Ventilatory Threshold Research Articles

Greater improvement in aerobic capacity after a polarized training program including cycling interval training at low cadence (50-70 RPM) than freely chosen cadence (above 80 RPM).

This study compared the impact of two polarized training programs (POL) on aerobic capacity in well-trained (based on maximal oxygen uptake and training experience) female cyclists. Each 8-week POL program consisted of sprint interval training (SIT) consisting of 8-12 repetitions, each lasting 30 seconds at maximal intensity, high-intensity interval training (HIIT) consisting of 4-6 repetitions, each lasting 4 minutes at an intensity of 90-100% maximal aerobic power, and low-intensity endurance training (LIT) lasting 150-180 minutes with intensity at the first ventilatory threshold. Training sessions were organized into 4-day microcycles (1st day-SIT, 2nd day-HIIT, 3rd day-LIT, and 4th day-active rest), that were repeated throughout the experiment. In the first POL program, exercise repetitions during SIT and HIIT training were performed with freely chosen cadence above 80 RPM (POLFC group, n = 12), while in the second POL program with low cadence 50-70 RPM (POLLC group, n = 12). Immediately before and after the 8-week POL intervention, participants performed an incremental test to measure maximal aerobic power (Pmax), power achieved at the second ventilatory threshold (VT2), maximal oxygen uptake (VO2max), maximal pulmonary ventilation (VEmax), and gross efficiency (GE). Moreover, participants performed VO2max verification test. Analysis of variance showed a repeated measures effect for Pmax (F = 21.62; η2 = 0.5; p = 0.00), VO2max (F = 39.39; η2 = 0.64; p = 0.00) and VEmax (F = 5.99; η2 = 0.21; p = 0.02). A repeated measures x group mixed effect was demonstrated for Pmax (F = 4.99; η2 = 0.18; p = 0.03) and VO2max (F = 6.67; η2 = 0.23; p = 0.02). Post-hoc Scheffe analysis showed that increase in Pmax were statistically significant only in POLLC group. The Friedman test showed that VT2 differed between repeated measures only in the POLLC group (χ2 = 11; p = 0.001; W = 0.917). In conclusion, it was found that POL program where SIT and HIIT were performed at low cadence was more effective in improving aerobic capacity in well-trained female cyclists, than POL with SIT and HIIT performed at freely chosen cadence. This finding is a practical application for athletes and coaches in cycling, to consider not only the intensity and duration but also the cadence used during various interval training sessions.

Changes in Exercise Performance in Patients During a 6-Week Inpatient Psychiatric Rehabilitation Program and Associated Effects on Depressive Symptoms

Background/Objectives: The impact of exercise on affective disorders has been demonstrated in various studies. However, almost no data are available on performance effects. Therefore, this study investigated exercise performance related to the severity of depression symptoms in a pre–post within-subjects design in a 6-week standard inpatient psychiatric rehabilitation program. Methods: A total of 53 individuals (20 female; mean age, 40.98 ± 11.33) with a primary diagnosis of depression performed a cardiopulmonary exercise test (CPX) to obtain maximal oxygen uptake (VO2max), maximal power output (Pmax), and the first and second ventilatory threshold (VT1, VT2) at the start and the end of the rehabilitation. Degree of depression was assessed by Becks Depression Inventory (BDI) and the Brief Symptom Inventory test (BSI). Overall activity was measured by accelerometer step-counts. Results: Mean total step-count per day during rehabilitation was high (12,586 ± 2819 steps/day). Patients’ BDI and BSI at entry were 21.6 ± 8.83 and 65.1 ± 6.8, respectively, and decreased significantly (p < 0.001) following rehabilitation, to 10.1 ± 9.5 and 54.5 ± 11.3, respectively. Pmax and VO2max increased significantly (p < 0.001) from entry values (182.6 ± 58.7 W, 29.74 ± 5.92 mL·kg−1·min−1) following rehabilitation: by 11.91 ± 12.09 W and 1.35 ± 2.78 mL·kg−1·min−1, respectively. VT1 and VT2 showed a similar behavior. An increase in physical performance could predict improvement in BDI (R2 = 0.104, F(1,48) = 5.582, p = 0.022) but not in BSI. Conclusions: The program was associated with improved mental health status in all patients and increased performance in the majority of patients, although increases were small. Since improvements in exercise performance may be positively related to depression symptoms and comorbidities, it is recommended to individualize and tailor exercise programs, which could yield larger effects.

