Cardiac response to exercise in young, normal weight and overweight men and women

Influence of Supervised Maternal Aerobic Exercise during Pregnancy on 1-Month-Old Neonatal Cardiac Function and Outflow: A Pilot Study

PURPOSE

The objective of this study is to assess the effects of supervised, recommended levels of prenatal aerobic exercise on 1-month-old infant cardiac function.

METHODS

Eligible pregnant women were randomly assigned to either an aerobic exercise group that participated in 150 min of supervised, moderate-intensity (40% to 59% V̇O 2peak , 12 to 14 on Borg rating of perceived exertion) aerobic exercise per week for 24 wk or more or a nonexercising group that consisted of 150 min·wk -1 of relaxation techniques. One-month-old infant echocardiogram was performed to assess infant cardiac function , including heart rate (HR), left-ventricular stroke volume, cardiac output, cardiac index, ejection fraction, fractional shortening, and velocity time integral at the aortic valve. Pearson correlation analyses and linear regression models were performed.

RESULTS

Prenatal aerobic exercise was negatively correlated with infant resting HR ( r = -0.311, P = 0.02). Similarly, when controlling for infant sex and activity state, exercise level/volume ( β = -0.316; 95% CI, -0.029 to -0.002; P = 0.02) predicted resting infant HR ( R2 = 0.18, P = 0.02). In infants of overweight/obese women, infants of aerobic exercisers had increased fractional shortening ( P = 0.03). In addition, infant ventricular ejection fraction was correlated with maternal exercise attendance ( r = 0.418, P = 0.03) as well as a trend for exercise level ( r = 0.351, P = 0.08). Similarly, the only significant regression model for infants of overweight/obese women controls infant activity state ( β = -0.444; 95% CI, -0.05 to -0.01; P = 0.006) and maternal exercise level ( β = 0.492; 95% CI, 5.46-28.74; P = 0.01) predicting infant resting HR ( F = 5.79, R2 = 0.40, P = 0.003).

CONCLUSIONS

The findings of this study demonstrate that women participating in exercise in the second and third trimesters of their pregnancy may have infants with increased cardiac function at 1 month of age. Importantly, the cardiac function effects were further augmented for infants born to overweight/obese women.

Systematic Review and Regression Modeling of the Effects of Age, Body Size, and Exercise on Cardiovascular Parameters in Healthy Adults

PURPOSE

Blood pressure, cardiac output, and ventricular volumes correlate to various subject features such as age, body size, and exercise intensity. The purpose of this study is to quantify this correlation through regression modeling.

METHODS

We conducted a systematic review to compile reference data of healthy subjects for several cardiovascular parameters and subject features. Regression algorithms used these aggregate data to formulate predictive models for the outputs-systolic and diastolic blood pressure, ventricular volumes, cardiac output, and heart rate-against the features-age, height, weight, and exercise intensity. A simulation-based procedure generated data of virtual subjects to test whether these regression models built using aggregate data can perform well for subject-level predictions and to provide an estimate for the expected error. The blood pressure and heart rate models were also validated using real-world subject-level data.

RESULTS

The direction of trends between model outputs and the input subject features in our study agree with those in current literature.

CONCLUSION

Although other studies observe exponential predictor-output relations, the linear regression algorithms performed the best for the data in this study. The use of subject-level data and more predictors may provide regression models with higher fidelity.

SIGNIFICANCE

Models developed in this study can be useful to clinicians for personalized patient assessment and to researchers for tuning computational models.

