Nasal high flow (NHF) has been proposed to sustain high intensity exercise in people with COPD, but we have a poor understanding of its physiological effects in this clinical setting.

What is the effect of NHF during exercise on dynamic respiratory muscle function and activation, cardiorespiratory parameters, endurance capacity, dyspnoea and leg fatigue as compared to control intervention.

Randomized single-blind crossover trial including COPD patients. Two constant workload exercise testing were performed at 75% of peak power with NHF (30L/min, 34°C) or with control intervention. Pressure time product of the transdiaphragmatic pressure (PTPdi/min) and other physiological measurements were continuously monitored. Dyspnoea and lower limb fatigue were assessed using the 10-Borg scale.

14 patients with severe obstruction (median FEV1: 40 (IQR 28 to 52) %) were included. Their median age was 70 (IQR 57 to 72) years. At isotime, NHF had little to no effect on PTPdi/min (MD -15cmH2O.s/min, 95% CI -62 to 33) but increased tidal volume (MD 77mL, 95% CI 21 to 133). NHF also improved endurance capacity (MD 20s, 95% CI 2 to 40) and dyspnoea at isotime (MD -1.1, 95% CI -2.1 to -0.1). NHF had no or uncertain effect on other outcomes.

NHF has little to no effect on dynamic respiratory muscle function and activation but improves Vt. It leads to a trivially small increase in endurance capacity but a worthwhile improvement in dyspnoea. NHF may be beneficial for individuals experiencing critical inspiratory constraints and significant dyspnoea.

Home-based pulmonary rehabilitation (PR) can enhance accessibility to PR, but no at-home field exercise test has been validated for individualized endurance training prescriptions.

What is the accuracy of the six-minute stepper test (6MST) in estimating endurance training intensity as determined during cardiopulmonary exercise testing (CPET)?

This multicenter (N = 3) cross-sectional study included individuals with COPD. Participants performed CPET and two 6MSTs to evaluate the 6MST's ability to estimate endurance training intensity based on CPET-derived heart rate at the first ventilatory threshold (HRvt1), the corresponding power output (Pvt1), and peak power output (Ppeak). Predictive equations were tested for external validity using data from two prior studies.

105 patients were included (mean age 61 (SD 9) years; mean FEV1 61 (SD 21) %). Predictive equations moderately predicted HRvt1 (r² = 0.38), strongly predicted Pvt1 (r² = 0.63) and very strongly predicted Ppeak (r² = 0.75). External validity was small to moderate for HRvt1 and Pvt1 but was strong for 60% of Ppeak (mean absolute difference: 10W, 95% CI 5 to 10). Passing and Bablok regression confirmed interchangeability for Pvt1 and 60% of Ppeak.

The 6MST offers a reliable method to set initial training intensity when CPET is unavailable.

NCT02842463.

Coronavirus disease (COVID-19) can affect cardiovascular function in health and disease. The present study assessed the effect of prior COVID-19 infection on cardiovascular phenotype at rest and in response to exercise in middle age and older individuals.

This case-control, single-centre study recruited 124 participants: 84 with a history of COVID-19 (59.9 ± 7.41 years, 54.8% female) and 40 participants without history of COVID-19 infection (62.8 ± 7.14 years, 62.5% female). All participants underwent non-invasive assessment of arterial function using pulse wave velocity (PWV), augmentation index (Alx) and hemodynamic function (i.e. cardiac index (CI), stroke volume index (SVI), heart rate (HR), mean arterial blood pressure (MAP)) at rest. Cardiopulmonary exercise stress testing with simultaneous gas exchange and hemodynamic (bioreactance) measurements was also performed.

There were no differences between COVID-19 and non-COVID-19 groups in PWV (COVID-19: 7.52 ± 1.66 m/s, non-COVID-19: 7.32 ± 1.79 m/s, p = 0.440); Alx (COVID-19: 29.2 ± 9.12%, non-COVID-19: 29.2 ± 8.44%, p = 0.980); CI (COVID-19: 2.85 ± 0.39 L/min/m2, non-COVID-19: 2.79 ± 0.37 L/min/m2, p = 0.407); SVI (COVID-19: 46.5 ± 7.54 mL/m2, non-COVID-19: 47.0 ± 7.59 mL/m2, p = 0.776), HR (COVID-19: 62.3 ± 10.6 beats/min, Non-COVID-19: 60.2 ± 8.52 beats/min, p = 0.263), or MAP (COVID-19: 98.1 ± 11.2 mmHg, non-COVID-19: 96.6 ± 9.46 mmHg, p = 0.464). COVID-19 participants however demonstrated lower O2 consumption at anaerobic threshold (15.5 ± 4.25 vs 16.8 ± 4.51 mL/kg/m2, p = 0.034), peak cardiac index (10.4 ± 2.3 vs 11.3 ± 2.5 L/min/m2, p = 0.040) and peak stroke volume index (82.1 ± 25.3 vs 98.6 ± 37.6 mL/m2, p = 0.028).

Healthy middle-age and older individuals with history COVID-19 infection demonstrate reduced exercise tolerance and cardiac function response to exercise.

Peak oxygen uptake (VO2) is considered the most important indicator of aerobic exercise capacity during cardiopulmonary exercise testing (CPET). However, its accuracy is compromised when maximal effort is not achieved. In such cases, submaximal parameters can serve as surrogates for assessing exercise performance.

To compare the differences in maximal and submaximal exercise parameters between children with obesity and normal weight.

A prospective study evaluating CPET using a treadmill completed by children with and without obesity.

A total of 153 children (50.9% females) were divided into two groups: obese (n = 87) and non-obese (n = 66). Children with obesity achieved lower exercise capacity (peakVO2 of 68% ± 16% vs. 89% ± 15%; p < 0.0001) with fewer achieving maximal effort (26.4% vs. 78.7%, respectively). VO2-derived submaximal parameters showed a significantly lower oxygen uptake efficiency slope per body weight (OUES/kg) (30.5 ± 6.1 vs. 39.0 ± 9.5; p < 0.0001) and lower VO2 at ventilatory threshold (VO2@AT) (21.2 ± 4.6 vs. 26.4 ± 5.3, p = 0.0001) in the obese group, with no significant differences in the CO2-derived parameters.

Maximal exercise data in children with obesity is frequently unavailable due to failure to achieve maximal effort. Submaximal parameters, such as OUES and VO2@AT, may be useful substitute options for assessing the health and functional level of this population.

Measurements of cardiorespiratory fitness are mandatory after a stroke. The 6-min step test emerges as an alternative method in absence of maximal tests.

To provide information regarding the measurement properties of the 6-min step test in individuals with chronic stroke.

A cross-sectional, methodological study was conducted. Participants were individuals with stroke, who performed the 6-min step test and the 6-min walk test for calculation of measurement properties and comparison purposes. Outcomes of interest were test-retest and inter-rater reliability, measurement error, minimal detectable change, construct validity, criterion validity by video, intra-rater and inter-rater reliability by video.

