Validation of VO2max Prediction Using International Formulae for Young Saudi Men.

Objectives: In this study, we aimed to assess the maximal oxygen uptake (VO2max) of young, healthy, non-athletic Saudi men using maximum graded exercise with instant breath-by-breath analysis and to compare this value to the predicted VO2max by international formulae. Methods: In this cross-sectional study, 88 young non-athletic normal-weight Saudi subjects were recruited from Eastern Province of Saudi Arabia with mean age (21.3 ± 1.5 years), weight: (64.7 ± 7.5 kg), height: (172.3 ± 6.1 cm) and body mass index: (21.8 ± 2.1). All subjects were interviewed and examined for eligibility, after which they performed maximum graded exercise testing on a treadmill to obtain VO2max. The predicted VO2max was also generated using the following formulae (Edvardsen, Fairbarns, FRIENDS, Hansen, and Jones). Results: The mean measured VO2max was 41.9 ± 7.2 ml/kg/min. While the predicted VO2max using the formulae were: Edvardsen = 66.8 ± 7.9, Fairbarns = 64.1 ± 4.7, FRIENDS = 53.5 ± 2.2, Hansen = 42.8 ± 0.54, and Jones = 50.9 ± 5.1 ml/kg/min. There was a significant difference between all the predicted VO2max and the measured one using the paired t-test (P < 0.001), except for the Hansen's predicted value (P = 0.212). The effect size index (Cohen's d) for the comparison of Hansen's VO2max and measured VO2max was trivial and equal to 0.13. The Bland-Altman test showed good agreement between the measured and Hansen's predicted VO2max. Conclusion: This study demonstrated the mean VO2max value of young, healthy, and non-athletic Saudi men. This value was lower than Western values, which might be due to low physical activity or racial differences. Most international formulae overestimate the VO2max in this population, except for the Hansen equation. Therefore, Hansen's predicted VO2max might be the best available reference value for the diagnosis and prognosis of young Saudi individuals undergoing maximum exercise testing.

The chronic heart failure evolutions: Different fates and routes.

AIMS: Individual prognostic assessment and disease evolution pathways are undefined in chronic heart failure (HF). The application of unsupervised learning methodologies could help to identify patient phenotypes and the progression in each phenotype as well as to assess adverse event risk. METHODS AND RESULTS: From a bulk of 7948 HF patients included in the MECKI registry, we selected patients with a minimum 2-year follow-up. We implemented a topological data analysis (TDA), based on 43 variables derived from clinical, biochemical, cardiac ultrasound, and exercise evaluations, to identify several patients' clusters. Thereafter, we used the trajectory analysis to describe the evolution of HF states, which is able to identify bifurcation points, characterized by different follow-up paths, as well as specific end-stages conditions of the disease. Finally, we conducted a 5-year survival analysis (composite of cardiovascular death, left ventricular assist device, or urgent heart transplant). Findings were validated on internal (n = 527) and external (n = 777) populations. We analyzed 4876 patients (age = 63 [53-71], male gender n = 3973 (81.5%), NYHA class I-II n = 3576 (73.3%), III-IV n = 1300 (26.7%), LVEF = 33 [25.5-39.9], atrial fibrillation n = 791 (16.2%), peak VO2% pred = 54.8 [43.8-67.2]), with a minimum 2-year follow-up. Nineteen patient clusters were identified by TDA. Trajectory analysis revealed a path characterized by 3 bifurcation and 4 end-stage points. Clusters survival rate varied from 44% to 100% at 2 years and from 20% to 100% at 5 years, respectively. The event frequency at 5-year follow-up for each study cohort cluster was successfully compared with those in the validation cohorts (R = 0.94 and R = 0.84, P < 0.001, for internal and external cohort, respectively). Finally, we conducted a 5-year survival analysis (composite of cardiovascular death, left ventricular assist device, or urgent heart transplant observed in 22% of cases). CONCLUSIONS: Each HF phenotype has a specific disease progression and prognosis. These findings allow to individualize HF patient evolutions and to tailor assessment.

