Blunted heart rate recovery is improved following exercise training in overweight adults with obstructive sleep apnea

Weight loss and lifestyle intervention for cardiorespiratory fitness in obstructive sleep apnea: The INTERAPNEA trial

INTRODUCTION

Although recent trials have shown benefits of weight loss and lifestyle interventions on obstructive sleep apnea (OSA) severity and comorbidities, the effect of these interventions on cardiorespiratory fitness (CRF) remains unknown. This study aimed to investigate the effects of an interdisciplinary weight loss and lifestyle intervention on CRF and self-reported physical fitness in adults with OSA.

METHODS

Eighty-nine men aged 18-65 years with moderate-to-severe OSA and a body mass index ≥25 kg/m2 were randomly assigned to a usual-care group or an 8-week interdisciplinary weight loss and lifestyle intervention. CRF was assessed through the 2-km walking test, and the International Fitness Scale (IFIS) was used to assess self-reported physical fitness.

RESULTS

As compared with usual-care, the intervention group had greater improvements at intervention endpoint in objective CRF (6% reduction in 2-km walking test total time, mean between-group difference, -1.7 min; 95% confidence interval, -2.3 to -1.1), and self-reported overall physical fitness (18% increase in IFIS total score, mean between-group difference, 2.3; 95% CI 1.2 to 3.3). At 6 months after intervention, the intervention group also had greater improvements in both 2-km walking test total time (10% reduction) and IFIS total score (22% increase), with mean between-group differences of -2.5 (CI 95%, -3.1 to -1.8) and 3.0 (CI 95%, 1.8 to 4.1), respectively.

CONCLUSIONS

An 8-week interdisciplinary weight loss and lifestyle intervention resulted in significant and sustainable improvements in CRF and self-reported physical fitness in men with overweight/obesity and moderate-to-severe OSA.

STUDY REGISTRATION

ClinicalTrials.gov registration (NCT03851653).

Exercise training affects hemodynamics and exercise capacity in cases of heart failure with preserved ejection fraction: a non-randomized controlled trial in individuals aged 65-80 years

Introduction

Exercise training is an established intervention method for improving exercise capacity and survival rates in patients with heart failure with preserved ejection fraction (HFpEF). However, most reports have focused on European and American patients, with limited data regarding the effects of exercise training on cardiac function, hemodynamics, and exercise capacity in East Asian patients. This study investigated the effects of exercise training on cardiac function, hemodynamics, and exercise capacity in Japanese patients aged 65-80 years with HFpEF.

Methods

This single-center, open-label, non-randomized, controlled trial prospectively enrolled 99 outpatients. Eligibility criteria for HFpEF patients were an HFA score ≥5 in addition to clinical symptoms of heart failure and left ventricular diastolic dysfunction. Exercise training in the intervention group consisted of aerobic exercise and strength training thrice weekly for 5 months. Patients in the control group continued the usual treatment for 5 months. Resting cardiac function was evaluated using echocardiography. Peak oxygen uptake (peakVO2), ventilatory equivalent (VE) vs. carbon dioxide output (VCO2) slope, peak cardiac output index, and arteriovenous oxygen difference were calculated using cardiopulmonary exercise testing combined with impedance cardiography.

Results

After 5 months of exercise training, remarkable interactions were observed, with peakVO2 as the primary outcome. Additionally, significant interactions were observed between hemodynamic indices and some echocardiographic parameters. The mean percentage change in peakVO2 from baseline was 8.3% in the intervention group. Fifteen study participants (30.1%) in the intervention group achieved a clinically meaningful change of 3.0 ml/min/kg (10% improvement) in peakVO2 from baseline. The group with 3.0 ml/min/kg or 10% improvement in peakVO2 from baseline had a considerably lower prevalence of diabetes mellitus and VE vs. VCO2 slope and considerably higher left atrial-global longitudinal strain values than the group without any notable improvements.

