [https://github.com/amergin/epimetal].

The effect of caloric restriction on blood pressure and cardiovascular function: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND & AIMS

Preclinical evidence suggests that caloric restriction is an effective therapy for a number of cardiovascular insults. Whether caloric restriction has cardio-protective effects in humans is not well understood. The aim was to systematically review and meta-analyze human randomized control trials (RCTs) testing the effect of caloric restriction on blood pressure (BP) and cardiovascular function.

METHODS

A systematic review was performed using Medline, EMBASE, CINAHL (up to June 2017) to search for RCTs of adults receiving a calorie-restricted intervention versus a control/standard diet. Random-effect meta-analyses were performed to calculate weighted mean difference and 95% CI.

RESULTS

Thirty-two RCTs with 1722 participants assessing BP (n = 29 studies), heart rate (n = 10), VO₂peak (n = 8), muscle sympathetic nerve activity (MSNA, n = 4), and endothelial function (n = 4) were included. Calorie-restricted interventions lasting 1-4 weeks had the largest effect on systolic (-5.5 mmHg, p < 0.001, 95% CI: -3.8, -7.1) and diastolic (-2.9 mmHg, p = 0.005, 95% CI: -5.0, -0.9) BP, but no effect on HR. Interventions lasting 1.5-6 months had similar effects on BP, and reduced HR (-4.4 beats/minute, p < 0.001, 95% CI: -6.1,-2.8). Relative VO₂peak improved (1.8 mL/kg/min, p < 0.001, 95% CI: 1.3, 2.2). There were also potential positive effects on MSNA and endothelial function.

CONCLUSIONS

The effect of 1-4 weeks of calorie restriction on BP was similar to that expected with medications, and larger than that reported for other lifestyle interventions or supplements. Cardiovascular risk could be further reduced by caloric restriction lasting up to six months to lower heart rate and improve VO₂peak.

Sex Differences in the Effects of Weight Reduction on Future Blood Pressure Elevation in a Mildly Obese Middle-Aged Population

Background: The effectiveness of weight loss (WL) in preventing blood pressure (BP) elevation is common knowledge; however, the effect of sex differences is not known. Methods and Results: Health checkup data from Kagoshima Kouseiren Medical Healthcare Center for middle-aged participants (40-49 years old) with mild obesity (body mass index [BMI] 25.0-29.9 kg/m2) who had examination data for 2 follow-up time-points (after 3 and 10 years) were analyzed. Propensity score (PS) matching using data from the first examination was used to match participants with a decrease in BMI ≥1.0 kg/m2 at 3 years (WL group) with those with a BMI decrease <1.0 kg/m2 or weight gain (non-WL group). BP values were compared after 3 and 10 years between the 2 groups, as was the prevalence of hypertension after 10 years. PS matching resulted in 232 men and 160 women in each group. Among women, systolic BP (SBP) and hypertension prevalence after 10 years were significantly lower in the WL than non-WL group (P<0.01 and P<0.05, respectively). There were no significant differences in SBP and hypertension prevalence after 10 years in men in the 2 groups. Conclusions: There were sex differences in the effectiveness of WL in preventing future BP elevation in mildly obese middle-aged participants: WL prevented future BP elevation and hypertension onset in women, but not in men.

β2 Adrenergic Regulation of the Phagocytic and Microbicide Capacity of Circulating Monocytes: Influence of Obesity and Exercise

Obese individuals present anomalous immune/inflammatory responses with dysregulations in neuroendocrine responses and immune/stress feedback mechanisms. In this context, exercise and β2 adrenergic activation present monocyte-mediated anti-inflammatory effects that are modulated by obesity. However, these anti-inflammatory effects could immunocompromise the monocyte-mediated innate response against a pathogen challenge. Thus, the objective of this work was to evaluate the effect of obesity, and exercise in this condition, on the β2 adrenergic regulation of the phagocytic and microbicide capacity of circulating monocytes. C57BL/6J mice were allocated to different sedentary or exercised, lean or obese groups. Obese mice showed a lower monocyte-mediated innate response than that of lean mice. Globally, selective β2 adrenergic receptor agonist terbutaline decreased the innate response of monocytes from lean and obese sedentary animals, whereas exercise stimulated it. Exercise modulates β2 adrenergic regulation of the innate response in lean and obese animals, with a global stimulatory or neutral effect, thus abolishing the inhibitory effect of terbutaline occurring in sedentary animals. These effects cannot be explained only by changes in the surface expression of toll-like receptors. Therefore, in general, terbutaline does not hinder the effects of regular exercise, but regular exercise does abolish the effects of terbutaline in sedentary individuals.

