Maximal O2 Pulse Research Articles

Six-year follow-up of a world record-breaking master marathon runner.

Endurance performance declines with advancing age. Of the three main physiological factors that determine endurance running performance [maximal oxygen consumption (V̇o2max), lactate threshold, and running economy (RE)], V̇o2max appears to be most affected by age. Although endurance performance declines with age, recently, endurance performance has rapidly improved in master athletes as the number of master athletes competing in endurance events has increased. Master athletes represent an intriguing model to study healthy aging. In this case study, we reassessed the physiological profile of a 76-yr-old distance runner who broke the marathon world record for men over 70 yr of age in 2018. This runner was tested a few months before breaking the world record and retested in 2024. Between 2018 and 2024, his marathon running velocity decreased significantly. Therefore, the purpose of this case study was to determine the physiological changes that explain his performance decline. RE remained similar to 2018, and while there was not a clear breakpoint in blood lactate, he still likely runs marathons at a high percentage (∼90%) of his V̇o2max. However, V̇o2max declined by 15.1%. HRmax declined by 3.2% and maximal O2 pulse declined by 12.4%, suggesting that maximal stroke volume and/or arteriovenous O2 difference decreased. Altogether, although this marathoner continues to compete at an elite level, his performance has declined since his record-breaking marathon due to a reduction in V̇o2max. This is likely caused by reductions in maximal stroke volume and/or arteriovenous O2 difference. We speculate that these changes reflect primarily age-related processes.NEW & NOTEWORTHY We performed 6-yr follow-up testing on a world record-breaking master marathon runner. We determined that his performance declined since his record-breaking marathon in 2018 primarily due to a reduction in V̇o2max. His max heart rate (HR) changed minimally, but his peak O2 pulse decreased, suggesting that his maximal stroke volume and/or arteriovenous O2 difference decreased. These changes likely reflect primarily age-related effects in the absence of an overt pathological disease process.

Effects of gypenoside L-containing Gynostemma pentaphyllum extract on fatigue and physical performance: A double-blind, placebo-controlled, randomized trial.

This study was conducted to investigate the effect of Gynostemma pentaphyllum extract containing gypenoside L (GPE) on improving the cognitive aspects of fatigue and performance of the motor system. One hundred healthy Korean adults aged 19-60 years were randomized to the treatment (GPE for 12 weeks) and control groups, and efficacy and safety-related parameters were compared between the two groups. Maximal oxygen consumption (VO2 max) and O2 pulse were significantly higher in the treatment group than in the control group (p=0.007 and p=0.047, respectively). After 12 weeks, the treatment group showed significant changes such as decreases in the levels of free fatty acids (p=0.042). In addition, there were significant differences in the rating of perceived exertion (RPE) (p < 0.05) and value of temporal fatigue between the treatment and control groups on the multidimensional fatigue scale (p < 0.05). Moreover, the level of endothelial nitric oxide synthase (eNOS) in the blood was significantly higher in the treatment group than in the control group (p=0.047). In summary, oral administration of GPE has a positive effect on resistance to exercise-induced physical and mental fatigue.

Characteristics of cardiopulmonary exercise test in tracheobronchial tuberculosis patients with central airway stenosis

BackgroundA typical symptom of central airway stenosis is progressive dyspnea. The exercise capacity and relationship between pulmonary function testing (PFT) and central airway stenosis have not been reported. ObjectivesTo investigate, for the first time, the impact of central airway stenosis due to tracheobronchial tuberculosis (TBTB) on exercise capacity in adults. MethodsFifty-one patients diagnosed with TBTB and 51 healthy, non-smoking adults (controls) were studied. All participants underwent a maximal cardiopulmonary exercise test (CPET) after completing PFT. ResultsAll participants completed the PFT and CPET. Significant differences existed between the two groups with respect to PFT parameters. At rest, no significant differences were detected between the two groups with respect to oxygen uptake (VO2), vital volume (VT), minute ventilation (VE), end-tidal carbon dioxide (PetCO2), and oxygen pulse (SPO2). Compared to controls, TBTB patients had lower peak work rate [WR, 100 (83,119) vs. 112 (95,146)], VO2 at maximal exercise (1309.51±323.83 vs. 1522.17±451.15), anaerobic threshold (905.8 ± 219.84 vs. 1024.72±296.27), maximal O2 pulse (8.02±1.61 vs. 9.26±2.36), and breath reserve [BR, 25 (15,42) vs. 49.5(39.4,61.3)]. The change in PetCO2 values at rest and maximal exercise was lower than in controls (P<0.05). However, no difference in VE/carbon dioxide production (VCO2)@AT were demonstrated between the two groups. The correlations between the degree of stenosis, PFT parameters, and VO2 peak were significant. RV/TLC%pred was a good predictor of exercise limitation in these patients. ConclusionThe maximal exercise capacity and PFT parameters of TBTB patients with central airway stenosis were impaired. Impaired exercise capacity correlated with the degree of central airway stenosis.

