Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies.

A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances, and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat by examining the benefits of heat acclimation, cooling strategies, and hyperhydration. Finally, contemporary controversies are summarized and future research directions are provided.

Effects of hypoxic compound exercise to promote HIF-1α expression on cardiac pumping function, sleep activity behavior, and exercise capacity in Drosophila.

Alteration of HIF-1α expression levels under hypoxic conditions affects the sequence of its downstream target genes thereby producing different effects. In order to investigate whether the effect of hypoxic compound exercise (HE) on HIF-1α expression alters cardiac pumping function, myocardial structure, and exercise capacity, we developed a suitable model of hypoxic exercise using Drosophila, a model organism, and additionally investigated the effect of hypoxic compound exercise on nocturnal sleep and activity behavior. The results showed that hypoxic compound exercise at 6% oxygen concentration for five consecutive days, lasting 1 h per day, significantly improved the cardiac stress resistance of Drosophila. The hypoxic complex exercise promoted the whole-body HIF-1α expression in Drosophila, and improved the jumping ability, climbing ability, moving speed, and moving distance. The expression of HIF-1α in the heart was increased after hypoxic exercise, which made a closer arrangement of myofilaments, an increase in the diameter of cardiac tubules, and an increase in the pumping function of the heart. The hypoxic compound exercise improved the sleep quality of Drosophila by increasing its nocturnal sleep time, the number of deep sleeps, and decreasing its nocturnal awakenings and activities. Therefore, we conclude that hypoxic compound exercise promoted the expression of HIF-1α to enhance the exercise capacity and heart pumping function of Drosophila, and improved the quality of sleep.

Physiological Characterization of Preserved Ratio Impaired Spirometry in the CanCOLD Study: Implications for Exertional Dyspnea and Exercise Intolerance.

Rationale: It is increasingly recognized that adults with preserved ratio impaired spirometry (PRISm) are prone to increased morbidity. However, the underlying pathophysiological mechanisms are unknown. Objectives: Evaluate the mechanisms of increased dyspnea and reduced exercise capacity in PRISm. Methods: We completed a cross-sectional analysis of the CanCOLD (Canadian Cohort Obstructive Lung Disease) population-based study. We compared physiological responses in 59 participants meeting PRISm spirometric criteria (post-bronchodilator FEV1 < 80% predicted and FEV1/FVC ⩾ 0.7), 264 control participants, and 170 ever-smokers with chronic obstructive pulmonary disease (COPD), at rest and during cardiopulmonary exercise testing. Measurements and Main Results: Individuals with PRISm had lower total lung, vital, and inspiratory capacities than healthy controls (all P < 0.05) and minimal small airway, pulmonary gas exchange, and radiographic parenchymal lung abnormalities. Compared with healthy controls, individuals with PRISm had higher dyspnea/[Formula: see text]o2 ratio at peak exercise (4.0 ± 2.2 vs. 2.9 ± 1.9 Borg units/L/min; P < 0.001) and lower [Formula: see text]o2peak (74 ± 22% predicted vs. 96 ± 25% predicted; P < 0.001). At standardized submaximal work rates, individuals with PRISm had greater Vt/inspiratory capacity (Vt%IC; P < 0.001), reflecting inspiratory mechanical constraint. In contrast to participants with PRISm, those with COPD had characteristic small airways dysfunction, dynamic hyperinflation, and pulmonary gas exchange abnormalities. Despite these physiological differences among the three groups, the relationship between increasing dyspnea and Vt%IC during cardiopulmonary exercise testing was similar. Resting IC significantly correlated with [Formula: see text]o2peak (r = 0.65; P < 0.001) in the entire sample, even after adjusting for airflow limitation, gas trapping, and diffusing capacity. Conclusions: In individuals with PRISm, lower exercise capacity and higher exertional dyspnea than healthy controls were mainly explained by lower resting lung volumes and earlier onset of dynamic inspiratory mechanical constraints at relatively low work rates. Clinical trial registered with www.clinicaltrials.gov (NCT00920348).

Ferric carboxymaltose and exercise capacity in heart failure with preserved ejection fraction and iron deficiency: the FAIR-HFpEF trial.

