Cardiac remodeling after six weeks of high-intensity interval training to exhaustion in endurance-trained men

Exercise and Fitness Quantification in Clinical Practice: Why and How; and Where Are We Going?

Exercise and fitness quantification is increasingly recognized as a critical component in clinical practice, particularly within preventive cardiology. In this article we explore the multifaceted importance of exercise quantification in clinical settings, addressing preventive care, cost-effectiveness, psychosocial benefits, treatment planning, and monitoring progress. Quantifying exercise habits allows clinicians to evaluate risk profiles, prescribe tailored interventions, and monitor patient progress. The methodologies for exercise quantification are discussed. In preventive cardiology, adherence to guidelines from organizations such as the American Heart Association, the European Society of Cardiology, and the Canadian Cardiovascular Society is emphasized, with particular focus on high-intensity interval training and the central role of physical therapists/kinesiologists. Special populations, such as weekend warriors, those reflecting the "fat and fit" concept, athletes, and those at risk of overtraining syndrome, are considered in prescribing exercise. Future directions in exercise and fitness quantification include the integration of advanced wearable technology, personalized medicine, telemedicine, and promotion of active, walkable communities. The incorporation of behavioral science is highlighted as a missing component that can enhance long-term adherence to exercise regimens through motivation, behavior change techniques, patient-centered approaches, and continuous monitoring and feedback. This comprehensive approach aims to optimize cardiovascular health and overall well-being through individualized, evidence-based exercise interventions that are both effective and sustainable.

The impact of exercise intensity and duration for swim training-induced adaptations in cardiac structure and function in women with mild hypertension

This study aimed to investigate the impact of swim training intensity and duration on cardiac structure and function in mildly hypertensive women. Sixty-two mildly hypertensive women were randomized to 15 weeks of either (1) high-intensity swimming (HIS, n = 21), (2) moderate-intensity swimming (MOD, n = 21) or (3) control (CON, n = 20). Training sessions occurred three times per week. Cardiac measurements were conducted using echocardiography pre- and post-intervention. Both the HIS and MOD groups demonstrated significant within-group increases in left ventricular mass: 7.3% [1.2; 13.2] (p = 0.02) for HIS and 6.2% [0.5; 11.8] (p = 0.03) for MOD. The MOD group also demonstrated a significant increase in left ventricular internal dimension at end-diastole by 2.4% [0.2; 4.6] (p = 0.03). Post-hoc analysis of diastolic function markers revealed reduced mitral valve A velocity in both HIS (-14% [-25; -3], p = 0.02) and MOD (-13% [-23; -3], p = 0.01), leading to increased mitral valve E/A ratios of 27% [10; 47] (p = 0.003) and 22% [5; 40] (p = 0.01), respectively. Additionally, only MOD demonstrated increased left atrial diameter of 4.9% [0.7; 9.1] (p =0.02). A significant time×group effect (p = 0.02) existed for global longitudinal strain, which increased by 1.6% [0.2; 3.0] (p = 0.03) in MOD only. In conclusion, swim training for 15 weeks increased left ventricular mass and improved markers of diastolic function in mildly hypertensive women. These independent of exercise intensity and duration in mildly hypertensive women.

15 weeks of soccer training increases left ventricular mass and improves indices of left ventricular diastolic function in previously sedentary, mildly hypertensive, middle-aged women

PURPOSE

To investigate the impact of soccer training on cardiac adaptations in mildly hypertensive middle-aged women.

METHODS

Hypertensive premenopausal women (n = 41; age (mean ± SD): 44 ± 7 years; height: 166 ± 6 cm; weight: 78.6 ± 11.6 kg; body fat: 43.3 ± 5.2%) were randomized to soccer training (SOC, n = 21) or control (CON, n = 20). SOC performed three weekly training sessions for 15 weeks, whereas CON had no training or lifestyle changes during the same period. Cardiac structure and function were assessed by echocardiography pre-intervention and post-intervention.