Average and Interindividual Effects to a Comprehensive Cardiovascular Rehabilitation Program.

Background: To describe the average effects and the interindividual variability after a comprehensive outpatient cardiovascular rehabilitation (CCR) program using concurrent exercise training prescribed according to cardiovascular risk stratification on cardiorespiratory fitness (CRF), anthropometric/body composition, quality of life and emotional health in patients of four cardiovascular disease profiles. Methods: CRF, anthropometric/body composition, quality of life, and emotional health were measured before and after a CCR and analyzed in heart valve surgery (HVS), heart failure with reduced ejection fraction (HFrEF), post-acute myocardial infarction (post-AMI), and in coronary artery disease (CAD) patients. Twenty, twenty-four, and thirty-two exercise sessions were prescribed according to mild, moderate, and severe baseline cardiovascular risk, respectively. In addition to concurrent exercise training, nutritional counseling, psychological support, and lifestyle education programs were performed. Results: The main outcomes by delta changes comparisons (Δ) revealed no significant differences at anthropometric/body composition as ΔBody fat decreases (HVS Δ−1.1, HFrEF Δ−1.0, post-AMI Δ−1.4, CAD Δ−1.2 kg) and ΔSkeletal muscle mass increases (HVS Δ+1.4, HFrEF Δ+0.8, post-AMI Δ+0.9, CAD Δ+0.9 kg), and CRF performance as ΔVO2peak increases (HVS Δ+4.3, HFrEF Δ+4.8, post-AMI Δ+4.1, CAD Δ+5.1 mL/kg/min) outcomes among HVS, HFrEF, post-AMI, and CAD (p > 0.05). Secondary outcomes showed significant pre-post delta changes in METs (HVS Δ+1.8, HFrEF Δ+0.7, post-AMI Δ+1.4, CAD Δ+1.4), and maximal O2pulse (HVS Δ+3.1, post-AMI Δ+2.1, CAD Δ+1.9). In addition, quality of life had a significant improvement in physical functioning (HVS Δ+17.0, HFrEF Δ+12.1, post-AMI Δ+9.8, CAD Δ+11.2), physical role (HVS Δ+28.4, HFrEF Δ+26.8, post-AMI Δ+25.6, CAD Δ+25.3), vitality (HVS Δ+18.4, HFrEF Δ+14.3, post-AMI Δ+14.2, CAD Δ+10.6) and social functioning (HVS Δ+20.4, HFrEF Δ+25.3, post-AMI Δ+20.4, CAD Δ+14.8) in all cardiovascular disease. For anxiety (HVS Δ−3.6, HFrEF Δ−2.3, post-AMI Δ−3.0, CAD Δ−3.1) and depression (HVS Δ−2.8, HFrEF Δ−3.4, post-AMI Δ−3.2, CAD Δ−2.3) significant changes were also observed. Conclusions: A CCR program that prescribes the number of exercise sessions using a cardiovascular risk stratification improves CRF, QoL, and emotional health, and the average results show a wide interindividual variability (~25% of non-responders) in this sample of four CVD profile of patients.