Fifty individuals with chronic stroke were included. The 6-min step test had a very-high test-retest (ICC 0.98; CI 95% 0.97-0.99) and inter-rater reliability (ICC 0.95; CI 95% 0.92-0.97). The test's measurement error was 4(5%) and the minimal detectable change was 11 repetitions. The correlation between the 6-min step test and the 6-min walk test suggested high construct validity (r = 0.79; CI 0.66-0.89). In addition, the 6-min step test by video had comparable results with the in-person administration with very high criterion validity (r = 1.00; CI 95% 1.00-1.00),intra-rater (ICC = 1.00; CI 95% 1.00-1.00) and inter-rater reliability (ICC = 1.00; CI 95% 1.00-1.00).

The 6-min step test has appropriate measurement properties to estimate cardiorespiratory fitness in individuals with chronic stroke. Moreover, the video administration of the 6-min step test produced comparable results with the in-person administration.

Exercise parameters can be altered in children with congenital heart disease or acquired heart disease compared with children with normal hearts. Exercise testing has proven a useful tool to predict patient outcomes and even the need for reintervention in several cardiovascular disease processes. There are established guidelines for serial exercise stress testing in adults with congenital heart disease, but corollary guidelines do not exist for the pediatric population.

A narrative literature review was completed. Evidence was ranked by a 4-point scale as outlined by the American College of Sports Medicine evidence categories. A survey was sent to experts in pediatric exercise physiology across the country regarding their current testing practices for 26 unique congenital heart disease or known or suspected acquired heart disease lesions. Survey questions were related to the frequency of testing, the age at which exercise testing is started, and if the frequency of testing is altered by a patient presenting with symptoms. Our literature search yielded 122 relevant studies pertaining to exercise stress testing in pediatric heart disease. We received 59 responses to our survey from 33 unique institutions in the United States and Canada.

Twenty-one summaries were provided regarding exercise stress testing in pediatric patients with heart disease. Multicentered or national stress testing registries may allow for adequate sample sizes of rare pediatric diseases to allow for development of improved guidelines regarding the type and timing of stress testing.

Bioimpedance cardiography offers a non-invasive and time-efficient method to measure hemodynamic parameters. Previous studies only investigated its reliability under steady-state conditions and at maximum load but not at ventilatory thresholds (VTs). This is the first study that assesses the reliability of measured hemodynamic parameters at different exercise stages during cardiopulmonary exercise testing (CPET) using prespecified strict criteria to assess reliability.

Data from 31 healthy, well-trained adults were analyzed. Each participant completed two CPETs, both following the same ramp protocol, with a 7-day interval between them. Hemodynamic parameters were measured with the PhysioFlow® (Manatec Biomedical, Poissy, France) at characteristic phases and thresholds [VT1, VT2, and peak oxygen uptake (V̇O2peak)]. To ensure comparability, the wattage (power) corresponding to the thresholds in Test 1 (PVT1, PVT2, and PV̇O2peak) was used for Test 2.

Heart rate, stroke volume, and cardiac output demonstrated good reliability on a group level (mean intraclass correlation >0.75) at both thresholds (0.91, 0.80, and 0.77 at PVT1; 0.92, 0.80, and 0.77 at PVT2) and at PV̇O2peak (0.93, 0.82, and 0.80). For stroke volume at PV̇O2peak, both individual differences (-39.0 to 36.9 mL for the women and -39.9 to 45.2 mL for the men) and mean detectable change (17.5 mL) were larger than the a priori defined acceptable ranges of agreement (-3.6 to 3.8 mL for the women and -4.5 to 3.3 mL for the men).

The PhysioFlow® reliably measures heart rate, stroke volume, and cardiac output during CPET on a group level. However, as shown by the Bland-Altman plots, the reliability is too low to be used for individual comparisons.

The performance of a cardiopulmonary exercise test (CPET) requires an individual to undertake a progressive, maximal exercise test to a symptom-limited end point. CPET is commonly performed using a treadmill or cycle ergometer (CE). Arm ergometry (AE) is an alternative exercise modality to CE; however, AE produces lower peak oxygen uptake (V̇O2) values as it involves smaller muscle groups and generates less cardiovascular stress. Current predicted equations for the interpretation of AE CPET are limited by small sample sizes, gender bias and limited age ranges.

To develop predicted equations and reference ranges for AE exercise testing.

Incremental ramp protocol CPET, to a symptom-limited end point, via AE was performed in a group of 116 (62 F) healthy volunteers of median age 38 (IQR 29-48) years. Breath-by-breath gas analysis was performed using the Ultima CPX (Medical Graphics, UK) metabolic cart. Quantile regression analysis was used to develop regression equations for AE V̇O2, peak work rate (WR), anaerobic threshold, peak ventilation (VE), peak heart rate, oxygen pulse, V̇E/V̇CO2 slope and V̇O2/WR slope.

Reference equations including upper and/or lower limits, based on quantile regression, were generated and verified using a validation cohort.

These findings represent the largest and most diverse set of predicted values and reference ranges for AE CPET parameters in healthy individuals to date. Implementation of these reference equations will allow AE to be more widely adopted, enabling the performance and interpretation of CPET in a wider population.

Unexplained exertional dyspnoea without significant elevation of natriuretic peptides is common. One of the causes might be early heart failure with preserved ejection fraction (HFpEF).

This study aimed to characterize patients with exertional dyspnoea and normal/near-to-normal N-terminal pro-brain natriuretic peptide (NT-proBNP) levels with regard to early stages of HFpEF and non-cardiac causes.

Sixty-six patients (age 62 ± 7 years old, 85% women) with dyspnoea assessed using the Multidimensional Dyspnea Profile (MDP) questionnaire and NT-proBNP level of <125 pg/mL for patients <75 years old or <300 pg/mL for patients >75 years old were recruited. Patients with known significant heart disease, lung disease (abnormal respiratory function tests) or renal insufficiency stage ≥ 4 were excluded. In 11 patients (16.7%), HFpEF was confirmed according to the European Society of Cardiology Heart Failure Association (ESC HFA) criteria, 31 patients (47%) presented isolated deconditioning and 5 patients (7.6%) had idiopathic hyperventilation. In the remaining 19 patients (28.8%) with normal echocardiography and cardiopulmonary exercise testing (CPX), no objective cause of dyspnoea could be found. Compared with patients without HFpEF, those with HFpEF were older, more often hypertensive and diabetic, with higher NT-proBNP levels. They had higher E/e' ratios during exercise echocardiography and lower volume of oxygen uptake (VO2) peaks and steeper minute ventilation (VE)/volume of carbon dioxide produced (VCO2) slopes during CPX. Psychological impact measured on the Short Form-36 (SF-36) questionnaire was less important in HFpEF patients than in other patients.

The most common causes of unexplained exertional dyspnoea in patients without significant elevation of natriuretic peptides are peripheral deconditioning, HFpEF and hyperventilation. Studying patients during exercise allows for getting more data about pathophysiology and improving patient phenotyping and management. Early unmasking of HFpEF using exercise echocardiography and/or CPX and initiation of treatment could prevent hospitalizations for acute heart failure. Although using exercise testing, many patients could not be classified according to their diagnosis, and this reinforces the need to better define exercise diagnostic criteria.

Spinal cord volume loss is associated with clinical disability in multiple sclerosis (MS). Aerobic capacity may mitigate the impact of central nervous system (CNS) damage accumulation, exerting beneficial effects on MS-related disability.