RESULTS

Soccer training increased (P = 0.001) left ventricular mass index by 10% [95% CI 4; 15], while no changes occurred in CON (time × group interaction, P = 0.005). In addition, only SOC demonstrated a within-group increase (P = 0.01) of 8% [95% CI 2; 14] in left ventricular septum diameter. For markers of right ventricular remodelling, a within-group increase (P = 0.02) occurred for tricuspid annulus plane systolic excursion of 8% [95% CI 1; 14] in SOC only. Left atrial diameter index increased (P < 0.001) by 6% [95% CI 3; 10] after SOC, while it was unaffected in CON (time × group interaction, P = 0.02). For makers of diastolic function, SOC demonstrated a within-group increase (P = 0.02) in the average early diastolic mitral annulus velocity of 10% [95% CI 2; 19]. In addition, a reduction (P < 0.001) in mitral valve A velocity of - 19% [95% CI - 29; - 10] was observed following soccer training, which manifested in increased (P < 0.001) mitral valve E/A ratio of 34% [95% CI 16; 53] in SOC. No within-group changes were apparent in CON.

CONCLUSION

In sedentary, mildly hypertensive, middle-aged women, 15 weeks of soccer training increases left ventricular mass and left atrial diameter and improves indices of left ventricular diastolic function.

Characterizing the influence of cardiorespiratory fitness on left atrial size and function in the general population

Increased left atrial (LA) size and reduced LA function have been associated with heart failure and atrial fibrillation (AF) in at-risk populations. However, atrial remodeling has also been associated with exercise training and the relationship between fitness, LA size, and function has not been defined across the fitness spectrum. In a cross-sectional study of 559 ostensibly healthy participants, comprising 304 males (mean age, 46 ± 20 yr) and 255 females (mean age, 47 ± 15 yr), we sought to define the relationship between cardiorespiratory fitness (CRF), LA size, and function. We also aimed to interrogate sex differences in atrial factors influencing CRF. Echocardiographic measures included biplane measures of LA volumes indexed to body surface area (LAVi) and atrial deformation using two-dimensional speckle tracking. CRF was measured as peak oxygen consumption (V̇o2peak) during cardiopulmonary exercise testing (CPET). Using multivariable regression, age, sex, weight, and LAVi (P < 0.001 for all) predicted V̇o2peak (P < 0.001, R2 = 0.66 for combined model). After accounting for these variables, heart rate reserve added strength to the model (P < 0.001, R2 = 0.74) but LA strain parameters did not predict V̇o2peak. These findings add important nuance to the perception that LA size is a marker of cardiac pathology. LA size should be considered in the context of fitness, and it is likely that the adverse prognostic associations of increased LA size may be confined to those with LA enlargement and low fitness.NEW & NOTEWORTHY Left atrial (LA) structure better predicts cardiorespiratory fitness (CRF) than LA function. LA function adds little statistical value to predictive models of peak oxygen uptake (V̇o2peak) in healthy individuals, suggesting limited discriminatory for CRF once LA size is factored. In the wider population of ostensibly healthy individuals, the association between increased LA volume and higher CRF provides an important counter to the association between atrial enlargement and heart failure symptoms in those with cardiac pathology.

Influence of exercise training on the left atrium: implications for atrial fibrillation, heart failure, and stroke

The left atrium (LA) plays a critical role in receiving pulmonary venous return and modulating left ventricular (LV) filling. With the onset of exercise, LA function contributes to the augmentation in stroke volume. Due to the growing focus on atrial imaging, there is now evidence that structural remodeling and dysfunction of the LA is associated with adverse outcomes including incident cardiovascular disease. In patients with established disease, pathological changes in atrial structure and function are associated with exercise intolerance, increased hospital admissions and mortality, independent of left ventricular function. Exercise training is widely recommended in patients with cardiovascular disease to improve patient outcomes and maintain functional capacity. There are widely documented changes in LV function with exercise, yet less attention has been given to the LA. In this review, we first describe LA physiology at rest and during exercise, before exploring its association with cardiac disease outcomes including atrial fibrillation, heart failure, and stroke. The adaptation of the LA to short- and longer-term exercise training is evaluated through review of longitudinal studies of exercise training in healthy participants free of cardiovascular disease and athletes. We then consider the changes in LA structure and function among patients with established disease, where adverse atrial remodeling may be implicated in the disease process. Finally, we consider important future directions for assessment of atrial structure and function using novel imaging modalities, in response to acute and chronic exercise.