BACKGROUND AND AIMS: Evidence is lacking that correcting iron deficiency (ID) has clinically important benefits for patients with heart failure with preserved ejection fraction (HFpEF). METHODS: FAIR-HFpEF was a multicentre, randomized, double-blind trial designed to compare intravenous ferric carboxymaltose (FCM) with placebo (saline) in 200 patients with symptomatic HFpEF and ID (serum ferritin < 100 ng/mL or ferritin 100-299 ng/mL with transferrin saturation < 20%). The primary endpoint was change in 6-min walking test distance (6MWTD) from baseline to week 24. Secondary endpoints included changes in New York Heart Association class, patient global assessment, and health-related quality of life (QoL). RESULTS: The trial was stopped because of slow recruitment after 39 patients had been included (median age 80 years, 62% women). The change in 6MWTD from baseline to week 24 was greater for those assigned to FCM compared to placebo [least square mean difference 49 m, 95% confidence interval (CI) 5-93; P = .029]. Changes in secondary endpoints were not significantly different between groups. The total number of adverse events (76 vs. 114) and serious adverse events (5 vs. 19; rate ratio 0.27, 95% CI 0.07-0.96; P = .043) was lower with FCM than placebo. CONCLUSIONS: In patients with HFpEF and markers of ID, intravenous FCM improved 6MWTD and was associated with fewer serious adverse events. However, the trial lacked sufficient power to identify or refute effects on symptoms or QoL. The potential benefits of intravenous iron in HFpEF with ID should be investigated further in a larger cohort.

Prolyl isomerase Pin1 in skeletal muscles contributes to systemic energy metabolism and exercise capacity through regulating SERCA activity.

The skeletal muscle is a pivotal organ involved in the regulation of both energy metabolism and exercise capacity. There is no doubt that exercise contributes to a healthy life through the consumption of excessive energy or the release of myokines. Skeletal muscles exhibit insulin sensitivity and can rapidly uptake blood glucose. In addition, they can undergo non-shivering thermogenesis through actions of both the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) and small peptide, sarcolipin, resulting in systemic energy metabolism. Accordingly, the maintenance of skeletal muscles is important for both metabolism and exercise. Prolyl isomerase Pin1 is an enzyme that converts the cis-trans form of proline residues and controls substrate function. We have previously reported that Pin1 plays important roles in insulin release, thermogenesis, and lipolysis. However, the roles of Pin1 in skeletal muscles remains unknown. To clarify this issue, we generated skeletal muscle-specific Pin1 knockout mice. Pin1 deficiency had no effects on muscle weights, morphology and ratio of fiber types. However, they showed exacerbated obesity or insulin resistance when fed with a high-fat diet. They also showed a lower ability to exercise than wild type mice did. We also found that Pin1 interacted with SERCA and elevated its activity, resulting in the upregulation of oxygen consumption. Overall, our study reveals that Pin1 in skeletal muscles contributes to both systemic energy metabolism and exercise capacity.

The Child Opportunity Index 2.0 and Disparities in Pediatric Cardiorespiratory Fitness.

OBJECTIVE: To evaluate the effect of neighborhood-level characteristics on cardiorespiratory fitness (CRF) via peak oxygen consumption (VO2peak) for healthy pediatric patients. STUDY DESIGN: The institutional cardiopulmonary exercise testing (CPET) database was analyzed retrospectively. All patients aged ≤ 18 years without a diagnosis of cardiac disease and with a maximal effort CPET were included. Patients were divided into three self-identified racial categories: White, Black, and Latinx. The Child Opportunity Index (COI) 2.0 was used to analyze social determinants of health. CRF was evaluated based on COI quintiles and race. Assessment of the effect of COI on racial disparities in CRF was performed using ANCOVA. RESULTS: A total of 1753 CPETs met inclusion criteria. The mean VO2peak was 42.1 ± 9.8 mL/kg/min. The VO2peak increased from 39.1 ± 9.6 mL/kg/min for patients in the very low opportunity cohort to 43.9 ± 9.4 mL/kg/min for patients in the very high opportunity cohort. White patients had higher percent predicted VO2peak compared with both Black and Latinx patients (P < .01 for both comparisons). The racial differences in CRF were no longer significant when adjusting for COI. CONCLUSION: In a large pediatric cohort, COI was associated with CRF. Racial disparities in CRF are reduced when accounting for modifiable risk factors.

Endovascular Ablation of the Right Greater Splanchnic Nerve in Heart Failure With Preserved Ejection Fraction: Rationale, Design and Lead-in Phase Results of the REBALANCE-HF Trial.