Cardiovascular and cerebral hemodynamics during exercise and recovery in obese individuals as a function of their fitness status

The aim of this study was to compare cardiovascular hemodynamics and cerebral oxygenation/perfusion (COP) during and after maximal incremental exercise in obese individuals according to their aerobic fitness versus age‐matched healthy controls (AMHC). Fifty‐four middle–aged obese (OB) and 16 AMHC were recruited. Maximal cardiopulmonary function (gas exchange analysis), cardiac hemodynamics (impedance cardiography), and left frontal COP (near‐infrared spectroscopy: NIRS) were measured continuously during a maximal incremental ergocycle test. During recovery, reoxygenation/perfusion rate (ROPR: oxyhemoglobin: ΔO₂Hb, deoxyhemoglobin: ΔHHb and total hemoglobin: ΔtHb; with NIRS) was also measured. Obese participants (OB, n = 54) were divided into two groups according to the median V˙O2 peak: the low‐fit obese (LF‐OB, n = 27) and the high‐fit obese (HF‐OB, n = 27). During exercise, end tidal pressure of CO₂ (PETCO₂), and COP (ΔO₂Hb, ΔHHb and ΔtHb) did not differ between groups (OB, LF‐OB, HF‐OB, AMHC). During recovery, PETCO₂ and ROPR (ΔO₂Hb, ΔHHb and ΔtHb) were similar between the groups (OB, LF‐OB, HF‐OB, AMHC). During exercise and recovery, cardiac index was lower (P < 0.05) in LF‐OB versus the other two groups (HF‐OB, AMHC). As well, systolic blood pressure was higher during exercise in the OB, LF‐OB and HF‐OB groups versus AMHC (P < 0.05). When compared to AMHC, obese individuals (OB, LF‐OB, HF‐OB) have a similar cerebral vasoreactivity by CO₂ and cerebral hemodynamics during exercise and recovery, but a higher systolic blood pressure during exercise. Higher fitness in obese subjects (HF‐OB) seems to preserve their cardiopulmonary and cardiac function during exercise and recovery.

Acute Strenuous Exercise Induces an Imbalance on Histone H4 Acetylation/Histone Deacetylase 2 and Increases the Proinflammatory Profile of PBMC of Obese Individuals

This study evaluated the response of global histone H4 acetylation (H4ac), histone deacetylase 2 (HDAC2) activity, as well as the production of proinflammatory cytokines and monocyte phenotypes of lean and obese males after exercise. Ten lean and ten obese sedentary men were submitted to one session of strenuous exercise, and peripheral blood mononuclear cells (PBMC) were stimulated in vitro with lipopolysaccharide (LPS). Global H4ac levels, HDAC2 activity in PBMC, and IL-6, IL-8, and TNF-α production were analyzed. Monocyte phenotype was determined in accordance with the expression of CD14 and CD16. At rest, obese individuals presented higher frequency of proinflammatory CD14⁺CD16⁺ monocytes. LPS induced a significant augment in global H4ac and in the production of IL-6, IL-8, and TNF-α mainly in obese individuals. After exercise, the increased production of IL-8 and TNF-α and peripheral frequency of CD14⁺CD16⁺ were observed in both groups. In addition, exercise also induced a significant hyperacetylation of histone H4 and decreased HDAC2 activity in both nonstimulated and LPS-stimulated PBMC of obese individuals. Our data indicate that the obesity impacts on H4ac levels and that strenuous exercise leads to an enhanced chronic low-grade inflammation profile in obesity via an imbalance on H4ac/HDAC2.

Causes of exercise intolerance in heart failure with preserved ejection fraction: searching for consensus

Exercise intolerance is one of the cardinal symptoms of heart failure with preserved ejection fraction (HFpEF). We review its mechanistic basis using evidence from exercise studies. One barrier to a consensus understanding of the pathophysiology is heterogeneity of the patient population. Therefore, we pay special attention to varying study definitions of the disease and their possible impact on the causal factors that are implicated. We then discuss the role of exercise testing and its potential to subtype HFpEF in to more homogeneous mechanism-based subclasses.