Abstract 4137678: Maximal Oxygen Uptake Prediction From Resting and Submaximal Variables of Cardiopulmonary Exercise Testing by Using Machine Learning Methods

Background: Cardiorespiratory fitness, as measured by maximal oxygen consumption (VO2max) during a cardiopulmonary exercise test (CPET), is a prognostic indicator for longevity and adverse cardiovascular event prevention. This study aims to formulate a regression model utilizing resting and submaximal variables during CPET evaluation in the general population to predict VO2max. Methods: We used 13,535 CPET results on cycle ergometer collected by the UCLA Exercise Physiology Research Laboratory over eight years. Patients were divided into a normal group (NG; n=1,400) and an other group (OG; n=12,135). The inclusion criteria for the NG were: the absence of any known clinical diagnosis, BMI <30, no current use of beta blocker, and VO2max >85% of the predicted value for age and sex (Wasserman equation). OG refers to all other patients not in NG. Models were trained and evaluated for each group using stratified 5-fold cross-validation. We also trained different models using only resting variables (R-VARS) and resting and submaximal exercise variables (R+S-VARS). Feature importance was assessed using Shapely additive explanations (SHAP) values to identify how the feature related to the VO2max prediction. Results: The regression models were trained on the NG, OG, and total (N+OG) groups. The optimal models were Bayesian Ridge for the NG and Light Gradient Boosting Machine for the other two groups. The mean (standard deviation) R2 when using only R-VARS was 0.67(0.037) for the NG, 0.54 (0.014) for the OG, and 0.55 (0.009) for the N+OG. When using R+S-VARS, performance increased to 0.82 (0.014) for the NG, 0.80 (0.010) for the OG, and 0.8 (0.008) for the N+OG. Chronotropic index (ci), body mass index (BMI), VO2 at the first ventilatory threshold (VO2h1kg), minute ventilation at the second ventilatory threshold (VEH2), and forced expiratory volume (FEV1) were important features across the models trained with R+S-VARS. CI, BMI, and VEH2 had a negative effect, while VO2h1kg, FEV1 had positive effect on VO2max prediction. Conclusion: Our VO2max prediction model demonstrated remarkable accuracy in this dataset representing a generally healthy, non-athlete population using R+S-VARS. Particularly noteworthy was the enhanced performance within subgroups exhibiting a lower VO2max. This methodology offers a means to assess VO2max for individuals who might not achieve maximal exhaustion during CPET due to non-cardiopulmonary reasons.

Abstract 4134947: Explainable Machine Learning to Predict Heart Failure Outcomes Using Exercise and Clinical Data

Background: Heart failure (HF) hospitalizations are associated with disease burden and cardiovascular mortality. International guidelines highlight cardiopulmonary testing (CPET) for risk stratification and prognosis in HF. Identifying individuals at risk could direct interventions to prevent admissions. This study uses explainable machine learning (XML) tools to identify CPET and clinical variables predictive of HF hospitalizations. Hypothesis: XML analysis of CPET parameters and clinical factors can yield accurate, patient-specific prediction of HF admission within one year. Methods: A retrospective single center review of 178 CPETs in patients referred for HF was completed. Clinical data within one year of CPET trained a boosted machine learning model (XGBoost). SHAP (Shapley Additive Explanations) explainability analysis emphasized key features for model predictions. Results: 44 (24.7%) patients with CPET were admitted for HF within one year. The model predicted this outcome with an area under the receiver operating characteristic curve (AUC) of 0.772. SHAP analysis (Figure 1) selected factors for decision making: pulmonary artery systolic pressure (PASP) via cardiac catheterization or echocardiogram; oxygen consumption at the ventilatory threshold (VO 2 at VT); O 2 pulse at rest; ventilatory efficiency (VE/VCO 2 slope); minute ventilation per oxygen consumption at maximal exercise (VE/VO 2 max) during CPET; left ventricle end diastolic volume by echocardiogram; and sodium-glucose cotransporter-2 inhibitor usage. Peak VO2, predicted VO2, predicted O2 pulse, and VE/VCO2 slope were significant, consistent with past studies (Table 1). Conclusion: Our XML analysis emphasizes PASP (partially related to high left ventricular filling pressures) and VO 2 (at ventilatory threshold) as predictive for HF hospitalization within one year of CPET testing. Studies to prospectively evaluate these highlighted factors are needed to continue exploring predictive capabilities to tailor interventions.

Effects of cryo-facial mask on running performance in amateur middle-distance runners

The excess heat accumulated during exercise can lead to stress-induced fatigue, possibly impairing athletic performance. Various precooling techniques have been applied to enhance thermal comfort, reduce perception of effort, and improve endurance. In this randomized crossover study, twelve male amateur middle-distance runners (age: 33.69 ± 5.9 years; body mass: 71.9 ± 4.4 kg; height: 178.4 ± 5.6 cm; V˙O2 peak: 63.3 ± 5.6 mL min−1·kg−1) wore a facial cooling mask before a time-to-exhaustion (TTE) test on a treadmill, under cryostimulation or control conditions. The running performance comprised also two constant load trials, one conducted before and another after wearing the mask, both performed at the velocity of the first ventilatory threshold. Under cryostimulation condition, the TTE was 13 % higher than the control condition (p = 0.0049; d = −0.19) with a significant main effect of time for both ratings of perceived exertion (F1, 22 = 50.10; p < 0.0001; η2p = 0.69) and heart rate (F1, 22 = 31.53; p < 0.0001; η2p = 0.59). A significant interaction “condition × time” was found for facial skin temperature (F2, 44 = 36.93; p < 0.0001; η2p = 0.63) and for heart rate during the constant load trial after wearing the mask (F1, 22 = 5.90; p = 0.0238; η2p = 0.21). The localized cryostimulation provided by the mask lowered the skin temperature on the face, potentially mitigating the negative effects of heat stress during running. Incorporating the cryo-facial mask as part of a pre-exercise routine for runners may offer a practical and convenient method to optimize performance and enhance overall training outcomes.

