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At least 325 records · Page 18Linked to original sources

PubMed2003

Sildenafil citrate does not reduce exercise tolerance in men with erectile dysfunction and chronic stable angina.

AIMS: The aim of this study was to evaluate whether sildenafil, used for treatment of erectile dysfunction (ED), affects the exercise tolerance and ischaemic threshold in men with exercise-induced angina not taking nitrates. METHODS: This was a double-blind placebo-controlled study in men with ED and chronic stable angina, assessing the effect of sildenafil on time to limiting angina during incremental treadmill exercise. Patients remained on their antianginal therapy and received a 100-mg dose of sildenafil or placebo 1h prior to treadmill exercise. Other measurements included times to onset of angina, 1-mm ST-segment depression, and total exercise time. RESULTS: Adjusted treatment differences for the time to limiting angina, time to onset of angina, total exercise time, and time to 1-mm ST-segment depression were (mean+/-SE) 20+/-10s (95% CI, 1-39; P=0.040), 32+/-11s (95% CI, 11-53; P=0.004), 20+/-10s (95% CI, 0-39; P=0.049), and 12+/-17s (95% CI, -21 to 45, P=0.48), respectively, in favour of sildenafil. There were no serious treatment-related adverse events. CONCLUSIONS: Sildenafil was well tolerated and did not adversely affect any exercise parameter in men with coronary artery disease and ED. Favourable trends in total exercise duration and times to onset of angina and limiting angina were recorded with sildenafil use.

Adolescent↗

PubMed2006

Exercise tolerance in a hot and humid climate in heat-acclimatized girls and women.

This study compared physiological responses associated with exercise tolerance in girls (G) and women (W) of similar fitness and heat acclimatization level during exercise in a hot and humid outdoor environment (33.4 degrees C and 55.1 % RH; WBGT = 29.9 +/- 0.2 degrees C). Nine pre-menarcheal G (age = 11.3 yr) and nine W (age = 26.8 yr), matched for aerobic capacity and heat acclimatization level, performed a cycling session at 60 % VO2max until fatigue. A sports drink was provided periodically to prevent dehydration. Tolerance time was not different between the groups (G = 56.9 +/- 6.3, W = 76.5 +/- 9.9 min, p > 0.05). During exercise, sweat rate (G = 9.1 +/- 1.1, W = 12.0 +/- 1.1 ml.m(-2).min(-1)), the increase in rectal temperature [T(re)] (G = 0.9 +/- 0.1, W = 1.1 +/- 0.1 degrees C), and heat storage (G = 10.6 +/- 5.3, W = 20.5 +/- 4.5 W.m(-2)) did not differ between the groups. At fatigue, T(re) (G = 38.2 +/- 0.1, W = 38.4 +/- 0.1 degrees C), heart rate (G = 167.3 +/- 7.3, W = 171 +/- 3.3 beats.min(-1)), stroke index (G = 48.3 +/- 1.5, W = 52.4 +/- 1.8 ml.m(-2)), and forearm skin blood flow (G = 9.5 +/- 1.3, W = 11.7 +/- 1.5 ml.100 ml(- 1).min(-1)) did not differ between the groups. Similar to women, the main reasons reported by girls to stop exercising in the heat were localized leg fatigue and gluteus muscle discomfort. We conclude that heat-acclimatized girls exhibit an adequate cardiovascular and thermoregulatory adjustment while exercising in a hot and humid outdoor environment when hypohydration is prevented.

Acclimatization↗

PubMedDate not supplied

Exercise tolerance testing after myocardial infarction.

Risk stratification after acute myocardial infarction (AMI) is essential in identifying those at high risk of future events. Treadmill exercise tolerance testing is one of a series of investigations commonly used to help determine AMI patients' prognosis. This article looks at the role of this investigation in risk stratification.

Electrocardiography↗

PubMed1990

Exercise tolerance and pulmonary gas exchange after deep saturation dives.