Differential impacts of body composition on oxygen kinetics and exercise tolerance of HFrEF and HFpEF patients.

This study aims to (1) compare the kinetics of pulmonary oxygen uptake (VO2p), skeletal muscle deoxygenation ([HHb]), and microvascular O2 delivery (QO2mv) between heart failure (HF) patients with reduced ejection fraction (HFrEF) and those with preserved ejection fraction (HFpEF), and (2) explore the correlation between body composition, kinetic parameters, and exercise performance. Twenty-one patients (10 HFpEF and 11 HFrEF) underwent cardiopulmonary exercise testing to assess VO2 kinetics, with near-infrared spectroscopy (NIRS) employed to measure [HHb]. Microvascular O2 delivery (QO2mv) was calculated using the Fick principle. Dual-energy X-ray absorptiometry (DEXA) was performed to evaluate body composition. HFrEF patients exhibited significantly slower VO2 kinetics (time constant [t]: 63 ± 10.8 s vs. 45.4 ± 7.9 s; P < 0.05) and quicker [HHb] response (t: 12.4 ± 9.9 s vs. 25 ± 11.6 s; P < 0.05). Microvascular O2 delivery (QO2mv) was higher in HFrEF patients (3.6 ± 1.2 vs. 1.7 ± 0.8; P < 0.05), who also experienced shorter time to exercise intolerance (281.6 ± 84 s vs. 405.3 ± 96 s; P < 0.05). Correlation analyses revealed a significant negative relationship between time to exercise and both QO2mv (ρ= -0.51; P < 0.05) and VO2 kinetics (ρ= -0.63). Body adiposity was negatively correlated with [HHb] amplitude (ρ= -0.78) and peak VO2 (ρ= -0.54), while a positive correlation was observed between lean muscle percentage, [HHb] amplitude, and tau (ρ= 0.74 and 0.57; P < 0.05), respectively. HFrEF patients demonstrate more severely impaired VO2p kinetics, skeletal muscle deoxygenation, and microvascular O2 delivery compared to HFpEF patients, indicating compromised peripheral function. Additionally, increased adiposity and reduced lean mass are linked to decreased oxygen diffusion capacity and impaired oxygen uptake kinetics in HFrEF patients.

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.

Cardiovascular risk and its influencing factors during exercise in apparently healthy Chinese adult population.

BACKGROUND: There are few studies on the safety of sub-maximal exercise testing of aerobic exercise in apparently healthy Chinese populations. The purpose of this study was to explore the frequency of exercise electrocardiography (ECG) abnormalities and the corresponding exercise intensities, as well as the associated influencing factors, during a symptom-limited stepwise incremental cardiopulmonary exercise test (CPET) in an apparently healthy Chinese population. METHODS: A cross-sectional study was done in four communities, one urban and one rural in the North (Beijing) and in the South (Hezhou, Guangxi) of China from 1 January 2017 to 31 December 2018, respectively. Total of 1642 participants was recruited, 918 were eligible and completed demographic indicators, routine blood indicators, physical activity status, symptom-limited CPET and exercise ECG were included in the analysis. RESULTS: Of the exercise ECG outcomes, 10 (1.1%) were positive and occurred at exercise intensities ≥ 62.50% heart rate reserve (HRR); 44 (4.8%) were equivocal and 864 (94.1%) were normal. Individuals with Cardiovascular Disease Risk Factor (CVDRF) = 3-4 were 2.6 times more likely to have a equivocal and abnormal exercise ECG than those with CVDRF = 0-2. Exercise ECGs of individuals with CVDRF = 5-7 were 5.4 times more likely to be positive and abnormal than exercise ECGs of individuals with CVDRF = 0-2. CONCLUSIONS: The exercise intensity of 62.5% HRR can be used as a safe upper limit for safe participation in exercise in apparently healthy Chinese population; the greater the number of CVDRFs, the greater the likelihood of cardiovascular risk during exercise.

