Utility of graded exercise tolerance tests for prediction of cardiovascular mortality in old age: The Rancho Bernardo Study

Novel wireless laser doppler flowmeter-based investigation of earlobe vascular dynamics in cardiopulmonary exercise testing

[Purpose] A new wireless laser Doppler blood flowmeter has facilitated easier, more stable measurement of skin perfusion during exercise. However, earlobe blood flow during the cardiopulmonary exercise test remains unascertained. This study aimed to clarify the characteristics of earlobe blood flow during incremental exercise load in healthy individuals. [Participants and Methods] Among 25 healthy males (age 23.6 ± 2.5 years), cycle ergometer-based symptom-limited cardiopulmonary exercise test, after 4 minutes of rest, was conducted with a 4-minute 20W warm-up and a continuous 2W-increase in the work rate every 6 seconds; earlobe blood flow was measured using a wireless laser Doppler blood flowmeter. [Results] Compared with that at rest, earlobe blood flow increased significantly from 50% of exercise peak intensity to a maximum of 1.7 times, but decreased immediately after exercise. The earlobe blood flow %change did not significantly correlate with hemodynamic parameters and its inflection point 36.4% Loadpeak was significantly lower than the anaerobic metabolic threshold 58.1% Loadpeak. [Conclusion] In healthy participants, earlobe blood flow during cardiopulmonary exercise test increased gradually with low-intensity exercise from approximately 1.5 times the resting rate and approached the anaerobic metabolic threshold with a maximum of 1.7 times the resting earlobe blood flow, but decreased quickly after exercise.

Exercise-Induced Blood Pressure Dynamics: Insights from the General Population and the Athletic Cohort

Blood pressure (BP) dynamics during graded exercise testing provide important insights into cardiovascular health, particularly in athletes. These measurements, taken during intense physical exertion, complement and often enhance our understanding beyond traditional resting BP measurements. Historically, the challenge has been to distinguish 'normal' from 'exaggerated' BP responses in the athletic environment. While basic guidelines have served their purpose, they may not fully account for the complex nature of BP responses in today's athletes, as illuminated by contemporary research. This review critically evaluates existing guidelines in the context of athletic performance and cardiovascular health. Through a rigorous analysis of the current literature, we highlight the multifaceted nature of exercise-induced BP fluctuations in athletes, emphasising the myriad determinants that influence these responses, from specific training regimens to inherent physiological nuances. Our aim is to advocate a tailored, athlete-centred approach to BP assessment during exercise. Such a paradigm shift is intended to set the stage for evidence-based guidelines to improve athletic training, performance and overall cardiovascular well-being.

Cardiorespiratory Fitness in the Prevention and Management of Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of death among adults in the U.S. and elsewhere. Variation in the presence, severity, and control of major modifiable risk factors accounts for much of the variation in CVD rates worldwide. Cardiorespiratory fitness (CRF) reflects the integration of ventilation, circulation, and metabolism for the delivery and utilization of oxygen in support of dynamic aerobic physical activity. The gold standard measure of CRF is maximal oxygen uptake. Because the primary factor underlying differences in this measure between individuals is maximal cardiac output, it can serve as a clinical indicator of cardiac function. Higher CRF is associated with favorable levels of major CVD risk factors, lower prevalence and severity of subclinical atherosclerosis, and lower risks of developing both primary and secondary clinical CVD events. The beneficial associations between CRF and CVD are seen in women and men, older and younger adults, in those with multiple coexisting risk factors or prior diagnosis of CVD. Exercise training and regular physical activity of at least moderate intensities and volumes improves CRF in adults, and improvements in CRF are associated with lower risks of subsequent CVD and mortality. Routine assessment of CRF in primary care settings could enhance individual-level CVD risk assessment and thereby guide implementation of appropriate measures to prevent future clinical events.

Cardiac Responses to Submaximal Isometric Contraction and Aerobic Exercise in Healthy Pregnancy

PURPOSE

The increased physiological demand of pregnancy results in the profound adaptation of the maternal cardiovascular system, reflected by greater resting cardiac output and left ventricular (LV) deformation. Whether the increased resting demand alters acute cardiac responses to exercise in healthy pregnant women is not well understood.

METHODS

Healthy nonpregnant (n = 18), pregnant (n = 14, 22-26 wk gestation), and postpartum women (n = 13, 12-16 wk postdelivery) underwent assessments of cardiac function and LV mechanics at rest, during a sustained isometric forearm contraction (30% maximum), and during low-intensity (LOW) and moderate-intensity (MOD) dynamic cycling exercise (25% and 50% peak power output). Significant differences (α = 0.05) were determined using ANCOVA and general linear model (resting value included as covariate).