Pulmonary function and exercise tolerance were measured before and after three saturation dives to a pressure of 3.7 MPa. The atmospheres were heliox with partial pressures of oxygen of 40 kPa during the bottom phase and 50 kPa during the compression and decompression phase. The bottom times were 3, 10, and 13 days. Decompression time was 13 days. Precordial Doppler monitoring was done daily during the decompression, and an estimate of the total bubble load on the pulmonary circulation was calculated as the accumulated sum of bubble scores recorded for each diver. Nine of the 18 divers had chest symptoms with retrosternal discomfort or nonproductive cough after the dive. There were no changes in dynamic lung volumes. Transfer factor for carbon monoxide was significantly reduced from 12.3 +/- 1.2 to 10.9 +/- 1.3 mmol.kPa-1.min-1 (P less than 0.01), and maximum oxygen uptake was reduced from 3.98 +/- 0.36 to 3.42 +/- 0.37 l/min STPD (P less than 0.01) after the dives. Resting heart rate was increased from 64 +/- 6 to 75 +/- 8 min-1 (P less than 0.01). The ventilatory requirements in relation to oxygen uptake and carbon dioxide elimination were significantly increased (P less than 0.01) after the dives. The physiological dead space fraction of tidal volume was significantly higher and showed an increase with larger tidal volumes (P less than 0.05). Anaerobic threshold estimated from gas exchange data decreased from an oxygen uptake of 2.30 +/- 0.25 to 1.95 +/- 0.28 l/min STPD (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2006

Atrial fibrillation is associated with increased neurohumoral activation and reduced exercise tolerance in patients with non-ischemic dilated cardiomyopathy.

OBJECTIVES: To assess atrial fibrillation (AF) associated differences in proinflammatory cytokines, natriuretic peptide levels and exercise capacity in patients with heart failure (HF) secondary to non-ischemic dilated cardiomyopathy (NIDC). METHODS: We studied 147 NIDC patients, mean age 58.3+/-12.5 years, left ventricular (LV) ejection fraction 27.8+/-10.9% and NYHA class II-III. Neurohumoral activation was assessed by measurement of interleukin IL-1, IL-6, tumor necrosis factor-a (TNF-a), its soluble receptors sTNFR I and II, N-terminal atrial (NT-ANP) and -brain (NT-BNP) natriuretic peptide levels, and functional class was assessed by cardiopulmonary exercise test. RESULTS: Forty patients (27.5%) had chronic AF and they did not differ in age, LV ejection fraction or HF duration compared to patients in sinus rhythm (SR). AF was associated with increased levels of IL-6 (p=0.001), TNF-a (p=0.002), sTNFRI (p=0.023), NT-ANP (p<0.001) and NT-BNP (p=0.003), decreased exercise duration (p<0.001) and slightly reduced maximal oxygen consumption at peak exercise (p=0.07) compared to SR patients. No significant differences in cytokine and natriuretic peptide levels or exercise tolerance were noted when patients in AF were compared to the subgroup of SR with restrictive LV filling pattern. Multivariate analysis showed that NT-ANP (p=0.003) and IL-6 (p=0.006) plasma levels were independently associated with the presence of AF in our patient population. CONCLUSION: AF is associated with increased inflammatory state, natriuretic peptide levels and reduced exercise capacity in patients with HF secondary to NIDC. These findings suggest that the presence of AF in HF represents a more advanced stage of the syndrome.

Atrial Fibrillation↗

PubMed2000

Effects of oral L-arginine supplementation on exercise-induced QT dispersion and exercise tolerance in stable angina pectoris.

We assessed the effects of L-arginine (an endogenous precursor of nitric oxide) on the magnitude of exercise-induced QT dispersion in patients with coronary artery disease. The study had a randomized double-blind cross-over design. Twenty-five patients with stable coronary artery disease underwent two separate exercise tests: after oral administration of L-arginine (6 g/24 h for 3 days) or placebo. Indications for cessation of exercise included: pulse limit, exhaustion, chest pain, ST segment depression >2 mm. We found that arginine significantly increased exercise duration from 604+/-146 to 647+/-159 s (P<0.03). However, it had no effect on the sum of exercise-induced ST segment depressions (1.9+/-2.3 and 2.4+/-3.3 on and off arginine, respectively, NS). Exercise shortened QT interval to a similar extent in patients treated with placebo or arginine. QT dispersion changed during exercise from 55+/-21 to 60+/-19 ms (NS) and from 60+/-21 to 53+/-17 ms (NS), respectively. We conclude that, in patients with coronary artery disease, oral supplementation of L-arginine does not affect exercise-induced changes in QT interval duration, QT dispersion or the magnitude of ST segment depression. However, it significantly increases exercise tolerance, most likely due to improved peripheral vasomotion. These results may be of clinical and therapeutic importance.