Effects of Exercise on the Body Composition and Lipid Profile of Individuals with Obesity: A Systematic Review and Meta-Analysis

Background

Numerous researchers have worked to develop treatments for obesity; however, the prevalence of obesity continues to increase in many countries. Moreover, the effects of physical activity and exercise on obesity remain unclear. Therefore, it is necessary to perform a systematic review and meta-analysis to assess the relationship between exercise and obesity using mediator variables such as the mode of exercise.

Methods

Our review focuses on research tracking the effects of exercise on obesity conducted from 2007 to 2016 and available in any of three databases: Embase, PubMed, and EBSCO Academic Search Premier. The keywords used in the search were “exercise and obesity” and “exercise and obese.”

Results

The average size of the effects that exercise interventions have on body mass index (standardized mean difference [SMD], 0.533), waist circumference (SMD, 0.666), total cholesterol (SMD, 0.721), and triglyceride (TG; SMD, 0.603) were medium or larger. Exercise had greater effects on the outward appearance of obesity (body mass index, waist circumference) than on its practical factors (weight, % body fat). The effect of exercise on TG (SMD, 0.603) was larger than that on low-density lipoprotein (SMD, 0.406) and high-density lipoprotein (SMD, −0.222). Exercise duration (weeks of exercise) and intensity correlate better than exercise time (minutes per week) with a large and consistent improvement in adult obesity.

Conclusion

We suggest that individuals with obesity should exercise consistently to achieve significant improvements in their health.

Impact of body mass index on cardiac adrenergic derangement in heart failure patients: a 123I-mIBG imaging study

PURPOSE

To assess the impact of body mass index (BMI) on cardiac adrenergic derangement, measured by iodine-123 meta-iodobenzylguanidine (¹²³I-mIBG) imaging in heart failure (HF) patients. Overweight and obesity represent relevant health issues, and augmented sympathetic tone has been described in patients with increased BMI. An extensive literature supports that HF-dependent cardiac denervation, measured through mIBG parameters, is an independent predictor of cardiovascular outcomes and mortality. However, the influence of BMI on cardiac mIBG uptake has not been largely investigated.

METHODS

We prospectively enrolled patients with systolic HF, collecting demographic, clinical, echocardiographic data, and mIBG imaging parameters. In order to detect the factors associated with mIBG parameters, a model building strategy, based on the Multivariable Fractional Polynomial algorithm, has been employed.

RESULTS

We studied 249 patients with systolic HF, mean age of 66.4 ± 10.6 years, and mean left ventricular ejection fraction (LVEF) of 30.7% ± 6.4, undergoing cardiac ¹²³I-mIBG imaging to assess HF severity and prognosis. Seventy-eight patients (31.3%) presented a BMI ≥ 30 kg/m² and obese patients showed a significant reduction in early heart to mediastinum (H/M) ratio (1.66 ± 0.19 vs. 1.75 ± 0.26; p = 0.008) and a trend to reduction in washout rate (33.6 ± 18.3 vs. 38.1 ± 20.1; p = 0.092) compared with patients with BMI < 30 kg/m². Multiple regression analysis revealed that BMI, age, and LVEF were significantly correlated with early and late H/M ratios.

CONCLUSIONS

Results of the present study indicate that BMI, together with LVEF and age, is independently correlated with cardiac mIBG uptake in HF patients.

Lifestyle Interventions with a Focus on Nutritional Strategies to Increase Cardiorespiratory Fitness in Chronic Obstructive Pulmonary Disease, Heart Failure, Obesity, Sarcopenia, and Frailty

Cardiorespiratory fitness (CRF) is an independent predictor for all-cause and disease-specific morbidity and mortality. CRF is a modifiable risk factor, and exercise training and increased physical activity, as well as targeted medical therapies, can improve CRF. Although nutrition is a modifiable risk factor for chronic noncommunicable diseases, little is known about the effect of dietary patterns and specific nutrients on modifying CRF. This review focuses specifically on trials that implemented dietary supplementation, modified dietary pattern, or enacted caloric restriction, with and without exercise training interventions, and subsequently measured the effect on peak oxygen consumption (VO₂) or surrogate measures of CRF and functional capacity. Populations selected for this review are those recognized to have a reduced CRF, such as chronic obstructive pulmonary disease, heart failure, obesity, sarcopenia, and frailty. We then summarize the state of existing knowledge and explore future directions of study in disease states recently recognized to have an abnormal CRF.