Impact of Bariatric Surgery on Women Aerobic Exercise Capacity

Bariatric surgery has a considerable positive effect on weight loss and on metabolic and cardiovascular risks. It has therefore been extensively used this last decade to overcome obesity. However, the impact of this surgery on exercise capacity remains unclear. The aim of this study is to clarify the impact of a surgically induced weight loss on aerobic exercise capacity (VO2max) in a specific middle-aged female population. Forty-two women with a body mass index > 40kg/m2 (age, 42 ± 13years; weight, 117 ± 15kg) underwent blood analyses and a cardiopulmonary exercise test (CPET) before and 1year after bariatric surgery. CPET was performed on a cycloergometer. The first ventilatory threshold (VT1) was measured according to the V-slope method. Absolute VO2max was reduced by 10% after surgery (2.0 ± 0.4 vs 1.8 ± 0.4l/min, p< 0.01) or increased when corrected for body weight (18 ± 4 vs 23 ± 4l/min/kg, p< 0.001) or unchanged when expressed as percentage of predicted values (111 ± 21 vs 105 ± 22, p= 0.06). Weight loss did not affect ventilatory or chronotropic response but increased maximal respiratory exchange ratio (RER) (p< 0.001), decreased maximal O2pulse (p< 0.05) and VT1 in milliliters per minute (p< 0.01). By multivariable analysis, decreased absolute VO2max after weight loss was associated with increased maximal RER and reduced maximal O2pulse (p< 0.05, p< 0.01 respectively), possibly related to a muscular mass limitation. Weight loss induced by bariatric surgery may reduce aerobic capacity in women in relation to muscle mass loss.

Use of Oxygen Pulse in Predicting Doppler-Derived Maximal Stroke Volume in Adolescents.

Clinical exercise physiologists and physicians administering stress tests in the young have used oxygen pulse as a surrogate measure of stroke volume. It is important to recognize 1) the accuracy of O₂ pulse in predicting maximal stroke volume during exercise, and 2) the normal pattern of O₂ pulse during a progressive exercise test. This study examined both of these issues in a cohort of 44 healthy adolescent males and females (ages 14-16 years) who performed routine progressive cycle exercise to exhaustion. Gas exchange variables were measured by standard open circuit techniques. Stroke volume at rest and during exercise was assessed by the Doppler ultrasound method. At peak exercise O₂ pulse correlated closely with stroke volume (r = .73) with a SEE of 12.6 ml·beat⁻¹. Values of maximal O₂ pulse in nonathletic boys and girls were 13.3 ± 2.5 and 11.0 ± 1.7 ml·beat⁻¹, respectively. After the initial workload, a steady rise was observed in O₂ pulse, entirely reflecting an increasing arterial venous oxygen difference, with a slope of approximately 4 ml/beat per 100 watts work load. The findings support the use of O₂ pulse as a valid predictor of stroke volume during exercise in youth with a moderately high level of accuracy.

EComment. Pectus excavatum surgical repair improves cardiopulmonary function in adults

Jayaramakrishnan et al. recently addressed the question: Does repair of pectus excavatum (PEx) improve cardiopulmonary function? [1]. Using an adequate keyword-based search strategy, the authors concluded that surgical repair using minimally invasive Nuss technique and Ravitch procedure caused an early, moderate decrease in pulmonary function tests (which are typically minimally impaired in PEx patients). In addition, cardiac function at rest improved during the early postoperative period, which is typically sustained in the mid-term. Here, we take the opportunity to mention that Jayaramakrishnan et al. have failed to identify our previous study based on a large series of 70 patients, which was recently published in the European Journal of Cardio-Thoracic Surgery [2]. We think this omission is critical regarding the clinical bottom-line proposed by Jayaramakrishnan et al. because our study clearly demonstrated that the modified Ravitch-type repair [3] in young adults significantly improved maximal oxygen uptake (VO2max) and O2 pulse [2]. Increase of O2 pulse (a surrogate of heart stroke volume) after surgery suggested that aerobic capacity (VO2max) improvement was the result of a better cardiovascular adaptation at maximal workload. In a short series of PE patients, we recently reported that normalization of thoracic geometry by PEx repair could restore adequate negative pulmonary pressure during ventilation (i.e., respiratory pump) that is necessary to enhanced venous return, heart filling and cardiac output [4, 5] . Overall, we would like to offer the possibility to include our results [2, 4] in the present evidence-based medicine proposal to support the conclusion by Jayaramakrishnan et al. [1] that PEx repair improves cardiopulmonary function and supports aerobic capacity. Conflict of interest: none declared.