We investigated whether aerobic capacity could moderate the association between spinal cord atrophy and clinical disability in MS.

In this cross-sectional analysis, expanded disability status scale (EDSS), peak of oxygen consumption (VO2peak), brain volumetric measures, and the normalized mean upper cervical cord area (nMUCCA) were collected from 51 MS patients and 33 healthy controls (HCs). Low aerobic capacity was defined as having a VO2peak z-score less than -1.64 standard deviations. In MS patients, we explored whether the association between nMUCCA and EDSS is moderated by the level of aerobic capacity.

The relationship between nMUCCA and EDSS was moderated by aerobic capacity, with a significant nMUCCA × aerobic capacity interaction (β = -0.099, 95% bootstrapped confidence interval [CI] = [-0.172; -0.014], p = 0.012). Lower nMUCCA was significantly associated with higher EDSS score in MS patients with low aerobic capacity (β = -0.073, p < 0.001), but not in those with high aerobic capacity (β = 0.026, p = 0.417).

In MS patients with mild disability, higher aerobic capacity can potentially mitigate the negative impact of spinal cord damage on clinical disability.

Cardiopulmonary exercise testing (CPET) is used in the evaluation of unexplained dyspnea. However, its interpretation requires expertise that is often not available. We aim to evaluate the utility of ChatGPT (GPT) in interpreting CPET results.

This cross-sectional study included 150 patients who underwent CPET. Two expert pulmonologists categorized the results as normal or abnormal (cardiovascular, pulmonary, or other exercise limitations), being the gold standard. GPT versions 3.5 (GPT-3.5) and 4 (GPT-4) analyzed the same data using pre-defined structured inputs.

GPT-3.5 correctly interpreted 67% of the cases. It achieved a sensitivity of 75% and specificity of 98% in identifying normal CPET results. GPT-3.5 had varying results for abnormal CPET tests, depending on the limiting etiology. In contrast, GPT-4 demonstrated improvements in interpreting abnormal tests, with sensitivities of 83% and 92% for respiratory and cardiovascular limitations, respectively. Combining the normal CPET interpretations by both AI models resulted in 91% sensitivity and 98% specificity. Low work rate and peak oxygen consumption were independent predictors for inaccurate interpretations.

Both GPT-3.5 and GPT-4 succeeded in ruling out abnormal CPET results. This tool could be utilized to differentiate between normal and abnormal results.

MASLD is a leading reason for liver transplant waitlisting. The relationship between cardiorespiratory fitness (CRF) and liver fibrosis in patients with MASLD remains unclear. This study aims to provide further evidence supporting the relationship between liver fibrosis and CRF.

Participants with MASLD across various fibrosis stages, including those with cirrhosis awaiting liver transplantation from three U.S. transplant centers, underwent cardiopulmonary exercise testing (CPX). We compared participants based on fibrosis stage (F0-F1, F2-F3, and F4) and CPX parameters such as VO2peak, respiratory exchange ratio (RER), ventilatory efficiency (VE/VCO2), double product (DP) and chronotropic incompetence (CI). Multivariable models were then built to evaluate factors associated with these parameters.

Sixty-one participants underwent CPX testing across three centers. Participants with F4 had lower VO2peak (11.8 mL/kg/min) compared to F0-F1 (22.2 mL/kg/min) and F2-F3 (22.9 mL/kg/min), p < 0.001. Participants with F4 had higher RER (median 1.25) compared to F0-F1 (1.08) and F2-F3 (1.05), p = 0.001. Similarly, F4 participants exhibited higher VE/VCO2 (median 36.5) compared to F0-F1 (31) and F2-F3 (30), p < 0.001. Additionally, F4 participants had lower DP values (median 17,696) compared to F0-F1 (25,460) and F2-F3 (25,372), and higher prevalence of CI (90%) compared to F0-F1 (39%) and F2-F3 (25%), both p =  < 0.001. Multivariable modeling confirmed advanced fibrosis (F > 3) as an independent predictor of low CRF.

In MASLD patients, advanced liver fibrosis, particularly cirrhosis, is associated with reduced CRF and poorer hemodynamic performance during CPX. Prioritizing exercise training for those in earlier stages (F3) may prevent fitness decline, which could hinder physical training and liver transplantation candidacy.

The objective of this study was to assess the accuracy of VO2 measurements in predicting long-term major adverse cardiac events (MACEs) in patients with high cardiovascular risk.

Based on a 10-year atherosclerotic cardiovascular disease risk score, 333 patients with high cardiovascular risk were included in this retrospective analysis. The study endpoint was MACEs, comprising all-cause mortality, cardiovascular mortality, non-fatal myocardial infarction or stroke, and coronary revascularization. The study cohort was divided into two groups according to the frequency of MACE occurrence. Measurements of VO2 were assessed for the prediction of MACEs.

The best predictive accuracy for 1‑year MACEs was determined to be a VO2 max value of ≥ 20.3 mL/kg/min, with 60% specificity and 60% sensitivity (area under the curve [AUC]: 0.61; 95% confidence interval [CI]: 0.51-0.71; p < 0.001), and for 5‑year MACEs it was ≥ 19.9 mL/kg/min, with 69% specificity and 64% sensitivity (AUC: 0.69; 95% CI: 0.62-0.76; p < 0.001). Multivariable Cox regression analysis, after adjusting for univariable factors, showed that VO2 max was independently associated with both short- and long-term MACEs in patients at high cardiovascular risk (hazard ratio [HR]: 0.900, 95% CI: 0.858-0.943, p < 0.001).

According to the results of this pilot study, VO2 max can predict both short- and long-term MACEs in patients at high cardiovascular risk.

The prevalence of asthma is increasing gradually worldwide. The pathophysiological process of asthma causes some alterations in the respiratory system and decreases oxygen-carbon dioxide exchange and respiration volume. These alterations may affect maximal exercise capacity, peripheral muscle strength, sleep quality, and disease-specific quality of life but have yet to be comprehensively investigated. To compare maximal exercise capacity, pulmonary function, peripheral muscle strength, dyspnea, sleep quality, and quality of life in adult patients with asthma, healthy controls were aimed.

Forty-one adult stable asthmatic patients (GINA I-III) and 41 healthy subjects were compared. Exercise capacity (cardiopulmonary exercise test [CPET]), pulmonary function (spirometry), peripheral muscle strength (dynamometer), dyspnea (modified Medical Research Council [mMRC] dyspnea scale), quality of life (Asthma Quality of Life Questionnaire [AQLQ]) and sleep quality (Pittsburgh Sleep Quality Index [PSQI]) were evaluated.

Peak VO2, VO2kg, MET, VE, HR, %VE, %HR, VCO2 parameters of CPET, FVC, FEV1, FEF25-75%, and FEV1/FVC and quadriceps femoris, shoulder abductors, and hand grip muscle strength were significantly decreased in patients with asthma (p < 0.05). MMRC dyspnea scale score was increased, and AQLQ and PSQI scores decreased in asthma patients (p < 0.05).

Cardiac and pulmonary system responses to peak exercise worsened, and maximal exercise capacity and peripheral muscle strength decreased in adult patients with stable asthma. In addition, dyspnea during daily activities increases, and quality of life and sleep quality are impaired. A variety of exercise training that would benefit asthmatic patients' outcomes should be investigated.