OBJECTIVE: Splanchnic vasoconstriction augments transfer of blood volume from the abdomen into the thorax, which may increase filling pressures and hemodynamic congestion in patients with noncompliant hearts. Therapeutic interruption of splanchnic nerve activity holds promise to reduce hemodynamic congestion in patients with heart failure with preserved ejection fraction (HFpEF). Here we describe (1) the rationale and design of the first sham-controlled, randomized clinical trial of splanchnic nerve ablation for HFpEF and (2) the 12-month results of the lead-in (open-label) trial's participants. METHODS: REBALANCE-HF is a prospective, multicenter, randomized, double-blinded, sham-controlled clinical trial of endovascular, transcatheter, right-sided greater splanchnic nerve ablation for volume management (SAVM) in patients with HFpEF. The primary objectives are to evaluate the safety and efficacy of SAVM and identify responder characteristics to inform future studies. The trial consists of an open-label lead-in phase followed by the randomized, sham-controlled phase. The primary efficacy endpoint is the reduction in pulmonary capillary wedge pressure (PCWP) at 1-month follow-up compared to baseline during passive leg raise and 20W exercise. Secondary and exploratory endpoints include health status (Kansas City Cardiomyopathy Questionnaire), 6-minute walk test distance, New York Heart Association class, and NTproBNP levels at 3, 6 and 12 months. The primary safety endpoint is device- or procedure-related serious adverse events at the 1-month follow-up. RESULTS: The lead-in phase of the study, which enrolled 26 patients with HFpEF who underwent SAVM, demonstrated favorable safety outcomes and reduction in exercise PCWP at 1 month post-procedure and improvements in all secondary endpoints at 6 and 12 months of follow-up. The randomized phase of the trial (n = 44 SAVM; n = 46 sham) has completed enrollment, and follow-up is ongoing. CONCLUSION: REBALANCE-HF is the first sham-controlled randomized clinical trial of greater splanchnic nerve ablation in HFpEF. Initial 12-month open-label results are promising, and the results of the randomized portion of the trial will inform the design of a future pivotal clinical trial. SAVM may offer a promising therapeutic option for patients with HFpEF. TRIAL REGISTRATION: NCT04592445.

A Comprehensive Assessment of the Chinese Version of the Duke Activity Status Index in Patients with Cardiovascular Diseases.

Background: Exercise capacity serves as a direct representation of cardiac function. The Duke Activity Status Index (DASI), a self-administered 12-item questionnaire, covers aspects of daily living, household tasks, sexual function, and physical activity. Although widely used to evaluate exercise capacity, its validation in Chinese cardiovascular disease (CVD) patients has not been thoroughly explored. Considering the significant cultural and lifestyle differences between China and Western countries, which may influence Chinese patients' comprehension and responses to DASI, our objective is to culturally adapt DASI for Chinese patients with CVD to ensure its precision in assessing exercise capacity. Methods: The cultural adaptation of the original DASI questionnaire into Chinese followed a rigorous process to ensure its validity, reliability, and sensitivity to Chinese CVD patients. The study included 107 outpatients diagnosed with CVD who completed the DASI and cardiopulmonary exercise testing (CPET). Cronbach's alpha, Spearman correlation, and factor analysis were utilized to test reliability and validity. Receiver operating characteristic (ROC) curve analysis was employed to assess the prognostic utility of the DASI. Results: Participants had a mean DASI score of 39.40 ± 10.75 and a peak oxygen uptake (Peak VO 2 ) of 19.53 ± 5.89 mL/min/kg. The Chinese version of the DASI exhibited satisfactory reliability and validity in CVD patients, with a Chronbach's alpha coefficient of 0.706. The DASI score demonstrated a moderate correlation with Peak VO 2 measured by CPET (r = 0.67, p < 0.001). Factor analysis yielded three factors, accounting for 56.76% of the total variance, with factor 1 contributing to 26.38% of the variance. ROC curve analysis demonstrated that the DASI exhibited discriminative utility in the identification of patients with improved long-term prognosis (p < 0.001). The ROC curve had an area of 0.788 [95% confidence interval (CI) = 0.704-0.871]. The DASI score ≥ 36.85 served as the optimal threshold for enhanced long-term prognosis, exhibiting a sensitivity of 0.80 and a specificity of 0.69. Conclusions: The culturally adapted DASI questionnaire is a straightforward and efficient tool for reasonably evaluating exercise capacity in Chinese CVD patients.