Functional Capacity Assessment in Adults After Fontan Palliation: A Cardiopulmonary Exercise Test-Invasive Exercise Hemodynamics Correlation Study.

Although cardiopulmonary exercise testing (CPET) parameters have known prognostic value in adults after Fontan palliation, there are limited data correlating treadmill CPET with invasive exercise hemodynamics. Furthermore, the invasive hemodynamic underpinnings of exercise limitations have not been thoroughly investigated. This is retrospective analysis of 55 adults (≥18 years) after Fontan palliation who underwent treadmill CPET before invasive exercise hemodynamic testing by way of supine cycle protocol between November 2018 and April 2023. The median age was 32.2 (24.1 to 37.2) years. The peak heart rate (HR) was 139.7 ± 28.1 beats per minute and the peak oxygen consumption (VO2) was 19.1 ± 5.7 ml/kg/min (47.4 ± 13.5% predicted). VO2/HR was directly related to exercise stroke volume index (r = 0.50, p = 0.0002), whereas no association was seen with exercise arterio-mixed venous O2 content difference (r = 0.14, p = 0.32). Peak HR was inversely related to exercise pulmonary artery (PA) pressures (r = -0 61, p <0.0001) and PA wedge pressures (PAWP) (r = -0.61, p <0.0001). Moreover, %predicted VO2 was inversely related to exercise PA pressures (r = -0.50, p <0.0001) and PAWP (r = -0.55, p <0.0001). Peak VO2 ≤19.1 ml/kg/min had a sensitivity of 81% and a specificity of 76% (area under the curve = 0.82) for predicting a ΔPAWP/ΔQs ratio >2 mm Hg/L/min and/or a ΔPA:ΔQp >3 mm Hg/L/min, whereas a predicted peak VO2 ≤48% had a sensitivity of 74% and a specificity of 81% (area under the curve = 0.79) for the same parameters. In summary, lower peak HR and peak VO2 were associated with higher exercise PAWP and PA pressure. Peak VO2 ≤48% predicted provided the optimal cutoff for predicting increased indexed exercise PAWP or PA pressures; therefore, low peak VO2 should alert clinicians of abnormal underlying hemodynamics.

Heart rate response and recovery in cycle exercise testing - normal values and association with mortality.

AIM: Chronotropic incompetence and impaired heart rate (HR) recovery are related to mortality. Guidelines lack specific reference values for HR recovery. We defined normal values and studied blunted HR response and recovery, and mortality risk. METHODS: We included 9,917 subjects (45% females) aged 18-85 years who performed a cycle exercise test. We defined normal values for peak HR, HR reserve, and HR recovery at 1 and 2 minutes (HRR1 and HRR2) based on individuals apparently healthy (N=2,242). Associations between blunted HR indices (<5th percentile) and mortality over a median follow-up of 8.6 years were analysed using Cox regression and competing risk analysis. RESULTS: All HR indices were age-dependent and independent predictors of all-cause and CV mortality. The 5th percentiles of HR reserve, HRR1, and HRR2 correlated weakly with existing reference values. HR recovery variables were the strongest predictors of all-cause mortality (HRR1, hazard ratio 1.70 [95% confidence interval, 1.49-1.94] and HRR2, 1.57 [1.37-1.79]), including in subjects with normal exercise capacity (HRR1, 1.96 [1.61-2.39] and HRR2, 1.76 [1.46-2.12]). Combining HR indices appeared to increase the risk of all-cause (HRR1 and HRR2, 1.96 [1.68-2.29] and peak HR and HRR1, 1.87 [1.56-2.23]) and CV mortality, although no specific combination was superior for predicting CV mortality. CONCLUSIONS: All HR variables were age-dependent and associated with all-cause and CV mortality. Blunted HR recovery variables were the strongest predictors of all-cause mortality, even in subjects with normal exercise capacity. Combined blunted HR indices appeared to add prognostic value.