Atrial fibrillation: primary prevention, secondary prevention, and prevention of thromboembolic complications: part 1

Atrial fibrillation (AF), is the most common sustained cardiac arrhythmia. It was once thought to be benign as long as the ventricular rate was controlled, however, AF is associated with significant cardiac morbidity and mortality. Increasing life expectancy driven by improved health care and decreased fertility rates has, in most of the world, resulted in the population aged ≥65 years growing more rapidly than the overall population. As the population ages, projections suggest that the burden of AF may increase more than 60% by 2050. Although considerable progress has been made in the treatment and management of AF, primary prevention, secondary prevention, and prevention of thromboembolic complications remain a work in progress. This narrative review was facilitated by a MEDLINE search to identify peer-reviewed clinical trials, randomized controlled trials, meta-analyses, and other clinically relevant studies. The search was limited to English-language reports published between 1950 and 2021. Atrial fibrillation was searched via the terms primary prevention, hyperthyroidism, Wolff-Parkinson-White syndrome, catheter ablation, surgical ablation, hybrid ablation, stroke prevention, anticoagulation, left atrial occlusion and atrial excision. Google and Google scholar as well as bibliographies of identified articles were reviewed for additional references. In these two manuscripts, we discuss the current strategies available to prevent AF, then compare noninvasive and invasive treatment strategies to diminish AF recurrence. In addition, we examine the pharmacological, percutaneous device and surgical approaches to prevent stroke as well as other types of thromboembolic events.

Exercise Training Does Not Attenuate Cardiac Atrophy or Loss of Function in Individuals With Acute Spinal Cord Injury: A Pilot Study

OBJECTIVE

To investigate the effects of 2 modes of exercise training, upper-body alone, and the addition of electrical stimulation of the lower body, to attenuate cardiac atrophy and loss of function in individuals with acute spinal cord injury (SCI).

DESIGN

Randomized controlled trial.

SETTING

Rehabilitation Hospital.

PARTICIPANTS

Volunteers (N=27; 5 women, 22 men) who were <24 months post SCI.

INTERVENTIONS

Volunteers completed either 6 months of no structured exercise (Control), arm rowing (AO), or a combination of arm rowing with electrical stimulation of lower body paralyzed muscle (functional electrical stimulation [FES] rowing).

MAIN OUTCOME MEASURES

Transthoracic echocardiography was performed on each subject prior to and 6 months after the intervention. The relations between time since injury and exercise type to cardiac structure and function were assessed via 2-way repeated-measures analysis of variance and with multilevel linear regression.

RESULTS

Time since injury was significantly associated with a continuous decline in cardiac structure and systolic function, specifically, a reduction in left ventricular mass (0.197 g/month; P=.049), internal diameter during systole (0.255 mm/month; P<.001), and diastole (0.217 mm/month; P=.019), as well as cardiac output (0.048 L/month, P=.019), and left ventricular percent shortening (0.256 %/month; P=.027). These associations were not differentially affected by exercise (Control vs AO vs FES, P>.05).

CONCLUSIONS

These results indicate that within the subacute phase of recovery from SCI there is a linear loss of left ventricular cardiac structure and systolic function that is not attenuated by current rehabilitative aerobic exercise practices. Reductions in cardiac structure and function may increase the risk of cardiovascular disease in individuals with SCI and warrants further interventions to prevent cardiac decline.

Change in Central Cardiovascular Function in Response to Intense Interval Training: A Systematic Review and Meta-analysis

INTRODUCTION

High-intensity interval training and sprint interval training significantly increase maximal oxygen uptake (V̇O 2max ), which enhances endurance performance and health status. Whether this response is due to increases in central cardiovascular function (cardiac output (CO) and blood volume) or peripheral factors is unknown.

PURPOSE

This study aimed to conduct a systematic review and meta-analysis to assess the effects of high-intensity interval training and sprint interval training (referred to as intense interval training) on changes in central cardiovascular function.