Cardiopulmonary exercise testing (CPET) is the gold standard for quantifying aerobic functional capacity, yet it is costly and not widely available. The CLINIMEX Aerobic Fitness Questionnaire (C-AFQ) may be a practical alternative as it estimates oxygen consumption at peak exercise (VO2 peak) based on patients' responses to a list of activities with known energy requirements. However, its applicability in cardiac patients is unclear and has not yet been studied. This study aims to assess the C-AFQ performance in predicting VO2 peak, measured via CPET, in adult patients with confirmed heart disease.

This was a single-center prospective study enrolling consecutive patients who underwent CPET from April/2022 to January/2023. The main indication for CPET was measuring aerobic functional capacity for cardiovascular risk stratification.

A total of 124 patients (mean age 62±12 years, 75% male, 59% in the early phase post-myocardial infarction, 61% had heart failure, mean left ventricular ejection fraction 47±12%) with maximal CPET were included. Overall, a strong correlation was found between CPET and C-AFQ VO2 peak values (r=0.723, p<0.001). However, when performing a Bland-Altman plot analysis, we found a heightened confidence interval for the agreement between CPET and C-AFQ VO2 peak: 0.62±6.93 (95% CI -12.96-14.21) mL kg-1 min-1. CPET VO2 peak and the VO2 peak estimated by the exercise test protocol were related (r=0.777, p<0.001).

Although cardiorespiratory fitness estimation from the C-AFQ performs well in a large population, the utility of this questionnaire to estimate cardiorespiratory fitness in this study's population sample has limited value. However, it may be useful to aid physicians in choosing the adequate exercise test protocol that best fits an individual patient.

This study aims to determine whether maximal oxygen consumption (VO2max) or predicted postoperative (ppo)-VO2max could still reliably predict postoperative complications and deaths in lung cancer patients undergoing pneumonectomy and which values could be more reliably considered as the optimal threshold. Methods: We retrospectively collected data of consecutive patients undergoing pneumonectomy for primary lung cancer at the European Oncological Institute (April 2019-April 2023). Routine preoperative assessment included cardiopulmonary exercise testing (CPET) and a lung perfusion scan. We evaluated the morbidity and mortality rates; associations between morbidity, mortality, VO2max, and ppoVO2max values were investigated through ANOVA or Fisher's exact test as appropriate. Receiver operating characteristic (ROC) curves were applied to further explore the relation between VO2max, ppoVO2max values, and 90-day mortality. Results: The cardiopulmonary morbidity rate was 32.2%; the 30-day and 90-day mortality rates were 2.2% and 6.7%. The PpoVO2max values were significantly lower in patients experiencing cardiopulmonary complications or deaths compared to the whole cohort, whereas VO2max, though showing a trend towards lower values, did not reach statistical significance. A VO2max value threshold of 15 mL/kg/min correlated significantly with 90-day mortality, while a ppoVO2max cut-off of 10 mL/kg/min was significantly associated with cardiopulmonary complications and 30-day and 90-day mortality rates. ROC curve analysis revealed ppoVO2max as a better predictor of 90-day mortality compared to VO2max. Conclusions: CPET and a lung perfusion scan are two key elements for the preoperative evaluation of patients undergoing pneumonectomy, since it provides a holistic assessment of cardiopulmonary functionality. We recommend the routine calculation of ppoVO2max, particularly when adopting a 10 mL/kg/min threshold.

The aims of this study are to evaluate the effectiveness of an online supervised training program in modulating lipid and glucose metabolism in children with obesity and to investigate the possible role of the 6-minute walking test (6MWT) as a predictor of metabolic improvement. A total of 35 Caucasian children with obesity (aged 8-13) were enrolled in the study and tested before (T0) and after (T1) a 12-week online supervised exercise training protocol: cardiovascular fitness (by means of 6MWT), metabolic biochemical profile, lifestyle (with ad hoc questionnaires focusing on physical activity, nutrition, sedentariness, sleep hours and quality, health perception) and Cardiac Autonomic Regulation (CAR) were assessed. Spearman correlations between the variations in the studied outcomes were explored. After intervention, the distance covered during 6MWT significantly increased (p < 0.001), and nutrition quality improved slightly but significantly (p = 0.03). The improvement in the 6MWT performance was shown to be significantly correlatee with the reduction of insulin levels (r = -0.455; p = 0.02), HOMA-IR Index (r = -0.452; p = 0.02), total cholesterol values (r = -0.549; p = 0.004) and Atherogenic Index of Plasma (AIP) (r = 0.422; p = 0.04). Moreover, there was a significant correlation between the improvement in 6MWT and health perception (r = 0.578; p = 0.002). We observed that the improvement in the 6MWT performance correlates with better metabolic profile after exercise training in children with obesity suggesting the goodness of this simple test on unveil changes in pathogenetic processes underlying obesity.

Liver transplant recipients experience comorbidities, including impaired physical fitness, which could be managed by exercise and physical activity interventions. This study aims to evaluate the feasibility, clinical effectiveness and cost-effectiveness of a 6-month exercise intervention, followed by a 15-month tailored physical activity maintenance intervention, in de novo liver transplant recipients. This single-centre, randomised, controlled, single-blinded trial will recruit 147 adult liver transplant recipients at 3-5 months post-transplant. Participants will be randomised into (1) 6 months of enhanced usual care, not followed by a physical activity intervention (control (CON) group, n=49), (2) 6 months of moderate-intensity exercise training, followed by a physical activity intervention (moderate-intensity training (MIT) group; n=49) or (3) consecutively 3 months of moderate-intensity exercise training, 3 months of high-intensity interval training and a physical activity intervention (moderate and high-intensity training (MHIT) group; n=49). Exercise training will consist of home-based stationary bicycling and muscle-strengthening exercises, partially supervised by participants' local physiotherapists. The physical activity intervention includes an array of behaviour change techniques. Primary hypothesis: after the exercise intervention, peak oxygen uptake (V̇O2peak) will be higher in MHIT versus CON (α-level 0.05). Secondary hypotheses: after the exercise intervention, V̇O2peak will be higher in MIT versus CON and MHIT versus MIT (α-level 0.025). Secondary outcomes, assessed up to 2 years post-transplant, include physical fitness, cardiovascular and graft health, quality of life, physical activity and implementation outcomes. Trial registration number NCT06302205.

The rapid growth in popularity of e-cigarettes over the past decade has prompted concerns about their impact on long-term respiratory health. Small airway injury is suspected to be a direct consequence of e-cigarette use and may be quantifiable by novel structural and functional diagnostic modalities.

In a multicentre observational longitudinal study, participants will be enrolled in either an adolescent (ages ≥12 and <19 years) or an adult arm (≥19 years old) and followed over 3 years across three time points (baseline, 18 months and 36 months). In the adolescent arm, a total of 50 e-cigarette and 50 non-e-cigarette users will be enrolled across 4 sites. In the adult arm, a total of 100 e-cigarette users, 100 non-e-cigarette users, and an additional 100 combustible cigarette-only users and 100 dual combustible cigarette-e-cigarette users will be enrolled across 5 sites. Participants will undergo respiratory questionnaires, pulmonary function tests, oscillometry, cardiopulmonary exercise testing, hyperpolarised 129-xenon gas MRI and blood collection. In adolescent participants only, multiple breath washout and induced sputum collection will be performed. Adult participants will also undergo inspiratory/expiratory chest CT and bronchoscopy. The primary endpoint will be a composite of small airway dysfunction according to oscillometry, cardiopulmonary testing and/or chest imaging parameters.