We provide a detailed description on the physiologic HR response and recovery kinetics in a population apparently CV risk-free referred for cycle exercise testing. When assessed in a larger population, blunted HR response and recovery were associated with increased mortality. HR response and recovery are age-dependent. We provide novel reference values.All blunted HR indices (peak HR, HR reserve, HRR1 and HRR2) are strong predictors of all-cause and CV mortality, and combined HR indices appeared to add prognostic value in all the analyses.Blunted HRR1 followed by HRR2 are the strongest predictor of all-cause mortality even in subjects with normal exercise capacity, highlighting the importance of their assessment in standard exercise testing.

Test-retest reliability of exercise blood pressure and the workload-indexed systolic blood pressure slope in healthy males and females.

The reliability of blood pressure (BP) measured during submaximal and maximal exercise, and confounding effects of biological sex, remain to be fully established but have implications for using exercise BP as a cardiovascular risk factor. We hypothesize that exercise BP test-retest reliability will not differ between sexes but will be higher during submaximal compared to maximal exercise. Eighty-four participants (22±5 years; 36 females) completed two maximal treadmill tests (modified Bruce protocol) separated by ≥2 days. Exercise BP was measured every 90-seconds using automated auscultation (Tango M2 monitor). Breath-by-breath oxygen uptake was analyzed. Test-retest reliability was assessed using two-way, mixed effects, consistency, single-rater intraclass correlation coefficient (ICC) analysis on the total group and separated by sex at submaximal and maximal exercise. Systolic BP during submaximal (ICC=0.65 [0.49-0.76], p<0.01) and maximal (ICC=0.66 [0.52-0.77], p<0.01) exercise both displayed substantial reliability between visits. In contrast, the SBP/MET slope showed poor submaximal (ICC=0.12 [-0.09-0.33], p=0.13) but substantial maximal (ICC=0.63 [0.48-0.75], p<0.01) exercise reliability. Females showed substantial reliability in submaximal systolic BP (ICC=0.73 [0.53-0.85], p<0.01), and peak systolic BP (ICC=0.74 [0.54-0.87], p<0.01) and SBP/MET slope (ICC=0.78 [0.60-0.88], p<0.01); the submaximal SBP/MET slope had fair reliability (ICC=0.28 [-0.06-0.56], p=0.05). Males showed moderate reliability in submaximal systolic BP (ICC=0.53 [0.26-0.72], p<0.01), and peak systolic BP (ICC=0.41 [0.15-0.62], p<0.01) and SBP/MET slope (ICC=0.48 [0.22-0.67], p<0.01); the submaximal SBP/MET slope had poor reliability (ICC=0.06 [-0.18-0.31], p=0.32). Systolic BP showed similar reliability during submaximal and maximal exercise, with females demonstrating higher reliability in exercise systolic BP compared to males.

Right-ventricle heart failure in PAH vs. HFrEF with secondary PH: Hemodynamic, ergospirometric, and organ function correlations.

PURPOSE: The goal of the study was to identify markers of organ function used in daily routines that could potentially aid in the overall evaluation of the cardiovascular system in patients with right-ventricle heart failure due to pulmonary arterial hypertension (PAH) and left-ventricle heart failure. We analyzed correlations between parameters from right heart catheterization (RHC), cardiopulmonary exercise test (CPET), and selected laboratory parameters of thyroid, liver, kidneys function and iron homeostasis. PATIENTS AND METHODS: A retrospective analysis included 107 patients (mean age 57.6 â€‹± â€‹16.2; 34.6 â€‹% women), comprising 57 patients with PAH (mean age 54.0 â€‹± â€‹18.2; 49.1 â€‹% women) and 50 patients with heart failure with reduced ejection fraction (HFrEF) â€‹< â€‹40 â€‹% (mean age 61.6 â€‹± â€‹12.7; 18 â€‹% women). All patients underwent CPET. Each patient in the PAH group had RHC performed. Fifteen patients from the HFrEF group underwent RHC, which confirmed the suspicion of pulmonary hypertension (HFrEF-SPH). RESULTS: CPET and laboratory parameters' analysis showed strong correlations between ventilation/carbon dioxide production (VE/VCO2) slope and NT-proBNP in HFrEF without secondary PH and HFrEF-SPH groups. In the PAH group, VE/VCO2 slope correlated with liver and thyroid function but also with morphological parameters of red-cell system. Analysis of correlations between laboratory and hemodynamic parameters revealed significant correlations between pulmonary arterial pressure, pulmonary vascular resistance (PVR) and red-cell parameters, especially strong with fT4 in the PAH group. CONCLUSIONS: In HFrEF-SPH patients, laboratory parameters strongly correlated with pulmonary pressures and pulmonary capillary wedge pressure (PCWP).