Conclusions

Although exercise training can help improve exercise intolerance in Japanese patients aged 65-80 years with HFpEF, its benefits are limited. Our results suggest that HFpEF, complicated by diabetes mellitus and decreased ventilatory efficiency during exercise, may require reconsideration of intervention strategies. This trial was registered with the University Hospital Medical Information Network, a trial registry in Japan (registration number: UMIN000045474).

Cardiovascular capacity in adults with obstructive sleep apnoea

BACKGROUND: Obstructive sleep apnoea (OSA) patients have a decreased exercise capacity. Potential cardiovascular capacity in patients with OSA with different severity without known cardiovascular disease has not been described.OBJECTIVE: To evaluate impaired potential exercise cardiovascular capacity during cardiopulmonary exercise testing (CPET) in OSA patients and to compare cardiovascular performance reaction with different severity during graded exercise stages.DESIGN: All participants were accompanied without cardiovascular disease, especially hypertension and arrhythmia. Parameters of different stages were compared between subjects with and without OSA, and among OSA patients with varied severity.RESULTS: Despite having significantly higher peak exercise diastolic blood pressure (DBP) and ventilatory equivalent for CO2 (EQCO₂), patients with OSA had a lower peak oxygen uptake (VO₂), heart rate (HR), heart rate recovery (HRR) and respiratory reserve (BR) than normal subjects. Furthermore, significant correlations were found between VO₂, DBP, EQCO₂, HRR, BR and the apnoea-hypopnea index. In severe OSA, there was a greater difference in HR and HRR during the anaerobic threshold stages.CONCLUSIONS: OSA patients demonstrate reduced potential cardiovascular capacity, even without documented cardiovascular disease. Patients with severe OSA develop impaired exercise capacity at early stage during exercise. These data point to exaggerated haemodynamic response to graded exercise and delayed post-exercise cardiovascular response recovery in OSA patients. CPET can be a supplement for assessment of OSA severity.

Exercise capacity remains supernormal, though mildly reduced in middle-aged military personnel with Moderate to Severe Obstructive Sleep Apnea

INTRODUCTION

The relationship between moderate to severe OSA and exercise capacity remains unclear. Prior studies showing a reduction in VO₂ max in this population have mostly involved middle-aged, overweight patients. We aimed to study this relationship in a similarly aged population of military personnel with previously undiagnosed moderate to severe OSA.

METHODS

We studied late-career male military personnel who underwent CPET and polysomnography (PSG). Patients were categorized either into an OSA group (apnea-hypopnea index (AHI) ≥ 15 events/h) or a control group (AHI < 15 events/h). VO₂ max was compared between groups.

RESULTS

170 male military personnel met criteria for the study. Mean AHI was 29.0/h in the OSA group (n = 58) versus 7.4/h in the controls (n = 112) while SpO₂ nadir was slightly lower (86.0% vs. 89.0%). Patients were of similar age (53.1 vs. 53.7 years), and BMI was slightly higher in the OSA group (27.5 kg/m² vs. 26.3 kg/m²). Percent-predicted VO₂ max was supernormal in both groups, though it was comparatively lower in the OSA group (117% vs. 125%; p < 0.001).

CONCLUSIONS

Military personnel with moderate to severe OSA were able to achieve supernormal VO₂ max values, yet had an 8% decrement in exercise capacity compared to controls. These findings suggest that OSA without significant hypoxemia may not significantly influence exercise capacity. It remains likely that the effects of untreated OSA on exercise capacity are complex and are affected by several variables including BMI, degree of associated hypoxemia, and regularity of exercise. Statistically lower VO₂ max noted in this study may suggest that untreated OSA in less fit populations may lead to significant decrements in exercise capacity.