Relation between cycling exercise capacity, fiber-type composition, and lower extremity muscle strength and muscle endurance

The aim of the study was to determine the relation between peak oxygen uptake V(O2)peak), peak work rate (WRpeak), fiber-type composition, and lower extremity strength and endurance during a maximal incremental cycle test. Thirty-nine healthy sedentary men, aged 30-46, participated in the study. Subjects performed a maximal incremental cycle test and isokinetic knee extension (KE) and flexion (KF) strength and endurance tests at velocities of 60 and 180° · s(-1). Muscle biopsies were taken from m. vastus lateralis and analyzed for fiber-type composition. A significant correlation existed between KE strength and V(O2)peak and WRpeak. Also, KF endurance correlated significantly to V(O2)peak and WRpeak. The KE endurance correlated significantly to WRpeak (rp = 0.32, p < 0.05) and almost significantly to V(O2)peak (rp = 0.28, p = 0.06). Stepwise multiple regression analyses showed that KE strength, KF endurance, and the percentage of type I fibers could explain up to 40% of the variation in V(O2) and WRpeak. The performance of sedentary subjects in a maximal incremental cycle test is highly affected by knee muscle strength and endurance. Fiber-type composition also contributes but to a smaller extent.

Cardiac function and arteriovenous oxygen difference during exercise in obese adults

The purpose of this study was to assess cardiac function and arteriovenous oxygen difference (a-vO(2) difference) at rest and during exercise in young, normal-weight (n = 20), and obese (n = 12) men and women who were matched for age and fitness level. Participants were assessed for body composition, peak oxygen consumption (VO(2peak)), and cardiac variables (thoracic bioimpedance)-cardiac index (CI), cardiac output (Q), stroke volume (SV), heart rate (HR), and ejection fraction (EF)-at rest and during cycling exercise at 65% of VO(2peak). Differences between groups were assessed with multivariate ANOVA and mixed-model ANOVA with repeated measures controlling for sex. Absolute VO(2peak) and VO(2peak) relative to fat-free mass (FFM) were similar between normal-weight and obese groups (Mean ± SEE 2.7 ± 0.2 vs. 3.3 ± 0.3 l min(-1), p = 0.084 and 52.4 ± 1.5 vs. 50.9 ± 2.3 ml kg FFM(-1) min(-1), p = 0.583, respectively). In the obese group, resting Q and SV were higher (6.7 ± 0.4 vs. 4.9 ± 0.1 l min(-1), p < 0.001 and 86.8 ± 4.3 vs. 65.8 ± 1.9 ml min(-1), p < 0.001, respectively) and EF lower (56.4 ± 2.2 vs. 65.5 ± 2.2%, p = 0.003, respectively) when compared with the normal-weight group. During submaximal exercise, the obese group demonstrated higher mean CI (8.8 ± 0.3 vs. 7.7 ± 0.2 l min(-1) m(-2), p = 0.007, respectively), Q (19.2 ± 0.9 vs. 13.1 ± 0.3 l min(-1), p < 0.001, respectively), and SV (123.0 ± 5.6 vs. 88.9 ± 4.1 ml min(-1), p < 0.001, respectively) and a lower a-vO(2) difference (10.4 ± 1.0 vs. 14.0 ± 0.7 ml l00 ml(-1), p = 0.002, respectively) compared with controls. Our study suggests that the ability to extract oxygen during exercise may be impaired in obese individuals.

Understanding changes in cardiovascular pathophysiology

Cardiovascular pathophysiological changes, such as hypertension and enlarged ventricles, reflect the altered functions of the heart and its circulation during ill-health. This article examines the normal and altered anatomy of the cardiac valves, the contractile elements and enzymes of the myocardium, the significance of the different factors associated with cardiac output, and the role of the autonomic nervous system in the heart beat. It also explores how certain diseases alter these functions and result in cardiac symptoms. Nurses can benefit from knowledge of these specific changes, for example, by being able to ask relevant questions in order to ascertain the nature of a patients condition, by being able to take an effective patient history and by being able to read diagnostic results, such as electrocardiograms and cardiac enzyme results. All this will help nurses to promote sound cardiac care based on a physiological rationale.