Pulmonary rehabilitation improves exercise capacity, health-related quality of life, and cardiopulmonary function in patients with non-small cell lung cancer.

BACKGROUND: Lung cancer significantly impairs exercise capacity and health-related quality of life (HRQL). Pulmonary rehabilitation (PR) has demonstrated positive effects on exercise capacity and HRQL in lung cancer patients. However, its impact on cardiopulmonary function needs further exploration. The aim of this study was to explore the effects of PR on cardiopulmonary function, exercise capacity and HRQL in patients with lung cancer. METHODS: Patients with lung cancer were enrolled in a 12-week PR program. Each participant underwent a thorough evaluation, which included spirometry, cardiopulmonary exercise testing, respiratory muscle strength test, and evaluation of HRQL using the Chronic Obstructive Pulmonary Disease Assessment Test (CAT). RESULTS: Fifty-six patients completed the PR program. Following PR, exercise capacity significantly improved, as evidenced by increased peak oxygen uptake and work rate (both p < 0.05). Exertional symptoms were notably reduced, including leg soreness and dyspnea at peak exercise, accompanied by a decrease in the CAT score (all p < 0.05). Furthermore, improvements in cardiopulmonary function were observed, encompassing respiratory muscle strength, ventilatory equivalent, tidal volume, stroke volume index, and cardiac index at peak exercise (all p < 0.05). CONCLUSIONS: PR demonstrated notable enhancements in cardiopulmonary function, exertional symptoms, exercise capacity, and HRQL in patients with lung cancer.

Impact of a 12-week high-intensity interval training intervention on cardiac structure and function after COVID-19 at 12-month follow-up.

In patients previously hospitalised for COVID-19, a 12-week high-intensity interval training (HIIT) intervention has previously been shown to increase left ventricular mass (LVM) immediately after the intervention. In the present study, we examined the effects of the same HIIT scheme on LVM, pulmonary diffusing capacity, symptom severity and functional capacity at 12-month follow-up. In this investigator-blinded, randomised controlled trial, 12 weeks of a supervised HIIT scheme (4 × 4 min, three times a week) was compared to standard care (control) in patients recently discharged from hospital due to COVID-19. At inclusion and at 12-month follow-up, LVM was assessed by cardiac magnetic resonance imaging (cMRI, primary outcome), while pulmonary diffusing capacity for carbon monoxide (DLCOc, secondary outcome) was examined by the single-breath method. Symptom severity and functional status were examined by the Post-COVID-19 Functional Scale (PCFS) and King's Brief Interstitial Lung Disease (KBILD) questionnaire score. Of the 28 patients assessed at baseline, 22 completed cMRI at 12-month follow-up (12.4 ± 0.6 months after inclusion). LVM was maintained in the HIIT but not the standard care group, with a mean between-group difference of 9.68 [95% CI: 1.72, 17.64] g (P = 0.0182). There was no differences in change from baseline to 12-month follow-up between groups in DLCOc % predicted (-2.45 [-11.25, 6.34]%; P = 0.578). PCFS and KBILD improved similarly in the two groups. In individuals previously hospitalised for COVID-19, a 12-week supervised HIIT scheme resulted in a preserved LVM at 12-month follow-up but did not affect pulmonary diffusing capacity or symptom severity.

Investigating physical inactivity and associated health parameters in patients with systemic lupus erythematosus.

BACKGROUND: Physical inactivity, which is highly prevalent in patients with systemic lupus erythematosus (SLE), is an independent risk factor for cardiovascular events and causes many complications. This study aimed to investigate the effect of objective measurement and physical activity level on peripheral muscle strength, exercise capacity, pain, dyspnea, fatigue, anxiety, and depression in patients with SLE. METHODS: The present cross-sectional study analyzed 41 patients with SLE. Clinical and demographic characteristics of patients were recorded. Functional exercise capacity, peripheral muscle strength, dyspnea, pain, fatigue, anxiety, and depression were assessed. The physical activity level was assessed by a wearable activity tracker (Mi Band four smart band). RESULTS: The number of steps measured by the activity tracker was 4384.43 ± 1558.21 steps per day in patients with SLE. Patients with physical activity levels below 5000 steps exhibited elevated levels of fatigue, along with diminished functional exercise capacity and knee muscle strength, in comparison to those who were above the 5000-step threshold. Physical activity levels correlated with functional exercise capacity (6MWT), physiological parameters (maximum heart rate, Δ heart rate, Δ dyspnea, QFM fatigue, Δ QFM fatigue), and knee extension muscle strength. The functional exercise capacity and knee extension were identified as significantly and dependently associated with physical activity levels in SLE patients. CONCLUSION: Physical activity level is associated with functional exercise capacity and knee muscle strength in patients with SLE.

