Heart rate behavior during an exercise stress test in obese patients

Italian Association of Hospital Cardiologists position paper-obesity in adults: a clinical primer

Obesity is a chronic and relapsing disease characterized by the interaction between individual predispositions and an obesogenic environment. Recent advances in understanding the mechanisms of energetic homoeostasis paved the way to more effective therapeutic approaches compared with traditional treatments. Since obesity is a complex disease, it necessitates a multi-disciplinary approach whose implementation remains challenging. Nonetheless, emerging pharmacological interventions appear promising. Currently, therapeutic success is discreet in the short term but often fails to maintain long-term weight loss due to a high likelihood of weight regain. Cardiologists play a key role in managing patients with obesity, yet often lack familiarity with its comprehensive management. The aim of this document is to summarize knowledge to consolidate essential knowledge for clinicians to effectively treat patients living with obesity. The paper emphasizes the pivotal role of a strong patient-clinician relationship in navigating successful treatment. We analyse the criteria commonly used to diagnose obesity and point out the strengths and limitations of different criteria. Furthermore, we discuss the role of obesiologists and the contributions of cardiologists. In addition, we detail key components of effective therapeutic strategies, including educational aspects and pharmacological options.

Dynamic vagal-mediated connectivity of cortical and subcortical central autonomic hubs predicts chronotropic response to submaximal exercise in healthy adults

BACKGROUND

Despite accumulation of a substantial body of literature supporting the role of exercise on frontal lobe functioning, relatively less is understood of the interconnectivity of ventromedial prefrontal cortical (vmPFC) regions that underpin cardio-autonomic regulation predict cardiac chronotropic competence (CC) in response to sub-maximal exercise.

METHODS

Eligibility of 161 adults (mean age = 48.6, SD = 18.3, 68% female) was based upon completion of resting state brain scan and sub-maximal bike test. Sliding window analysis of the resting state signal was conducted over 45-s windows, with 50% overlap, to assess how changes in photoplethysmography-derived HRV relate to vmPFC functional connectivity with the whole brain. CC was assessed based upon heart rate (HR) changes during submaximal exercise (HR change /HRmax (206-0.88 × age) - HRrest).

RESULTS

During states of elevated HRV the vmPFC showed greater rsFC with an 83-voxel region of the hypothalamus (p < 0.001, uncorrected). Beta estimates of vmPFC connectivity extracted from a 6-mm sphere around this region emerged as the strongest predictor of CC (b = 0.283, p <.001) than age, BMI, and resting HRV F(8,144) = 6.30, p <.001.

CONCLUSION

Extensive glutamatergic innervation of the hypothalamus by the vmPFC allows for top-down control of the hypothalamus and its various autonomic efferents which facilitate chronotropic response during sub-maximal exercise.

ANMCO (Italian Association of Hospital Cardiologists) scientific statement: obesity in adults-an approach for cardiologists

Obesity is a complex, chronic disease requiring a multidisciplinary approach to its management. In clinical practice, body mass index and waist-related measurements can be used for obesity screening. The estimated prevalence of obesity among adults worldwide is 12%. With the expected further increase in overall obesity prevalence, clinicians will increasingly be managing patients with obesity. Energy balance is regulated by a complex neurohumoral system that involves the central nervous system and circulating mediators, among which leptin is the most studied. The functioning of these systems is influenced by both genetic and environmental factors. Obesity generally occurs when a genetically predisposed individual lives in an obesogenic environment for a long period. Cardiologists are deeply involved in evaluating patients with obesity. Cardiovascular risk profile is one of the most important items to be quantified to understand the health risk due to obesity and the clinical benefit that a single patient can obtain with weight loss. At the individual level, appropriate patient involvement, the detection of potential obesity causes, and a multidisciplinary approach are tools that can improve clinical outcomes. In the near future, we will probably have new pharmacological tools at our disposal that will facilitate achieving and maintaining weight loss. However, pharmacological treatment alone cannot cure such a complex disease. The aim of this paper is to summarize some key points of this field, such as obesity definition and measurement tools, its epidemiology, the main mechanisms underlying energy homeostasis, health consequences of obesity with a focus on cardiovascular diseases and the obesity paradox.Level of evidence V: report of expert committees.