Cigarette Smoking Impairs Cardiorespiratory and Metabolic Response at Peak Incremental Exercise and during Recovery in Young, Physically Active Adults

ABSTRACT Purpose: Cigarette smoking (CS) induces systemic changes that impair cardiorespiratory and muscular function both at rest and during exercise. Although these abnormalities are reported in sedentary, middle-aged smokers (SM) with pulmonary disease, few and controversial studies focused on young, physically active SM at the early stage of smoking history. This study aimed at assessing the impact CS on cardiorespiratory and metabolic response during an incremental test and the subsequent recovery in young, physically active SM without known lung or cardiovascular disease. Methods: After pulmonary function evaluation, 12 SM (age: 22±2 yr; body mass: 75±8 kg; stature: 1.78±0.06 m; 12±4 cigarette/day for 6±2 years; mean±SD) and 12 non-smokers (CTRL; age: 23±1 yr; body mass: 76±8 kg; stature: 1.79±0.08 m) matched for age and exercise habits, underwent an exhaustive incremental step test (25 W/2 min) on a cycle ergometer. Pulmonary O2 uptake (V’O2), expiratory ventilation (V’E), heart rate (f H) responses and lactate concentration were assessed during the test and subsequent recovery. Results: Despite similar static lung volumes, SM reported lower peak expiratory flow (-23%; P = 0.003) and maximal voluntary ventilation (-10%; P = 0.003). At submaximal exercise, no differences in the cardiorespiratory and metabolic were noted between the two groups. However, SM exhibited ventilatory (P &lt; 0.01) and lactate thresholds at lower work rates (P = 0.01). At peak exercise, SM exhibited lower V’O2 (-8%; P = 0.02), mechanical power (-11%; P = 0.02) and V’E (-9%; P = 0.01). During recovery, SM showed longer time constants (τ) in V’O2 (+52%; P = 0.002), V’E (+19%; P = 0.027) and f H (+21%; P = 0.022) and smaller f H at 30 s of recovery (HRR30; -31%; P = 0.032). Conclusions: These results are compatible with an early CS-related impairment of the cardiorespiratory and metabolic function even in young individuals with relatively short smoking history.

Effects of concentric and eccentric exercise regimens on bioenergetic efficiency of lymphocytes in sedentary males.

Eccentric exercise training (EET) increases physical performance while having lower metabolic demand than concentric exercise training (CET). Whether EET influences bioenergetic efficiency in peripheral blood mononuclear cells (PBMCs) remains unclear. This study investigates the effects of EET and CET on PBMC phenotypes and mitochondrial functions in blood. Thirty three sedentary healthy males were randomly assigned to either EET (n=11) or CET (n=11) that performed at progressively increased from 60% to 80% of maximal absolute workload for 30min/day, 5days/week for 6weeks, or a control group (n=11) that did not receive any exercise intervention. A graded exercise stress test (GXT) was performed before and after the intervention. PBMC phenotypes and mitochondrial respiratory capacity were analyzed using flowcytometry and high-resolution respirometry, respectively. In the same absolute workload, EET elicited lower heart rate and rating of perceived exertion than CET. However, EET as CET increased the VO2 level at the ventilatory threshold. Notably, both EET and CET increased central memory (CD45RO+/CD62+/CD3+) T cells and decreased effector memory T cells reexpressing CD45RA (CD45RA+/CD62-/CD3+). Moreover, the two exercise regimens diminished the loss of mitochondrial membrane potential (ΔΨm) caused by GXT, increased maximal/reserve O2 consumption rates (OCR), and bioenergetic health index in intact PBMCs and enhanced complex I-/II-related OCR in PBMCs with a substrate-rich environment. EET improves aerobic fitness with a lower cardiovascular response to exercise than CET. Moreover, EET as CET reduces senescent T-cell distribution in blood and improves PBMC bioenergetic efficiency by stabilizing ΔΨm and increasing capacity of oxidative phosphorylation.

Effect of Footwear Longitudinal Bending Stiffness on Energy Cost, Biomechanics, and Fatigue During a Treadmill Half-Marathon.