Association Between Subclinical Right Ventricular Alterations and Aerobic Exercise Capacity in Type 2 Diabetes.

BACKGROUND: Type 2 Diabetes (T2D) leads to cardiovascular remodeling, and heart failure has emerged as a major complication of T2D. There is a limited understanding of the impact of T2D on the right heart. This study aimed to assess subclinical right heart alterations and their contribution to aerobic exercise capacity (peak VO2) in adults with T2D. METHODS: Single center, prospective, case-control comparison of adults with and without T2D, and no prevalent cardiac disease. Comprehensive evaluation of the left and right heart was performed using transthoracic echocardiography and stress cardiovascular magnetic resonance. Cardiopulmonary exercise testing on a bicycle ergometer with expired gas analysis was performed to determine peak VO2. Between group comparison was adjusted for age, sex, race and body mass index using ANCOVA. Multivariable linear regression including key clinical and left heart variables, was undertaken in people with T2D to identify independent associations between measures of right ventricular (RV) structure and function with peak VO2. RESULTS: 340 people with T2D (median age 64 years, 62% male, mean HbA1c 7.3%) and 66 controls (median age 58 years, 58% male, mean HbA1c 5.5%) were included. T2D participants had markedly lower peak VO2 (adjusted mean 20.3(95% CI: 19.8-20.9) vs. 23.3(22.2-24.5) mL/kg/min, P<0.001) than controls and had smaller left ventricular (LV) volumes and LV concentric remodeling. Those with T2D had smaller RV volumes (indexed RV end-diastolic volume: 84(82-86) vs. 100(96-104) mL/m, P<0.001) with evidence of hyperdynamic RV systolic function (global longitudinal strain: 26.3(25.8-26.8) vs. 23.5(22.5-24.5) %, P<0.001) and impaired RV relaxation (longitudinal peak early diastolic strain rate: 0.77(0.74-0.80) vs. 0.92(0.85-1.00) s-1, P<0.001). Multivariable linear regression demonstrated that RV end-diastolic volume (ß=-0.342, P=0.004) and RV cardiac output (ß=0.296, P=0.001), but not LV parameters, were independent determinants of peak VO2. CONCLUSIONS: In T2D, markers of RV remodeling are associated with aerobic exercise capacity, independent of left heart alterations.

Association Between Coronary Microvascular Dysfunction and Exercise Capacity in Dilated Cardiomyopathy.

BACKGROUND: Aerobic exercise capacity is an independent predictor of mortality in dilated cardiomyopathy (DCM), but the central mechanisms contributing to exercise intolerance in DCM are unknown. OBJECTIVES: Characterize coronary microvascular function in DCM and determine if cardiovascular magnetic resonance (CMR) measures are associated with aerobic exercise capacity. METHODS: Prospective case-control comparison of adults with DCM and matched controls. Adenosine-stress perfusion CMR to assess cardiac structure, function and automated inline myocardial blood flow quantification, and cardiopulmonary exercise testing (CPET) to determine peak VO2, were performed. Pre-specified multivariable linear regression, including key clinical and cardiac variables, was undertaken to identify independent associations with peak VO2. RESULTS: Sixty-six patients with DCM (mean age 61 years, 71% male) were propensity-matched to 66 controls (mean age 59 years, 71% male) based on age, sex, body mass index and diabetes. DCM patients had markedly lower peak VO2 (19.8±5.5 versus 25.2±7.3mL/kg/min; P<0.001). The DCM group had greater left ventricular (LV) volumes, lower systolic function, and had more fibrosis compared to controls. In the DCM group, there was similar rest but lower stress myocardial blood flow (1.53±0.49 versus 2.01±0.60mL/g/min; P<0.001) and lower MPR (2.69±0.84 versus 3.15±0.84; P=0.002). Multivariable linear regression demonstrated that LV ejection fraction, extracellular volume fraction and MPR, were independently associated with percentage predicted peak VO2 in DCM (R2=0.531, P<0.001). CONCLUSIONS: In comparison to controls, DCM patients have lower stress myocardial blood flow and MPR. In DCM, MPR, LV ejection fraction and fibrosis are independently associated with aerobic exercise capacity.