Cardiac decompression and right ventricular function improvement after bar removal in patients with pectus excavatum.

Pectus excavatum, the most frequent malformation of the chest wall, has been related to cardiac compression and exercise intolerance. Cardiac outcomes after minimally invasive repair of pectus excavatum with retrosternal implants, particularly after removal (> 2 years postoperative) are generally unknown. We evaluated stress echocardiography outcomes before repair and after bar removal. This study comprised a retrospective cohort of patients with diagnosis of isolated pectus excavatum who underwent stress echocardiography before minimally invasive repair with retrosternal implants, and after bar removal. The diastolic function was evaluated by means of the trans tricuspid flow and tissue doppler imaging. The compression of the atrioventricular groove was assessed using the trans tricuspid gradient and the tricuspid area. We included 43 patients, with a mean age of 15.7 ± 4.0 years (91% male). After bar removal, 83% of patients referred improvement of exercise capacity. Furthermore, we found a significant improvement in right ventricular filling patterns, including a better E/A ratio profile during exercise (p = 0.001), lower filling pressures both at rest (p < 0.0001) and during exercise (p = 0.031), and lower rates of resting paradoxical septal motion [70% vs. 20%, p = 0.0007]. The trans tricuspid mean gradient during exercise was significantly lower after bar removal (p < 0.0001). In this study involving patients with minimally invasive repair of pectus excavatum, we demonstrated a beneficial impact of such intervention after bar removal, with significant improvements related to the right ventricular function, as well as signs of relief of cardiac compression.

Validity of estimated aortic pulse wave velocity measured during the 6-min walk test to predict anaerobic fitness before major non-cardiac surgery.

BACKGROUND: This study aimed to assess the efficacy of estimated preoperative aortic pulse wave velocity (AoPWV) to discriminate between low and high 6 min walk test (6MWT) distance in patients awaiting major non-cardiac surgery. METHODS: Prospective observational study in 133 patients undergoing non cardiac surgery. AoPWV and the distance walked during a 6MWT were assessed. Receiver operating characteristic (ROC) curve analysis was used to determine two different AoPWV cut-points for predicting a distance of 427 m in the 6MWT. We also calculated lower and upper AoPWV cut-points (probability ≥ 0.75) for predicting a distance of < 427 m, ≥427 m, and also 563 m in the 6MWT. RESULTS: The ROC curve analysis for the < 427 m distance revealed an area under the curve (AUC) of 0.68 (95% confidence interval 0.56-0.79) and an AUC of 0.72 (95% confidence interval 0.61-0.83) for >563 m. Patients with AoPWV > 10.97 m/s should be considered high risk, while those with <9.42 m/s can be considered low risk. CONCLUSIONS: AoPWV is a simple, non-invasive, useful clinical tool for identifying and stratifying patients awaiting major non-cardiac surgery. In situations of clinical uncertainty, additional measures should be taken to assess the risk.

Establishing a novel model to assess exercise capacity in chronic heart failure based on stress echocardiography.