This protocol has been approved by The University of British Columbia-Providence Health Care Research Ethics Board (Certificate H24-00374). The use of hyperpolarised 129-xenon gas in this study has been approved by Health Canada (Certificate HC6-024-c291776). Written documentation of informed consent will be required prior to study initiation. We will seek to enrol adolescent participants who are capable of providing informed consent with an optional support statement from a parent encouraged but not required. Study findings will be disseminated to medical/scientific audiences through scientific conferences and published manuscripts respecting the Strengthening the Reporting of Observational Studies in Epidemiology statement, to youths through outreach events at high schools and community programmes and through social media, and to adults through lung health community events.

NCT06819969.

Cardiopulmonary exercise testing (CPET) is the gold-standard for quantification of peak oxygen uptake (VO2) and cardiorespiratory and muscle responses to exercise. Its application to Duchenne muscular dystrophy (DMD) has been scarce due to the notion that muscle weakness inherent to disease restricts the cardiorespiratory system from reaching maximal capacity.

To investigate the utility of CPET in DMD by 1) establishing whether patients can perform maximal-effort exercise for valid VO2 peak assessment; 2) quantifying VO2 peak repeatability; 3) characterizing muscle and cardiorespiratory responses; 4) comparing VO2 peak to 6-min walk distance (6MWD).

Twenty-seven DMD and eight healthy boys (6 years and older) underwent CPET using an incremental work-rate protocol for leg (ambulatory) or arm (non-ambulatory) cycling with measurement of heart rate (HR) and gas-exchange variables from rest to maximal-effort. The oxygen cost of work (ΔVO2/Δwork-rate) was calculated, and peak exercise parameters (VO2, HR, O2 pulse, ventilation (VE) and ventilatory threshold (VT)) were considered valid if the respiratory exchange ratio ≥1.01.

VO2 peak was valid (81.5% of patients), repeatable (intraclass correlation coefficient = 0.998) and low in ambulatory and non-ambulatory DMD compared to controls (19.0 ± 6.0; 10.7 ± 2; 35.2 ± 4.5 mL/kg/min respectively). VT was low (30.8 ± 10.7; 19.4 ± 3.0; 61.2 ± 6.9% VO2 peak) reflecting significant muscle metabolic impairment. Peak HR in ambulatory-DMD (172 ± 14 bpm) was similar to controls (183 ± 8.3 bpm), but O2 pulse was low (3.4 ± 1.0; 6.5 ± 1.1 mL/beat). Peak VE/VO2 (ambulatory = 42.1 ± 6.8; non-ambulatory = 42.2 ± 7.8; controls = 34.3 ± 4.6) and ΔVO2/Δwork-rate were elevated (ambulatory = 12.4 ± 4.9; non-ambulatory = 19.0 ± 9.7; controls = 10.1 ± 0.8) revealing ventilatory and mechanical inefficiency. Despite strong correlation between VO2 peak and 6MWD, severity of impairment was discordant.

Valid CPET is feasible in DMD, revealing low VO2 peak due to abnormal muscle metabolic and cardiorespiratory responses during dynamic exercise. CPET reveals cardiorespiratory limitations in DMD boys with unremarkable 6MWD, and should be considered an integrative approach in clinical care and assessment of emerging therapeutics.

This study assessed the impact of a 12-wk, home-based exercise training (HBET) program on health-related quality of life (HRQOL; primary outcome), and cardiovascular and metabolic parameters in pediatric COVID-19 patients.

This was a single-center, randomized controlled trial conducted in a tertiary hospital in Sao Paulo, from October 2020 to January 2022. Thirty-two patients (mean age, 12 ± 3.3 yr) were randomly assigned to either HBET or standard of care (CONTROL) in a 2:1 ratio 4 months (range: 0.7-6.6 months) after COVID-19 discharge ( n = 25 mild, n = 4 moderate, n = 3 severe illness). The HBET group underwent supervised and unsupervised sessions three times a week for 12 wk emphasizing aerobic and body weight exercises, while the CONTROL group received standard care, which included general advice for a healthy lifestyle with no prescribed exercise intervention. HRQOL (evaluated by the Pediatric Quality of Life Inventory), cardiopulmonary exercise test, brachial endothelial function and echocardiography assessments were conducted in both groups. Statistical analysis was performed using an intention-to-treat approach for the primary analysis and complete case (per-protocol) as sensitivity analysis.The significance was set at P ≤ 0.05 and P ≤ 0.10 was considered as trend.

There was no difference in HRQOL between groups. Intention-to-treat analysis indicated a trend toward increased oxygen uptake (V̇O 2 ) at anaerobic threshold following the intervention in the HBET group. In addition, a sensitivity analysis showed significant changes in peak heart rate and 1-min recovery, respiratory exchange ratio, and chronotropic response. A trend toward significance was observed in ventilation-to-maximum voluntary ventilation ratio and chronotropic response in the HBET group. No other between-group differences were detected for the cardiopulmonary exercise test, brachial flow-mediated dilation, and echocardiography variables (all P > 0.05).

In this randomized controlled trial, a 12-wk HBET intervention did not impact HRQOL in pediatric COVID-19 patients. However, exercise was able to improve the V̇O 2 at the ventilatory anaerobic threshold, heart rate peak and 1-min recovery, ventilation-to-maximum voluntary ventilation ratio, and chronotropic response, with no changes observed in other cardiovascular parameters. Further studies are needed to investigate the long-term effects of exercise interventions on the recovery of pediatric COVID-19 patients with and without preexisting chronic conditions.

Despite the importance of objective measures for prescribing aerobic exercise for mitigating cardiovascular risk in people with coronary artery disease (CAD), no study has examined sex differences in the utility of the cardiopulmonary exercise test (CPET) for developing the exercise prescription.

CPET results from 1352 females and 5875 males with CAD were analysed to determine if there was a sex difference in achieving maximal oxygen uptake (V˙O2max) or an identifiable first ventilatory threshold (VT1). Secondary outcomes were to determine correlates of not achieving V˙O2max or VT1 in all patients and in males and females separately.

A greater proportion of males than females achieved V˙O2max or VT1 (89.7% vs 71.3%; P < 0.001) as well as specifically achieving V˙O2max (40.2% vs 26.7%; P < 0.001) and VT1 (88.0% vs 69.2%; P < 0.001). The most influential correlates of not achieving V˙O2max or VT1 were female sex (odds ratio 3.1, 95% confidence interval 2.6-3.7), age > 60 years, tested on treadmill vs cycle, depressive symptoms, and a secondary heart failure diagnosis. At entry to cardiac rehabilitation, these correlates were more prevalent in females than in males. Correlates differed by sex. The threshold for when age affected achieving V˙O2max or VT1 on the cycle CPET was earlier for females (> 50 years of age) than for males (> 70 years of age) with no difference on treadmill (> 80 years of age for both).