Introduction: Carbon plates have been used to increase running shoes' longitudinal bending stiffness (LBS), but their effect during a long duration run remains unknown. Our study aimed to identify the effect of LBS on energy cost of running (Cr), biomechanics, and fatigue during a half-marathon.Methods: Thirteen well-trained male runners (half-marathon time < 1 h40) performed two half-marathons at 95% of the running speed associated with their second ventilatory threshold on two separate visits, with either high-LBS shoes (HLBS, with carbon-plates) or standard-LBS (SLBS) shoes. Before and after the half-marathon, Cr at 12 km/h with both shoes (two 6-min bouts: Cr12) and ankle plantarflexors (PF) force were measured. During the half-marathon, running kinematics, shoe perceived comfort, and Cr were assessed.Results: During Cr12 measurements before and after the half-marathon, HLBS was 1.0 ± 2.1% more economical than SLBS (p < 0.001). During the half-marathon, Cr increased with running duration (p = 0.048) but there was no distance × condition effect. HLBS increased contact time (+3%, p = 0.01), decreased metatarsophalangeal joint dorsiflexion (-9%, p = 0.01), and was perceived less comfortable than SLBS, independently from running duration. At the end of the half-marathon, HLBS shoes led to higher PF force loss (-20.0 ± 9.8% vs -13.3 ± 11.0%, p = 0.048).Conclusions: Adding curved carbon plates in the running shoes slightly improved Cr during short running bouts at low intensity but not during a half-marathon. This discrepancy may be explained by day-to-day Cr variability and variation in shoe comfort. PF fatigue was higher with HLBS shoes but the accentuated fatigue did not further impact the biomechanical perturbations induced by the plates. Our results suggest that carbon plates alone do not provide a significant advantage for half-marathon performance.

Effect of Glycated Haemoglobin (HBA1c) on Cardiorespiratory Fitness (CRF) in a Population with Type 2 Diabetes Mellitus (T2DM): A Cross-Sectional Study

Background and Objective: The aim of this study was to evaluate cardiorespiratory fitness (CRF) measures, maximal oxygen consumption (VO2 max), and minute ventilation/carbon dioxide production (VE/VCO2 slope and others) among the T2DM population based on glycated haemoglobin (HBA1c). Material and Methods: The present study comprised a cross-sectional design, with two groups, based on HbA1c values (≤7 and ≥7.1). Laboratory samples were taken to evaluate glycated haemoglobin and fasting blood glucose (FBS). Cardiopulmonary exercise testing was performed to calculate various fitness-related parameters. Data analysis: An independent t-test was used to analyse the outcomes in the two groups. p &lt; 0.05 was considered significant. Linear regression was used to examine the influence of predictor variables on dependent variables. Results: A total of 70 patients agreed to participate in the study, with 19 females and 51 males. The mean (standard deviation) BMI (body mass index) of all participants was 29.7(5.2), the mean (SD) weight was 84.4 (18.9) kg, and the mean height was 167.4 (23) cm. The average age of the individuals was 52 ± 8 years. The independent t-test revealed a significant difference between the two groups in terms of CRF measures. Conclusions: The current research identified the presence of poor glycaemic control and cardiorespiratory fitness measures among the Brazilian population with T2DM. HBA1c, duration of diabetes, age, and BMI can be employed to predict the ventilatory threshold (VT) and VO2 max.

Valoración fisiológica y manejo de pacientes post-COVID con pruebas funcionales cardiopulmonares y de imagen normales

ObjectiveContributing to elucidate the pathophysiology of dyspnoea and exertion intolerance in post-COVID syndrome patients with normal cardiopulmonary imaging and functional tests at rest, while determining their fitness and level of endurance in order to individualize working parameters for physical rehabilitation. Material and methodsAfter an anamnesis and clinical examination at rest, 27 subjects (50±11.9 years) (14 women) with post-COVID syndrome of more than 6 months of evolution performed a continuous maximal-incremental graded cardiopulmonary exercise test (CPET) with breath-by-breath gas-exchange monitoring and continuous ECG registration, on an electromagnetically braked cycle ergometer. The values obtained were compared with those of reference, gender or controls, using the Chi-square, t-Student or ANOVA test. ResultsThe clinical examination at rest and the CPET were clinically normal and without adverse events. Reasons for stopping exercise were leg discomfort. It is only worth noting a BMI=29.9±5.8kg/m2 and a basal lactate concentration of 2.1±0.7mmol/L. The physiological assessment of endurance showed the following results relative to predicted VO2máx: 1)peakVO2=80.5±18.6%; 2)VO2 at ventilatory threshold1 (VO2VT1): 46.0±12.9%; 3)VO2VT2: 57.2±16.4%; 4)working time in acidosis: 5.6±3,0minutes; and 5)maximum lactate concentration: 5.1±2.2mmol/L. ConclusionsThe CPET identified limited aerobic metabolism and early increase in glycolytic metabolism as causes of dyspnoea and exercise intolerance, determined fitness for physical rehabilitation, and individualized it based on the level of endurance.

Cardiopulmonary exercise testing in aortic stenosis patients before and after aortic valve replacement

BackgroundKnowledge about how patients with symptomatic aortic stenosis (AS) perform on cardiopulmonary exercise testing (CPET) is sparse. Since exercise testing in patients with symptomatic AS is not advised, submaximal parameters...