Comprehensive Cardiac Rehabilitation Following Acute Myocardial Infarction Improves Clinical Outcomes Regardless of Exercise Capacity.

BACKGROUND: Reduced exercise capacity is a prognostic indicator of adverse outcomes in patients with acute myocardial infarction (AMI). However, few studies have evaluated the effectiveness of comprehensive cardiac rehabilitation (CR) in this population. This study aimed to clarify the efficacy of comprehensive CR in patients with AMI and reduced exercise capacity. METHODS AND RESULTS: This cohort study included 610 patients with AMI who underwent percutaneous coronary intervention. Major adverse cardiovascular events (MACE) were compared between patients who participated in comprehensive outpatient CR for 150 days (CR group; n=430) and those who did not (non-CR group; n=180). During the mean (±SD) follow-up period of 6.1±4.0 years, the CR group exhibited a lower incidence of MACE (log-rank P=0.002). Multivariable analysis revealed that Killip classification, diuretics at discharge, and participation in comprehensive CR were independently associated with MACE. The CR group was further divided into 2 groups, namely reduced exercise capacity (% predicted peak V̇O2<80%; n=241) and preserved exercise capacity (≥80%; n=147), based on the initial cardiopulmonary exercise test. Despite distinct exercise capacities, the incidence of MACE was comparable and physical parameters improved similarly after comprehensive CR in both groups. CONCLUSIONS: Comprehensive CR in patients with AMI effectively reduced the incidence of MACE regardless of initial exercise capacity. Cardiologists should actively encourage patients with low exercise capacity to participate in comprehensive CR.

Right Ventricular to Pulmonary Artery Uncoupling Is Associated With Impaired Exercise Capacity in Patients With Transthyretin Cardiac Amyloidosis.

BACKGROUND: Exercise capacity is related to mortality and morbidity in heart failure (HF) patients. Determinants of exercise capacity in transthyretin cardiac amyloidosis (ATTR-CA) have not been established. METHODS AND RESULTS: This single-center study retrospectively evaluated ATTR-CA patients and patients with non-amyloidosis HF with preserved/mildly reduced ejection fraction (HFpEF/HFmrEF) (n=32 and n=51, respectively). In the ATTR-CA group, the median age was 75.5 years (interquartile range [IQR] 71.3-78.8 years), 90.6% were male, and the median left ventricular (LV) ejection fraction was 53.5% (IQR 41.4-65.6%). Cardiopulmonary exercise tests revealed a median peak oxygen consumption and anaerobic threshold of 15.9 (IQR 11.6-17.4) and 10.6 (IQR 8.5-12.0] mL/min/kg, respectively, and ventilatory efficiency (minute ventilation/carbon dioxide production [V̇E/V̇CO2] slope) of 35.5 (IQR 32.0-42.5). Among exercise variables, V̇E/V̇CO2slope has the greatest prognostic value. Univariate analysis revealed a significant correlation between V̇E/V̇CO2slope and age, LV global longitudinal strain, tricuspid annular plain systolic excursion/pulmonary arterial systolic pressure (TAPSE/PASP) ratio, and mixed venous oxygen saturation. In multivariate analyses, the TAPSE/PASP ratio was an independent predictor of V̇E/V̇CO2slope (95% confidence interval -44.5, -10.8; P=0.0067). In non-amyloidosis HFpEF/HFmrEF patients, the TAPSE/PASP ratio was not independently correlated with V̇E/V̇CO2slope. CONCLUSIONS: Right ventricular-pulmonary artery coupling estimated by the TAPSE/PASP ratio determines exercise capacity in ATTR-CA patients. This highlights the importance of early therapeutic intervention against underappreciated right ventricular dysfunction associated with ATTR-CA.

Effect of body mass index on exercise capacity following pediatric heart transplantation.