Maximal exercise oxygen pulse as a predictor of mortality among male veterans referred for exercise testing

Maximal oxygen pulse (O(2) pulse) mirrors the stroke volume response to exercise, and should therefore be a strong predictor of mortality. Limited and conflicting data are, however, available on this issue. Nine hundred forty-eight participants, classified as those with cardiopulmonary disease (CPD) and those without (non-CPD), underwent cardiopulmonary exercise testing (CPX) for clinical reasons between 1993 and 2003. The ability of maximal O(2) pulse and maximal oxygen uptake (peak VO(2)) to predict mortality was investigated using proportional hazards and Akaike information criterion analyses. All-cause mortality was the endpoint. Over a mean follow-up of 6.3+/-3.2 years, there were 126 deaths. Maximal O(2) pulse, expressed in either absolute or relative to age-predicted terms, and peak VO(2) were significant and independent predictors of mortality in those with and without CPD (P<0.04). Akaike information criterion analysis revealed that the model including both maximal O(2) pulse and peak VO(2) had the highest accuracy for predicting mortality. The optimal cut-points for O(2) pulse and peak VO(2) (<12; > or =12 ml/beat and <16; > or =16 ml/(kg.min) respectively) were established by the area under the receiver-operating-characteristic curve. The relative risks of mortality were 3.4 and 2.2 (CPD and non-CPD, respectively) among participants with both maximal O(2) pulse and peak VO(2) responses below these cut-points compared with participants with both responses above these cut-points. These results indicate that maximal O(2) pulse is a significant predictor of mortality in patients with and without CPD. The addition of absolute and relative O(2) pulse data provides complementary information for risk-stratifying heterogeneous participants referred for CPX and should be routinely included in the CPX report.

Exercise training improves lung diffusing capacity and exercise ventilation in patients with heart failure

Background: In heart failure (HF) patients, benefits deriving from exercise training (ET) programs are multifactorial. It is unexplored whether lung gas exchange and exercise ventilation may benefit from ET and have a role in the patients clinical improvement. Objective: To test whether in stable HF, ET facilitates lung diffusing capacity and ameliorates exercise ventilatory efficiency (VE/VCO2 slope). Methods: Diffusing lung capacity for carbon monoxide (DLco) at rest and its subdivisions (DM, alveolar-capillary membrane conductance, and VC, pulmonary capillary blood volume) as well as VE/VCO2 slope and peak VO2 on exercise (cycle ergometry ramp protocol), were assessed in 15 stable HF patients (NYHA class II to III), preceding and following a low-intensity training program. Results: Baseline DLco (20 ml/min/ mmHg), DM (17 ml/min/mmHg), peak VO2 (16 ml/min/kg) and VE/VCO2 slope (38) were abnormal in these patients. ET was associated with a significant improvement (p 0.01) of DLco ( 20%), peak VO2 ( 21%) time to anaerobic threshold ( 29.4%) and maximal O2 pulse ( 12.3%) and with a significant reduction in VE/VCO2 slope ( 27%). Improvement in DLco was mediated by an increased DM ( 21.6%) despite a reduction in VC ( 16.5%). There were no variations in cardiac index and ejection fraction at rest. Changes in DM correlated with those in VE/VCO2 slope (r 0.88, p 0.002). Conclusions: Although the mechanisms are not completely defined, the evidence is in favor of a beneficial influence of ET programs on the lung pathophysiology in patients with stable HF. An improvement in gas exchange, related to a specific influence on alveolar-capillary membrane conductance, significantly contributes to the amelioration in exercise ventilatory efficiency and functional capacity. Hemoglobin Level is Associated with Adverse Outcomes in Patients with Severe Chronic Heart Failure: Results from the COPERNICUS Study Stefan Anker, Andrew J.S. Coats, Ellen B. Roecker, Paul Mohacsi, Milton Packer5—Clinical Cardiology, NHLI, London, United Kingdom; Faculty of Medicine, University of Sydney, Sydney, Australia; Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI; Department of Cardiology, Inselspital, Bern, Switzerland; Center for Heart Failure Research, College of Physicians and Surgeons, New York, NY