Third ventilatory threshold in heart failure patients undergoing CPET: a prognostic analysis

Abstract Introduction One crucial element in cardiopulmonary exercise testing (CPET) involves identifying the first and second ventilatory thresholds (VT), VT1 and VT2, which hold known prognostic implications. If the individual can sustain exercise considerably beyond VT2, a third breakpoint (VT3 – Figure A) may emerge, coinciding with heightened hyperventilation to counter metabolic acidosis. Historically, this point has been mainly described among athletes and its meaning is still not entirely clear. We aimed to assess the prognostic value of VT3 in patients with heart failure (HF). Methods Retrospective, single-center study enrolling HF patients undergoing CPET from 2015 to 2021. We evaluated the typical CPET parameters along with the three ventilatory thresholds: VT1, VT2, and the newly introduced VT3. The primary outcome was a composite of cardiovascular death, urgent heart transplant, need for left ventricle assistance device and HF hospitalizations. Results We included 221 patients (82% men, mean age 58±12 years), among whom 69% had ischemic heart failure aetiology. The mean left ventricular ejection fraction (LVEF) was 34±9%, with a mean respiratory exchange ratio 1.15±0.082, mean pVO2 18.5±6.3, and a mean VE/VCO2 slope of 41.3±12.9. VT3 was attained by 43% (n = 94) of the patients. In comparison to those who did not achieve VT3, patients who reached this threshold were younger (56±11 vs 60±12; p = 0.05), had a higher pVO2 (20.5±6.9 vs 17±5.4; p = 0.05), higher RER (1.16±0.86 vs 1.13±0.78; p = 0.05), and lower VE/VCO2 slope (39±10.3 vs 43±14.3; p = 0.05). Regarding the three ventilatory thresholds (VT1, VT2, VT3), 7% (n=17) achieved a maximum of one threshold, 50% (n=110) achieved two thresholds, and 43% (n=94) reached all three thresholds. After a median follow-up of 2,3 years patients with identifiable VT3 had significantly better prognosis (HR 0,434; 95%CI 0,246-0,767; p=0,004) than those without this threshold. Furthermore, the number of identifiable ventilatory thresholds correlated positively with prognosis. In fact, patients with only 2 thresholds have twice the probability of developing an event and those with one or zero identifiable thresholds have a 4-fold increase in the probability of events (Figure C). Conclusion In a cohort of patients with HF, those with identifiable VT3 had a lower incidence of events. This parameter may aid in prognostic stratification in this population. However, this findings warrant further prospective validation.Figure 1

Acute Effects of Overload Running on Physiological and Biomechanical Variables in Trained Trail Runners

Background: The biomechanical and physiological adaptations to resisted running have been well documented in sprinting; however, their impact at submaximal speeds, such as those typical of long-distance running, remains unclear. This study aimed to evaluate the impact of running with a weighted vest, loaded with 5% and 10% of body mass, on the physiological and mechanical variables of trained trail runners. Methods: Fifteen male trail runners completed an incremental protocol to exhaustion on a treadmill with 0%, 5%, and 10% of their body mass (BM), in random order, with one week of separation between the tests. The maximality of the test was confirmed by measuring lactate concentrations at the end of the test. Oxygen consumption (V˙O2) and respiratory exchange ratio (RER) were recorded using a portable gas analyzer (Cosmed K5), and ventilatory thresholds 1 and 2 (VT1, VT2) were calculated individually. Running power was averaged for each speed stage using the Stryd device. Finally, the peak values and those associated with VT1 and VT2 for speed, power (absolute and normalized by body mass), V˙O2, RER, and the cost of transport (CoT) were included in the analysis. Results: One-way repeated-measures ANOVA revealed a detrimental effect of the extra load on maximum speed and speed at ventilatory thresholds (p ≤ 0.003), with large effect sizes (0.34–0.62) and a nonlinear trend detected in post hoc analysis. Conclusions: Using running power to control the intensity of effort while carrying extra weight provides a more stable metric than speed, particularly at aerobic intensities. Future research in trail running should investigate the effects of weighted vests across various terrains and slopes.

Importance of cardiac rehabilitation on cardiorrespiratory fitness in patients undergoing percutaneous aortic valve replacement

