Cardiorespiratory responses and myocardial function within incremental exercise in healthy unmedicated older vs. young men and women

Effects of aging and endurance exercise training on cardiorespiratory fitness and cardiac structure and function in healthy midlife and older women

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in women in developed societies. Unfavorable structural and functional adaptations within the heart and central blood vessels with sedentary aging in women can act as the substrate for the development of debilitating CVD conditions such as heart failure with preserved ejection fraction (HFpEF). The large decline in cardiorespiratory fitness, as indicated by maximal or peak oxygen uptake (V̇o2max and V̇o2peak, respectively), that occurs in women as they age significantly affects their health and chronic disease status, as well as the risk of cardiovascular and all-cause mortality. Midlife and older women who have performed structured endurance exercise training for several years or decades of their adult lives exhibit a V̇o2max and cardiac and vascular structure and function that are on par or even superior to much younger sedentary women. Therefore, regular endurance exercise training appears to be an effective preventative strategy for mitigating the adverse physiological cardiovascular adaptations associated with sedentary aging in women. Herein, we narratively describe the aging and short- and long-term endurance exercise training adaptations in V̇o2max, cardiac structure, and left ventricular systolic and diastolic function at rest and exercise in midlife and older women. The role of circulating estrogens on cardiac structure and function is described for consideration in the timing of exercise interventions to maximize beneficial adaptations. Current research gaps and potential areas for future investigation to advance our understanding in this critical knowledge area are highlighted.

Systolic and diastolic function during cycling at the respiratory threshold between elderly and young healthy individuals

The hemodynamic consequences of aging have been extensively investigated during maximal incremental exercise. However, less is known about the effects of aging on hemodynamics during submaximal steady-state exercise. The aim of the present investigation was to compare the hemodynamics of healthy elderly and young subjects during an exercise bout conducted at the gas threshold (GET) intensity. Two groups of healthy, physically active subjects were studied: the elderly group—EG (n = 11; > 60 years old) and the young group—YG (n = 13; < 35 years old). Both groups performed a 5-min rectangular exercise test at the GET intensity. Hemodynamics were measured using echocardiography. The main finding was that stroke volume responses were higher in the YG than the EG (72.5 ± 16.7 vs. 52.4 ± 8.4 ml, respectively). The increased stroke volume capacity in the YG was the consequence of a greater capacity to increase cardiac preload and contractility and, to a lesser extent, to reduce systemic vascular resistance. Importantly, the atrial contribution to ventricular diastolic filling was substantially higher in the YG when compared to the EG.

Cardiorespiratory response to exercise in endurance-trained premenopausal and postmenopausal females

PURPOSE

To assess the influence of different hormonal profiles on the cardiorespiratory response to exercise in endurance-trained females.

METHODS

Forty-seven eumenorrheic females, 38 low-dose monophasic oral contraceptive (OC) users and 13 postmenopausal women, all of them endurance-trained, participated in this study. A DXA scan, blood sample tests and a maximal aerobic test were performed under similar low-sex hormone levels: early follicular phase for the eumenorrheic females; withdrawal phase for the OC group and at any time for postmenopausal women. Cardiorespiratory variables were measured at resting and throughout the maximal aerobic test (ventilatory threshold 1, 2 and peak values). Heart rate (HR) was continuously monitored with a 12-lead ECG. Blood pressure (BP) was measured with an auscultatory method and a calibrated mercury sphygmomanometer. Expired gases were measured breath-by-breath with the gas analyser Jaeger Oxycon Pro.

RESULTS

One-way ANCOVA reported a lower peak HR in postmenopausal women (172.4 ± 11.7 bpm) than in eumenorrheic females (180.9 ± 10.6 bpm) (p = 0.024). In addition, postmenopausal women exhibited lower VO₂ (39.1 ± 4.9 ml/kg/min) compared to eumenorrheic females (45.1 ± 4.4 ml/kg/min) in ventilatory threshold 2 (p = 0.009). Nonetheless, respiratory variables did not show differences between groups at peak values. Finally, no differences between OC users and eumenorrheic females' cardiorespiratory response were observed in endurance-trained females.

CONCLUSIONS

Cardiorespiratory system is impaired in postmenopausal women due to physiological changes caused by age and sex hormones' decrement. Although these alterations appear not to be fully compensated by exercise, endurance training could effectively mitigate them. In addition, monophasic OC pills appear not to impact cardiorespiratory response to an incremental running test in endurance-trained females.

