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

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.

Effects of different treatments on metabolic syndrome in patients with obstructive sleep apnea: a meta-analysis

Background

Obstructive sleep apnea (OSA) and metabolic syndrome (MetS) often coexist, and the causal relationship between them is not yet clear; treatments for OSA include continuous positive airway pressure (CPAP), mandibular advancement device (MAD), surgery, and lifestyle intervention and so on. However, the effects of different treatments on metabolic syndrome in OSA patients are still under debate.

Objectives

Review the effects of different treatments on metabolic syndrome in OSA patients by meta-analysis.

Methods

we searched articles in PubMed, Embase, Cochrane Library, CNKI, CBM, and Wanfang data from database construction to Feb. 2024.RevMan5.4 and Stata software were used to conduct a meta-analysis of 22 articles.

Results

A total of 22 articles were finally included. The results showed that CPAP treatment could reduce the prevalence of metabolic syndrome in OSA patients in randomized controlled trials (RCTs) (RR = 0.82 [95% CI, 0.75 to 0.90]; p < 0.01) and single-arm studies (RR = 0.73 [95% CI, 0.63 to 0.84]; p < 0.01). As for metabolic syndrome components, CPAP treatment reduces blood pressure, fasting glucose (FG), triglycerides (TG), and waist circumference (WC) but can't affect high-density lipoprotein cholesterol (HDL-C) levels. Lifestyle intervention could significantly reduce the prevalence of metabolic syndrome in OSA patients (RR = 0.60 [95% CI, 0.48 to 0.74]; p < 0.01) and can lower blood pressure, fasting glucose, and waist circumference but can't affect the lipid metabolism of OSA patients. Upper airway surgery can only reduce TG levels in OSA patients (MD = -0.74 [95% CI, -1.35 to -0.13]; p = 0.02) and does not affect other components of metabolic syndrome. There is currently no report on the impact of upper airway surgery on the prevalence of metabolic syndrome. No study has reported the effect of MAD on metabolic syndrome in OSA patients.

Conclusion

We confirmed that both CPAP and lifestyle intervention can reduce the prevalence of MetS in OSA patients. CPAP treatment can lower blood pressure, fasting glucose, waist circumference, and triglyceride levels in OSA patients. Lifestyle intervention can lower blood pressure, fasting glucose, and waist circumference in OSA patients. Upper airway surgery can only reduce TG levels in OSA patients.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022326857.

Influence of Obstructive Sleep Apnea Severity on Muscle Sympathetic Nerve Activity and Blood Pressure: a Systematic Review and Meta-Analysis

BACKGROUND

We conducted meta-analyses to identify relationships between obstructive sleep apnea (OSA) severity, muscle sympathetic nerve activity (MSNA), and blood pressure (BP). We quantified the effect of OSA treatment on MSNA.

METHODS

Structured searches of electronic databases were performed until June 2021. All observational designs (except reviews) were included: population (individuals with OSA); exposures (OSA diagnosis and direct measures of MSNA); comparator (individuals without OSA or different severity of OSA); outcomes (MSNA, BP, and heart rate).

RESULTS

Fifty-six studies (N=1872) were included. MSNA burst frequency was higher in OSA (27 studies; n=542) versus controls (n=488; mean differences [MDs], +15.95 bursts/min [95% CI, 12.6-17.6 bursts/min]; I²=86%). As was burst incidence (20 studies; n=357 OSA, n=312 Controls; MD, +22.23 bursts/100 hbs [95% CI, 18.49-25.97 bursts/100 hbs]; I²=67%). Meta-regressions indicated relationships between MSNA and OSA severity (burst frequency, R²=0.489; P<0.001; burst incidence, R²=0.573; P<0.001). MSNA burst frequency was related to systolic pressure (R²=0.308; P=0.016). OSA treatment with continuous positive airway pressure reduced MSNA burst frequency (MD, 11.91 bursts/min [95% CI, 9.36-14.47 bursts/min] I²=15%) and systolic (n=49; MD, 10.3 mm Hg [95% CI, 3.5-17.2 mm Hg]; I²=42%) and diastolic (MD, 6.9 mm Hg [95% CI, 2.3-11.6 mm Hg]; I²=37%) BP.

