Biventricular Response of the Heart to Endurance Exercise Training in Previously Untrained Subjects

Conditioning Program Prescribed from the External Training Load Corresponding to the Lactate Threshold Improved Cardiac Function in Healthy Dogs

This research focuses on the adjustments in systolic and diastolic functions that are not fully understood in dogs submitted to athletic training. Beagle dogs carried out an endurance training program (ETP) prescribed from the external training load, corresponding to 70-80% of the lactate threshold (VLT) velocity. Eighteen dogs were randomly assigned to two groups: control (C, n = 8), active dogs that did not perform any forced exercise, and trained (T, n = 10), submitted to the ETP during eight weeks. All dogs were evaluated before and after the ETP period using two-dimensional echocardiography, M-mode, Doppler, and two-dimensional speckle tracking. A principal component analysis (PCA) of the echocardiographic variables was performed. The ETP improved the left ventricular internal dimension at the end of diastole (LVDd), the left ventricular internal dimension at the end of diastole to aorta ratio (LVDd: Ao), and the strain rate indices. PCA was able to capture the dimensionality and qualitative echocardiography changes produced by the ETP. These findings indicated that the training prescribed based on the lactate threshold improved the diastolic and systolic functions. This response may be applied to improve myocardial function, promote health, and mitigate any injuries produced during heart failure.

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.

Impact of aerobic training periodisation on global and regional right ventricular strain in coronary heart disease

Linear aerobic training periodisation (LP) is recommended for patients with coronary heart disease (CHD). However, the effects of training periodisation on the right heart mechanics in patients with CHD have never been examined. This study aimed to explore the effects of LP and non-linear periodisation (NLP) on right heart mechanics. We prospectively randomised CHD patients to 12 weeks of aerobic training with LP or NLP. While there was a weekly increase in energy expenditure with LP, there was a steeper increase during the first 3 weeks, followed by a decrease in the fourth week with NLP. Echocardiography was performed at baseline and after the training period to assess the right ventricular free wall (RVFW) and right atrial strain. Thirty patients with CHD were included (NLP, n = 16; LP, n = 14). The traditional right and left heart parameters showed no significant time effects. There was a decrease of RVFW strain with time in both groups (+1.3 ± 0.9% with NLP, and +1.5 ± 0.8% with LP; p = 0.033). Mid-ventricular RVFW strain changed significantly with time (+2.0 ± 1.3% with NLP, and from +2.3 ± 1.2% with LP; p = 0.025). There was no time effect on the right atrial strain. In stable CHD patients, LP and NLP resulted in right ventricular strain decrements with a segment-specific pattern. This study was registered at ClinicalTrials.gov (identifier number: NCT03414996). Novelty: In stable coronary heart disease patients, both linear and non-linear aerobic training periodisation programs result in right ventricular strain decrements with time, particularly in the mid-ventricular segment. Traditional right and left heart parameters and right atrial strain showed no significant time effect in both 12 weeks aerobic training periodisation programs.

Home-Based Exercise Training Improves Left Ventricle Diastolic Function in Survivors of Childhood ALL: A Tissue Doppler and Velocity Vector Imaging Study

BACKGROUND

Advanced echocardiographic methods may reveal signs of late anthracycline cardiac toxicity (ACT) even in asymptomatic patients. We studied echocardiographic tissue Doppler imaging (TDI) and velocity vector imaging (VVI) in long-term survivors of childhood acute lymphoblastic leukemia (ALL) before and after an exercise intervention.

METHODS

Twenty-one asymptomatic, anthracycline-treated, long-term childhood ALL survivors with matched controls were studied at baseline. Seventeen of the survivors participated in a 3-month home-based exercise program. Echocardiography with TDI and VVI was performed.

RESULTS

At baseline, ejection fraction (60.7 ± 4.7% vs. 62.3 ± 3.7%, P = 0.22) and fractional shortening (32.6 ± 3.1% vs. 34.0 ± 2.8%, P = 0.13) were similar in survivors and controls. Lateral early diastolic mitral annulus velocity E' (32.81 ± 5.71 cm/sec vs. 38.03 ± 6.21 cm/sec, P = 0.01), E'/A' (1.60 ± 0.48 vs. 2.07 ± 0.63, P = 0.01), and E/E' (2.78 ± 0.35 vs. 2.42 ± 0.62, P = 0.04) were impaired compared to controls. Peak circumferential strain and strain rate were attenuated at apex (-24.50 ± 3.46% vs. -28.06 ± 4.39%, P = 0.01 and -1.47 ± 0.22 sec(-1) vs. -1.68 ± 0.33 sec(-1) , P = 0.02) compared to controls. After the intervention, early diastolic mitral inflow velocity E (87.76 ± 12.54 cm/s vs. 95.28 ± 10.48 cm/s, P = 0.04) and E' increased (31.78 ± 5.50 cm/s vs. 34.96 ± 5.41 cm/s, P < 0.01). Peak circumferential systolic and diastolic strain rates at mid-level (-1.22 ± 0.21 sec(-1) vs. -1.35 ± 0.24 sec(-1) , P = 0.04 and 1.25 ± 0.25 sec(-1) vs. 1.48 ± 0.35 sec(-1) , P < 0.01) improved after the exercise program.

CONCLUSIONS

A simple home-based exercise program improved cardiac function in asymptomatic childhood ALL survivors. Adding TDI in routine echocardiographic examination may improve the recognition of early signs of ACT, and VVI may bring additional information. The improvements in cardiac function after the exercise program emphasize the importance of physical activity in this population.