Assessment of Cardiovascular Parameters on Submaximal Treadmill Exercise in Obese versus Nonobese Adults

Background

Obesity and overweight, irrespective of metabolic status, confer an increased risk of adverse consequences including cardiovascular diseases (CVDs). The mechanisms underlying altered cardiovascular responses in obese individuals during and after submaximal treadmill exercise are the subjects of great interest to public health. After graded exercise, delayed heart rate recovery (HRR), exaggerated blood pressure (BP) response, and prolongation of QT interval are the powerful predictors of cardiovascular morbidity and mortality that may facilitate timely identification of individuals at risk of CVD and help to evaluate the effectiveness of treatment interventions.

Aim

To compare the cardiovascular parameters on submaximal treadmill exercise in obese and nonobese adults.

Materials and Methods

This study was conducted on 80 subjects, 40 obese (cases) and 40 normal-weight individuals (controls), belonging to the age group of 18-60 years. Each participant was subjected to submaximal treadmill exercise according to the Bruce protocol. Heart rate (HR), systolic BP and diastolic BP (SBP and DBP), mean arterial pressure (MAP), QT and corrected QT (QTc) intervals, and rate pressure product (RPP) were measured preexercise, immediately after exercise, and during passive recovery at 1 min and 5 min after exercise. The Chi-square test and Mann-Whitney U-test, whichever is appropriate, were employed for the comparison of variables between the two study groups. P < 0.05 was considered statistically significant.

Results

Mean HR immediately after exercise, at 1 min and 5 min postexercise was significantly higher in obese when compared to nonobese participants (P = 0.006, P = 0.001, P = 0.001) despite similar resting HR in both the groups (P = 0.874). Mean SBP, DBP, MAP, and RPP were significantly higher in obese in comparison to nonobese subjects in all stages, i.e. before exercise, immediately after exercise, at 1 min and 5 min after exercise. QT and QTc intervals were also found to be significantly greater in obese than nonobese subjects in all stages (P = 0.001 each).

Conclusion

Obese subjects had higher resting BP (SBP, DBP, and MAP), QT/QTc interval, RPP, and increased response to submaximal treadmill exercise activity. Delayed HRR after exercise was also noted in obese subjects which indicates that obese populations are at risk of developing CVDs due to alteration in autonomic functions with sympathetic hyperactivity.

Higher Heart Rate Is Independently Associated With Abnormal Body Mass Index in a J Shape Pattern

BACKGROUND

High heart rate (HR) is independently associated with higher cardiovascular mortality and usually occurs in sedentary persons. Inactivity can also lead to obesity. The purpose of this study was to evaluate the associations between body mass index as an independent marker of high HR.

METHOD

Data generated from screening echocardiography, for the prevention of sudden death at the Anthony Bates Foundation, was used. Data from 1340 subjects, with documented HR and body mass index, between the ages 19-79 years with a mean age of 32 years, were studied. We correlated the presence of a high HR >90 beats per minute (bpm) with different body mass index (BMI) categories.

RESULTS

High HR was significantly associated with higher BMI categories and underweight subjects in adults suggesting a J shape association. A total of 22.7% of participants with an HR of more than 90 bpm had BMI >40 kg/m 2 , versus 19.0% of patients with BMI of 35-40 kg/m 2 versus 13.5% of subjects with BMI of 30-35 kg/m 2 versus 12.2% of subjects with BMI of 25-30 kg/m 2 -29.9 kg/m 2 , versus in 10.3% of subjects with BMI between 18.5 and 25 kg/m 2 , P < 0.01) Furthermore, increased HR was also more prevalent in underweight patient (17.4% in subjects with BMI < 18.5 kg/m 2 ).

CONCLUSION

High HR is strongly associated with obesity and underweight suggesting that maintaining a normal weight is associated with most positive effect on the cardiovascular system.

Chronotropic incompetence is more frequent in obese adolescents and relates to systemic inflammation and exercise intolerance

BACKGROUND

Adults with obesity may display disturbed cardiac chronotropic responses during cardiopulmonary exercise testing, which relates to poor cardiometabolic health and an increased risk for adverse cardiovascular events. It is unknown whether cardiac chronotropic incompetence (CI) during maximal exercise is already present in obese adolescents and, if so, how that relates to cardiometabolic health.