Insulin ameliorates exercise ventilatory efficiency and oxygen uptake in patients with heart failure–type 2 diabetes comorbidity

ObjectivesThis study sought to test whether insulin improves exercise ventilatory efficiency (VE/VCO2slope) and oxygen uptake at peak exercise (peak VO2) in patients with type 2 diabetes–heart failure (HF) comorbidity. BackgroundIn type 2 diabetes–HF comorbidity, depression of alveolar–capillary diffusion (DLCO) correlates with deterioration of exercise VE/VCO2slope and peak VO2. Insulin potentiates DLCOin these patients. MethodsExercise ventilatory efficiency and peak VO2(cycle ergometry ramp protocol), as well as DLCOat rest and its subdivisions (membrane conductance [DM] and pulmonary capillary blood volume [VC]) were assessed in 18 patients with type 2 diabetes–HF comorbidity at baseline and after 50 ml of saline + regular insulin (10 IU), or saline, was infused on consecutive days, according to a random crossover design. Glycemia was kept at pre-insulin level for the experiment duration. ResultsBaseline DLCO, DM, peak VO2, and VE/VCO2slope were compromised in these patients. At measurements performed in the 60 min after infusions, compared with at baseline, saline was ineffective, whereas insulin augmented peak VO2(+13.5%) and lowered VE/VCO2slope (−18%), and also increased time to anaerobic threshold (+29.4%), maximal O2pulse (+12.3%), aerobic efficiency (+21.2%), DLCO(+12.5%), and DM(+21.6%), despite a reduction in VC(−16.3%); insulin did not vary cardiac index and ejection fraction at rest. Changes in peak VO2and VE/VCO2slope (r = 0.67, p = 0.002; r = −0.73, p < 0.001, respectively) correlated with those in DLCO. These responses were unrelated to glycohemoglobin and baseline fasting blood sugar. They were persistent at 6 h after insulin infusion, and were undetectable at 24 h. ConclusionsIn diabetes–HF comorbidity, insulin causes a prolonged improvement in physical performance through activation of multiple factors, among which facilitation of gas conductance seems to be predominant.

The Correlation between HRCT Emphysema Score and Exercise Pulmonary Testing Parameters

Background The correlation between the high resolution computed tomography(HRCT) emphysema score and the physiologic parameters including resting and exercise pulmonary function test was investingated in 14 patients(60.6±10.3 years) with pulmonary emphysema. Methods The patients underwent a HRCT, a resting pulmonary function test, and incremental exercise testing(cycle ergometer, 10 W/min). Computed tomography scans were obtained on a GE highlight at 10 mm intervals using 10 mm collimation, from the apex to the base after a full inspiration. The emphysema scores wer determined by a CT program 'Density mask' outlining the areas with attenuation values less than -900 HU, indicating the emphysema areas, and providing an overall percentage of lung involvement by emphysema. Results Among the resing PFT parameters, only the diffusing capacity(r=-0.75) and PaO2 (r=-0.66) correlated with the emphysema score(p<0.05). Among the exercise test parameers, the emphysema score correlated significantly with the maximum power(r=-0.74), maximum oxygen consumption(r=-0.68), anaerobic threshold(V-slope method : r=-0.69), maximal O2-pulse(r=-0.73), and the physiologic dead space ratio at the maximum workload(r=-0.80)(p<0.01). Conclusion We could find that exercise testing parameters showed a much better correlation with the HRCT emphysema score, which is known to have a good correlation with the pathologic severity than the resting PFT parameters. Therefore it is suggested that exercise testing is superior to resting PFT for estimating in the estimation of the physiologic disturbance in emphysema patients.