Effect of exercise training on body composition in patients with obstructive sleep apnea: a systematic review and meta-analysis

Reduction in adiposity is considered a cornerstone in the treatment of obstructive sleep apnea (OSA). Exercise training is one of the interventions used in the treatment of OSA. However, it remains unclear whether exercise training alleviates OSA by improving body composition. This study aimed to verify the effect of exercise training on body composition and the apnea-hypopnea index (AHI) in patients with OSA. This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered in PROSPERO. PubMed/Medline, Scopus, and Cochrane databases were used for systematic review. Analyses were performed using Review Manager software (version 5.3; R Foundation for Statistical Computing, Vienna, Austria). Exercise training significantly reduced body mass index (mean difference = -0.55 kg/m²; 95% CI = -0.95 to -0.15), body fat percentage (mean difference = -1.19%; 95% CI = -2.03 to -0.35), neck circumference (mean difference = -0.55 cm; 95% CI = -1.08 to -0.02), total body weight (mean difference = -2.13 kg; 95% CI = -4.30 to 0.04), and AHI -8.06 events/hour; 95% CI = -10.47 to -5.66). Although body composition was improved by exercise, this improvement was clinically small. Moreover, improvement in AHI by exercise may not be entirely due to improvements in adiposity. PROSPERO #: CRD42020210509.

Effects of short-term aerobic training versus CPAP therapy on heart rate variability in moderate to severe OSA patients

We compared the effects of 2-month CPAP or exercise training (ET) therapies on the autonomic balance in moderate to severe obstructive sleep apnea (OSA) through heart rate variability (HRV) analysis. Thirty-nine OSA patients were divided into CPAP (n = 18) and ET (n = 21) groups, being further split into hypertensive and non-hypertensive subgroups. All patients were submitted to continuous ECG recordings for HRV analysis. Hemodynamic parameters were recorded by oscillometry. Excessive daytime sleepiness and sleep quality were assessed through the Epworth Sleepiness Scale and the Pittsburgh questionnaire, respectively. ET decreased systolic arterial pressure in hypertensive and non-hypertensive participants when compared to baseline values, whereas diastolic arterial pressure was decreased only in non-hypertensive ones. CPAP had no effect over hemodynamic parameters in either subgroup. ET significantly increased the HRV parameters SDNN and pNN50 in non-hypertensive participants, while reducing the LF/HF ratio in both subgroups. CPAP significantly decreased SDNN in both subgroups. ET significantly decreased excessive daytime sleepiness in both subgroups, but did not affect sleep quality. CPAP significantly improved sleep quality in both subgroups, although global scores were still those of poor sleepers, while excessive daytime sleepiness was normalized only in hypertensive patients. In conclusion, while short-term ET modulated different HRV parameters, leading to a predominant vagal tone in the cardiac sympathovagal balance and decreasing blood pressure in moderate to severe OSA, short-term CPAP had next to no effect in these parameters. We believe ET should be considered as an adjunct interventional strategy in the conservative management of hypertensive or non-hypertensive OSA patients.

Dietary phenotype and advanced glycation end-products predict WTC-obstructive airways disease: a longitudinal observational study

Background

Diet is a modifier of metabolic syndrome which in turn is associated with World Trade Center obstructive airways disease (WTC-OAD). We have designed this study to (1) assess the dietary phenotype (food types, physical activity, and dietary habits) of the Fire Department of New York (FDNY) WTC-Health Program (WTC-HP) cohort and (2) quantify the association of dietary quality and its advanced glycation end product (AGE) content with the development of WTC-OAD.

Methods

WTC-OAD, defined as developing WTC-Lung Injury (WTC-LI; FEV₁ < LLN) and/or airway hyperreactivity (AHR; positive methacholine and/or positive bronchodilator response). Rapid Eating and Activity Assessment for Participants-Short Version (REAP-S) deployed on 3/1/2018 in the WTC-HP annual monitoring assessment. Clinical and REAP-S data of consented subjects was extracted (7/17/2019). Diet quality [low-(15–19), moderate-(20–29), and high-(30–39)] and AGE content per REAP-S questionnaire were assessed for association with WTC-OAD. Regression models adjusted for smoking, hyperglycemia, hypertension, age on 9/11, WTC-exposure, BMI, and job description.

Results

N = 9508 completed the annual questionnaire, while N = 4015 completed REAP-S and had spirometry. WTC-OAD developed in N = 921, while N = 3094 never developed WTC-OAD. Low- and moderate-dietary quality, eating more (processed meats, fried foods, sugary drinks), fewer (vegetables, whole-grains),and having a diet abundant in AGEs were significantly associated with WTC-OAD. Smoking was not a significant risk factor of WTC-OAD.