METHODS

Sixty-nine obese adolescents (body mass index standard deviation score = 2.23 ± 0.32, age = 14.1 ± 1.2 years; mean ± SD) and 29 lean adolescents (body mass index standard deviation score = -0.16 ± 0.84, age = 14.0 ± 1.5 years) performed a maximal cardiopulmonary exercise testing from which indicators for peak performance were determined. The resting heart rate and peak heart rate were used to calculate the maximal chronotropic response index. Biochemistry (lipid profile, glycemic control, inflammation, and leptin) was studied in fasted blood samples and during an oral glucose tolerance test within obese adolescents. Regression analyses were applied to examine associations between the presence of CI and blood or exercise capacity parameters, respectively, within obese adolescents.

RESULTS

CI was prevalent in 32 out of 69 obese adolescents (46%) and 3 out of 29 lean adolescents (10%). C-reactive protein was significantly higher in obese adolescents with CI compared to obese adolescents without CI (p = 0.012). Furthermore, peak oxygen uptake and peak cycling power output were significantly reduced (p < 0.05) in obese adolescents with CI vs. obese adolescents without CI. The chronotropic index was independently related to blood total cholesterol (standardized coefficient β = -0.332; p = 0.012) and C-reactive protein concentration (standardized coefficient β = -0.269; p = 0.039).

CONCLUSION

CI is more common in the current cohort of obese adolescents, and is related to systemic inflammation and exercise intolerance.

Effects of Exercise Mode on Improving Cardiovascular Function and Cardiorespiratory Fitness After Bariatric Surgery: A Narrative Review

ABSTRACT

Obesity affects 600 million people globally and increases the risk of developing cardiovascular disease, stroke, diabetes, and cancer. Bariatric surgery is an increasingly popular therapeutic intervention for morbid obesity to induce rapid weight loss and reduce obesity-related comorbidities. However, some bariatric surgery patients, after what is considered a successful surgical procedure, continue to manifest obesity-related health issues, including weight gain, reduced physical function, persistent elevations in blood pressure, and reduced cardiorespiratory fitness. Cardiorespiratory fitness is a strong predictor of mortality and several health outcomes and could be improved by an appropriate exercise prescription after bariatric surgery. This review provides a broad overview of exercise training for patients after bariatric surgery and discusses cardiorespiratory fitness and other potential physiological adaptations in response to exercise training.

Progressive Additive Benefits of Prehabilitation and Subsequent Bariatric Surgery on Cardiac Autonomic Regulation as Assessed by Means of a Simple Unitary Composite Index: Preliminary Data from an Observational Study

Obesity is associated with an increased risk of several chronic comorbidities, which may also be determined by dysfunctional autonomic nervous system (ANS). The influence of bariatric surgery (BS) on ANS balance was explored in previous studies, but with high heterogeneity in both the assessment timing and methods employed. In the present observational study, we applied a clinical protocol which considers two subsequent phases. Twenty-nine non-diabetic obese subjects were studied at baseline (T0), after one month of lifestyle modification (prehabilitation) (phase 1-T1), and after eight months following BS (phase 2-T2). ANS regulation was assessed across the three study epochs by means of ANSI, a single composite percent-ranked proxy of autonomic balance, being free of gender and age bias, economical and simple to apply in a clinical setting. The aim of the present study was to investigate the effects of the clinical protocol based on prehabilitation and subsequent BS on the ANS regulation by means of ANSI. Potential intertwined correlations with metabolic parameters were also investigated. Notably, we observed a progressive improvement in ANS control, even by employing ANSI. Moreover, the reduction in the markers of sympathetic overactivity was found to significantly correlate with the amelioration in some metabolic parameters (fasting glucose, insulin levels, and waist circumference), as well as in stress and tiredness perception. In conclusion, this study provides convincing evidence that a unitary proxy of cardiac autonomic regulation (CAR) may reflect the progressive improvement in autonomic regulation following behavioral and surgical interventions in obese patients. Intriguingly, this might contribute to reducing cardiovascular and metabolic risk.