Although most patients achieved V˙O2max or VT1 on the CPET, females were 3 times less likely than males to achieve V˙O2max or VT1. Strategies to improve utility of CPETs for females, such as alternative exercise test protocols and investigation into underlying mechanisms for effects of depressive symptoms, should be conducted.

Exercise capacity is decreased in diabetes mellitus due to impaired insulin sensitivity, endothelial dysfunction and mitochondrial dysfunction. The aim of the study was to evaluate the effect of metformin on exercise capacity in treatment naïve patients with type 2 diabetes mellitus.

Newly diagnosed type 2 diabetes mellitus patients were tested for baseline insulin resistance and exercise capacity, before starting on metformin. Exercise capacity was measured by incremental exercise testing in treadmill (ZAN 600 CPET system) using modified Bruce protocol at baseline, 6 weeks and 12 weeks following metformin therapy.

A total of 33 treatment naïve type 2 diabetes patients were enrolled of which 19 patients completed the study. There was no significant change in any of the exercise capacity parameters at the end of 12 weeks of metformin. Nevertheless, there was a significant improvement in VO2/kg among those with insulin resistance as compared to those without insulin resistance.

Metformin monotherapy did not produce any change in exercise capacity in treatment naïve type 2 diabetes patients. However, a significant fall in exercise capacity (VO2/kg) was observed in patients without insulin resistance as compared to those with insulin resistance at the end of 12 weeks of metformin therapy.

Heart failure (HF) and atrial fibrillation (AF) are highly prevalent in hemodialysis. They are well-known significant modifiers of the disease associations with cardiovascular outcomes, but there is a lack of evidence regarding the effects of HF and AF on cardiorespiratory fitness. This study is the first to examine the possible association of the presence of HF and AF with exercise intolerance in patients undergoing hemodialysis.

This analysis included 40 sex- and age-matched participants [10 hemodialysis patients with HF or AF, 10 hemodialysis patients without HF or AF, 10 patients with HF or AF without chronic kidney disease (CKD) and 10 healthy controls] that underwent CPET and spirometry examinations. The total of patients with HF had preserved ejection fraction.

VO2peak(ml/kg/min) showed a graded increase between hemodialysis patients with HF or AF, hemodialysis patients without HF or AF, non-CKD patients with HF or AF and controls (13.17 ± 2.45 vs 15.26 ± 3.29 vs 19.64 ± 5.84 vs 25.11 ± 6.94 ml/kg/min, p < 0.001); VO2peak(ml/min) followed the same pattern (1172 ± 197 vs 1269 ± 314 vs 1817 ± 583 vs 1952 ± 592 ml/min respectively, p = 0.001). VO2peak(%predicted), VO2AT(ml/kg/min), VO2AT(ml/min) and maximal work load significantly differed between the study groups, with a tendency for higher values from hemodialysis patients to non-CKD patients with HF or AF and to healthy controls. FEV1 and FVC levels were similar between the study groups. In the whole population, VO2peak(ml/kg/min) showed a positive correlation with hemoglobin (r = 0.663, p < 0.001) and negative correlations with high-sensitivity cardiac troponin I (r = - 0.493, p = 0.001) and BNP (r = - 0.479, p = 0.002).

Hemodialysis patients have low exercise tolerance, and the presence of HF or AF is associated with further decreased values of VO2peak, the most important determinant of cardiorespiratory fitness.

COPD management is guided by the respiratory symptom burden, assessed using the modified Medical Research Council (mMRC) scale, the COPD Assessment Test (CAT), or both.

What are the abilities of mMRC and CAT to detect abnormally high exertional breathlessness on incremental cardiopulmonary cycle exercise testing (CPET) in people with COPD?

Analysis of people aged ≥ 40 years with FEV1 to FVC ratio of < 0.70 after bronchodilator administration and ≥ 10 pack-years of smoking from the Canadian Cohort Obstructive Lung Disease study. Abnormal exertional breathlessness was defined as a breathlessness (Borg scale 0-10) intensity rating more than the upper limit of normal at the symptom-limited peak of CPET using normative reference equations.

We included 318 people with COPD (40% female) with a mean (SD) age of 66.5 (9.3) years and FEV1 of 79.5% predicted (19.0% predicted); 26% showed abnormally low exercise capacity (peak oxygen uptake less than the lower limit of normal). Abnormally high exertional breathlessness was present in 24%, including 9% and 11% of people with mMRC score of 0 and CAT score of < 10, respectively. An mMRC score of ≥ 2 and CAT score of ≥ 10 was most specific (95%) to detect abnormal exertional breathlessness, but showed low sensitivity of only 12%. Accuracy for all scale cutoffs or combinations was < 65%. Compared with people with true-negatives findings, people with abnormal exertional breathlessness but low mMRC score, low CAT scores (false-negatives findings), or both showed worse self-reported and physiologic outcomes during CPET, were more likely to have physician-diagnosed COPD, but were not more likely to be taking any respiratory medication (37% vs 30%; mean difference, 6.1%; 95% CI, -7.2 to 19.4; P= .36).

In COPD, mMRC and CAT showed low concordance with CPET and failed to identify many people with abnormally high exertional breathlessness.

ClinicalTrials.gov; No.: NCT00920348; URL: www.

gov.

To investigate the cut-off value of the breathing reserve for predicting a decline in cardiorespiratory fitness (CRF) among healthy middle-aged Chinese individuals.

Healthy middle-aged individuals who underwent cardiopulmonary exercise testing (CPET) at the Peking University Third Hospital from May to October 2021 were selected. The study included 321 participants, with an average age of 48.8 ± 5.7 years. They were divided into two groups based on the peak oxygen uptake (VO2peak): the adequate CRF group and the CRF decline group. Multivariate logistic regression analysis was used to explore the factors influencing CRF.

In the male CRF decline group, heart rate, alanine aminotransferase, end-tidal partial pressure of carbon dioxide (PETCO2), and breathing reserve (BR%) were significantly higher, while the oxygen uptake at the anaerobic threshold (VO2@AT) was lower. An elevated BR% was independently associated with CRF decline (OR = 1.111, 95% CI: 1.068-1.156). The female CRF decline group had significantly higher FEV1/FVC and BR% and significantly lower age, fasting glucose, hemoglobin, and VO2@AT compared to the adequate CRF group. Elevated BR% was independently associated with CRF decline (OR = 1.086, 95% CI: 1.038-1.137). The receiver operating characteristic (ROC) curve for the males showed an area under the curve (AUC) of 0.769 (95% CI: 0.703-0.827) with an appropriate BR% cut-off value of 49.9%, sensitivity of 59.9%, and specificity of 77.8%. For the females, the ROC curve displayed an AUC of 0.694 (95% CI: 0.607-0.773) with an appropriate BR% cut-off value of 57.0%, sensitivity of 58.7%, and specificity of 86.0%.

The breathing reserve was independently associated with CRF. The appropriate cut-off values for BR% to predict CRF decline were 49.9% for the males and 57.0% for the females.