Conclusions

REAP-S was successfully implemented in the FDNY WTC-HP monitoring questionnaire and produced valuable dietary phenotyping. Our observational study has identified low dietary quality and AGE abundant dietary habits as risk factors for pulmonary disease in the context of WTC-exposure. Dietary phenotyping, not only focuses our metabolomic/biomarker profiling but also further informs future dietary interventions that may positively impact particulate matter associated lung disease.

Epicardial fat accumulation is an independent marker of impaired heart rate recovery in obese patients with obstructive sleep apnea

BACKGROUND

Sympathetic nervous system activation plays a pivotal role in obese patients with obstructive sleep apnea (OSA), contributing to increased cardiovascular risk. Epicardial adipose tissue (EAT) activates cardiac autonomic nervous system. Our main study objective was to investigate effects of these autonomic dysfunction factors on post-exercise heart rate recovery (HRR).

METHODS

36 patients, referred for clinical assessment of obesity (BMI > 30 kg/m²), underwent overnight polysomnography, transthoracic echocardiography and cardiopulmonary exercise testing.

RESULTS

Compared to non-OSA patients, OSA patients were older and displayed reduced body weight-indexed peak VO₂. Cardiac output at peak exercise was similar among groups. Peak exercise arterio-venous oxygen content difference D[a-v]O₂ was lower in OSA patients. In univariate linear analysis, age, AHI, EAT thickness, peak VO₂ and diabetes were associated with blunted HRR. Multiple linear regression analysis showed that increased EAT thickness, AHI and diabetes were independently associated with lower HRR. For identical AHI value and diabetes status, HRR significantly decreased by 61.7% for every 1 mm increase of EAT volume (p = 0.011). If HRR was treated as a categorical variable, EAT [odds ratio (OR) 1.78 (95% confidence interval [CI] 1.19-2.66); p = 0.005], and type 2 diabetes [OR 8.97 (95% CI 1.16-69.10); p = 0.035] were the only independent predictors of blunted HRR.

CONCLUSIONS

Aerobic capacity and peak exercise D[a-v]O₂ are impaired in obese OSA patients, suggesting abnormal peripheral oxygen extraction. EAT thickness is an independent marker of post-exercise HRR, which is a noninvasive marker of autonomic nerve dysfunction accompanying poor cardiovascular prognosis in obese patients.

Heart rate recovery and blood pressure response during exercise testing in patients with microvascular angina

Background

Angina pectoris with a normal coronary angiogram, termed microvascular angina (MVA), is an important clinical entity; however, its causes remain unclear. Autonomic dysfunction is one of the possible causes. Therefore, this study aimed to investigate parasympathetic dysfunction assessed by heart rate recovery (HRR) and increased sympathetic activity assessed by exaggerated blood pressure (BP) response (EBPR) to exercise in MVA.

Methods

The study participants were consecutive patients with anginal chest pain who underwent both coronary angiography with an ergonovine provocation test and a treadmill exercise test between January 2008 and February 2015. Patients with significant coronary artery disease (coronary artery stenosis ≥50%) or significant coronary artery spasm (≥90%) were excluded. Based on the treadmill exercise test, patients were categorized into the microvascular angina (MVA) group (patients with uniform ST depression ≥1 mm) and the control group. HRR was defined as peak heart rate minus heart rate after a 1 min recovery; blunted HRR was defined as ≤12 beats/min. EBPR was defined as a peak exercise systolic BP ≥210 mmHg in men and ≥ 190 mmHg in women. These parameters were compared between patients with MVA and the controls.

Results

Among the 970 enrolled patients (mean age 53.1 years; female 59.0%), 191 (20.0%) were diagnosed with MVA. In baseline characteristics, the MVA group had older participants, female predominance, and a higher prevalence of hypertension. The MVA group showed significantly lower HRR 1 min (24.9 ± 15.9 vs. 31.3 ± 22.7, p <  0.001) compared with the control group. Moreover, the proportion of EBPR was significantly higher in the MVA group than in the control group (21.5% vs. 11.6%, p <  0.001). Multivariable logistic regression analysis showed that age (odds ratio (OR), 1.045; 95% confidence interval (CI), 1.026-1.064; p <  0.001), HRR 1 min (OR, 0.990; 95% CI, 0.982-0.999; p = 0.022), and EBPR (OR, 1.657; 95% CI, 1.074-2.554; p = 0.022) were independently associated with MVA.