AIMS: The aim of this study was to develop a simple, fast and efficient clinical diagnostic model, composed of exercise stress echocardiography (ESE) indicators, of the exercise capacity of patients with chronic heart failure (CHF) by comparing the effectiveness of different classifiers. METHODS AND RESULTS: Eighty patients with CHF (aged 60 ± 11 years; 78% male) were prospectively enrolled in this study. All patients underwent both cardiopulmonary exercise test (CPET) and ESE and were divided into two groups according to the VE/VCO2 slope: 30 patients with VE/VCO2 slope ventilation classification (VC)1 (i.e., VE/VCO2 slope < 30) and 50 patients with VC2 (i.e., VE/VCO2 slope ≥ 30). The analytical features of all patients in the four phases (rest, warm-up, peak and recovery phases) of ESE included the following parameters: left ventricular (LV) systolic function, LV systolic function reserve, LV diastolic function, LV diastolic function reserve and right ventricular function. Logistic regression (LR), extreme gradient boosting trees (XGBT), classification regression tree (CART) and random forest (RF) classifiers were implemented in a K-fold cross-validation model to distinguish VC1 from VC2 (LVEF in VC1 vs. VC2: 44 ± 8% vs. 43 ± 11%, P = 0.617). Among the four models, the LR model had the largest area under the curve (AUC) (0.82; 95% confidence interval [CI]: 0.73 to 0.92). In the multiple-variable LR model, the differences between the peak-exercise-phase and resting-phase values of E (ΔE), s'peak and sex were strong independent predictors of a VE/VCO2 slope ≥ 30 (P value: ΔE = 0.002, s'peak = 0.005, sex = 0.020). E/e'peak, ΔLVEF, ΔLV global longitudinal strain and Δstroke volume were not predictors of VC in the multivariate LR model (P > 0.05 for the above). CONCLUSIONS: Compared with the LR, XGBT, CART and RF models, the LR model performed best at predicting the VE/VCO2 slope category of CHF patients. A score chart was created to predict VE/VCO2 slopes ≥ 30. ΔE, s'peak and sex are independent predictors of exercise capacity in CHF patients.

Short-term exercise training benefits pulmonary arterial hypertension patients.

OBJECTIVES: Studies have shown exercise rehabilitation training improves exercise tolerance in pulmonary arterial hypertension (PAH) patients. However, implementing such programs in developing countries can be challenging. We investigated the benefits of short-term exercise rehabilitation training for PAH patients in a developing country. METHODS: This study was a prospective study of adult PAH patients attending the cardiology outpatient unit of a tertiary referral hospital. The patients were equally divided into an intervention group and a control group. We measured hemodynamic characteristics and six-minute walking distance (6MWD) before and after four weeks of exercise rehabilitation training. The Shapiro-Wilk normality test was performed, followed by an independent t-test or Mann-Whitney test to statistically compare the data. RESULTS: We included 28 patients aged 29.1 ± 11 years. We found no significant differences in all hemodynamic characteristics between the groups before and after the rehabilitation (all p-values >0.05). The intervention group showed a significant increase in 6MWD (300.6 ± 90.8 (95% CI: 248.2, 352.9) vs 436.3 ± 58.8 (95% CI: 402.3, 470.2), p-value <0.001) and consequently, the Δ6MWD in the intervention group was remarkably higher (17.1 ± 48.3 (95% CI: -10.8, 44.9) vs 115.36 ± 54.69 m (95% CI: 83.8, 146.9), p-value <0.001). CONCLUSION: A short-term exercise rehabilitation training safely improved the exercise tolerance of patients with PAH. Our findings may lead to the improvement of rehabilitation strategies for this detrimental disease in countries with limited resources.

Exercise intensity prescription in cardiovascular rehabilitation: bridging the gap between best evidence and clinical practice.