Obesity and Cardiovascular Disease: A Scientific Statement From the American Heart Association

The global obesity epidemic is well established, with increases in obesity prevalence for most countries since the 1980s. Obesity contributes directly to incident cardiovascular risk factors, including dyslipidemia, type 2 diabetes, hypertension, and sleep disorders. Obesity also leads to the development of cardiovascular disease and cardiovascular disease mortality independently of other cardiovascular risk factors. More recent data highlight abdominal obesity, as determined by waist circumference, as a cardiovascular disease risk marker that is independent of body mass index. There have also been significant advances in imaging modalities for characterizing body composition, including visceral adiposity. Studies that quantify fat depots, including ectopic fat, support excess visceral adiposity as an independent indicator of poor cardiovascular outcomes. Lifestyle modification and subsequent weight loss improve both metabolic syndrome and associated systemic inflammation and endothelial dysfunction. However, clinical trials of medical weight loss have not demonstrated a reduction in coronary artery disease rates. In contrast, prospective studies comparing patients undergoing bariatric surgery with nonsurgical patients with obesity have shown reduced coronary artery disease risk with surgery. In this statement, we summarize the impact of obesity on the diagnosis, clinical management, and outcomes of atherosclerotic cardiovascular disease, heart failure, and arrhythmias, especially sudden cardiac death and atrial fibrillation. In particular, we examine the influence of obesity on noninvasive and invasive diagnostic procedures for coronary artery disease. Moreover, we review the impact of obesity on cardiac function and outcomes related to heart failure with reduced and preserved ejection fraction. Finally, we describe the effects of lifestyle and surgical weight loss interventions on outcomes related to coronary artery disease, heart failure, and atrial fibrillation.

Influence of Body Composition on Post-Exercise Parasympathetic Reactivation of Firefighter Recruits

Firefighters have a sustained risk for experiencing a sudden cardiac event after completing a fire call. Heart rate recovery (HRR) can be utilized to characterize autonomic nervous system (ANS) recovery and has been linked to cardiac events. Research suggests that body composition influences post-exercise HRR responses in non-firefighter populations. The purpose of this study was to examine the influence of body mass index (BMI), waist circumference (WC), and percent body fat (BF) on the HRR response of firefighter recruits. BMI (kg·m-2), WC (cm), and BF (%) data from 57 firefighter recruits were collected. HRR (b·min-1) data were collected at completion (HR0), as well as 15 (HR15), 30 (HR30), 45 (HR45), 60 (HR60), 120 (HR120), and 180 (HR180) seconds following a submaximal step test, and commonly utilized clinical HRR indices were calculated (ΔHRR30, ΔHRR60, ΔHRR120, and ΔHRR180). After controlling for sex, linear mixed regression models did not identify significant interactions between body composition (ps > 0.05) and HRR response across time. However, significant (ps < 0.05) indirect semi-partial correlations were identified between BF and ΔHRR30 (rsp = -0.31) and ΔHRR60 (rsp = -0.27), respectively. Reducing overall BF (vs. BMI or WC) should be prioritized to improve the post-exercise ANS recovery of firefighter recruits.

Demographic/anthropometric factors and physiological performance-related parameters associated with the six-minute walk test in bariatric surgery candidates, from Valdivia, Chile

ABSTRACT The six-minute walk test (6MWT) is widely used to measure functional capacity in special populations. However, the factors associated with its performance in candidates for bariatric surgery are unclear. Therefore, this study aimed to investigate the influence of anthropometric and physiological factors in the 6MWT performance in bariatric surgery candidates. This cross-sectional study included 107 candidates for bariatric surgery. Anthropometric factors considered: gender, weight, height, body mass index (BMI), waist-to-hip, and waist-to-height ratios. Along with distance covered during 6MWT, physiological factors such as ratings of perceived exertion (RPE) and heart rate reserve percentage used (%HRR) were recorded. Among the 107 patients (mean age: 39.6 years), 83 volunteers were accepted to perform the 6MWT. No gender differences were observed in terms of distance covered, %HRR, and RPE during the 6MWT. Moreover, BMI and %HRR explained 21% of the 6MWT distance covered. Furthermore, participants with BMI ≤41.5 kg/m2 walked ~50 meters more than their peers above this level (p=0.05). Interestingly, heart rate increase during the 6MWT was lower than described for healthy populations. BMI and %HRR partially explain the variability of the 6MWT performance in bariatric surgery candidates.