Recovery and Limitation of Exercise Capacity After Lung Resection for Lung Cancer

To assess the effects of pulmonary resection for lung cancer on postoperative recovery and limitation of exercise capacity. Eighty-two patients (20 pneumonectomies, 62 lobectomies) underwent spirometric pulmonary tests and exercise capacity tests preoperatively, and at 3 months and more than 6 months after the operation. In the lobectomy group, FEV1 vital capacity (VC), and maximum oxygen consumption (VO2max) decreased significantly 3 months after the operation and improved after more than 6 months, but did not reach the preoperative values. In the pneumonectomy group, FEV1 VC, and VO2max decreased 3 months after the surgery and the values did not recover thereafter. In comparison with preoperative values, the functional percentage losses after more than 6 months for lobectomies and pneumonectomies were 11.2% and 36.1% for FEV1, 11.6% and 40.1% for VC, and 13.3% and 28.1% for VO2max, respectively. Postoperatively, maximal minute ventilation (VEmax), the maximal heart rate percentage, and maximal O2 pulse during the exercise test significantly decreased in both the lobectomy and pneumonectomy groups. Nevertheless, VEmax and O2 pulse improved more than 6 months after lobectomy compared with the value at 3 months, but not after pneumonectomy. Breathing reserve did not differ before and after surgery in the lobectomy group, although it decreased significantly after surgery in the pneumonectomy group. Subjectively, postoperative exercise after lobectomy was limited by leg discomfort (64% at more than 6 months after surgery); after pneumonectomy, exercise was limited by dyspnea (60%). These results suggest that there are differences between lobectomy and pneumonectomy for lung cancer in terms of recovery and limitation of exercise capacity.

A model of oxygen transport capacity changes for independently living older men and women.

The purpose of the present investigation was to describe, for a subset of a large random survey of men and women, restricted to the ages of 55 to 85 years, the physiological decay pattern for aerobic fitness and contributing factors of cardiovascular and pulmonary function. The time course of the age-related changes in maximal oxygen uptake (VO2max), ventilatory threshold (TVE), maximal ventilation (VEmax), maximal heart rate (HRmax), and O2 pulse (VO2max/HRmax) were examined by fitting the data to a decaying exponential model by use of a least-squares parameter estimation technique. The time constant (tau) was used to describe the rate of decline. The women showed a much slower decline in VO2max (tau = 47.4 years) and TVE (tau = 83.3 years) than the men (tau = 20.8 and 15.4 years, respectively). There was a significant age-related decrease in body weight (0.45 kg.yr-1) in the men, whereas the women showed no change. Pulmonary function did not limit performance based on the very slow decline in VEmax and the normal FEV1.0. The decay in HRmax was better described by a linear model, resulting in an extremely slow tau. Maximal O2 pulse clearly exhibited an exponential decay, with a shorter tau (tau men = 13.5 years; tau women = 28.5 years) than any other variable.

Effects of Cardiac Rehabilitation in Patients with Myocardial Infarction

Background:Since the 1980s, early ambulation and cardiac rehabilitation have been emphasized in clinical practice after myocardial infarction. This is based on the belief that cardiac rehabilitation can reduce cardiovascular mortality, improve functional capacity and reduce the risk of further coronary events. In this study, we investigate the effect of aerobic exercise-based cardiac rehabilitation on functional capacity and cardiopulmonary responses in patients with myocardial infarction. Methods:19 patients were divided into two groups(9 patients for training group and 10 patients for control group at 4- 6 weeks after acute myocardial infarction. Training group performed aerobic exercise for 8 weeks(3 sessions per week, mean 53mins per session at 40-60% of heart rate(HR reserve, while control group did not. Before and after 8 weeks, all patients performed symptom- limited exercise test using modified Bruce protocol. Also, breath by breath respiratory gas analysis was carried out throughout exercise test. Results:For body composition, body weight(-2.7%, p<0.001, body mass index(-2.5%, p<0.001 and %body fat(-2.6%, p<0.05 were decreased significantly in training group after 8 week cardiac rehabilitation. Resting HR(-13%, p<0.05 was reduced significantly in training group, but no sig- nificant change occurred in resting blood pressure between the two groups. Maximal oxygen uptake(18%, p<0.01 and anaerobic threshold(21%, p<0.05 were increased significantly in training group after 8 week cardiac rehabilitation as compared with the control group. There was no significant change in maximal O2pulse between the two groups. Submaximal rate-pressure product(-17%,