Aged↗

PubMed1997

[Efficacy of increase of cardiac index during exercise in the chronic phase of various cardiovascular diseases: evaluation by exercise tolerance and brain natriuretic peptide].

Cardiac index is widely used as a parameter of cardiac function for cardiovascular patients, but its value is limited when measured in the resting supine position, because it never demonstrates the maximal cardiac index performance. The incremental increase in cardiac index (delta CI) was evaluated during incremental exercise (delta work rate: delta WR), delta CI/delta WR, in patients with chronic congestive heart failure, and compared to brain natriuretic peptide (BNP), which is known to be increased in patients with chronic left ventricular dysfunction. The subjects were 18 heart failure patients (16 males and 2 females, mean age [+/-SD] 63.8 +/- 8.9 years). Symptom-limited cardiopulmonary exercise test using cycle ergometer was performed. Cardiac index was calculated with the Benchmark Exercise Test device using oxygen uptake, carbon dioxide output and respired flow. Blood samples were taken in the resting state before the exercise test. A positive correlation was obtained between delta CI/delta WR and peak oxygen uptake (peak VO2) (r = 0.71, p < 0.01), and delta CI/delta WR and peak oxygen pulse (r = 0.66, p < 0.01). A negative correlation was obtained between delta CI/delta WR and BNP (r = 0.45) in the resting state. Peak VO2 (20.9 +/- 7.5 vs 13.9 +/- 2.7 ml/min/kg, p < 0.05), peak cardiac index (7.2 +/- 1.7 vs 5.5 +/- 0.9 l/min/m2, p < 0.05), and delta CI/delta WR (20.1 +/- 8.1 vs 12.4 +/- 2.5 ml/m2/W, p < 0.05) were significantly higher in the group with normal BNP (mean [+/-SD] 11.0 +/- 3.2 pg/ml) than in the group with high BNP (40.7 +/- 22.7 pg/ml). Delta CI/delta WR reflects the grade of exercise tolerance and may be useful for evaluating exercise capacity in patients with congestive heart failure.

Aged↗

PubMed2005

Gas exchange and exercise tolerance following bullectomy.

This study evaluates the physiological responses to giant bullectomy. A 42-year-old female with bilateral giant bullae presented with dyspnoea and exercise limitation. At baseline and 3 months after bullectomy she had tests of lung function; exercise capacity via a symptom-limited cycle test and a 6-min walk test (6MWT). Quality of life (QoL) and gas exchange using the multiple inert gas elimination technique (MIGET) were also assessed. There were significant improvements in pulmonary function following surgery with the FEF(25-75%) predicted increasing from 16 to 96. The 6MWT increased by 10% and the peak leg work capacity by 48%. A MIGET measure of the distribution of perfusion (Log SDQ) fell from 0.52 to 0.36. There was also radiological improvement in hyperinflation and diaphragmatic configuration. The QoL total score decreased from 56 to 25. This patient demonstrated significant improvements in exercise tolerance, gas exchange and QoL following bullectomy.

Adult↗

PubMed1993

Effects of buspirone on anxiety levels and exercise tolerance in patients with chronic airflow obstruction and mild anxiety.

The objective of this study was to determine if buspirone would alleviate anxiety and improve exercise tolerance of anxious patients with chronic airflow obstruction (CAO). Eleven male patients with mild to moderate anxiety and CAO completed this study comparing buspirone, 10 to 20 mg given three times a day, with placebo. Patients were evaluated with State Trait Anxiety Inventory, spirometry, 12-min walk, incremental exercise on a cycle ergometer to symptom limitation and measurement of dyspnea with a modified Borg scale at exercise levels and the end of each 2 min on 12-min walk. There were no significant differences in anxiety scores, work load, maximum oxygen consumption per minute, maximum expired volume per minute, PETCO2, PETO2, 12-min walking distance or dyspnea scores after 6 weeks of buspirone or placebo therapy. We conclude that administration of buspirone has no significant effect on anxiety levels, exercise capabilities or PETO2 or PETCO2 in patients with CAO and mild anxiety.