METHODS

We performed a systematic search of eight databases for studies denoting increases in V̇O 2max in which CO, stroke volume (SV), blood volume, plasma volume, end-diastolic/systolic volume, or hematocrit were measured.

RESULTS

Forty-five studies were included in this analysis, comprising 946 men and women of various health status (age and V̇O 2max , 20-76 yr and 13-61 mL·kg -1 ·min -1 ) who performed 6-96 sessions of interval training. Results showed an increase in V̇O 2max with intense interval training that was classified as a large effect ( d = 0.83). SV ( d = 0.69), and CO ( d = 0.49) had moderate effect sizes in response to intense interval training. Of 27 studies in which CO was measured, 77% exhibited significant increases in resting CO or that obtained during exercise. Similarly, 93% of studies revealed significant increases in SV in response to intense interval training. Effect sizes for these outcomes were larger for clinical versus healthy populations. Plasma volume, blood volume, and hematocrit had small effect sizes after training ( d = 0.06-0.14).

CONCLUSIONS

Increases in V̇O 2max demonstrated with intense interval training are attendant with increases in central O 2 delivery with little contribution from changes in hematocrit, blood volume, or plasma volume.

Effect of angiotensin-converting enzyme inhibition on cardiovascular adaptation to exercise training

Angiotensin-converting enzyme (ACE) activity may be one determinant of adaptability to exercise training, but well-controlled studies in humans without confounding conditions are lacking. Thus, the purpose of the present study was to investigate whether ACE inhibition affects cardiovascular adaptations to exercise training in healthy humans. Healthy participants of both genders (40 ± 7 years) completed a randomized, double-blind, placebo-controlled trial. Eight weeks of exercise training combined with placebo (PLA, n = 25) or ACE inhibitor (ACEi, n = 23) treatment was carried out. Before and after the intervention, cardiovascular characteristics were investigated. Mean arterial blood pressure was reduced (p < 0.001) by -5.5 [-8.4; -2.6] mmHg in ACEi , whereas the 0.7 [-2.0; 3.5] mmHg fluctuation in PLA was non-significant. Maximal oxygen uptake increased (p < 0.001) irrespective of ACE inhibitor treatment by 13 [8; 17] % in ACEi and 13 [9; 17] % in PLA. In addition, skeletal muscle endurance increased (p < 0.001) to a similar extent in both groups, with magnitudes of 82 [55; 113] % in ACEi and 74 [48; 105] % in PLA. In contrast, left atrial volume decreased (p < 0.05) by -9 [-16; -2] % in ACEi , but increased (p < 0.01) by 14 [5; 23] % in PLA. Total hemoglobin mass was reduced (p < 0.01) by -3 [-6; -1] % in ACEi , while a non-significant numeric increase of 2 [-0.4; 4] % existed in PLA. The lean mass remained constant in ACEi but increased (p < 0.001) by 3 [2; 4] % in PLA. In healthy middle-aged adults, 8 weeks of high-intensity exercise training increases maximal oxygen uptake and skeletal muscle endurance irrespective of ACE inhibitor treatment. However, ACE inhibitor treatment counteracts exercise training-induced increases in lean mass and left atrial volume. ACE inhibitor treatment compromises total hemoglobin mass.

Longitudinal Associations Between Cumulative Physical Activity and Change in Structure and Function of the Left Side of the Heart: The Tromsø Study 2007–2016

Background

Current knowledge about the relationship between physical activity (PA) and cardiac remodeling is mainly derived from cross-sectional studies of athletes, and there is a knowledge gap of this association in the general adult and elderly population. Therefore, we aimed to explore the longitudinal association between cumulative PA and change in cardiac structure and function in a general adult and elderly population.

Methods

This longitudinal study includes 594 participants from the sixth (Tromsø6, 2007–08) and seventh (Tromsø7, 2015–16) survey of the Tromsø Study. Cardiac structure and function were assessed by echocardiography at two time points, and PA was self-reported by questionnaire at both time points. PA volume was expressed as cumulative PA (Low, Moderate, and Hard) and the association with left atrial (LA) and left ventricular (LV) structure and function was assessed using ANCOVA.