Low Carbohydrate and Low-Fat Diets: What We Don't Know and Why we Should Know It

In the 1940s, the diet-heart hypothesis proposed that high dietary saturated fat and cholesterol intake promoted coronary heart disease in "at-risk" individuals. This hypothesis prompted federal recommendations for a low-fat diet for "high risk" patients and as a preventive health measure for everyone except infants. The low carbohydrate diet, first used to treat type 1 diabetes, became a popular obesity therapy with the Atkins diet in the 1970s. Its predicted effectiveness was based largely on the hypothesis that insulin is the causa prima of weight gain and regain via hyperphagia and hypometabolism during and after weight reduction, and therefore reduced carbohydrate intake would promote and sustain weight loss. Based on literature reviews, there are insufficient randomized controlled inpatient studies examining the physiological significance of the mechanisms proposed to support one over the other. Outpatient studies can be confounded by poor diet compliance such that the quality and quantity of the energy intake cannot be ascertained. Many studies also fail to separate macronutrient quantity from quality. Overall, there is no conclusive evidence that the degree of weight loss or the duration of reduced weight maintenance are significantly affected by dietary macronutrient quantity beyond effects attributable to caloric intake. Further work is needed.

β2 Adrenergic Regulation of the Phagocytic and Microbicide Capacity of Macrophages from Obese and Lean Mice: Effects of Exercise

Macrophages are crucial in the inflammation associated with obesity. Exercise is the main non-pharmacological strategy against obesity, not only for improving metabolic impairment, but also because of its anti-inflammatory effects, particularly those mediated by β2 adrenergic receptors (β2-AR). Nevertheless, these anti-inflammatory effects could immunocompromise the innate response against pathogen challenge. Thus, the objective of this work was to evaluate the effect of obesity, and of exercise in this condition, on the β2 adrenergic regulation of the innate function of macrophages. High fat diet-induced obese C57BL/6J mice were used to evaluate the effects of acute and regular exercise on the phagocytic and microbicide capacities of peritoneal macrophages. Selective β2-AR agonist terbutaline (1 µM) decreased the phagocytic and microbicide activities of macrophages from control lean and obese sedentary animals. While acute exercise did not modify the inhibitory capacity of terbutaline, regular exercise abolished this inhibitory effect. These effects cannot be explained only by changes in the surface expression of β2-AR. In conclusion, (1) obesity does not alter the β2-AR-mediated decrease of the innate response of macrophages and (2) regular exercise can revert the inhibitory effect of terbutaline on the phagocytic activity of macrophages, although obesity seems to hinder this immunophysiological adaptation.

Practical Guidance for Interventions in Adults with Metabolic Syndrome: Diet and Exercise vs. Changes in Body Composition

(1) Objective: to establish practical guidance for the design of future clinical trials in MS (metabolic syndrome) patients aged 18 and older, based on a systematic review of randomized clinical trials connecting diet, physical exercise and changes in body composition. (2) Method: this systematic review of randomized clinical trials (RCT) is based on the guidelines recommended by PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses). Criteria of selection: ≥18 years of age; patients diagnosed with MS; intervention programs including diet, physical exercise and/or modifications in the style of life as treatment, as well as the magnitude of changes in body composition (BC); randomized clinical trial published between 2004 and 2018. (3) Results: the multidisciplinary interventions describe major changes in BC, and the recurring pattern in these clinical trials is an energy reduction and control in the percentage of intake of macronutrients along with the performance of regularly structured exercise; the most analyzed parameter was waist circumference (88.9% of the trials), followed by body weight (85.2%), BMI (77.8%) and body fat (55.6%). (4) Conclusions: The analysis of the information here reported sheds light for the design of future clinical trials in adults with MS. The best anthropometric parameters and units of measurement to monitor the interventions are related to dietary and physical exercise interventions. A list of practical advice that is easy to implement in daily practice in consultation is here proposed in order to guarantee the best results in changes of body composition.