RESULTS

When accounting for higher resting cardiac output in pregnant women, pregnant women had greater cardiac output during isometric contraction (2.0 ± 0.3 L·min-1·m-1.83; nonpregnant, 1.3 ± 0.2 L·min-1·m-1.83; postpartum, 1.5 ± 0.5 L·min-1·m-1.83; P = 0.02) but similar values during dynamic cycling exercise (pregnant, LOW = 2.8 ± 0.4 L·min-1·m-1.83, MOD = 3.4 ± 0.7 L·min-1·m-1.83; nonpregnant, LOW = 2.4 ± 0.3 L·min-1·m-1.83, MOD = 3.0 ± 0.3 L·min-1·m-1.83; postpartum, LOW = 2.3 ± 0.4 L·min-1·m-1.83, MOD = 3.0 ± 0.5 L·min-1·m-1.83; P = 0.96). Basal circumferential strain was higher in pregnant women at rest, during the sustained isometric forearm contraction (-23.5% ± 1.2%; nonpregnant, -14.6% ± 1.4%; P = 0.001), and during dynamic cycling exercise (LOW = -27.0% ± 4.9%, MOD = -27.4% ± 4.6%; nonpregnant, LOW = -15.8% ± 4.5%, MOD = -15.2% ± 6.7%; P = 0.012); however, other parameters of LV mechanics were not different between groups.

CONCLUSION

The results support that the maternal heart can appropriately respond to additional cardiac demand and altered loading experienced during acute isometric and dynamic exercise, although subtle differences in responses to these challenges were observed. In addition, the LV mechanics that underpin global cardiac function are greater in pregnant women during exercise, leading to the speculation that the hormonal milieu of pregnancy influences regional deformation.

The relationship between arterial stiffness and maximal oxygen consumption in healthy young adults

Objective

Arterial stiffness is associated with an increased risk of cardiovascular diseases in various populations. There was little research on the relationship between arterial stiffness and maximal aerobic capacity (VO_2max) in healthy young adults. The aim of this study was to investigate the relationship between VO_2max and arterial stiffness in young adults.

Methods

The subjects were 13 men and 10 women with mean age of 22.9 ± 0.7, 23.6 ± 0.4 years, respectively. Height, weight, body mass index, body fat (%), waist to hip ratio, total/high density lipoprotein (HDL)/low density lipoprotein (LDL) cholesterol, triglycerides, fasting glucose, blood pressure, heart rate, glycated hemoglobin and blood lactate were measured. In addition, peripheral arterial stiffness was assessed by measuring brachial-ankle pulse wave velocity (baPWV) and VO_2max was determined using graded exercise test.

Results

VO_2max had no significant correlation with baPWV (r = 0.2, p = 0.2). Total cholesterol correlated significantly to variables such as HDL (r = 0.6, p = 0.0015) and LDL cholesterol (r = -0.6, p = 0.0018). VO_2max had a significant association with triglyceride (r = -0.5, p = 0.0033).

Conclusions

This study suggests that there is no relationship between arterial stiffness and aerobic capacity in healthy young adults.

Functional hemodynamic testing in pregnancy: recommendations of the International Working Group on Maternal Hemodynamics

In the general population, functional hemodynamic testing, such as that during submaximal aerobic exercise and isometric handgrip, and the cold pressor test, has long been utilized to unmask abnormalities in cardiovascular function. During pregnancy, functional hemodynamic testing places additional demands on an already stressed maternal cardiovascular system. Dysfunctional responses to such tests in early pregnancy may predict the development of hypertensive disorders that develop later in gestation. For each of the above functional hemodynamic tests, these recommendations provide a description of the test, test protocol and equipment required, and an overview of the current understanding of clinical application during pregnancy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Resting heart rate and measures of effort-related cardiac autonomic dysfunction predict cardiovascular events in asymptomatic type 2 diabetes

BACKGROUND

Autonomic control of the cardiovascular system may be impaired in type 2 diabetes and is associated with increased morbidity and mortality. Parameters obtained during stress testing may reflect early stages of cardiac autonomic dysfunction and provide prognostic information in asymptomatic type 2 diabetes.

METHODS

We performed maximal exercise treadmill testing in 594 patients with type 2 diabetes without known coronary heart disease. The prognostic significance of physiological parameters associated with autonomic dysfunction was assessed, including chronotropic incompetence (<80% heart rate reserve), abnormal heart rate recovery at 1 minute <18 beats/minute, and resting tachycardia >100 beats/minute. Cox proportional hazards analysis was used to determine the association of exercise parameters with a composite outcome of all-cause mortality, myocardial infarction or stroke.

RESULTS

Resting heart rate >100 beats/minute was observed in 18% of patients, chronotropic incompetence in 30% and heart rate recovery at 1 minute <18 beats/minute in 35%. Over 79 ± 16 months, there were 72 (12%) events. Each parameter was significantly associated with event risk in an adjusted multivariate analysis: chronotropic incompetence (hazard ratio 1.89, 95% confidence interval 1.18-3.01; P = 0.008), resting heart rate ≥100 beats/minute (hazard ratio 1.97, 95% confidence interval 1.19-3.26; P = 0.008) and heart rate recovery at 1 minute <18 beats (hazard ratio 1.77, 95% confidence interval 1.12-2.81; P = 0.015). A progressive relationship between the number of abnormal parameters and event risk was observed (log rank P < 0.001).

CONCLUSIONS

Chronotropic incompetence, resting tachycardia and reduced heart rate recovery are independently and additively associated with long-term mortality, myocardial infarction or stroke in type 2 diabetes without known coronary heart disease.