Exercise Enhances the Effect of Bariatric Surgery in Markers of Cardiac Autonomic Function

BACKGROUND

Bariatric surgery improves cardiovascular health, which might be partly ascribed to beneficial alterations in the autonomic nervous system. However, it is currently unknown whether benefits from surgery on cardiac autonomic regulation in post-bariatric patients can be further improved by adjuvant therapies, namely exercise. We investigated the effects of a 6-month exercise training program on cardiac autonomic responses in women undergoing bariatric surgery.

METHODS

Sixty-two women eligible for bariatric surgery were randomly allocated to either standard of care (control) or an exercise training intervention. At baseline (PRE) and 3 (POST3) and 9 (POST9) months after surgery, we assessed chronotropic response to exercise (CR%; i.e., percentage change in heart rate from rest to peak exercise) and heart rate recovery (HRR30s, HRR60s, and HRR120s; i.e., decay of heart rate at 30, 60, and 120 s post exercise) after a maximal exercise test.

RESULTS

Between-group absolute changes revealed higher CR% (Δ = 8.56%, CI95% 0.22-19.90, P = 0.04), HRR30s (Δ = 12.98 beat/min, CI95% 4.29-21.67, P = 0.01), HRR60s (Δ = 22.95 beat/min, CI95% 11.72-34.18, P = 0.01), and HRR120s (Δ = 34.54 beat/min, CI95% 19.91-49.17, P < 0.01) in the exercised vs. non-exercised group.

CONCLUSIONS

Our findings demonstrate that exercise training enhanced the benefits of bariatric surgery on cardiac autonomic regulation. These results highlight the relevance of exercise training as a treatment for post-bariatric patients, ensuring optimal cardiovascular outcomes.

Obesity and parasympathetic reactivation of the heart following exercise testing in young male adults: a pilot study

BACKGROUND

In elderly people, obesity may induce changes in the autonomic nervous system via alteration of the balance between the sympathetic and parasympathetic nervous systems. Little is known about obesity and parasympathetic reactivation following exercise testing, particularly in young people in Saudi Arabia, and its relationship with body composition parameters.

OBJECTIVES

Compare parasympathetic reactivation using heart rate recovery (HRR) following the exercise test between young obese and nonobese people and explore the association between body composition parameters with HRR.

DESIGNS

Cross-sectional study.

SETTING

University research lab.

PATIENTS AND METHODS

Twenty-seven young male college students underwent anthropometric measurements and treadmill exercise testing, during which the heart rate was monitored via 12-lead electro-cardiography. Participants were divided into a group (n=15) with high body fat percentage (>30%), and a group (n=12) with a normal body fat percentage (<30%) to compare multiple parameters including HRR, which was defined as the absolute change from heart rate (HR) peak during exercise to 1-minute post-HR peak.

MAIN OUTCOME MEASURES

HRR, body mass index, waist-to-hip ratio, fat percentage, and trunk fat. SAMPLE SIZE AND CHARACTERISTICS: n=27, mean (SD) age=22.4 (0.98) years, range 21-25 years.

RESULTS

There was no significant difference in HRR between the groups (32.20 [13.42] bpm for high body fat percentage vs 35.42 [13.35] bpm for normal body fat percentage) ( P=.54). We found a non-significant inverse correlations of HRR with BMI (r=-0.18, P=.37), WHR (r=-0.04, P=.86), fat percentage (r=-0.18, P=.38) and trunk fat (r=-0.23, P=.25).

CONCLUSION

HRR was preserved in our young obese people and was not different from nonobese people. Furthermore, it seems that obese people with higher body composition parameters may have slower HRR, or slower recovery indicating poorer parasympathetic reactivation.

LIMITATIONS

Need a larger sample to confirm the findings of this pilot study.

CONFLICT OF INTEREST

None.