Weight Loss and Hypertension in Obese Subjects

Arterial hypertension is strongly related to overweight and obesity. In obese subjects, several mechanisms may lead to hypertension such as insulin and leptin resistance, perivascular adipose tissue dysfunction, renal impairment, renin-angiotensin-aldosterone-system activation and sympathetic nervous system activity. Weight loss (WL) seems to have positive effects on blood pressure (BP). The aim of this review was to explain the mechanisms linking obesity and hypertension and to evaluate the main studies assessing the effect of WL on BP. We analysed studies published in the last 10 years (13 studies either interventional or observational) showing the effect of WL on BP. Different WL strategies were taken into account-diet and lifestyle modification, pharmacological intervention and bariatric surgery. Although a positive effect of WL could be identified in each study, the main difference seems to be the magnitude and the durability of BP reduction over time. Nevertheless, further follow-up data are needed: there is still a lack of evidence about long term effects of WL on hypertension. Hence, given the significant results obtained in several recent studies, weight management should always be pursued in obese patients with hypertension.

Sympathetic activity in obesity: a brief review of methods and supportive data

The increase in the prevalence of obesity and the concomitant rise in obesity-related illness have led to substantial pressure on health care systems throughout the world. While the combination of reduced exercise, increased sedentary time, poor diet, and genetic predisposition is undoubtedly pivotal in generating obesity and increasing disease risk, a large body of work indicates that the sympathetic nervous system (SNS) contributes to obesity-related disease development and progression. In obesity, sympathetic nervous activity is regionalized, with activity in some outflows being particularly sensitive to the obese state, whereas other outflows, or responses to stimuli, may be blunted, thereby making the assessment of sympathetic nervous activation in the clinical setting difficult. Isotope dilution methods and direct nerve recording techniques have been developed and utilized in clinical research, demonstrating that in obesity there is preferential activation of the muscle vasoconstrictor and renal sympathetic outflows. With weight loss, sympathetic activity is reduced. Importantly, sympathetic nervous activity is associated with end-organ dysfunction and changes in sympathetic activation that accompany weight loss are often reflected in an improvement of end-organ function. Whether targeting the SNS directly improves obesity-related illness remains unknown, but merits further attention.

Sympathetic nervous system in age-related cardiovascular dysfunction: Pathophysiology and therapeutic perspective

Cardiovascular diseases such as heart failure and metabolic syndrome have high prevalence in the elderly population and are leading causes of death, disability, hospitalization, driving high healthcare costs worldwide. To reduce this social and economic burden there is urgency to find effective therapeutic targets. Several studies have linked the dysfunction of the Sympathetic Nervous System and β-adrenergic receptor signaling with the pathogenesis of age-related cardiovascular diseases. Therapeutic treatments that restore their functions have been shown to be effective in subjects with cardiovascular comorbidities. In fact, lifestyle interventions (such as exercise training and diet) as well as pharmacologic treatments (e.g. β-blockers or moxonidine) and mini-invasive interventions (renal sympathetic denervation) have beneficial effects on age-related cardiovascular diseases. In the current "Medicine in focus" article we will discuss the pathogenic role of the Sympathetic Nervous System in age-related cardiovascular diseases as well as current and new therapeutic approaches.

The Effect of Chronic Exercise Training on Leptin: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Leptin is a hormone associated with satiety, lipid oxidation, energy expenditure, and energy homeostasis. To date, the current body of research examining the effect of chronic exercise training on leptin has yielded inconsistent results.

OBJECTIVE

The purpose of this meta-analysis was to provide a quantitative estimate of the magnitude of change in leptin levels following participation in exercise interventions lasting ≥ 2 weeks.

METHODS

All studies included were peer-reviewed and published in English. To be included, studies randomized human participants to an exercise training group or non-exercise comparison group for an exercise training intervention. Leptin levels were measured at baseline, during, and/or after completion of the exercise training program. Random-effects models were used to aggregate a mean effect size (ES) and 95% confidence intervals (CIs), and identify potential moderators.

RESULTS

Seventy-two randomized controlled trials met the inclusion criteria and resulted in 107 effects (n = 3826). The mean ES of 0.24 (95% CI 0.16-0.32, p < 0.0001) indicated a decrease in leptin following an exercise training program. A decrease in %Fat (β = - 0.07, p < 0.01) was associated with a decrease in leptin after accounting for the type of control group (β = - 0.38, p < 0.0001) used in each study.