Tidal breathing in awake humans is variable. This variability causes changes in lung gas stores that affect gas exchange measurements. To overcome this, several algorithms provide solutions for breath-by-breath alveolar gas exchange measurement; however, there is no consensus on a physiologically robust method suitable for widespread application. A recent approach, the 'independent-breath' (IND) algorithm, avoids the complexity of measuring breath-by-breath changes in lung volume by redefining what is meant by a 'breath'. Specifically, it defines a single breathing cycle as the time between equal values of theF O 2 ${F_{{{\mathrm{O}}_2}}}$ /F N 2 ${F_{{{\mathrm{N}}_2}}}$ (orF C O 2 ${F_{{\mathrm{C}}{{\mathrm{O}}_2}}}$ /F N 2 ${F_{{{\mathrm{N}}_2}}}$ ) ratio, that is, the ratio of fractional concentrations of lung-expired O2 (or CO2) and nitrogen (N2). These developments imply that the end of one breath is not, by necessity, aligned with the start of the next. Here we demonstrate how the use of the IND algorithm fails to conserve breath-by-breath mass balance of O2 and CO2 exchanged between the atmosphere and tissues (and vice versa). We propose a new term, within the IND algorithm, designed to overcome this limitation. We also present the far-reaching implications of using algorithms based on alternative definitions of the breathing cycle, including challenges in measuring and interpreting the respiratory exchange ratio, pulmonary gas exchange efficiency, dead space fraction of the breath, control of breathing, and a broad spectrum of clinically relevant cardiopulmonary exercise testing variables. Therefore, we do not support the widespread adoption of currently available alternative definitions of the breathing cycle as a legitimate solution for breath-by-breath alveolar gas exchange measurement in research or clinical settings.

Background: The US Food and Drug Administration (FDA) and International Organization for Standardization (ISO) clearance standards for the clinical use of smart device pulse oximetry require in-laboratory human hypoxemia testing in healthy human individuals using arterial blood gas analysis. Methods: We evaluated the SpO2 measurements of the Samsung smartphone (Galaxy S9/10) and smartwatch (Galaxy 4) at stable arterial oxygen saturations (SaO2) between 70 and 100% in 24 healthy participants. Testing followed FDA/ISO-stipulated procedures for pulse oximetry performance validation, which include questionnaire estimation of skin tone based on Fitzpatrick estimation of skin types I-VI. During testing, inspired oxygen, nitrogen, and carbon dioxide partial pressures were monitored and adjusted via partial rebreathing circuits to achieve stable target arterial blood oxygen (SaO2) plateaus between 70% and 100%. Arterial blood samples were taken at each plateau, with device SpO2 readings taken at each sample extraction. An ABL-90FLEX blood gas analyzer determined arterial blood sample SaO2. Bias, calculated from device readings minus corresponding arterial blood measurements, was reported as root mean square deviation (RMSD). Results: Combined Participants demographics were: 62.5% female; median age 26 years (range 21-46); and race/ethnicity 16.7% African American, 33.3% Asian, 12.5% multi-ethnic, and 37.5% Caucasian. Fitzpatrick Skin Scale-identified skin tones were: white-fair (I&II), 20.8%; average-light brown (III-IV), 54% and brown-black (V-VI), 25%. There were no adverse events. The RMSD values of SpO2 measurements were: smartphone 2.6% (257 data pairs) and smartwatch 1.8% (247 data pairs). Conclusions: Device SpO2 demonstrated RMSD < 3.0% to SaO2, meeting FDA/ISO clearance standards at the time of study. However, additional testing in persons with darker skin tones is necessary. Smartphones and paired wearables, when cleared for clinical use following revision of FDA clearance standards, may expand access to remote pulse oximetry.

Patients with Chronic Obstructive Pulmonary Disease (COPD) show ventilatory limitation to exercise due to dynamic hyperinflation (DH). Breathing pattern can be expressed by TI/TTOT (inspiratory time/total time) and VT/TI (tidal volume/inspiratory time). Both parameters significantly increase during exertional hyperpnea in healthy subjects, but they have never been studied in COPD. In a large cohort of COPD patients, we analysed TI/TTOT and VT/TI at rest and during maximal exercise.

We enrolled clinically stable COPD patients with wide degree of airflow obstruction. All participants underwent spirometry and cardiopulmonary exercise testing (CPET) on a cycle ergometer.

In 234 COPD patients (75 females; age range 41-89 years), TI/TTOT and VT/TI values significantly increased during exercise, from 0.259 ± 0.040-0.304 ± 0.038 and from 854.1 ± 229,6 ml/s to 2100 ± 622.5 ml/s respectively (p < 0.05). TI/TTOT peak and VT/TI peak were positively related (p < 0.05) with VO2peak (ml/min/kg), maximal workload (Watt). TI/TTOT peak, but not VT/TI peak values showed a positive correlation (p < 0.05) with the peak-rest difference of inspiratory capacity (ΔIC, in ml). When related to minute ventilation TI/TTOT and VT/TI rest values in patients with DH (ΔIC ≥150 ml), compared with those without DH, did not differ between the two groups, though TI/TTOT, but not VT/TI values, significantly increased during exercise in patients without DH CONCLUSIONS: TI/TTOT and VT/TI values significantly increase during maximal exercise in COPD. TI/TTOT values were significantly correlated with dynamic hyperinflation. Our results suggest that TI/TTOT and VT/TI assessment may provide further information on exercise ventilatory limitation in COPD.

Whether impairments in submaximal and maximal effort capacities in individuals following acute COVID-19 infection resemble those found in patients with chronic pulmonary disease remains unclear. We aimed to analyze the submaximal and maximal effort capacities of patients after COVID-19 infection and those with alterations in lung mechanics similar to those observed in patients with chronic respiratory diseases. This retrospective cross-sectional observational study paired a group of post-COVID-19 individuals with another group of patients with chronic respiratory disease, using spirometric patterns similar to those observed post-COVID-19. Data from Spirometry, 6 min walk test (6-MWT), and cardiopulmonary exercise test (CPET) variables were compared, and correlations between spirometric variables and 6-WT/CPET were examined. The final sample comprised 20 patients, including 10 post-COVID-19 patients with a restrictive lung disease (RLD) pattern identified using spirometry and 10 patients with RLD. Both groups presented similar patterns of the analyzed variables, with significant correlations observed between forced vital capacity (FVC) the distance and speed achieved during the 6-MWT, and a negative correlation between FVC and V' E max. The degree of restriction in the overall sample influenced the covered distance and speed during the 6-MWT as well as the maximum minute ventilation during maximal effort.