Optimizing endurance exercise intensity prescription is crucial to maximize the clinical benefits and minimize complications for individuals at risk for or with cardiovascular disease (CVD). However, standardization remains incomplete due to variations in clinical guidelines. This review provides a practical and updated guide for health professionals on how to prescribe endurance exercise intensity for cardiovascular rehabilitation (CR) populations, addressing international guidelines, practical applicability across diverse clinical settings and resource availabilities. In the context of CR, cardiopulmonary exercise test (CPET) is considered the gold standard assessment, and prescription based on ventilatory thresholds (VTs) is the preferable methodology. In settings where this approach isn't accessible, which is frequently the case in low-resource environments, approximating VTs involves combining objective assessments-ideally, exercise tests without gas exchange analyses, but at least alternative functional tests like the 6-minute walk test-with subjective methods for adjusting prescriptions, such as Borg's ratings of perceived exertion and the Talk Test. Therefore, enhancing exercise intensity prescription and offering personalized physical activity guidance to patients at risk for or with CVD rely on aligning workouts with individual physiological changes. A tailored prescription promotes a consistent and impactful exercise routine for enhancing health outcomes, considering patient preferences and motivations. Consequently, the selection and implementation of the best possible approach should consider available resources, with an ongoing emphasis on strategies to improve the delivery quality of exercise training in the context of FITT-VP prescription model (frequency, intensity, time, type, volume, and progression).

Body Oxygen Level Test (BOLT) is not associated with exercise performance in highly-trained individuals.

Introduction: The analysis of chemoreflex and baroreflex sensitivity may contribute to optimizing patient care and athletic performance. Breath-holding tests, such as the Body Oxygen Level Test (BOLT), have gained popularity as a feasible way to evaluate the reflex control over the cardiorespiratory system. According to its proponents, the BOLT score reflects the body's sensitivity to carbon dioxide and homeostasis disturbances, providing feedback on exercise tolerance. However, it has not yet been scientifically validated or linked with exercise performance in highly-trained individuals. Therefore, we investigated the association of BOLT scores with the results of standard performance tests in elite athletes. Methods: A group of 49 speedskaters performed BOLT, Wingate Anaerobic Test (WAnT), and cardiopulmonary exercise test (CPET) on a cycle ergometer. Peak power, total work, and power drop were measured during WAnT. Time to exhaustion and maximum oxygen uptake were measured during CPET. Spearman's rank correlation and multiple linear regression were performed to analyze the association of BOLT scores with parameters obtained during the tests, age, somatic indices, and training experience. Results: No significant correlations between BOLT scores and parameters obtained during WAnT and CPET were found, r(47) = -0.172-0.013, p = 0.248-0.984. The parameters obtained during the tests, age, somatic indices, and training experience were not significant in multiple linear regression (p = 0.38-0.85). The preliminary regression model showed an R 2 of 0.08 and RMSE of 9.78 sec. Conclusions: Our findings did not demonstrate a significant relationship between BOLT scores and exercise performance. Age, somatic indices, and training experience were not significant in our analysis. It is recommended to interpret BOLT concerning exercise performance in highly-trained populations with a great degree of caution.

A detailed analysis of body composition in relation to cardiopulmonary exercise test indices.

A cardiopulmonary exercise test (CPET) is a test assessing an individual's physiological response during exercise. Results may be affected by body composition, which is best evaluated through imaging techniques like magnetic resonance imaging (MRI). The aim of this study was to assess relationships between body composition and indices obtained from CPET. A total of 234 participants (112 female), all aged 50 years, underwent CPETs and whole-body MRI scans (> 1 million voxels). Voxel-wise statistical analysis of tissue volume and fat content was carried out with a method called Imiomics and related to the CPET indices peak oxygen consumption (V̇O2peak), V̇O2peak scaled by body weight (V̇O2kg) and by total lean mass (V̇O2lean), ventilatory efficiency (V̇E/V̇CO2-slope), work efficiency (ΔV̇O2/ΔWR) and peak exercise respiratory exchange ratio (RERpeak). V̇O2peak showed the highest positive correlation with volume of skeletal muscle. V̇O2kg negatively correlated with tissue volume in subcutaneous fat, particularly gluteal fat. RERpeak negatively correlated with tissue volume in skeletal muscle, subcutaneous fat, visceral fat and liver. Some associations differed between sexes: in females ΔV̇O2/ΔWR correlated positively with tissue volume of subcutaneous fat and V̇E/V̇CO2-slope with tissue volume of visceral fat, and, in males, V̇O2peak correlated positively to lung volume. In conclusion, voxel-based Imiomics provided detailed insights into how CPET indices were related to the tissue volume and fat content of different body structures.