CONCLUSION

These results suggest that engaging in chronic exercise training (≥ 2 weeks) is associated with a decrease in leptin levels for individuals regardless of age and sex. However, a greater decrease in leptin occurred with a decreased percentage of body fat.

Diet associated with exercise improves baroreflex control of sympathetic nerve activity in metabolic syndrome and sleep apnea patients

PURPOSE

We tested the hypothesis that (i) diet associated with exercise would improve arterial baroreflex (ABR) control in metabolic syndrome (MetS) patients with and without obstructive sleep apnea (OSA) and (ii) the effects of this intervention would be more pronounced in patients with OSA.

METHODS

Forty-six MetS patients without (noOSA) and with OSA (apnea-hypopnea index, AHI > 15 events/h) were allocated to no treatment (control, C) or hypocaloric diet (- 500 kcal/day) associated with exercise (40 min, bicycle exercise, 3 times/week) for 4 months (treatment, T), resulting in four groups: noOSA-C (n = 10), OSA-C (n = 12), noOSA-T (n = 13), and OSA-T (n = 11). Muscle sympathetic nerve activity (MSNA), beat-to-beat BP, and spontaneous arterial baroreflex function of MSNA (ABR_MSNA, gain and time delay) were assessed at study entry and end.

RESULTS

No significant changes occurred in C groups. In contrast, treatment in both patients with and without OSA led to a significant decrease in weight (P < 0.05) and the number of MetS factors (P = 0.03). AHI declined only in the OSA-T group (31 ± 5 to 17 ± 4 events/h, P < 0.05). Systolic BP decreased in both treatment groups, and diastolic BP decreased significantly only in the noOSA-T group. Treatment decreased MSNA in both groups. Compared with baseline, ABR_MSNA gain increased in both OSA-T (13 ± 1 vs. 24 ± 2 a.u./mmHg, P = 0.01) and noOSA-T (27 ± 3 vs. 37 ± 3 a.u./mmHg, P = 0.03) groups. The time delay of ABR_MSNA was reduced only in the OSA-T group (4.1 ± 0.2 s vs. 2.8 ± 0.3 s, P = 0.04).

CONCLUSIONS

Diet associated with exercise improves baroreflex control of sympathetic nerve activity and MetS components in patients with MetS regardless of OSA.

Inverse association between sympathetic nervous system activity and bone mass in middle aged overweight individuals

BACKGROUND/PURPOSE

Sympathetic nervous system activation in obesity is associated with impaired cardiovascular and metabolic function. Animal studies have shown a direct link between sympathetic nervous activation and bone health but little is known about this link in humans. This study examined whether sympathetic activation may impact bone health in overweight adults.

METHODS

This cross sectional study included 96 overweight or obese middle-aged adults (51 males, mean body mass index: 32.8 kg/m², mean age: 55.3 years). Multivariate linear regression models evaluated associations between whole body and leg bone mineral density (BMD) and bone mineral content (BMC) derived from dual-energy X-ray absorptiometry and muscle sympathetic nervous system activity (MSNA) measured by microneurography.

RESULTS

Older age, male sex and higher weight were associated with higher leg and body BMC and BMD. After adjustment for age, sex and weight, MSNA was significantly inversely associated with total BMC (p = 0.012) and with leg BMC (p < 0.01) but was not associated with either total or leg BMD (p = 0.159 and p = 0.063 respectively). When the analysis was sex specific, the relationships between MSNA and total and leg BMC were only significant in males.

CONCLUSIONS

Our study indicates that in middle aged overweight or obese males, sympathetic activation may have a deleterious effect on bone mineral content.

Aerobic, resistance or combined training: A systematic review and meta-analysis of exercise to reduce cardiovascular risk in adults with metabolic syndrome

BACKGROUND AND AIMS

Exercise is beneficial to individuals with metabolic syndrome (MetS). An understudied group, who represent the majority of the MetS population, are individuals who have not developed diabetes. This review examined aerobic, resistance and combined (aerobic + resistance) exercise for cardiovascular risk factors in MetS without diabetes.