Aged↗

PubMed1993

Effect of cilazapril on exercise tolerance in congestive heart failure.

Cilazapril (C), an angiotensin-converting enzyme inhibitor with effective antihypertensive efficacy, was examined for its ability to alter exercise tolerance testing (ETT) and respiratory oxygen uptake in 33 patients with congestive heart failure (CHF). C was administered in capsules daily to patients with New York Heart Association Class II or Class III CHF for 12 weeks, in parallel double-blind treatment groups of 0 mg (n = 8), 0.5 mg (n = 8), 1.0 mg (n = 9), and 2.5 mg (n = 8). The blood pressure (BP) was reduced by 2.5 mg C: systolic BP (SBP) from 126 to 114 mm Hg; diastolic BP from 76 to 69 mm Hg. The maximum heart rate (MHR) during ETT was increased by 2.5 mg C from 137 to 143 bpm, as was the double product (MHR x maximum SBP x 0.01) from 237 to 251. There was an insignificant change in duration of exercise (548-610 s), anaerobic threshold (AT), and maximum oxygen uptake (14.1-15.7 ml/kg/min). The results suggest a positive effect of 2.5 mg C on energy utilization in CHF patients.

Aged↗

PubMed1997

Effect of inadequate cardiac output reserve on exercise tolerance in patients with moderate mitral stenosis.

Twenty-nine patients with moderate mitral stenosis and 29 age-matched normal controls underwent symptom-limited upright bicycle exercise testing with simultaneous hemodynamic monitoring. Exercise tolerance in the mitral stenosis group was found to be limited by inadequate cardiac output reserve and not by resting mitral valve area or exercise pulmonary capillary wedge pressure.

Adult↗

PubMedDate not supplied

Longitudinal study (32 years) of exercise tolerance, breathing response, blood pressure, and blood lipids in young men.

Changes in exercise tolerance, blood lipids, and blood pressure from youth to middle age was studied in 106 subjects followed 32 years. In addition, the responses to cold pressor and CO2 stress were studied as correlates of future lipids and blood pressure. Treadmill exercise test, cold pressor test, response to breathing a mixture of 6% CO2, and 21% O2, for 5 minutes, blood pressure, and lipid measurements were performed in 1947 when subjects were 20 +/- 2 years old. Exercise, blood pressure and lipid tests were repeated in 1979. Tracking of blood pressure and pulse response to exercise over the period was demonstrated. Baseline exercise response correlated with future blood pressure, cholesterol, triglycerides, and high density lipoproteins. Change in exercise pulse rate over the period correlated with change in cholesterol. Cold pressor systolic blood pressure response correlated with future systolic blood pressure and triglycerides. Pulse and blood pressure response to CO2 breathing correlated with cholesterol, triglyceride and high density lipoprotein 32 years later. These correlations were independent of baseline values of the variables and body mass index. Individuals who were judged "fit" (exercise pulse rise less than median) at both baseline and follow-up had the best cardiovascular risk profile (blood pressure and lipids). Blood pressure and pulse response to exercise tracked between ages 20 and 50. Exercise, cold pressor, and CO2 responses in youth correlated with blood lipid levels in middle age.

Adolescent↗

PubMed1975

Effect of nifedipine on exercise tolerance in patients with angina pectoris.

To test if nifedipine, 10 mg sublingually, could increase exercise tolerance, ten patients with angina pectoris each performed two types of bicycle exercise test, one with a stepwise increase in load and the other with a continuously increasing load. The drug was given in a double-blind cross-over trial. Nifedipine raised the heart rate and diminished the systemic blood pressure at rest, on standing and during exercise at comparable loads. Work time was prolonged and higher work loads were achieved. The total work performed rose by 50 per cent in one of the tests and by 23 per cent in the other, about 50 minutes after taking the drug. The mechanism of the greater work capacity in angina pectoris after nifedipine was assumed to be diminished heart work due to a fall in systemic vascular resistance.

Adult↗

PubMed2003

Non-invasive evaluation of gas exchange during a shuttle walking test vs. a 6-min walking test to assess exercise tolerance in COPD patients.