Background/Objectives: Pulmonary rehabilitation clinics are traditionally located at higher altitudes (HAs), where lower PO2 reduces exercise capacity and blood oxygenation. Eccentric cycling exercise (ECC), with its lower cardiorespiratory demand compared to concentric cycling (CON), might therefore be a potential advantageous training modality at HAs, particularly for individuals with reduced exercise capacity. This study aimed to compare the cardiorespiratory responses of ECC while breathing normoxic versus hypoxic gas in healthy participants. Methods: This randomized, controlled crossover trial involved healthy participants performing CON in normoxia (FiO2 = 0.21), followed by two incremental ECC tests until 70-100% of peak exercise, one with normoxia and one with normobaric hypoxia (FiO2 = 0.15), in a randomized order. Oxygen uptake (V'O2) and additional outcomes were measured breath-by-breath. Endpoints were defined at rest, 50%, 70%, peak exercise, and isotime. The trial is registered on clinicaltrails.gov (NCT05185895). Results: Twelve healthy participants (age: 30 ± 11 years, six females) completed the study. During both interventions, V'O2 increased linearly with exercise intensity, with no significant differences between normoxic and hypoxic conditions. At peak exercise, SpO2 and peak work rate were significantly lowered by 5% (95%CI: 3 to 8%, p < 0.001) and by 22 W (95%CI: 8 to 36 W, p = 0.009) in hypoxia compared to normoxia. Other outcomes were unchanged. When comparing CON to ECC in normoxia, the mean differences in V'O2 increased with higher loads. Conclusions: This study demonstrated that V'O2 and other cardiopulmonary parameters remain unchanged when performing ECC in hypoxia compared to normoxia. Comparing CON to ECC in normoxia, participants achieved higher workloads and greater V'O2 consumption during CON compared to ECC at comparable watts, confirming the higher metabolic cost associated with CON. We identified that the optimal submaximal ECC intensities, with the highest difference in V'O2 between CON versus ECC, are around 40% of peak V'O2.

This study assessed the prognostic value of submaximal cardiopulmonary exercise testing (CPET) in cardiac amyloidosis and explored CPET as an alternative to the 6-min walk test (6MWT).

In this single-center prospective observational study, 160 patients with cardiac amyloidosis (87% male; mean age 78±7 years) were evaluated. A total of 145 performed maximum symptom limited CPET. The V̇E/V̇CO2 slope was 39±8, submaximal power output (SPO) was 24.75±11.50 W, and V̇O2 at anaerobic threshold (AT) was 8.13±2.29 mL/min/kg. During follow up, 34 (21.25%) patients died, and another 34 (21.25%) experienced heart failure (HF)-related hospitalization, with 15 (9.38%) patients experiencing both events. Univariate analysis showed that V̇E/V̇CO2 slope (hazard ratio [HR] 0.89; 95% confidence interval [CI] 0.86-0.93; P<0.001) and SPO (HR 0.91; 95% CI 0.87-0.96; P<0.001) were predictors of mortality. In multivariate analysis, V̇E/V̇CO2 slope remained a significant predictor (HR 0.92; 95% CI 0.88-0.97; P<0.001) for both all-cause mortality and HF-related hospitalization independently. A SPO cut-off of <28 W predicted a worse outcome for both measures independently. Moderate correlations for V̇E/V̇CO2 slope (-0.56 [CI -0.67, -0.42]) and SPO (0.55 [CI 0.42, 0.67]) with 6MWT distance have been found.

These findings highlight CPET parameters, particularly V̇E/V̇CO2 slope and SPO with a cut-off <28 W, as predictors of survival and HF-related hospitalization in cardiac amyloidosis.

Chronic obstructive pulmonary disease (COPD) is characterized by high morbidity and mortality, with physical inactivity being a major contributor to poor outcomes. This study aims to identify subgroups of inactive COPD patients by analyzing reported barriers to physical activity and the perceived impact of inactivity on their disease.

In 91 consecutive stable COPD patients, physical activity was measured using a SenseWear armband and the SAQ-COPD questionnaire, to define inactivity as a physical activity level <1.69. Clinical and functional assessment included measurement of lung volumes, diffusing capacity, muscle strength, six-minute walk test and progressive cardiorespiratory exercise test. Cluster analysis was performed based on patients' responses to the profile and impact sections of SAQ-COPD questionnaire.

In 70 inactive COPD patients, three distinct clusters were identified: Cluster 1 showed significant functional limitations, particularly dyspnea and leg fatigue, alongside worse exercise tolerance and dynamic hyperinflation. Cluster 2 displayed few functional limitations but reported a lack of interest in physical activity as the primary reason for inactivity, with poorer sleep quality observed. Cluster 3 exhibited a high perceived impact of inactivity despite reporting fewer physical limitations, with psychological factors such as fear and discouragement acting as primary barriers. Factor analysis revealed two principal components: perceived impact of inactivity and limiting factors for exercise.

These findings highlight the heterogeneity among inactive COPD patients and emphasize the need for tailored interventions targeting both physical and psychological barriers. SAQ-COPD questionnaire may be a useful instrument for this individualized assessment of inactive COPD patients.

Hemoglobin mass (Hbmass) prediction enhance the accessibility and practicality of athletes' hemoglobin status monitoring, facilitating better performance. Therefore, we aimed to create prediction equations for Hbmass in well-trained endurance athletes (EA), based on easily obtained measures. The population of 220 well-trained EA (40% females, maximal oxygen uptake = 63.4 ± 8.00 mL·kg·min-1) was randomly split for the models' derivation and validation in 2:1 ratio. Equations to predict total Hbmass (tHbmass) and Hbmass adjusted to fat-free mass (rHbmass) were developed with multivariable linear regression. The models were stratified for five complexity levels with the inclusion of anthropometric, biochemical, and fitness indices. Models for tHbmass (R2 = 0.87-0.92; root-mean-square error [RMSE] = 60.6-76.5 g) outperform the models for rHbmass (R2 = 0.28-0.58; RMSE = 1.00-1.26 g·kg-1). During internal validation, 9 of 10 of equations accurately predicted tHbmass (0.11 ± 54.7-54.8 ± 45.5 g; p = 0.18-0.99) and only 1 model differed significantly (p = 0.03). There were also no significant differences between observed and predicted values in 8 of 10 of equations for rHbmass (0.1 ± 1.4-1.0 ± 0.1 g·kg-1; p = 0.07-0.65) and 2 models showed significant differences (p = 0.01-0.04). Models present moderate-to-high accuracy. Equations are precise enough to provide complementary data in the epidemiology of diseases with abnormal hemoglobin values, antidoping policy or talent identification. However, they should not substitute direct testing of Hbmass in EA.

Abnormal breathlessness at maximal exercise may be caused by a range of conditions, including exercise-induced bronchospasm, breathing pattern disorder, or exercise-induced laryngeal obstruction. These three disorders may not be detected on standard cardiopulmonary exercise testing. The aim of this study was to describe diagnostic outcomes of an expanded protocol during cardiopulmonary exercise testing.

Retrospective cohort study.

Patients presenting with abnormal breathlessness on maximal exercise underwent continuous laryngoscopy with cardiopulmonary exercise testing on a stationary cycle ergometer. Breathing pattern disorder was evaluated by video and ventilatory data. Pre- and post-exercise spirometry was performed.

24 adult patients were evaluated; 10 were professional athletes. Mean age was 40 years (range 18-73). Nine of 24 (38 %) were diagnosed with exercise-induced laryngeal obstruction and referred for speech pathology. Six of these had supraglottic exercise-induced laryngeal obstruction; all were aged <30 years; 5/6 were professional athletes. One patient had breathing pattern disorder and was referred for physiotherapy; one had exercise-induced bronchospasm, requiring escalation of asthma medication; one had muscle tension dysphonia resulting in referral to an otolaryngologist who administered a laryngeal injection of botulinum toxin. A further four patients had unexplained lower maximal oxygen consumption with cardiac limitation and were referred for further cardiac investigation.

In patients reporting abnormal breathlessness at maximal exercise, this expanded exercise protocol provided diagnostic information in 66.7 % cases which contributed to further personalised management.