Conclusion

HRR and EBPR were associated with MVA, which suggests a link between MVA and autonomic dysregulation.

Does obstructive sleep apnea affect exercise capacity and the hemodynamic response to exercise? An individual patient data and aggregate meta-analysis

Obstructive sleep apnea (OSA) has been linked to altered cardiovascular response to exercise. A systematic review and individual patient data (IPD) meta-analysis were conducted to assess whether OSA patients present reduced exercise capacity. PubMed, Embase and Web of Science were searched until September 2018. Studies which performed sleep recording in both OSA patients and controls and measured maximal oxygen consumption (VO_2peak) via a maximal exercise test were included. IPD were provided for five trials upon the 18 eligible (N = 289) and a two-stage IPD meta-analysis model was used, allowing to standardize the apnea cutoff and adjust for confounders. IPD meta-analysis demonstrated that moderate to severe OSA patients had similar VO_2peak (mean difference: -1.03 mL·kg^-1 min^-1; 95% CI: -3.82 to 1.76; p = 0.47) and cardiovascular response to exercise compared to mild or non-OSA patients. By contrast, aggregate data (AD) meta-analysis including the 13 trials for which IPD were unavailable (N = 605) revealed that VO_2peak was reduced in OSA patients compared to controls (mean difference: -2.30 mL·kg^-1 min^-1; 95% CI: -3.96 to -0.63; p < 0.001) with high heterogeneity. In conclusion, IPD meta-analysis suggests that VO_2peak and the cardiovascular response to exercise are preserved in moderate to severe OSA patients while AD meta-analysis suggests lower VO_2peak in severe OSA.

Maximal exercise capacity in patients with obstructive sleep apnoea syndrome: a systematic review and meta-analysis

Maximal aerobic capacity is a strong health predictor and peak oxygen consumption (V'_O2peak) is considered a reflection of total body health. No systematic reviews or meta-analyses to date have synthesised the existing data regarding V'_O2peak in patients with obstructive sleep apnoea (OSA).A systematic review of English and French articles using PubMed/MEDLINE and Embase included studies assessing V'_O2peak in OSA patients either in mL·kg^-1·min^-1 compared with controls or in % predicted. Two independent reviewers analysed the studies, extracted the data and assessed the quality of evidence.Mean V'_O2peak expressed in mL·kg^-1·min^-1 was significantly lower in patients with OSA than in controls (mean difference -2.7 mL·kg^-1·min^-1; p<0.001; n=850). This reduction in V'_O2peak was found to be larger in non-obese patients (body mass index <30 kg·m^-2). Mean V'_O2peak % pred was 89.9% in OSA patients (n=643).OSA patients have reduced maximal aerobic capacity, which can be associated with increased cardiovascular risks and reduced survival in certain patient subgroups. Maximal exercise testing can be useful to characterise functional limitation and to evaluate health status in OSA patients.

Age-related decline in cardiac autonomic function is not attenuated with increased physical activity

Age and physical inactivity are important risk factors for cardiovascular mortality. Heart rate response to exercise (HRRE) and heart rate recovery (HRR), measures of cardiac autonomic function, are strong predictors of mortality. The present study defined the effect of age and physical activity on HRRE and HRR. Healthy women (N=72) grouped according to age (young, 20-30 years; middle, 40-50 years; and older, 65-81 years) and daily physical activity (low active <7500, high active >12,500 steps/day) performed a maximal cardiopulmonary exercise test. The HRRE was defined as an increase in heart rate from rest to 1, 3 and 5 minutes of exercise and at 1/3 of total exercise time, and HRR as the difference in heart rate between peak exercise and 1, 2, and 3 minutes later. Age was associated with a significant decline in HRRE at 1 min and 1/3 of exercise time (r= − 0.27, p=0.04, and r=−0.39, p=0.02) and HRR at 2 min and 3 min (r=−0.35, p=0.01, and r=−0.31, p=0.02). There was no significant difference in HRRE and HRR between high and low-active middle-age and older women (p>0.05). Increased level of habitual physical activity level appears to have a limited effect on age-related decline in cardiac autonomic function in women.