METHODS

Eight electronic databases were searched up to September 2017 for randomised controlled trials >4 weeks in duration that compared an exercise intervention to the non-exercise control in MetS without diabetes. MetS criteria, cardiorespiratory fitness and cardiovascular risk factors were meta-analysed in a random effects model.

RESULTS

Eleven studies with 16 interventions were included (12 aerobic, 4 resistance). Aerobic exercise significantly improved waist circumference -3.4 cm (p < 0.01), fasting glucose -0.15 mmol/L (p = 0.03), high-density cholesterol 0.05 mmol/L (p = 0.02), triglycerides -0.29 mmol/L (p < 0.01), diastolic blood pressure -1.6 mmHg (p = 0.01), and cardiorespiratory fitness 4.2 ml/kg/min (p < 0.01), among other outcomes. No significant effects were determined following resistance exercise possibly due to limited data. Sub-analyses suggested that aerobic exercise progressed to vigorous intensity, and conducted 3 days/week for ≥12 weeks offered larger and more widespread improvements.

CONCLUSIONS

Aerobic exercise following current guidelines offers widespread benefits to individuals with MetS without diabetes. More studies on resistance/combined exercise programs in MetS are required to improve the quality of evidence.

The effect of exercise training on clinical outcomes in patients with the metabolic syndrome: a systematic review and meta-analysis

Background

Purpose: to establish if exercise training improves clinical outcomes in people with metabolic syndrome (MetS). Registered with PROSPERO international prospective register of systematic reviews (https://www.crd.york.ac.uk/PROSPERO/Identifier:CRD42017055491). Data sources: studies were identified through a MEDLINE search strategy (1985 to Jan 12, 2017), Cochrane controlled trials registry, CINAHL and SPORTDiscus. Study selection: prospective randomized or controlled trials of exercise training in humans with metabolic syndrome, lasting 12 weeks or more.

Results

We included 16 studies with 23 intervention groups; 77,000 patient-hours of exercise training. In analyses of aerobic exercise studies versus control: body mass index was significantly reduced, mean difference (MD) −0.29 (kg m⁻²) (95% CI −0.44, −0.15, p < 0.0001); body mass was significantly reduced, MD −1.16 kg (95% CI −1.83, −0.48, p = 0.0008); waist circumference was significantly reduced MD −1.37 cm (95% CI −2.02, −0.71, p < 0.0001), peak VO₂ was significantly improved MD 3.00 mL kg⁻¹ min⁻¹ (95% CI 1.92, 4.08, p < 0.000001); systolic blood pressure and diastolic blood pressure were significantly reduced, MD −2.54 mmHg (95% CI −4.34, −0.75, p = 0.006), and, MD −2.27 mmHg (95% CI −3.47, −1.06, p = 0.0002) respectively; fasting blood glucose was significantly reduced MD −0.16 mmol L⁻¹ (95% CI −0.32, −0.01, p = 0.04); triglycerides were significantly reduced MD −0.21 mmol L⁻¹ (95% CI −0.29, −0.13, p < 0.00001); and low density lipoprotein was significantly reduced MD −0.03 mmol L⁻¹ (95% CI −0.05, −0.00, p = 0.02). In analyses of combined exercise versus control: waist circumference, MD −3.80 cm (95% CI −5.65, −1.95, p < 0.0001); peak VO₂ MD 4.64 mL kg⁻¹ min⁻¹ (95% CI 2.42, 6.87, p < 0.0001); systolic blood pressure MD −3.79 mmHg (95% CI −6.18, −1.40, p = 0.002); and high density lipoprotein (HDL) MD 0.14 (95% CI 0.04, 0.25, p = 0.009) were all significantly improved. We found no significant differences between outcome measures between the two exercise interventions.

Conclusions

Exercise training improves body composition, cardiovascular, and, metabolic outcomes in people with metabolic syndrome. For some outcome measures, isolated aerobic exercise appears optimal.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0590-y) contains supplementary material, which is available to authorized users.