Changes in hematopoietic stem cell numbers following acute exercise in non-athlete marathon runners.

PURPOSE: Hematopoietic stem cell (HSC) transplant is one of the curative methods for some patients with hematological malignancies. Granulocyte colony-stimulating factor (G-CSF) is the most common drug used to mobilize CD34+ cells, generally found in small numbers. Recent evidence showed that exercise causes transient mobilization in HSC. However, the type and intensity of exercise have not been fully revealed. We aimed to detect a significant increase in stem cell levels following 60 â€‹min of running at a personalized running pace. MATERIALS/METHODS: Eighteen runners, 48.2 â€‹± â€‹1.9 years with peak oxygen consumption of 46.2 â€‹± â€‹1.4 â€‹ml/kg/min, were enrolled in the study. The cardiopulmonary exercise test was performed to determine the individual running pace, and the participants ran 60-min on a treadmill at an intensity close to their ventilatory threshold (VT). The blood sampling for HSC count was performed before, immediately after, at the 1st, 4th and 24th hour after the 60-min running. RESULTS: The CD34+ HSCs were 13.9 â€‹± â€‹2.3 â€‹cells/µl before and significantly increased immediately after to 19.5 â€‹± â€‹3.6 â€‹cells/µl (p â€‹< â€‹0.05). The consecutive HSC counts were 15.3 â€‹± â€‹2.2, 19.5 â€‹± â€‹4.8 and 15.1 â€‹± â€‹3.4 â€‹cells/µl at the 1st, 4th, and 24th hour, respectively. CONCLUSION: The individual data showed that some runners had higher HSC levels than the transplantation limit before and after the 60-min running trail, which was maintained for 24 â€‹h. Pre-running high CD34+ HSCs may reflect an adaptive response to regular exercise, with a 60-min run near the VT further elevating HSCs. Individualized exercise may be a valuable tool to mobilize the CD34+ HSCs in peripheral blood for donors.

Associations between physical fitness, body composition, and heart rate variability during exercise in older people: exploring mediating factors.

Background: Age-related changes in body composition affect physical fitness in older adults. However, whether the autonomic response is associated with body fat percentage and its implication for physical fitness is not fully understood. Aim: To understand the association between physical fitness, body composition, and heart rate variability in older people and its mediating factors. Methods: A cross-sectional study with 81 older adults was conducted, assessing Short Physical Performance Battery (SPPB), Two-minute Step Test (TMST), body composition, and cardiac autonomic response. Correlation and mediation analyses were performed. Results: Body fat percentage negatively correlated with physical fitness (SPPB: r =  - 0.273, p = 0.015; TMST: r =  - 0.279, p = 0.013) and sympathetic activity (sympathetic nervous system (SNS) index: r =  - 0.252, p = 0.030), yet positively correlated with parasympathetic tone (root mean square of successive differences (RMSSD): r = 0.253, p = 0.029; standard deviation of NN intervals (SDNN): r = 0.269, p = 0.020). Physical fitness associated with sympathetic nervous system index (SPPB: r = 0.313, p = 0.006; TMST: r = 0.265, p = 0.022) and parasympathetic nervous system index (TMST: r =  - 0.344, p = 0.003). Muscle mass mediated body fat's impact on physical fitness, while physical fitness mediated body fat's impact on autonomic response. Conclusion: Body composition and cardiac autonomic response to exercise are associated with physical fitness in older people, highlighting a possible protective effect of muscle mass against the decline in physical fitness associated with increased body fat.