Blunted heart rate recovery is associated with coronary artery spasm in patients with suspected vasospastic angina

Background

Autonomic nervous system activity has been shown to be altered in patients with vasospastic angina (VA). Heart rate recovery (HRR) is a simple, non-invasive measurement of autonomic nervous system dysfunction. We aimed to investigate whether HRR is related to VA, as established by an ergonovine test.

Methods

A total of 976 consecutive patients (47.5% male, mean age 55 years) without significant coronary artery disease who underwent both an ergonovine provocation test and a treadmill exercise test were enrolled. The relationship between VA and HRR was evaluated.

Results

A total of 30.7% (300/976) of patients were diagnosed with VA, as documented by the ergonovine provocation test. HRR was significantly reduced in patients with VA compared to patients without VA (24.6 ± 18.0 vs. 30.5 ± 22.2, p < 0.001), and HRR was lowest in patients with multi-vessel spasm (21.9 ± 17.3). The proportion of blunted HRR, which was defined as HRR less than 12 beats, was significantly higher in patients with VA than in those without coronary artery spasm (26.6% vs. 39.3%, p < 0.001). In multivariable regression analyses, age (odds ratio (OR) = 1.03; 95% confidence interval (CI): 1.01–1.04; p = 0.001), blunted HRR (OR = 1.71; 95% CI: 1.26–2.31; p < 0.001), current smoking status (OR = 2.11; 95% CI: 1.50–2.98; p < 0.001), and male gender (OR = 2.00; 95% CI: 1.43–2.78; p < 0.001) were significant independent predictors of VA presence.

Conclusion

Blunted HRR was an independent predictor of VA presence, which suggests a link between coronary artery spasm and autonomic dysregulation.

An update on cardiovascular effects of obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome is an important health problem which may cause or worsen systemic diseases. Chronic intermittent hypoxia during repetitive airflow cessations may cause endothelial dysfunction. Sleep apnoea is also shown to be associated with hypercoagulability which may be due to decreased nitric oxide levels and impaired vasodilatation. Endothelial dysfunction, increased systemic inflammation, sympathetic nervous system activation, increased oxidative stress and dysglycaemia may all contribute to cardiovascular processes such as hypertension, arrhythmia, stroke, heart failure and coronary artery disease in patients with obstructive sleep apnoea. Treatment approaches in patients with obstructive sleep apnoea mainly focus on maintaining upper airway patency either with positive airway pressure devices or upper airway appliances. Strategies involving positive airway pressure therapy are associated with decreased morbidity and mortality. Obstructive sleep apnoea should be suspected as an underlying mechanism in patients with cardiovascular disease and warrants appropriate treatment.

Association among epicardial fat, heart rate recovery and circadian blood pressure variability in patients with hypertension

Background

Epicardial fat tissue is known to have an unique endocrine function which affect the cardiac autonomic system. Heart rate recovery (HRR) is a simple non-invasive measurement that assesses autonomic nervous system dysfunction. We aimed to investigate the association among epicardial fat thickness (EFT), HRR and circadian blood pressure (BP) variation in patients with hypertension.

Methods

A total of 358 consecutive patients who underwent both 24-hour ambulatory BP monitoring (ABPM) and a treadmill test were enrolled. Echocardiographic EFT and HRR, defined as peak heart rate minus heart rate after a 1-min recovery time, were measured. Patients were classified according to the ABPM; 147 patients with hypertension with a dipping pattern at night (dippers), 140 patients with hypertension with a non-dipping pattern at night (non-dippers) and 71 normotensive controls.