Abstract Background Percutaneous Aortic Valve Replacement (TAVR) significantly improves cardiac function in patients with severe aortic stenosis. However, the vast majority of these patients do not reach an adequate functional class despite the valve change, due to the deterioration of hemodynamic function and the repercussions of afterload over time. Cardiac rehabilitation (CR) program is an interdisciplinary intervention aimed at restoring functionality in Post-TAVR patients and the key to optimizing the recovery and enhancing cardiorrespiratory fitness (CRFit). The Purpose of the study is to provide an analysis of the effects of CR on exercise capacity and CRFit in TAVR patients. Methods Quasi-experimental study in TAVR patients that underwent a 4-6 week CR program, including personalized aerobic and strength training. Outcomes assessed pre- and post-rehabilitation included VO2 max, ventilatory thresholds (VT1 and VT2), and exercise capacity. The study also evaluated METs efficiency by comparing actual to predicted METs values before and after the therapy, alongside expired gas analysis test to examine exercise tolerance and its relation to VO2max gains. Results A total of 28 patients were analyzed, with an average age of 73 years (±8.1), initial weight of 68 kg (±12.32), and final weight of 65 kg (±11.13). The average ejection fraction (EF) from echocardiographic parameters was 62% (±10.1). All patients underwent cardiopulmonary exercise testing (CPET) after post-TAVR with improvements in CRFit. Initial exercise test parameters showed an average METs-load at 8.1 (±1.98), VO2max at 4.75 (±1.86), VT1 at 3.05 (±1.86), VAT at 3.85 (±1.62), VT2 at 4.5 (±2.28), and VE/VCO2 at 38 (±5.32). Final test parameters revealed VO2max at 5.8 (±2.09), VT1 at 3.2 (±1.33), VAT at 4.65 (±1.60), VT2 at 5.15 (±2.3), and VE/VCO2 at 36.4 (±69.95). Pearson's correlation analysis between CPET variables and the percentage improvement of various exercise test parameters found no statistically significant correlation. Except for METs-load and final time in Bruce, which show a significant and inversely proportional correlation (r=-0.67, p&amp;lt; 0.001). Conclusions The study demonstrates the effect of cardiac rehabilitation program in enhancing cardiorespiratory fitness and exercise capacity in post-TAVR patients. Notably, improvements in VO2max and ventilatory thresholds highlight the program's efficacy in promoting cardiovascular health. The inverse correlation between initial time in Bruce and METs improvement underscores the importance of baseline exercise capacity in predicting rehabilitation outcomes. Our results allow us to conclude that training volume is not the only variable to consider for proper CR. This insight could guide personalized rehabilitation strategies, making a significant contribution to the field of cardiac recovery post-TAVR.Measured METsBruce time - METs correlation

Recent cardiac rehabilitation and its impact on cardiopulmonary exercise test variables in Brazilian cardiac transplant recipients

Abstract Introduction Heart transplantation (HTx) is an option for restoring the functional capacity of individuals with end-stage heart failure (HF). Cardiac rehabilitation (CR) plays an important role in improving variables related to cardiopulmonary exercise testing (CPET) in post-HTx patients. Purpose To evaluate whether CR is effective in improving CPET variables in Brazilian patients post-recent HTx compared to a Control Group (CG). Methods Retrospective comparative study composed of two groups: CR group (CRG) and CG. These recent HTx patients (aged 14 to 73 years) initiated CR within 150 days and were recruited from an HTx outpatient clinic at a south Brazilian public university hospital between 2014 and 2023. CPET was performed at three different times: pre-HTx (Time 01), post-recent HTx (Time 02), and post-CR or post-follow-up for CG (Time 03). This study was approved by the Institutional Review Board (protocol No. 20180651). Statistical analysis used Generalized Estimating Equations with alpha ≤ 0.05, and the mean difference (MD) data were presented along with 95% confidence interval (CI). Results CRG (n=18) had a mean age of 47.3±15.6 years and CG (n=11) 48.6±12.5 years (P=0.81). The mean time to start CRG was 62.2±9.6 days (minimum: 21; maximum: 147). There was an interaction for the Group*Time factor for the following CPET variables: VO2peak (P=0.039); VEmax (P=0.009); VO2 on second ventilatory threshold (P&amp;lt;0.001); HR on VT2 (P=0.030) and T½ (P=0.002). The main results are summarized in Table 1. We highlight that there was a difference in the comparison between groups at Time 03 for the variable VO2peak: MD: 5.16 ± 1.95 (95% CI: 1.3 to 9.0; P = 0.008), favorable to CRG. Conclusion Early CR after very recent HTx significantly increase peak VO2peak, VEmax, T½ and VO2 and HR at the VT2 compared to the control group (CG).

Relationship between six-minute walk distance and cardiopulmonary exercise testing in non-obstructive hypertrophic cardiomyopathy