Walking tests, such as the "shuttle" incremental walking test (SWT) and the 6-min walking test (6'WT), are commonly utilized in evaluating exercise intolerance in patients with chronic obstructive pulmonary disease (COPD) and the distance covered is the variable usually considered. Because lung gas exchange indexes are not measured, little is known about the physiological response elicited by different walking protocols. We compared exercise adaptation during the 6'WT and SWT in 13 male stable COPD patients [mean (SE) age: 70 (1) years; forced expiratory volume in 1 s (FEV(1)): 1.2 (0.1) l; arterial O(2) tension (PaO(2)): 72 (2) mmHg; arterial CO(2) tension (PaCO(2)): 41 (1) mmHg]. Oxygen uptake (.VO(2)), CO(2) output (.VCO(2)), minute ventilation (.V(E)), and heart rate (HR) were monitored by a portable telemetric system. During the SWT a linear response in lung gas exchange indexes was observed while, during the 6'WT, the response was exponential. During the 6'WT, .VO(2), .VCO(2), .V(E), and HR values at steady-state (SS) were significantly lower compared to SWT peak values. For SWT, distance covered correlated with .VO(2PEAK), (R=0.86, p<0.001), .VCO(2PEAK), (R=0.87, p<0.001) and .V(EPEAK) (R=0.74, p<0.01); moreover, distance and .VO(2PEAK) were significantly correlated with peak .VO(2) values obtained during cycle ergometer incremental exercise (R=0.72, p<0.01 and R=0.92, p<0.0001, respectively). For 6'WT, the distance covered did not correlate with any pertinent physiological index. The two walking protocols reveal substantial differences in pathophysiologic adaptations and provide evidence that SWT is more accurate than the 6'WT in the evaluation of maximal exercise tolerance in COPD patients.

Adaptation, Physiological↗

PubMed2005

[Effect of cardiac resynchronization therapy (CRT) on exercise tolerance, functional capacity and quality of life in patients with congestive heart failure].

This review article summarizes the effect of cardiac resynchronization therapy (CRT) on exercise tolerance, functional capacity and quality of life, as it has been shown in previous randomized controlled trials. Based on these data we carefully have to reconsider the initial goals of this therapy. An early prophylactic implantation is not justified today. Especially patient selection has to be performed with more care in the future using new methods for detection of cardiac asynchrony to avoid a mismatch between implant numbers and real functional benefit.

Cardiac Pacing, Artificial↗

PubMed1998

Mechanisms by which COPD affects exercise tolerance.

In view of the recent advances in our understanding of the pathophysiology of COPD, we felt that it would be appropriate to examine the contribution of several abnormalities, not hitherto examined, to exercise limitation in this disease. These included: (1) The ability to exceed maximum expiratory flow (determined during forced maneuvers from TLC) during partial expiratory maneuvers. This is referred to as deltaFEV1. (2) Shape of the flow-volume curve (Shape). (3) Susceptibility to develop dynamic hyperinflation (dynamic hyperinflation index, DHI). (4) Ventilatory response to exercise (VEmax/VEpred). Twenty-four COPD patients (FEV1 = 42 +/- 13% pred) underwent symptom-limited progressive exercise. DeltaFEV1, shape, DHI and VEmax/VEpred were determined. All values were normalized to eliminate the effects of age, sex, and body size. Shape had no impact on peak VO2 (r = 0.8). DeltaFEV1 (r = 0.50), DHI (r = 0.50) and VEmax/VEpred (r = 0.46) correlated significantly with peak VO2 with all three exceeding FEV1 (r = 0.43). DHI and deltaFEV1 correlated significantly with each other (r = 0.43) suggesting that the latter exerts its beneficial effects by reducing the tendency to develop DH. We conclude that variability among patients in ventilatory response to exercise and in deltaFEV1 (likely an expression of extent of regional mechanical heterogeneity) contribute importantly to variability of exercise tolerance in COPD.

Aged↗

PubMed1986

Effects of breathing a normoxic He-O2 gas mixture on exercise tolerance and VO2 max.