Results

EFT was significantly higher in hypertensive patients, especially in the non-dipper group, compared to the controls (non-dippers, 7.5 ± 2.9 mm; dippers, 6.6 ± 1.6 mm; controls, 5.5 ± 2.1 mm; p < 0.001). HRR was significantly lower in both hypertensive groups as compared to the control group and was the lowest in the non-dipper group (non-dipper, 26.6 ± 18.6; dipper, 29.5 ± 21.5; control, 71.4 ± 19.8; p < 0.001). EFT was significantly correlated with age, body mass index, 24-hour mean systolic BP and 24 h mean BP variability, whereas exercise duration, metabolic equivalents (METs) and HRR were inversely correlated with EFT. Furthermore, EFT > 6.7 mm was associated with a blunted HRR with 76 % sensitivity and 61 % specificity (ROC area under curve: 0.71, 95 % confidence interval, CI = 0.65–0.76, p < 0.001). In a multivariate analysis, EFT (odds ratio, OR = 3.53, 95 % CI = 1.20–10.37, p = 0.022) and 24-hour mean BP variability (OR = 1.09, 95 % CI = 1.03–1.16, p = 0.005) were independent predictors of a blunted HRR defined as HRR ≤ 12 beats (n = 63) in patients with hypertension.

Conclusion

EFT and HRR were significantly correlated with circadian BP variability in patients with hypertension. EFT and circadian BP variability were independent predictors of blunted HRR, which suggests a link between epicardial fat and autonomic dysregulation in hypertension.

The Effect of Changes in Cardiorespiratory Fitness and Weight on Obstructive Sleep Apnea Severity in Overweight Adults with Type 2 Diabetes

STUDY OBJECTIVES

To examine the effect of changes in cardiorespiratory fitness on obstructive sleep apnea (OSA) severity prior to and following adjustment for changes in weight over the course of a 4-y weight loss intervention.

METHODS

As secondary analyses of a randomized controlled trial, 263 overweight/obese adults with type 2 diabetes and OSA participated in an intensive lifestyle intervention or education control condition. Measures of OSA severity, cardiorespiratory fitness, and body weight were obtained at baseline, year 1, and year 4. Change in the apnea-hypopnea index (AHI) served as the primary outcome. The percentage change in fitness (submaximal metabolic equivalents [METs]) and change in weight (kg) were the primary independent variables. Primary analyses collapsed intervention conditions with statistical adjustment for treatment group and baseline METs, weight, and AHI among other relevant covariates.

RESULTS

At baseline, greater METs were associated with lower AHI (B [SE] = -1.48 [0.71], P = 0.038), but this relationship no longer existed (B [SE] = -0.24 [0.73], P = 0.75) after adjustment for weight (B [SE] = 0.31 [0.07], P < 0.0001). Fitness significantly increased at year 1 (+16.53 ± 28.71% relative to baseline), but returned to near-baseline levels by year 4 (+1.81 ± 24.48%). In mixed-model analyses of AHI change over time without consideration of weight change, increased fitness at year 1 (B [SE] = -0.15 [0.04], P < 0.0001), but not at year 4 (B [SE] = 0.04 [0.05], P = 0.48), was associated with AHI reduction. However, with weight change in the model, greater weight loss was associated with AHI reduction at years 1 and 4 (B [SE] = 0.81 [0.16] and 0.60 [0.16], both P < 0.0001), rendering the association between fitness and AHI change at year 1 nonsignificant (B [SE] = -0.04 [0.04], P = 0.31).

CONCLUSIONS

Among overweight/obese adults with type 2 diabetes, fitness change did not influence OSA severity change when weight change was taken into account.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identification number NCT00194259.

Effects of exercise training on sleep apnea: a meta-analysis

BACKGROUND

Several studies have shown a favorable effect of supervised exercise training on obstructive sleep apnea (OSA). This meta-analysis was conducted to analyze the data from these studies on the severity of OSA (primary outcome) in adults. Secondary outcomes of interest included body mass index (BMI), sleep efficiency, daytime sleepiness and cardiorespiratory fitness.