Abstract Background Recent studies have shown the promise of new approaches to the management of hypertrophic cardiomyopathy (HCM) symptoms. However, as HCM is a chronic disorder that evolves slowly over decades with low annual event rates, therapeutic trials in the disease rely on surrogate measures of disease severity and progression rather than hard endpoints such as mortality. Exercise capacity is one potential surrogate endpoint. Purpose To examine the relationship between peak oxygen uptake (VO2) and six-minute walk test distance (6MWD) in patients with non-obstructive hypertrophic cardiomyopathy (nHCM) and describe the association with clinical parameters and quality of life. Methods We examined baseline data from patients with nHCM enrolled in a randomised placebo-controlled trial of trimetazidine therapy. The study was conducted in a single European centre. Cardiopulmonary exercise testing (CPET) was performed to assess peak oxygen consumption (pVO2), ventilatory anaerobic threshold (VAT) and ventilatory equivalent for carbon dioxide (minute ventilation to carbon dioxide production (VEVCO2). Health related quality of life was assessed with the Minnesota Living with Heart Failure Questionnaire (MLHFQ). ECG and echocardiography were performed on the same day and biomarkers (NT-proBNP and cardiac Troponin T, cTnT) were measured prior to exercise testing. Results In 51 patients (age 50 ± 13 years; 71% male) with nHCM, pVO2 ranged from 10 to 24.3 ml/kg/min and 6MWD from 188 to 650 metres. 6MWD correlated with peak VO2 (Pearson r=0.41, 95% CI 0.15 to 0.67, p=0.003) and anaerobic threshold (r=0.32, 95%CI 0.04 to 0.55, p=0.024). After adjusting for age and sex, NT-proBNP concentration correlated with peak VO2 (radi=-0.35, 95% CI -0.69 to -0.01, p=0.042) but not 6MWD (radj=-0.05, 95% CI -0.42 to 0.32, p=0.779). Health related quality of life assessed by the Minnesota Living with Heart Failure Questionnaire (MLHFQ) correlated moderately with 6MWD (radi=-0.54, 95% CI -0.79 to -0.29, p&amp;lt;0.001) but weakly with peak VO2 (radi 0.28, 95% CI -0.55 to -0.01, p=0.042). I Conclusions There is a modest correlation between peak VO2 and 6MWD in nHCM. The pVO2 correlates more strongly with NT-proBNP whereas 6MWD better reflects quality of life. These data suggest pVO2 and 6MWD provide complementary information about health status in nHCM.Relationship between 6MWD and CPETCharacteristics of study cohort

What is the true normal: comparison of different equations for estimating peak oxygen uptake for outcome prediction in heart failure

Abstract Background and Objectives One of the strongest prognostic parameters obtained during Cardiopulmonary exercise testing (CPET) in patients with heart failure (HF) is the peak oxygen uptake (pVO2), as a standalone or as a percentage of the predicted peak oxygen uptake (ppVO2) reached. However, traditional standards by which ppVO2 is calculated have limitations, having been derived from small cohorts, lacking portability and poorly represented by women. Thus, we aim to compare the FRIEND Registry equation to previously used methods of calculating ppVO2 as it relates to prognostic value imparted by the percentage of ppVO2 (%ppVO2) reached during CPET and portability to the Portuguese HF population. Methods Single centre retrospective study of patients with HF with LVEF &amp;lt; 50% who underwent CPET between 2015-2021. Patients who did not reach RER≥ 1.05 were excluded from our analysis. All tests were evaluated and ventilatory thresholds determined by 3 independent, experienced operators. ppVO2 was calculated according to 1) the Wasserman equation; 2) the Wasserman equation using ideal body weight; 3) the Neder equation, 4) the SHIP equation and 5) the FRIEND equation. Our primary endpoint was a composite of CV death, urgent transplant or left ventricular assist device implantation and HF hospitalization. Results We included 238 patients (mean age 59 ± 11 years, 83% males). The HF aetiology was mostly ischemic in nature (68%), with LVEF of 34 ± 9% and median NTproBNP of 776 (2566 – 2342) pg/mL. Most patients (67%) were in class NYHA I-II and with high prevalence of GDMT (93% ACEi/ARB; 97% beta-blockers and 64% on MRA). Mean BMI in this group was 27.3 ± 4.7 kg/min. Patients performed CPET on a treadmill with a protocol adjusted to their predicted exercise capacity. Mean pVO2 was 18.1 ± 6.2mL/kg/min, corresponding to a median %ppVO2 that ranges from 51 ± 16% to 71 ± 22%, depending on the equation that is used. Mean VE/VCO2 Slope was 42 ± 13 and 48 % (n = 98) of patients showed exercise oscillatory ventilation (EOV). Mean ppVO2 as per the FRIEND and Wasserman equations was 18.9 ± 6.6 and 21.2 ± 4.5 mL/kg/min, with no statistically significant difference between both. %ppVO2 as calculated through all equations was an independent predictor of prognosis on multivariate analysis adjusted for LVEF, NTproBNP and VE/VCO2 Slope (p &amp;lt; 0.001 for values derived from all equations). However, the FRIEND and Wasserman equations showed a slight advantage over the remaining 2 equations, with higher AUC on ROC curve analysis (see figure). Conclusions In our population of Portuguese patients with HF, both the FRIEND registry and Wasserman equations for predicting pVO2 yielded strong prognostic power. However, these equations provide different absolute predicted VO2 values for the same patients and thus should not be used interchangeably. Standardisation of the type ppVO2 equation used should be recommended by local scientific societies.

Ventilatory thresholds in professional female soccer players.