Effects of various interval training regimes on changes in maximal oxygen uptake, body composition, and muscular strength in sedentary women with obesity

PURPOSE

We determined the effects of two high-intensity interval training (HIIT) regimens [the traditional (TRAD) and periodized (PER)] on changes in maximal oxygen uptake (VO2max), body composition, and muscular strength in sedentary, obese women.

METHODS

Seventeen women (age and BMI = 37.5 ± 10.5 year and 39.1 ± 4.3 kg/m2) were randomized into a 6 week regime of TRAD or PER which consisted of three sessions per week, two in the laboratory, and one on their own. Pre- and post-training, VO2max, body composition, and muscular strength of the knee extensors (KE) and flexors (KF) were assessed via ramp cycling to exhaustion, air displacement plethysmography, and isokinetic dynamometry, respectively.

RESULTS

VO2max was increased by 4-5% in response to training (p = 0.045) with no group-by-time interaction (p = 0.79). Body mass, fat mass, and waist-to-hip ratio were unaltered (p > 0.05) in response to training, yet there was a significant change in percent body fat (p = 0.03), percent fat-free mass (p = 0.03), and absolute fat-free mass (p = 0.03) in TRAD but not PER. No change occurred in KE (p = 0.36) or KF torque (p = 0.75) in response to training and there was no group-by-time interaction (p > 0.05).

CONCLUSIONS

Low-volume HIIT improved VO2max and body composition but did not modify muscular strength, which suggests that obese women desiring to increase strength should initiate more intense HIIT or partake in formal resistance training.

Effect of Body Mass Index on Exercise Capacity in Patients With Hypertrophic Cardiomyopathy

The objective of this study was to evaluate the relation between body mass index (BMI), exercise capacity, and symptoms in patients with hypertrophic cardiomyopathy (HC) and to utilize results of cardiopulmonary exercise tests (CPX) and transthoracic echocardiograms to understand the mechanism(s) of reduced exercise capacity across body mass index groups. Over a 6-year period, 510 consecutive patients with HC seen at a tertiary referral center underwent (CPX) and a transthoracic echocardiogram. Increasing BMI was associated with decreased exercise capacity as assessed by peak VO₂ (ml/kg/min). However, the prevalence of cardiac impairment did not vary by BMI group. In conclusion, these findings suggest that in some patients with hypertrophic cardiomyopathy, cardiac impairment is not the primary cause of exercise limitation and weight loss may result in improved exercise capacity.

Influence of central obesity in estimating maximal oxygen uptake

OBJECTIVE:

To assess the influence of central obesity on the magnitude of the error of estimate of maximal oxygen uptake in maximal cycling exercise testing.

METHOD:

A total of 1,715 adults (68% men) between 18-91 years of age underwent cardiopulmonary exercise testing using a progressive protocol to volitional fatigue. Subjects were stratified by central obesity into three quartile ranges: Q1, Q2-3 and Q4. Maximal oxygen uptake [mL.(kg.min)-1] was estimated by the attained maximal workload and body weight using gender- and population-specific equations. The error of estimate [mL.(kg.min)-1] and percent error between measured and estimated maximal oxygen uptake values were compared among obesity quartile ranges.

RESULTS:

The error of estimate and percent error differed (mean ± SD) for men (Q1=1.3±3.7 and 2.0±10.4; Q2-3=0.5±3.1 and -0.5±13.0; and Q4=-0.3±2.8 and -4.5±15.8 (p<0.05)) and for women (Q1=1.6±3.3 and 3.6±10.2; Q2-3=0.4±2.7 and -0.4±11.8; and Q4=-0.9±2.3 and -10.0±22.7 (p<0.05)).

CONCLUSION:

Central obesity directly influences the magnitude of the error of estimate of maximal oxygen uptake and should be considered when direct expired gas analysis is unavailable.