Results

Overall, LA diameter index (LADi) increased significantly more in Hard compared to Moderate PA (+0.08 cm/m², 95% CI 0.01–0.15, p = 0.020) from Tromsø6 to Tromsø7. When stratified by sex or age, higher levels of cumulative PA were associated with increased LADi in males and in participants <65 years only. Indexed LV mass (LVMi) increased significantly more in Moderate than in Low PA (+3.9 g/m^2.7, 95% CI 0.23–7.57, p = 0.037). When stratified by sex or age, these changes in LVMi and indexed LV diameter (LVDi) were only significant in females. No significant associations were observed between cumulative PA and change in relative wall thickness, E/e' ratio, e' velocity, LV ejection fraction, and LADi/LVDi ratio.

Conclusion

Higher levels of cumulative PA were associated with increased LADi in males and participants <65 years, and with increased LVMi and LVDi in females. Despite cardiac chamber enlargement, the pump function of the heart did not change with higher levels of PA, and the atrioventricular ratio was unchanged. Our results indicate that cardiac chamber enlargement is a physiological response to PA.

Effects of a New Form of Resistance-Type High-Intensity Interval Training on Cardiac Structure, Hemodynamics, and Physiological and Performance Adaptations in Well-Trained Kayak Sprint Athletes

This study examined the effects of a resistance-type high-intensity interval training (RHIIT) matched with the lowest velocity that elicited V.O_2peak (100% vV.O_2peak) in well-trained kayak sprint athletes. Responses in cardiac structure and function, cardiorespiratory fitness, anaerobic power, exercise performance, muscular strength, and hormonal adaptations were examined. Male kayakers (n = 24, age: 27 ± 4 years) were randomly assigned to one of three 8-wk conditions (N = 8): (RHIIT) resistance training using one-armed cable row at 100% vV.O_2peak; paddling-based HIIT (PHIIT) six sets of paddling at 100% vV.O_2peak; or controls (CON) who performed six sessions including 1-h on-water paddling/sessions at 70–80% maximum HR per week. Significant increases (p < 0.05) in V.O_2peak, vV.O_2peak, maximal cardiac output, resting stroke volume, left ventricular end-systolic dimension, 500-m paddling performance were seen pre- to post-training in all groups. Change in V.O_2peak in response to PHIIT was significantly greater (p = 0.03) compared to CON. Also, 500-m paddling performance changes in response to PHIIT and RHIIT were greater (p = 0.02, 0.05, respectively) than that of CON. Compared with pre-training, PHIIT and RHIIT resulted in significant increases in peak and average power output, maximal stroke volume, end-diastolic volume, ejection fraction, total testosterone, testosterone/cortisol ratio, and 1,000-m paddling performance. Also, the change in 1,000-m paddling performance in response to PHIIT was significantly greater (p = 0.02) compared to that of CON. Moreover, maximum strength was significantly enhanced in response to RHIIT pre- to post-training (p < 0.05). Overall, RHIIT and PHIIT similarly improve cardiac structure and hemodynamics, physiological adaptations, and performance of well-trained kayak sprint athletes. Also, RHIIT enhances cardiorespiratory fitness and muscular strength simultaneously.

Effect of aerobic exercise on physiological and left ventricular echocardiographic characteristics of non-athletic adult males in Northern Ethiopia

BACKGROUND

Regular aerobic exercise can induce alterations in structural and hemodynamic physiology of the heart in both athletic and nonathletic populations. This is because due to cardiac adaptation to exercise improves cardiac workout capacity by increasing left ventricular function. The aim of the present study was to examine the effect of aerobic exercise on blood pressure and left ventricular structural and myocardial function in Ethiopian non-athletic males.

METHODS

Twenty male adults (aged 19-23 years) were recruited and they were engaged in aerobic exercise training for 3 months (3days/week, 50-75%MHR). Selected participants underwent standard transthoracic doppler echocardiographic examinations before and after intervention of the exercise training. Collected data were analyzed through Paired Sample T test using IBM SPSS version 21 statistical software with significance level set at p<0.05.