This study investigated the ventilatory thresholds (VT1 and VT2) along with the corresponding heart rates, velocities and % of V̇O2 max at which these thresholds are reached in professional female soccer players. It also examined positional differences in the aforementioned parameters. Thirty-three professional players from two teams (age range 18-31 years) were recruited. The players underwent maximal exercise testing on the treadmill for the detection of VT1 (V̇E versus V̇O2 plot) and VT2 (V̇E versus V̇CO2 plot). The test began at a speed of 6km/h and was increased by 2 km/h every 3.15 minutes, with the inclination constant at 1%. Results indicated that the players had an average V̇O2 max of 50.24 ml·kg- 1.min- 1. VT1 (% max) and VT2 (% max) were shown at 72.87% and 91.26% of V̇O2 max, respectively. The respective velocities at VT1 and VT2 were indicated at 10.85 km/h and 12.91 km/h, respectively, while the average VV̇O2 max was 14.61 km/h. The average heart rates at VT1, VT2 and V̇O2 max were 159.33, 185.15 and 192.85 beats per minute, respectively. Furthermore, analysis of variance ANOVA indicated significant differences in velocity at V̇O2max. This study provides important normative data regarding the ventilatory thresholds of female soccer players.

Investigating the Role of Exercise Pattern in Acute Cardiovagal Recovery.

Research on intermittent training has mainly focused on the effects of exercise intensity while overlooking the specific impact of the modulations associated with alternating exercise and recovery. This study investigated how the frequency of modulations during moderate-intensity exercise affects post-exercise vagal reactivation. Healthy, active females and males aged 18-39 years were recruited for the study. Participants completed three treadmill running sessions on separate days. Each moderate-intensity session accumulated 30 min at 90% of the intensity associated with the second ventilatory threshold and were performed as either high-frequency intermittent (HiFi; 15 x [2 min + 2 min recovery]), low-frequency intermittent (LoFi; 5 x [6 min + 2 min recovery]), or continuous training (MICT; 1 x 30 min). Heart rate recovery (HRrec) at 1 min and heart rate variability recovery (HRVrec; lnRMSSD) were assessed in response to submaximal constant-speed tests performed prior to (CST1) and following (CST2) each of the exercise sessions. HRrec, HRVrec, blood lactate (BLa), and blood pressure were also collected during the exercise sessions. Twenty-one individuals (8 females, 13 males) participated in the study. HRrec from CST2 was faster in HiFi vs. MICT (p < 0.001), while HRVrec post-CST2 was higher following HiFi vs. both LoFi (p = 0.024) and MICT (p < 0.001). BLa increased in all conditions (p = 0.007) but remained lower during HiFi compared to LoFi and MICT (both p < 0.001). Diastolic blood pressure did not change during exercise with HiFi (p = 0.939) but decreased during LoFi (p = 0.006) and MICT (p = 0.008). Exercise pattern influences the physiologic response to exercise. Higher frequencies of modulations can preserve vagal activity and expedite post-exercise recovery, suggesting moderate-intensity intermittent exercise as a potential strategy to mitigate autonomic impact and acute physiological stress while maintaining total work performed.

Acute ergogenic effects of repetitive maximal breath-holding maneuvers on hematological and physiological responses: a graded exercise test investigation.

Repetitive maximal breath-holds (BHs or apneas) have been noted to induce advantageous hematological and blood buffering changes. Building on this, the hypothesis was formulated that the execution of repeated maximal BH efforts might lead to subsequent enhancements in performance during a time-to-exhaustion test. This study investigated the acute effects of five static maximal breath-holding maneuvers conducted with face immersion in cold water (10°C) on subsequent graded exercise test (GET) performance. Seventeen well-trained participants completed a GET on a motorized treadmill under two randomized cross-over conditions: baseline measurement (CON) and after five repeated maximal breath-holding efforts (EXP). The GET protocol consists of incremental increases in speed until exhaustion. After the fifth breath-hold, participants in the EXP condition exhibited significant (P < 0.05) increases in hematocrit, hemoglobin concentration, red blood cell count, and muscle deoxygenation, accompanied by a reduction in blood lactate concentration (4.09 ± 2.21%, 3.9 ± 1.76%, 3.96 ± 2.1%, 81.48 ± 23.83%, and 15.22 ± 17.64%, respectively), compared to CON. During GET, the EXP condition showed a significantly (P < 0.05) delayed onset time of the second ventilatory threshold (3.14 ± 5.85%) and (P < 0.05) increased time to exhaustion (0.75 ± 1.02%). This evidence suggests that repeated maximal static breath-holding maneuvers enhance the oxygen delivery system by increasing the circulation of reserve red blood cells, heightened muscle oxygen deoxygenation, enhanced aerobic metabolism utilization, and postponing the transition from aerobic to anaerobic metabolism, implying a potential ergogenic effect. While pre-exercise breath-holding shows promise for improving time-to-exhaustion and optimizing subsequent distance running performance, further in-depth investigation is essential to fully elucidate the underlying mechanistic factors.