The effects of body weight status on orthostatic intolerance and predisposition to noncardiac syncope

Orthostatic intolerance (OI) is frequently the mechanism underlying the occurrence of noncardiac syncope (NCS) and is associated with substantial risk for injury. Body weight status appears to be a modifier of orthostatic responses and possibly influences the propensity to NCS. The majority of cross-sectional studies have found that the lower the body mass index (BMI) the greater the predisposition to OI is, accompanied with both down-regulation of sympathetic nervous system activity and up-regulation of parasympathetic nervous system activity. These changes appear to occur across the whole spectrum of BMI values from underweight to obesity, while they may be associated more strongly with central body fat than total body fat. Weight loss following bariatric surgery has been consistently found to increase OI, attributed first to the effects of weight loss per se, second to the specific type of surgical procedure and third to the potential postoperative autonomic neuropathy due to vitamin deficiency. The increased OI following bariatric surgery renders this intervention not easily tolerable for the affected individuals, mandating increased fluid and salt intake, pharmacological measures or surgical adjustments to attenuate OI. All future studies investigating orthostatic responses and NCS should implement a matching of the population arms for BMI and ideally for body fat.

Muscle Sympathetic Nerve Activity Is Associated with Liver Insulin Sensitivity in Obese Non-Diabetic Men

Introduction: Muscle sympathetic nerve activity (MSNA) may play a role in insulin resistance in obesity. However, the direction and nature of the relationship between MSNA and insulin resistance in obesity remain unclear. We hypothesized that resting MSNA would correlate inversely with both muscle and liver insulin sensitivity and that it would be higher in insulin-resistant vs. insulin-sensitive subjects. Materials and methods: Forty-five non-diabetic obese subjects were studied. As no significant relationships were found in women, the data presented in on 22 men aged 48 ± 12 years. Two-step (15 and 80 mU/m2/min) hyperinsulinaemic-euglycaemic clamps were performed using deuterated glucose to determine liver and muscle insulin sensitivity. Clinical and metabolic parameters were assessed. MSNA was measured via a microelectrode inserted percutaneously into the common peroneal nerve. Results: MSNA burst frequency correlated inversely with liver insulin sensitivity (r = -0.53, P = 0.02) and positively with the hepatokines C-reactive protein (CRP) and fibroblast growth factor (FGF)-19 (r = 0.57, P = 0.006, and r = -0.47, P = 0.03, respectively). MSNA burst frequency was lower in Liversen compared to Liverres (27 ± 5 vs. 38 ± 2 bursts per minute; P = 0.03). Muscle insulin sensitivity was unrelated to MSNA. Discussion: Sympathetic neural activation is related to liver insulin sensitivity and circulating hepatokines CRP and FGF-19 in non-diabetic obese men. These results suggest a potential hepato-endocrine-autonomic axis. Future studies are needed to clarify the influence of MSNA on liver insulin sensitivity in men.

Markers of sympathetic nervous system activity associate with complex plasma lipids in metabolic syndrome subjects

BACKGROUND AND AIMS

Plasma sphingolipids including ceramides, and gangliosides are associated with insulin resistance (IR) through effects on insulin signalling and glucose metabolism. Our studies of subjects with metabolic syndrome (MetS) showed close relationships between IR and sympathetic nervous system (SNS) activity including arterial norepinephrine (NE). We have therefore investigated possible associations of IR and SNS activity with complex lipids that are involved in both insulin sensitivity and neurotransmission.

METHODS

We performed a cross-sectional assessment of 23 lipid classes/subclasses (total 339 lipid species) by tandem mass spectrometry in 94 overweight untreated subjects with IR (quantified by HOMA-IR, Matsuda index and plasma insulin).

RESULTS

Independently of IR parameters, several circulating complex lipids associated significantly with arterial NE and NEFA (non-esterified fatty acids) and marginally with heart rate (HR). After accounting for BMI, HOMA-IR, systolic BP, age, gender, and correction for multiple comparisons, these associations were significant (p < 0.05): NE with ceramide, phosphatidylcholine, alkyl- and alkenylphosphatidylcholine and free cholesterol; NEFA with mono- di- and trihexosylceramide, G_M3 ganglioside, sphingomyelin, phosphatidylcholine, alkyl- and alkenylphosphatidylcholine, phosphatidylinositol and free cholesterol; HR marginally (p = or <0.1>0.05) with ceramide, G_M3 ganglioside, sphingomyelin, lysophosphatidylcholine, phosphatidylinositol, lysophosphatidylinositol and free cholesterol. Multiple subspecies of these lipids significantly associated with NE and NEFA. None of the IR biomarkers associated significantly with lipid classes/subclasses after correction for multiple comparisons.