BACKGROUND: Obesity and impaired exercise tolerance following heart transplantation increase the risk of post-transplant morbidity and mortality. The aim of this study was to evaluate the effect of body mass index on markers of exercise capacity in pediatric heart transplant recipients and compare this effect with a healthy pediatric cohort. METHODS: A retrospective analysis of cardiopulmonary exercise test data between 2004 and 2022 was performed. All patients exercised on a treadmill using the Bruce protocol. Inclusion criteria included patients aged 6-21 years, history of heart transplantation (transplant cohort) or no cardiac diagnosis (control cohort) at the time of testing, and a maximal effort test. Patients were further stratified within these two cohorts as underweight, normal, overweight, and obese based on body mass index groups. Two-way analyses of variance were performed with diagnosis and body mass index category as the independent variables. RESULTS: A total of 250 exercise tests following heart transplant and 1963 exercise tests of healthy patients were included. Heart transplant patients across all body mass index groups had higher resting heart rate and lower maximal heart rate, heart rate recovery at 1 min, exercise duration, and peak aerobic capacity (VO2peak). Heart transplant patients in the normal and overweight body mass index categories had higher VO2peak and exercise duration when compared to underweight and obese patients. CONCLUSION: Underweight status and obesity are strongly associated with lower VO2peak and exercise duration in heart transplant patients. Normal and overweight heart transplant patients had the best markers of exercise capacity.

Effectiveness of Exercise Interventions on Body Composition, Exercise Capacity, Fatigue, and Quality of Life in Patients with Liver Cirrhosis: A Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: Diminished muscle protein synthesis in cirrhosis leads to reduced strength and mass, impacting daily activities and overall quality of life. AIMS: This study aimed to examine the effectiveness of exercise intervention in body composition, exercise capacity, fatigue, and quality of life in patients with liver cirrhosis. METHODS: A systematic search of medical databases, including PubMed, Embase, Cochrane, and CINAHL, was executed from their inception to November 2022. The inclusion criteria were randomized controlled trials comparing exercise interventions with a control group that did not receive exercise interventions. RESULTS: From the initially identified 2,565 articles, eight studies with a total of 220 patients were eligible for inclusion in this meta-analysis. According to the meta-analysis, exercise significantly improved the six-minute walk distance (6MWD) by 68.93 m (95% CI 14.29-123.57) compared to the control group. Furthermore, the subgroup analysis revealed that combing exercise with amino acid supplementation had a greater positive effect on the 6MWD (MD = 144.72, 95% CI 87.44-202.01). Exercise also significantly increased thigh circumference (MD = 1.26, 95% CI 0.12-2.39) and the thigh ultrasound average compression index (MD = 0.07, 95% CI 0.00-0.14). Moreover, exercise significantly decreased fatigue levels by 0.7 points in patients with liver cirrhosis (95% CI 0.38-1.03). However, no significant effects were observed on body mass index (BMI), fat mass, fat-free mass, and quality of life. CONCLUSIONS: Exercise can improve exercise capacity, thigh muscle thickness, and fatigue in patients with cirrhosis, but it does not have a significant impact on fat mass, BMI, or quality of life.

Impact of preterm birth on muscle mass and function: a systematic review and meta-analysis.

Individuals born preterm present lower exercise capacity. Along with the cardiopulmonary responses and activity level, muscle strength is a key determinant of exercise capacity. This systematic review aimed to summarize the current knowledge on the impact of preterm birth on skeletal muscle mass and function across the lifespan. The databases PubMed, MEDLINE, EBM, Embase, CINAHL Plus, Global Index Medicus, and Google Scholar were searched using keywords and MeSH terms related to skeletal muscle, preterm birth, and low birth weight. Two independent reviewers undertook study selection, data extraction, and quality appraisal using Covidence review management. Data were pooled to estimate the prematurity effect on muscle mass and function using the R software. From 4378 studies retrieved, 132 were full-text reviewed and 25 met the inclusion/exclusion criteria. Five studies presented a low risk of bias, and 5 had a higher risk of bias due to a lack of adjustment for confounding factors and presenting incomplete outcomes. Meta-analyses of pooled data from homogenous studies indicated a significant reduction in muscle thickness and jump test (muscle power) in individuals born preterm versus full-term with standardized mean difference and confidence interval of - 0.58 (0.27, 0.89) and - 0.45 (0.21, 0.69), respectively.    Conclusion: Overall, this systematic review summarizing the existing literature on the impact of preterm birth on skeletal muscle indicates emerging evidence that individuals born preterm, display alteration in the development of their skeletal muscle mass and function. This work also highlights a clear knowledge gap in understanding the effect of preterm birth on skeletal muscle development. What is Known: • Preterm birth, which occurs at a critical time of skeletal muscle development and maturation, impairs the development of different organs and tissues leading to a higher risk of comorbidities such as cardiovascular diseases. • Preterm birth is associated with reduced exercise capacity. What is New: • Individuals born preterm display alterations in muscle mass and function compared to individuals born at term from infancy to adulthood. • There is a need to develop preventive or curative interventions to improve skeletal muscle health in preterm-born individuals.