Gender Differences in Hemodynamic Regulation and Cardiovascular Adaptations to Dynamic Exercise

Exercise is a major challenge for cardiovascular apparatus since it recruits chronotropic, inotropic, pre-load, and afterload reserves. Regular physical training induces several physiological adaptations leading to an increase in both cardiac volume and mass. It appears that several gender-related physiological and morphological differences exist in the cardiovascular adjustments and adaptations to dynamic exercise in humans. In this respect, gender may be important in determining these adjustments and adaptations to dynamic exercise due to genetic, endocrine, and body composition differences between sexes. Females seem to have a reduced vasoconstriction and a lower vascular resistance in comparison to males, especially after exercise. Significant differences exist also in the cardiovascular adaptations to physical training, with trained women showing smaller cardiac volume and wall thickness compared with male athletes. In this review, we summarize these differences.

Physical activity, exercise, and chronic diseases: A brief review

Chronic diseases are the leading cause of death worldwide with increasing prevalence in all age groups, genders, and ethnicities. Most chronic disease deaths occur in middle-to low-income countries but are also a significant health problem in developed nations. Multiple chronic diseases now affect children and adolescents as well as adults. Being physically inactive is associated with increased chronic disease risk. Global societies are being negatively impacted by the increasing prevalence of chronic disease which is directly related to rising healthcare expenditures, workforce complications regarding attendance and productivity, military personnel recruitment, and academic success. However, increased physical activity (PA) and exercise are associated with reduced chronic disease risk. Most physiologic systems in the body benefit positively from PA and exercise by primary disease prevention and secondary disease prevention/treatment. The purpose of this brief review is to describe the significant global problem of chronic diseases for adults and children, and how PA and exercise can provide a non-invasive means for added prevention and treatment.

Methods and considerations concerning cardiac output measurement in pregnant women: recommendations of the International Working Group on Maternal Hemodynamics

Cardiac output (CO), along with blood pressure and vascular resistance, is one of the most important parameters of maternal hemodynamic function. Substantial changes in CO occur in normal pregnancy and in most obstetric complications. With the development of several non-invasive techniques for the measurement of CO, there is a growing interest in the determination of this parameter in pregnancy. These techniques were initially developed for use in critical-care settings and were subsequently adopted in obstetrics, often without appropriate validation for use in pregnancy. In this article, methods and devices for the measurement of CO are described and compared, and recommendations are formulated for their use in pregnancy, with the aim of standardizing the assessment of CO and peripheral vascular resistance in clinical practice and research studies on maternal hemodynamics. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Small intra-individual variability of the pre-ejection period justifies the use of pulse transit time as approximation of the vascular transit

Background

Vascular transit time (VTT) is the propagation time of a pulse wave through an artery; it is a measure for arterial stiffness. Because reliable non-invasive VTT measurements are difficult, as an alternative we measure pulse transit time (PTT). PTT is defined as the time between the R-wave on electrocardiogram and arrival of the resulting pulse wave in a distal location measured with photoplethysmography (PPG). The time between electrical activation of the ventricles and the resulting pulse wave after opening of the aortic valve is called the pre-ejection period (PEP), a component of PTT. The aim of this study was to estimate the variability of PEP at rest, to establish how accurate PTT is as approximation of VTT.

Methods

PTT was measured and PEP was assessed with echocardiography (gold standard) in three groups of 20 volunteers: 1) a control group without cardiovascular disease aged <50 years and 2) aged >50 years, and 3) a group with cardiovascular risk factors, defined as arterial hypertension, dyslipidemia, kidney failure and diabetes mellitus.

Results

Per group, the mean PEP was: 1) 58.5 ± 13.0 ms, 2) 52.4 ± 11.9 ms, and 3) 57.6 ± 11.6 ms. However, per individual the standard deviation was much smaller, i.e. 1) 2.0–5.9 ms, 2) 2.8–5.1 ms, and 3) 1.6–12.0 ms, respectively. There was no significant difference in the mean PEP of the 3 groups (p = 0.236).

Conclusion

In conclusion, the intra-individual variability of PEP is small. A change in PTT in a person at rest is most probably the result of a change in VTT rather than of PEP. Thus, PTT at rest is an easy, non-invasive and accurate approximation of VTT for monitoring arterial stiffness.