CONCLUSIONS

This is the first demonstration that arterial norepinephrine and NEFA, that reflect both SNS activity and IR, associate significantly with circulating complex lipids independently of IR, suggesting a role for such lipids in neural mechanisms operating in MetS.

Potential role of endurance training in altering renal sympathetic nerve activity in CKD?

Chronic kidney disease (CKD), is characterized by a progressive loss of renal function and increase in cardiovascular risk. In this review paper, we discuss the pathophysiology of increased sympathetic nerve activity in CKD patients and raise the possibility of endurance exercise being an effective countermeasure to address this problem. We specifically focus on the potential role of endurance training in altering renal sympathetic nerve activity as increased renal sympathetic nerve activity negatively impacts kidney function as well indirectly effects multiple other systems and organs. Recent technological advances in device based therapy have highlighted the detrimental effect of elevated renal sympathetic nerve activity in CKD patients, with kidney function and blood pressure being improved post renal artery nerve denervation in selected patients. These developments provide optimism for the development of alternative and/or complementary strategies to lower renal sympathetic nerve activity. However, appropriately designed studies are required to confirm preliminary observations, as the widespread use of the renal denervation approach to lower sympathetic activity presently has limited feasibility. Endurance training may be one alternative strategy to reduce renal sympathetic nerve activity. Here we review the role of endurance training as a potential alternative or adjunctive to current therapy in CKD patients. We also provide recommendations for future research to assist in establishing an evidence base for the use of endurance training to lower renal sympathetic activity in CKD patients.

Comparable Attenuation of Sympathetic Nervous System Activity in Obese Subjects with Normal Glucose Tolerance, Impaired Glucose Tolerance, and Treatment Naïve Type 2 Diabetes following Equivalent Weight Loss

Background and Purpose: Elevated sympathetic nervous system (SNS) activity is a characteristic of obesity and type 2 diabetes (T2D) that contributes to target organ damage and cardiovascular risk. In this study we examined whether baseline metabolic status influences the degree of sympathoinhibition attained following equivalent dietary weight loss.

Methods: Un-medicated obese individuals categorized as normal glucose tolerant (NGT, n = 15), impaired glucose tolerant (IGT, n = 24), and newly-diagnosed T2D (n = 15) consumed a hypocaloric diet (29% fat, 23% protein, 45% carbohydrate) for 4-months. The three groups were matched for baseline age (56 ± 1 years), body mass index (BMI, 32.9 ± 0.7 kg/m²), and gender. Clinical measurements included whole-body norepinephrine kinetics, muscle sympathetic nerve activity (MSNA, by microneurography), spontaneous cardiac baroreflex sensitivity (BRS), and oral glucose tolerance test.

Results: Weight loss averaged −7.5 ± 0.8, −8.1 ± 0.5, and −8.0 ± 0.9% of body weight in NGT, IGT, and T2D groups, respectively. T2D subjects had significantly greater reductions in fasting glucose, 2-h glucose and glucose area under the curve (AUC₀₋₁₂₀) compared to NGT and IGT (group effect, P <0.001). Insulinogenic index decreased in IGT and NGT groups and increased in T2D (group × time, P = 0.04). The magnitude of reduction in MSNA (−7 ± 3, −8 ± 4, −15 ± 4 burst/100 hb, respectively) and whole-body norepinephrine spillover rate (−28 ± 8, −18 ± 6, and −25 ± 7%, respectively), time effect both P <0.001, did not differ between groups. After adjustment for age and change in body weight, Δ insulin AUC₀₋₁₂₀ was independently associated with reduction in arterial norepinephrine concentration, whilst Δ LDL-cholesterol and improvement in BRS were independently associated with decrease in MSNA.

Conclusions: Equivalent weight loss through hypocaloric diet is accompanied by similar sympathoinhibition in matched obese subjects with different baseline glucose tolerance. Attenuation of hyperinsulinemia and hyperlipidemia, rather than glycemic indices, is associated with reduction in SNS activity following weight loss intervention.

Adrenergic signaling in heart failure and cardiovascular aging

Both cardiovascular disease and aging are associated with changes in the sympathetic nervous system. Indeed, mounting evidence indicates that adrenergic receptors are functionally involved in numerous processes underlying both aging and cardiovascular disorders, in particular heart failure. This article will review the pathophysiological role of the sympathetic nervous system in heart failure and cardiovascular aging.