CONCLUSIONS

MSNA is higher in individuals with OSA and related to severity. This sympathoexcitation is also related to BP in patients with OSA. Treatment effectively reduces MSNA and BP, but limited data prevents an assessment of the link between these reductions. These data are clinically important for understanding cardiovascular disease risk in patients with OSA.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: CRD42021285159.

Sympathetic neural responses to sleep disorders and insufficiencies

Short sleep duration and poor sleep quality are associated with cardiovascular risk, and sympathetic nervous system (SNS) dysfunction appears to be a key contributor. The present review will characterize sympathetic function across several sleep disorders and insufficiencies in humans, including sleep deprivation, insomnia, narcolepsy, and obstructive sleep apnea (OSA). We will focus on direct assessments of sympathetic activation, e.g., plasma norepinephrine and muscle sympathetic nerve activity, but include heart rate variability (HRV) when direct assessments are lacking. The review also highlights sex as a key biological variable. Experimental models of total sleep deprivation and sleep restriction are converging to support several epidemiological studies reporting an association between short sleep duration and hypertension, especially in women. A systemic increase of SNS activity via plasma norepinephrine is present with insomnia and has also been confirmed with direct, regionally specific evidence from microneurographic studies. Narcolepsy is characterized by autonomic dysfunction via both HRV and microneurographic studies but with opposing conclusions regarding SNS activation. Robust sympathoexcitation is well documented in OSA and is related to baroreflex and chemoreflex dysfunction. Treatment of OSA with continuous positive airway pressure results in sympathoinhibition. In summary, sleep disorders and insufficiencies are often characterized by sympathoexcitation and/or sympathetic/baroreflex dysfunction, with several studies suggesting women may be at heightened risk.

Interplay between baroreflex sensitivity, obesity and related cardiometabolic risk factors (Review)

The baroreflex represents a rapid negative feedback system implicated in blood pressure regulation, which aims to prevent blood pressure variations by regulating peripheral vascular tone and cardiac output. The aim of the present review was to highlight the association between baroreflex sensitivity (BRS) and obesity, including factors associated with obesity, such as metabolic syndrome, hypertension, cardiovascular disease and diabetes. For the present review, a literature search was conducted using the PubMed database until August 21, 2021. The searched terms included ‘baroreflex’, and other terms such as ‘sensitivity’, ‘obesity’, ‘metabolic syndrome’, ‘hypertension’, ‘diabetes’, ‘gender’, ‘aging’, ‘children’, ‘adolescents’, ‘physical activity’, ‘bariatric surgery’, ‘autonomous nervous system’ and ‘cardiometabolic risk factors’. Obesity and its related metabolic disorders can influence baroreflex functionality and decrease BRS, mostly by potentiating sympathetic nervous system activity. Obesity induces inflammation, which can increase sympathetic system activity and lead to a higher incidence of cardiovascular events. Obesity also represents an important risk factor for hypertension through numerous mechanisms; in this setting, dysfunctional baroreceptors are not able to protect against constantly elevated blood pressure. Furthermore, diabetes mellitus and oxidative stress result in deterioration of BRS, whereas aging is also generally related to reduced cardiovagal BRS. Differences in BRS have also been observed between men and women, and overall cardiovagal BRS in healthy women is less intense compared with that in men. BRS appears lower in children with obesity compared with that in children of a healthy weight. Notably, physical exercise can increase BRS in both hypertensive and normotensive subjects, and BRS can also be significantly improved following bariatric surgery and weight loss. In conclusion, obesity and its related metabolic disorders may influence baroreflex functionality and decrease BRS, and baroreceptors cannot protect against the constantly elevated blood pressure in obesity. However, following bariatric surgery and weight loss, BRS can be significantly improved. The present review summarizes the role of obesity and related metabolic risk factors in BRS, providing details on possible mechanisms and shedding light on their interplay leading to autonomic neuropathy.

Exercise training reduces sympathetic nerve activity and improves executive performance in individuals with obstructive sleep apnea

OBJECTIVE

To investigate the effects of exercise training (ET) on muscle sympathetic nerve activity (MSNA) and executive performance during Stroop Color Word Test (SCWT) also referred to as mental stress test.