METHODS

Two independent reviewers searched PubMed and Embase (from inception to March 6, 2013) to identify studies on the effects of supervised exercise training in adults with OSA. Pre- and postexercise training data on our primary and secondary outcomes were extracted.

RESULTS

A total of 5 studies with 6 cohorts that enrolled a total of 129 study participants met the inclusion criteria. The pooled estimate of mean pre- to postintervention (exercise) reduction in AHI was −6.27 events/h (95 % confidence interval [CI] -8.54 to -3.99; p < 0.001). The pooled estimates of mean changes in BMI, sleep efficiency, Epworth sleepiness scale and VO2 peak were -1.37 (95 % CI −2.81 to 0.07; p = 0.06), 5.75 % (95 % CI 2.47-9.03; p = 0.001), -3.3 (95 % CI -5.57 to -1.02; p = 0.004), and 3.93 mL/kg/min (95 % CI 2.44-5.42; p < 0.001), respectively.

CONCLUSIONS

This meta-analysis shows a statistically significant effect of exercise in reducing the severity of sleep apnea in patients with OSA with minimal changes in body weight. Additionally, the significant effects of exercise on cardiorespiratory fitness, daytime sleepiness, and sleep efficiency indicate the potential value of exercise in the management of OSA.

Sleep apnoea and metabolic dysfunction

Obstructive sleep apnoea (OSA) is a highly prevalent condition often associated with central obesity. In the past few years, several studies have analysed the potential independent contribution of OSA to the pathogenesis of metabolic abnormalities, including type 2 diabetes, the metabolic syndrome and non-alcoholic fatty liver disease. New perspectives in OSA patient care have been opened by the promotion of lifestyle interventions, such as diet and exercise programmes that could improve both OSA and the metabolic profile. The rich clinical literature on this subject, together with the growing amount of data on pathophysiological mechanisms provided by animal studies using the chronic intermittent hypoxia model, urged the organising Committee of the Sleep and Breathing meeting to organise a session on sleep apnoea and metabolic dysfunction, in collaboration with the European Association for the Study of Diabetes. This review summarises the state-of-the-art lectures presented in the session, more specifically the relationship between OSA and diabetes, the role of OSA in the metabolic consequences of obesity, and the effects of lifestyle interventions on nocturnal respiratory disturbances and the metabolic profile in OSA patients.

Clinical usefulness of response profiles to rapidly incremental cardiopulmonary exercise testing

The advent of microprocessed "metabolic carts" and rapidly incremental protocols greatly expanded the clinical applications of cardiopulmonary exercise testing (CPET). The response normalcy to CPET is more commonly appreciated at discrete time points, for example, at the estimated lactate threshold and at peak exercise. Analysis of the response profiles of cardiopulmonary responses at submaximal exercise and recovery, however, might show abnormal physiologic functioning which would not be otherwise unraveled. Although this approach has long been advocated as a key element of the investigational strategy, it remains largely neglected in practice. The purpose of this paper, therefore, is to highlight the usefulness of selected submaximal metabolic, ventilatory, and cardiovascular variables in different clinical scenarios and patient populations. Special care is taken to physiologically justify their use to answer pertinent clinical questions and to the technical aspects that should be observed to improve responses' reproducibility and reliability. The most recent evidence in favor of (and against) these variables for diagnosis, impairment evaluation, and prognosis in systemic diseases is also critically discussed.

Association between sleep disorders, obesity, and exercise: a review

Decreased sleep duration and quality is associated with an increase in body weight and adiposity. Insomnia, obstructive sleep apnea, and restless legs syndrome are three of the most prevalent types of sleep disorder that lead to an increased risk for numerous chronic health conditions. Various studies have examined the impact of these sleep disorders on obesity, and are an important link in understanding the relationship between sleep disorders and chronic disease. Physical activity and exercise are important prognostic tools in obesity and chronic disease, and numerous studies have explored the relationship between obesity, sleep disorders, and exercise. As such, this review will examine the relationship between sleep disorders and obesity. In addition, how sleep disorders may impact the exercise response and how exercise may impact patient outcomes with regard to sleep disorders will also be reviewed.