Cardiopulmonary function in paediatric post-COVID-19: a controlled clinical trial.

Recently, the importance of post-COVID-19 in children has been recognized in surveys and retrospective chart analysis. However, objective data in the form of cardiopulmonary exercise test as performed in adults suffering from this condition are still lacking. This study aimed to investigate the cardiopulmonary effects of post-COVID-19 on children and adolescents. In this cross-sectional study (the FASCINATE study), children fulfilling the criteria of post-COVID-19 and an age- and sex-matched control group underwent cardiopulmonary exercise testing on a treadmill and completed a questionnaire with regard to physical activity before, during and after the infection with SARS-CoV-2. We were able to recruit 20 children suffering from post-COVID-19 (mean age 12.8 ± 2.4 years, 60% females) and 28 control children (mean age 11.7 ± 3.5 years, 50% females). All participants completed a maximal treadmill test with a significantly lower V ˙ O 2 peak in the post-COVID-19 group (37.4 ± 8.8 ml/kg/min vs. 43.0 ± 6.7 ml/kg/min. p = 0.019). This significance did not persist when comparing the achieved percentage of predicted V ˙ O 2 peak . There were no significant differences for oxygen pulse, heart rate, minute ventilation or breathing frequency.   Conclusion: This is the first study to investigate post-COVID-19 in children using the cardiopulmonary exercise test. Although there was a significantly reduced V ˙ O 2 peak in the post-COVID-19 group, this was not true for the percent of predicted values. No pathological findings with respect to cardiac or pulmonary functions could be discerned. Deconditioning was the most plausible cause for the experienced symptoms.    Trial registration: clinicaltrials.gov, NCT054445531, Low-field Magnetic Resonance Imaging in Pediatric Post Covid-19-Full Text View-ClinicalTrials.gov. What is Known: • The persistence of symptoms after an infection with SARS-CoV 2, so-called post-COVID-19 exists also in children. • So far little research has been conducted to analyze this entity in the pediatric population. What is New: • This is the first study proving a significantly lower cardiopulmonary function in pediatric patients suffering from post-COVID-19 symptoms. • The cardiac and pulmonary function appear similar between children suffering from post-COVID-19 and those who don't, but the peripheral muscles seem affected.

Benefits of chest wall mobilization on respiratory efficiency and functional exercise capacity in people with severe chronic obstructive pulmonary disease (COPD): A randomized controlled trial.

BACKGROUND: Coexistence of chest wall hypomobility and lung hyperinflation compromises respiratory muscle function and respiratory efficiency in people with severe chronic obstructive pulmonary disease (COPD). This study aimed to investigate the effect of chest wall mobilization on functional exercise capacity, respiratory muscle activity and respiratory muscle tissue oxygen saturation for people with severe COPD. METHODS: Thirty male adults (age: 75 ± 6) diagnosed with severe COPD completed a 6-week programme (twice/week) according to intervention randomization (chest wall mobilization group, CWMG, n = 15; control group, CG, n = 15). Both groups received standardized education and walking exercise, while CWMG also received chest wall and thoracic spine mobilization. Electromyography of the essential and accessory respiratory muscles and tissue oxygen saturation of the intercostal muscle (StO2, measured by near-infrared spectroscopy) during incremental cycle exercise test were measured and compared between the two groups at pre-programme, post-programme and 3-month follow-up. RESULTS: Patients in CWMG demonstrated a significant increase in exercise tolerance from <3 METS to 4-6 METS (p = 0.000) after intervention. A significant decrease in activity of scalene, sternocleidomastoids and intercostal muscle during exercise test (p < 0.01) was found in CWMG, as compared to CG. A significant decrease in StO2 (p < 0.05) and greater decline in the slope of oxygenation dissociation (p = 0.000) were seen in CWMG during exercise test. These positive results were maintained at 3-month follow-up in CWMG. CONCLUSION: Improvements in exercise tolerance, respiratory muscle efficiency and oxygenation extraction ability in CWMG suggest a potential clinical benefit of integrating chest wall and thoracic spine mobilization for rehabilitation of people with severe COPD.