Cardiorespiratory function before and after corrective surgery in pectus excavatum

To determine whether pectus excavatum (PE) results in cardiopulmonary abnormalities, and whether surgical repair results in improvement. We performed pulmonary function testing and incremental exercise testing in 36 adolescents with PE (aged 16 +/- 3 (SD) years) and 10 age-matched, healthy control subjects. Fifteen PE subjects were reexamined postoperatively, as were six control subjects. Preoperatively, PE subjects had a significantly lower forced vital capacity than control subjects had (81% +/- 14% vs 98% +/- 9% of the predicted value; p < 0.001). Chest computed tomography ratios of internal transverse to antero-posterior diameters correlated inversely with total lung capacity (r = 0.56; p < 0.01). Fifty-eight percent of PE subjects had subjective complaints of exercise limitation. PE subjects exercised at a workload similar to that of control subjects. Maximal heart rate and O2 pulse did not differ between the two groups. Respiratory measurements during exercise were similar between the two groups. Respiratory measurements during exercise were similar between the two groups. Postoperatively there was no change in forced vital capacity (as a percentage of the predicted value). The PE subjects exercised for a slightly longer period and had a slightly higher O2 pulse, whereas control subjects showed no change. Some subjects with PE have mild restrictive lung disease, which is not affected by surgical repair. Postoperatively they have a slight increase in exercise tolerance and O2 pulse, which suggests improved cardiac function during exercise. However, the clinical implications of this modest improvement are unclear.

Comparison of aerobic capacity between racing standardbred horses

A standardized treadmill test was used to compare metabolic and ventilatory measurements between 10 standardbred racehorses. The horses were divided into two groups: group A (n = 5) had mean racing speeds of 4.4 s faster than group B (n = 5) over a 1-mi. distance. Each horse was fitted with a venous catheter and connected to a valved gas-collection system. The exercise test consisted of 1-min incremental workloads ranging from 4.0 to 12.0 m/s at a treadmill incline of 3 degrees. Group A had significantly higher (P < 0.05) measurements of maximal O2 consumption (VO2max), O2 pulse, and tidal volume. Venous lactate concentration and respiratory exchange ratio measured at VO2max were also significantly higher (P < 0.05) in group A. Similar treadmill velocities were required to achieve a respiratory exchange ratio of > 1 and venous blood lactate concentration of > 4 mmol/l; however, group A was able to complete a significantly higher (P < 0.01) number of workloads before fatigue. The high aerobic and anaerobic capacity of group A horses may be a major contributor to a faster racing performance.

Maximal functional capacity in patients with endomyocardial fibrosis.

We evaluated objectively the cardiocirculatory dysfunction of patients with EMF, and related the functional class (FC-NYHA) to the data obtained by analysis of maximal functional capacity. We studied 55 subjects, divided into three groups: group 1 (G1) 21 (38.1%) normal persons, group 2 (G2) seven (12.7%) patients with EMF who were in FC I or II, and group 3 (G3) 27 (49%) patients in FC III or IV. Maximal oxygen consumption (VO2max) and O2 pulse index (PO2max) were obtained using a Beckman computerized gas analyser. The mean values were significantly different among the three groups. We conclude that the greater the clinical impairment, the greater the alterations that occur in the indices of cardiac function.

Physiologic and nonphysiologic determinants of aerobic fitness in mild to moderate asthma.