The purpose of these experiments was to compare the effects of breathing air (79% N2-21% O2) and a normoxic helium oxygen gas mixture (He-O2) (79% He-21% O2) on maximal oxygen uptake (VO2 max) and work tolerance during both incremental and high-intensity constant load exercise. First, eight subjects underwent two separate short incremental cycle ergometer exercise tests until the subject could not maintain the desired power output. Second, four subjects exercised to exhaustion on two separate occasions at a constant exercise intensity (100% VO2 max). Each exercise protocol required the subject to breathe air on one test and a normoxic He-O2 mixture on an additional occasion. Data analysis revealed higher (P less than 0.05) minute ventilations, an increased time to exhaustion, and a greater VO2 max during He-O2 breathing in both exercise conditions. Small but significant (P less than 0.05) differences existed in the percent hemoglobin saturated with O2 (% SO2) at exercise demands greater than 120 W during the incremental experiment and during each minute of the constant load test with He-O2 giving the higher value. These data support the hypothesis that breathing a normoxic He-O2 gas mixture during exercise elevates VO2 max and increases exercise tolerance. Further, although it appears that breathing a He-O2 mixture results in higher %SO2 during intense exercise, the increase in arterial O2 content is small and probably does not fully account for the higher VO2 max observed under these conditions.

Adult↗

PubMed2003

The spectrum of exercise tolerance in mitochondrial myopathies: a study of 40 patients.

Impaired skeletal muscle oxidative phosphorylation in patients with severe mitochondrial respiratory chain defects results in disabling exercise intolerance that is associated with a markedly blunted capacity of muscle to increase oxygen utilization in relation to circulatory and ventilatory responses that increase oxygen delivery to muscle during exercise. The range of oxidative limitation and the relationship between the severity of oxidative defects and physiological responses to exercise among a broader spectrum of mitochondrial respiratory chain defects has not been defined. We evaluated oxidative capacity and circulatory and ventilatory responses to maximal cycle exercise in 40 patients with biochemically and/or molecularly defined mitochondrial myopathy (MM) associated with varying levels of exercise tolerance, and compared responses with those in healthy sedentary individuals. In the MM patients, mean peak work capacity (0.88 +/- 0.6 W/kg) and oxygen uptake (VO(2), 16 +/- 8 ml/kg/min) were significantly lower (P < 0.01) than in controls (mean work capacity = 2.2 +/- 0.7 W/kg; VO(2) = 32 +/- 7 ml/kg/min), but the patient range was broad (0.17-3.2 W/kg; 6-47 ml/kg/min). Oxidative capacity in patients was limited by the ability of muscle to extract available oxygen from blood [mean peak systemic arteriovenous O(2) difference (a-vO(2)); patients = 7.7 +/- 3.5, range 2.7-17.6 ml/dl, controls = 15.2 +/- 2.1 ml/dl], as indicated by a linear correlation between peak VO(2) and peak systemic a-vO(2) difference (r(2) = 0.69). In the patients, the increase in cardiac output relative to VO(2) (mean DeltaQ/DeltaVO(2) = 15.0 +/- 13.6; range 3.3-73) and ventilation (mean peak VE/VO(2) = 65 +/- 24; range 21-104) were exaggerated compared with controls (mean DeltaQ/DeltaVO(2) = 5.1 +/- 0.7; VE/VO(2) = 41.2 +/- 7.4, P < 0.01). There was a negative exponential relationship between DeltaQ/DeltaVO(2) and peak systemic a-vO(2) difference (r(2) = 0.92) and between peak VE/VO(2) and systemic a-vO(2) difference (r(2) = 0.53). In patients with heteroplasmic mtDNA mutations, we found an inverse relationship between the proportion of skeletal muscle mutant mtDNA and peak extraction of available oxygen during exercise (r(2) = 0.70). We conclude that the degree of exercise intolerance in MM correlates directly with the severity of impaired muscle oxidative phosphorylation as indicated by the peak capacity for muscle oxygen extraction. Exaggerated circulatory and ventilatory responses to exercise are direct consequences of the level of impaired muscle oxidative phosphorylation and increase exponentially in relation to an increasing severity of oxidative impairment. In patients with mtDNA mutations, muscle mutation load governs mitochondrial capacity for oxidative phosphorylation and determines exercise capacity.

Adolescent↗