Obesity and the Role of Short Duration Submaximal Work on Cardiovascular and Cerebral Hemodynamics

The objective of this study was to compare gas exchange, cardiac and cerebral hemodynamic responses between 10 non-obese and 10 obese men during submaximal work. With the increasing prevalence of obesity, there is a need to understand the impact of obesity on work-induced responses. Participants completed a step-wise incremental cycling until they reached 60% of their age-predicted maximum heart rate. Gas exchange, cardiac and pre-frontal cortex hemodynamic responses were simultaneously measured during rest, work, and recovery. The non-obese group reached ~43% of their predicted maximal aerobic capacity as compared to ~34% in the obese group, with the non-obese working at a relatively higher workload and for more duration than the obese. The obese had elevated baseline heart rate and reduced whole-body oxygen uptake per body weight at baseline and task termination. Other cardiac and cerebral responses, although increased from baseline, were similar between groups during submaximal effort. In the obese, during recovery oxygen uptake and heart-rate recovery were slowest; cardiac output and rate pressure product were greatest, and left ventricle ejection time was shortest. However, both groups exhibited similar cerebral hemodynamics during recovery. These finding imply that, irrespective of their low aerobic fitness, obesity does not impair myocardial performance and cerebrovascular function during graded submaximal work, however, recovery from a short duration of work was influenced by their fitness level. Since a majority of activities of daily living are performed at individual’s submaximal level, understanding influence of obesity on submaximal work is critical.

Relation between heart rate recovery after exercise testing and body mass index

INTRODUCTION

Impaired heart rate (HR) recovery after exercise testing is considered a predictor of cardiovascular mortality as it reflects vagus nerve dysfunction.

OBJECTIVE

To assess the relationship between body mass index (BMI) and HR recovery after exercise.

METHODS

We analyzed the records of 2443 patients of both sexes, aged between 20 and 59 years, in sinus rhythm, not using negative chronotropic agents and with no myocardial ischemic response to exercise testing carried out at a specialist clinic, between 2005 and 2011. BMI was categorized as normal (18.5-<25 kg/m(2)), overweight (25-≤30 kg/m(2)) or obese (>30 kg/m(2)). The different BMI groups were compared in terms of HR recovery after exercise, which was calculated as the difference between maximum HR during exercise and in the first minute of recovery. Recovery was considered impaired when the difference was ≤12 bpm.

RESULTS

Eighty-seven (3.6%) patients presented impaired recovery, which was three times more prevalent in the obese group and twice as prevalent in the overweight group compared with the normal group (p<0.001 and p=0.010, respectively). Obese patients presented higher basal HR and lower maximum HR, as well as reduced chronotropic reserve (p<0.001). In multivariate analysis, impaired HR recovery was associated with overweight (relative risk [RR]=1.8; p=0.035), obesity (RR=2; p=0.016), number of metabolic equivalents (RR=0.82; p<0.001) and resting HR (RR=1.05; p<0.001). The hazard ratio for hypertension was 2 (p=0.083, NS).

CONCLUSION

Impaired HR recovery was associated with higher BMI, demonstrating that obese individuals present vagus nerve dysfunction.

Obesity Modifies the Effect of Fitness on Heart Rate Indices during Exercise Stress Testing in Asymptomatic Individuals

<b><i>Objective:</i></b> To assess the impact of aerobic fitness on exercise heart rate (HR) indices in an asymptomatic cohort across different body mass index (BMI) categories. <b><i>Methods:</i></b> We performed a cross-sectional analysis of 506 working-class Brazilian subjects, free of known clinical cardiovascular disease (e.g. ischemic heart disease and stroke) who underwent an exercise stress test. <b><i>Results:</i></b> There was a significant trend towards decreased HR at peak exercise, HR recovery and chronotropic index (CI) measures as BMI increased, but resting HR increased significantly across BMI categories. In multivariate analysis, the change in CI per unit change in metabolic equivalents of task was greater among the obese subjects than the normal-weight (2.7 vs. -0.07; p interaction = 0.029) and overweight (2.7 vs. 0.7; p interaction = 0.044) subjects. A similar pattern was seen with peak HR and HR recovery, although the formal tests of interaction did not achieve statistical significance. <b><i>Conclusion:</i></b> Our findings strongly suggest that fitness is associated with a favorable HR profile and is modified by BMI. Intervention programs should place emphasis on fitness and not only on weight loss.