We studied 27 patients (seven male, 20 female) with stable mild-to-moderate asthma to measure their level of physical fitness and to determine if a relationship existed between aerobic fitness and the degree of airway reactivity, expiratory flow rates, or the amount of habitual leisure-time physical activity. Nonspecific bronchial hyperreactivity (NSBHR) was quantified by methacholine inhalation challenge. On a separate day, exercise capacity was evaluated with incremental exercise testing to exhaustion after bronchodilator pretreatment. The level of physical activity was assessed with a validated written questionnaire. FEV, was 78 +/- 13% predicted prebronchodilator and 92 +/- 14% predicted postbronchodilator. The mean provoking concentration of methacholine that caused a 20% decrease in FEV1 (PC20) was 1.14 +/- 1.38 mg/ml and ranged from 0.019 to 5.71 mg/ml. There was no correlation between PC20 and prebronchodilator FEV1 r = 0.37, p greater than 0.05). Mean maximal oxygen uptake (VO2max) was not significantly different from predicted normal values (36.9 +/- 10.8 versus 38.5 +/- 5.3, p = 0.32). Mean maximal O2pulse (maximal heart rate/VO2max), anaerobic threshold, and dyspnea index were within normal limits. There was no relationship between VO2max and FEV1 when expressed as percentages of predicted values (r = 0.08, p = 0.71) or between VO2max and PC20 (r = 0.23, p = 0.25). There was, however, a significant relationship between VO2max and the level of habitual leisure-time activity (F = 3.64, p less than 0.05). Results from the exercise questionnaire suggested that asthmatics perceive their disease as a limiting factor to improved aerobic fitness and that they lack adequate knowledge about asthma and exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Supplemental Oxygen and Exercise Performance in Patients with Cystic Fibrosis with Severe Pulmonary Disease

Patients with cystic fibrosis (CF) and advanced pulmonary disease have pulmonary limitation of exercise, often associated with arterial oxygen desaturation. Improving oxygenation during exercise by providing supplemental oxygen may improve exercise performance in these patients. To test this, we performed graded exercise stress tests in 22 CF patients with severe pulmonary disease (mean PaO2, 64 +/- 2 mm Hg [+/- SE]; PaCO2 46 +/- 2 mm Hg; RV/TLC, 57 +/- 4 percent; FEV1, 38 +/- 4 percent of predicted; FEF25-75%, 13 +/- 2 percent of predicted; median age, 26 years) and compared them to 21 controls (RV/TLC, 27 +/- 4 percent; FEV1, 112 +/- 2 percent of predicted; FEF25-75%, 80 +/- 4 percent of predicted; median age, 29 years). Each subject performed graded exercise stress tests while breathing FIO2 of 0.21 and FIO2 of 0.30. Subjects were blinded to the composition of the inspired gas, and the order of testing was randomized. We found that CF subjects exercised longer, had a higher maximal VO2, higher O2 pulse, and less arterial oxygen desaturation when receiving supplemental O2. Control subjects exercised longer when breathing supplemental O2 but had no significant change in maximal VO2, O2 pulse, or SaO2. Both CF and control subjects had increased end-tidal PCO2 when exercising while breathing supplemental O2. We conclude that CF patients with advanced pulmonary disease have increased exercise tolerance and aerobic capacity when exercising while breathing supplemental O2.

Sweating and skin blood flow during exercise: effects of age and maximal oxygen uptake

Individuals greater than or equal to 60 yr of age are more susceptible to hyperthermia than younger people. However, the mechanisms involved remain unclear. To gain further insight, we examined the heat loss responses of 7 young (24-30 yr) and 13 older (58-74 yr) men during 20 min of cycle exercise [67.5% maximal O2 uptake (VO2max)] in a warm environment (30 degrees C, 55% relative humidity). Forearm blood flow (FBF) and chest sweat rate (SR) were plotted as a function of the weighted average of mean skin and esophageal temperatures [Tes(w)] during exercise. The sensitivity and threshold for each response were defined as the slope and Tes(w) at the onset of the response, respectively. When the young sedentary men were compared with a subgroup (n = 7) of the older physically active men with similar VO2max, the SR and FBF responses of the two groups did not differ significantly. However, when the young men were compared with a subgroup of older sedentary men with a similar maximal O2 pulse, the SR and FBF sensitivities were significantly reduced by 62 and 40%, respectively. These findings suggest that during a short exercise bout either 1) there is no primary effect of aging on heat loss responses but, rather, changes are associated with the age-related decrease in VO2max or 2) the decline in heat loss responses due to aging may be masked by repeated exercise training.