METHODS

Forty-four individuals with obstructive sleep apnea (OSA) and no significant co-morbidities were randomized into 2 groups; 15 individuals completed the control period, and 18 individuals completed the ET. Mini-mental state of examination and intelligence quotient were also assessed. MSNA assessed by microneurography, heart rate by electrocardiography, blood pressure (automated oscillometric device) were measured at baseline and during 3 min of the SCWT. Peak oxygen uptake (VO2 peak) was evaluated using cardiopulmonary exercise testing. Executive performance was assessed by the total correct responses during 3 min of the SCWT. ET consisted of 3 weekly sessions of aerobic exercise, resistance exercises, and flexibility (72 sessions, achieved in 40±3.9 weeks).

RESULTS

Baseline parameters were similar between groups. Heart rate, blood pressure, and MSNA responses during SCWT were similar between groups (p>0.05). The comparisons between groups showed that the changes in VO2 (4.7±0.8 vs -1.2±0.4) and apnea-hypopnea index (-7.4±3.1 vs 5.5±3.3) in the exercise-trained group were significantly greater than those observed in the control group respectively (p<0.05) after intervention. ET reduced MSNA responses (p<0.05) and significantly increased the number of correct answers (12.4%) during SCWT. The number of correct answers was unchanged in the control group (p>0.05).

CONCLUSIONS

ET improves sympathetic response and executive performance during SCWT, suggesting a prominent positive impact of ET on prefrontal functioning in individuals with OSA. ClinicalTrials.gov: NCT002289625.

Cardiac and Peripheral Autonomic Responses to Orthostatic Stress During Transcutaneous Vagus Nerve Stimulation in Healthy Subjects

Previous studies showed that transcutaneous vagus nerve stimulation (tVNS) modulates the autonomic nervous system (ANS) in resting condition. However, the autonomic regulation in response to an orthostatic challenge during tVNS in healthy subjects remains unknown. We tested the hypothesis that tVNS reduces heart rate (HR) and alters the responsivity of ANS to orthostatic stress in healthy subjects. In a randomized and cross-over trial, thirteen healthy subjects underwent two experimental sessions on different days: (1) tVNS and (2) control. Using a tVNS device, an auricular electrode was placed on the left cymba conchae of the external ear; an electric current with a pulse frequency of 25 Hz and amplitude between 1 and 6 mA was applied. For the assessment of ANS, the beat-to-beat HR and systolic arterial pressure (SAP) were analyzed using linear and nonlinear approaches during clinostatic and orthostatic conditions. In clinostatic conditions, tVNS reduced HR (p < 0.01), SAP variability (p < 0.01), and cardiac and peripheral sympathetic modulation (p < 0.01). The responsivity of the peripheral sympathetic modulation to orthostatic stress during tVNS was significantly higher when compared to the control session (p = 0.03). In conclusion, tVNS reduces the HR and affects cardiac and peripheral autonomic control and increases the responses of peripheral autonomic control to orthostatic stress in healthy subjects.

Reported obstructive sleep apnea does not diminish the cardiometabolic health benefits from a comprehensive lifestyle intervention program

Obstructive sleep apnea (OSA) commonly coexists with the metabolic syndrome, a condition for which behavioral changes are often prescribed. Whether OSA diminishes the cardiometabolic health benefits from lifestyle interventions remains unclear. We evaluated 278 consecutive metabolic syndrome participants enrolled in a 12-week comprehensive lifestyle intervention program. The changes in blood pressure (BP), along with other metabolic health parameters, from baseline to follow-up were compared between those with and without OSA. Mean age was 52.4 ± 10.9 years and 37% were male. At enrollment, mean body mass index (BMI) was 38.2 ± 7.7 kg/m² . OSA was reported in 126 of 269 final participants (47%). At baseline, participants with reported OSA were more likely to be male, older, have a higher BMI, waist and neck size (all P < 0.05). At program completion, participants with (-5.8 ± 16.1/-3.0 ± 10.0 mm Hg) and without OSA (-4.7 ± 13.1/-3.3 ± 8.2 mm Hg) had significant reductions in systolic and diastolic BP as well as BMI, fasting glucose, and triglyceride levels. There were no significant differences in the absolute or percentage changes in BP or other metabolic parameters between groups. Our findings support that patients with the metabolic syndrome can derive substantial health benefits, including reductions in BP, by a lifestyle intervention program regardless of the presence of OSA.