Obesity and coronary artery disease: evaluation and treatment

With the increasing prevalence of obesity, clinicians are now facing a growing population of patients with specific features of clinical presentation, diagnostic challenges, and interventional, medical, and surgical management. After briefly discussing the effect of obesity on atherosclerotic burden in this review, we will focus on strategies clinicians might use to ensure better outcomes when performing revascularization in obese and severely obese patients. These patients tend to present comorbidities at a younger age, and their anthropometric features might limit the use of traditional cardiovascular risk stratification approaches for ischemic disease. Alternative techniques have emerged, especially in nuclear medicine. Positron emission tomography-computed tomography might be the diagnostic imaging technique of choice. When revascularization is considered, features associated with obesity must be considered to guide therapeutic strategies. In percutaneous coronary intervention, a radial approach should be favoured, and adequate antiplatelet therapy with new and more potent agents should be initiated. Weight-based anticoagulation should be contemplated if needed, with the use of drug-eluting stents. An "off-pump" approach for coronary artery bypass grafting might be preferable to the use of cardiopulmonary bypass. For patients who undergo bilateral internal thoracic artery grafting, harvesting using skeletonization might prevent deep sternal wound infections. In contrast to percutaneous coronary intervention, lower surgical bleeding has been observed when lean body mass is used for perioperative heparin dose determination.

Exercise tolerance in obese vs. lean adolescents: a systematic review and meta-analysis

To prescribe feasible and medically safe exercise interventions for obese adolescents, it remains to be determined whether exercise tolerance is altered and whether anomalous cardiopulmonary responses during maximal exercise testing are present. Studies that examined cardiopulmonary responses to maximal exercise testing in obese adolescents were searched: cardiopulmonary exercise tests with respiratory gas exchange measurements of peak oxygen uptake (VO2peak) were performed and comparisons between obese and lean adolescents were made. Study quality was assessed using a standardized item list. By meta-analyses VO2peak, peak cycling power output (Wpeak) and peak heart rate (HRpeak) were compared between groups. Nine articles were selected (333 obese vs. 145 lean adolescents). VO2peak (L min(-1)), HRpeak and Wpeak were not different between groups (P ≥ 0.10), while a trend was found for a reduced VO2peak (mL min(-1) kg(-1) lean tissue mass) (P=0.07) in obese vs. lean adolescents. It remained uncertain whether anomalous cardiopulmonary responses occur during maximal exercise testing in obese adolescents. In conclusion, a trend was found for lowered VO2peak (mL min(-1)kg(-1) lean tissue mass) in obese vs. lean adolescents. Whether cardiopulmonary anomalies during maximal exercise testing would occur in obese adolescents remains uncertain. Studies are therefore warranted to examine the cardiopulmonary response during maximal exercise testing in obese adolescents.

Exercise-induced improvements in cardiorespiratory fitness and heart rate response to exercise are impaired in overweight/obese postmenopausal women

OBJECTIVE

The purpose of this study was to compare the heart rate response to exercise and the exercise-induced improvements in muscle strength, cardiorespiratory fitness and heart rate response between normal-weight and overweight/obese postmenopausal women.

METHODS

Sedentary women (n = 155) were divided into normal-weight (n = 79; BMI <25 kg/m(2); 58.3 ± 8.6 years) and overweight/obese (n = 76; BMI >25 kg/m(2); 58.3 ± 8.6 years) groups, and have their 1-repetition maximum strength (adjusted for body mass), cardiorespiratory fitness and heart rate response to a graded exercise test compared before and after 12 months of a three times-per-week exercise-training program.

RESULTS

Overweight/obese women displayed decreased upper and lower extremity muscle strengths, decreased cardiorespiratory fitness, and lower peak and reserve heart rates compared to normal-weight women. After follow-up, both groups improved their upper (32.9% and 41.5% in normal-weight and overweight/obese women, respectively) and lower extremity(49.5% and 47.8% in normal-weight and overweight/obese women, respectively) muscle strength. However, only normal-weight women improved their cardiorespiratory fitness (6.6%) and recovery heart rate (5 bpm). Resting, reserve and peak heart rates did not change in either group.

CONCLUSIONS

Overweight/obese women displayed impaired heart rate response to exercise. Both groups improved muscle strength, but only normal-weight women improved cardiorespiratory fitness and heart rate response to exercise. These results suggest that exercise-induced improvements in cardiorespiratory fitness and heart rate response to exercise may be impaired in overweight/obese postmenopausal women.