RESULTS

Finding of the study indicated that significant reduction in systolic and diastolic blood pressure was observed after exercise training (p<0.05). Improvement was recorded in PWT (7.4±0.94mm vs 7.95±0.61mm, p=0.017) and IVST (7.95±0.83mm vs 8.25±0.72mm, p=0.030) while significant reduction was recorded in LVIDS (33.85±0.99mm vs 32.45±2.04mm, p=0.002). Aerobic exercises also induced significant improvement on left ventricular myocardial function parameters (p<0.05) in end diastolic volume (95.8±8.4ml vs 100.45±11.42ml), stroke volume (52.55±7.12ml vs 58.15±11.18ml) and ejection fraction (54.73±4.11 vs 57.53±6.2). However, exercise didn't stimulate significant change in the internal diameter at end diastole (0.086), end systolic volume (p=0.173) and cardiac output (p=0.13).

CONCLUSIONS

Aerobic exercise induces structural and myocardial physiological changes within the left ventricle in Ethiopian non-athletic young adult males.

The impact of demographic, anthropometric and athletic characteristics on left atrial size in athletes

The structural adaptations of the “athlete's heart” include left atrial (LA) enlargement. A literature search was performed based on PubMed listings up to November 2, 2019 using “athletes AND left atrium,” “athletes AND LA,” “sports AND left atrium,” “sports AND LA,” “exercise AND left atrium,” and “exercise AND LA” as the search terms. Eligible studies included those reporting the influence of demographic, anthropometric and athletic characteristics on LA size in athletes. A total of 58 studies were included in this review article. Although LA volume has been reported to be greater in males compared to females when indexed for body surface area (BSA), there was no difference between sexes. The positive association between LA size and age in athletes may reflect the increase in body size with maturation in nonadult athletes and the training age of endurance athletic activity in adult athletes. Caucasian and black athletes have been demonstrated to exhibit similar LA enlargement. The positive association of LA size with lean body mass (LBM) possibly accounts for the relationship of LA size with BSA. LA enlargement has been reported only in endurance‐trained, but not in strength‐trained athletes. LA size appears to increase with an increase in both the volume and intensity of endurance training. LA size correlates independently with the training age of endurance athletes. The athlete's characteristics that independently determine LA size include LBM, endurance training, and training age.

Cerebral blood flow responses to exercise are enhanced in left ventricular assist device patients after an exercise rehabilitation program

Cerebral blood flow during exercise is impaired in patients with heart failure implanted with left ventricular assist devices (LVADs). Our aim was to determine whether a 3-mo exercise training program could mitigate cerebrovascular dysfunction. Internal carotid artery (ICA) blood flow and intracranial middle (MCAv) and posterior cerebral (PCAv) artery velocities were measured continuously using Doppler ultrasound, alongside cardiorespiratory measures at rest and in response to an incremental cycle ergometer exercise protocol in 12 LVAD participants (5 female, 53.6 ± 11.8 yr; 84.2 ± 15.7 kg; 1.73 ± 0.08) pre- (PreTR) and post- (PostTR) completion of a 3-mo supervised exercise rehabilitation program. At rest, only PCAv was different PostTR (38.1 ± 10.4 cm/s) compared with PreTR (43.0 ± 10.8 cm/s; P < 0.05). PreTR, the reduction in PCAv observed from rest to exercise (5.2 ± 1.8%) was mitigated PostTR (P < 0.001). Similarly, exercise training enhanced ICA flow during submaximal exercise (~8.6 ± 13.7%), resulting in increased ICA flow PostTR compared with a reduced flow PreTR (P < 0.001). Although both end-tidal partial pressure of carbon dioxide and mean arterial pressure responses during incremental exercise were greater PostTR than PreTR, only the improved PETCO2 was related to the improved ICA flow (R² = 0.14; P < 0.05). Our findings suggest that short-term exercise training improves cerebrovascular function during exercise in patients with LVADs. This finding should encourage future studies investigating long-term exercise training and cerebral and peripheral vascular adaptation.NEW & NOTEWORTHY Left ventricular assist devices, now used as destination therapy in end-stage heart failure, enable patients to undertake rehabilitative exercise training. We show, for the first time in humans, that training improves cerebrovascular function during exercise in patients with left ventricular assist devices. This finding may have implications for cerebrovascular health in patients with heart failure.