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PubMed1986

Exercise capacity of patients with post-operative tetralogy of Fallot.

Twenty-one patients with tetralogy of Fallot following intracardiac repair underwent a treadmill test for evaluation of their exercise capacity. They were divided into two groups according to their post-operative hemodynamic status, the good result group and the poor result group. The maximum oxygen consumption during exercise was significantly decreased in the poor result group, but that of the good result group showed no significant difference from the control group. However, the maximum heart rate in both the good and the poor result groups was significantly lower than that of the control group. Thus, the exercise tolerance in post-operative tetralogy patients was found to be within the normal range as long as their hemodynamic operative result was satisfactory, but the limited capability of increasing heart rate with exercise could present a potential problem in the long-term prognosis.

Adolescent↗

PubMed1994

Prognostic significance of peak exercise capacity in patients with coronary artery disease.

OBJECTIVES: The aim of this study was to investigate the prognostic significance of peak oxygen uptake in patients with coronary artery disease who had an exercise test that could be sustained to exhaustion without limiting symptoms. BACKGROUND: Many studies have reported an inverse association between the level of exercise reached during a stress test and mortality or cardiovascular morbidity. These studies have used submaximal or symptom-limited exercise testing in patients with a recent myocardial infarction. METHODS: Peak oxygen uptake was measured in male patients > or = 4 weeks after myocardial infarction (312 patients) or coronary artery surgery (215 patients) by use of a graded uninterrupted exercise test performed to exhaustion. Apart from peak oxygen uptake, several risk factors for cardiovascular disease, patient and exercise characteristics and drug treatment were considered in the Cox proportional hazards model. RESULTS: During the total follow-up period of 3,213 patient-years, 53 patients died. Of these 53 patients, 33 died of cardiovascular causes. All-cause and cardiovascular mortality decreased with increasing peak oxygen uptake, even after adjustment for significant covariates. The relative hazard rates of 0.43 and 0.29 indicate that a hypothetic increase in peak oxygen uptake by 1 liter/min could be associated with decreases in all-cause and cardiovascular mortality of 57% and 71%, respectively. CONCLUSIONS: Exercise capacity is an independent predictor for subsequent all-cause and cardiovascular mortality in patients able to perform an exercise test until exhaustion.

Coronary Artery Bypass↗

PubMed1986

Six minute walking test for assessing exercise capacity in chronic heart failure.

Twenty six patients, mean age 58 years (range 36-68), with stable chronic heart failure, New York Heart Association class II-III, and 10 normal subjects of a similar age range were studied. Exercise capacity was assessed by determining oxygen consumption reached during a maximal treadmill exercise test and by measuring the distance each patient walked in six minutes. There were significant differences in the distance walked in six minutes between normal subjects, patients with heart failure, class II, and those with class III heart failure (683 m, 558 m, and 402 m, respectively (p less than 0.003)). The relation between maximal oxygen consumption and the distance walked in six minutes was curvilinear; thus the distance walked varied considerably in those with a low maximal oxygen consumption but varied little in patients and normal subjects with a high maximal oxygen consumption. All subjects preferred performing the six minute walking test to the treadmill exercise test, considering it to be more closely related to their daily physical activity. The six minute test is a simple objective guide to disability in patients with chronic heart failure and could be of particular value in assessing patients with severe heart failure but less useful in assessing patients with mild heart failure.

Adult↗

PubMed2006

Left ventricular diastolic dysfunction is related to oxidative stress and exercise capacity in hypertensive patients with preserved systolic function.

BACKGROUND: Left ventricular diastolic dysfunction and oxidative stress are important determinants in heart failure development. Peak oxygen uptake, maximal oxygen consumption, metabolic equivalents (MET), ventilatory response and time to respiratory gas exchange assess cardiopulmonary capacity. AIM: It was the aim of this study to investigate the impact of oxidative stress on diastolic indexes and cardiopulmonary exercise capacity in hypertensive patients with left ventricular diastolic dysfunction. METHODS: Mitral flow velocities (E, A), ejection fraction, left atrial and ventricular diameters were assessed by Doppler echocardiography. Superoxide dismutase (SOD) and glutathione peroxidase activity in blood were evaluated. Sixty patients (aged 49.8 +/- 9.2 years) with essential hypertension and preserved systolic function (ejection fraction 58.3 +/- 7%) performed a bicycle exercise test. Forty patients showed impaired left ventricular relaxation (E/A <1, deceleration time of E >220 ms) and were assigned to group 1, while 20 had normal relaxation (group 2). RESULTS: An increase in SOD was significantly blunted after exercise in group 1 compared with group 2 (p = 0.049). A significant difference between groups in the glutathione peroxidase level was observed before exercise (p = 0.038). There were significantly lower values of peak oxygen uptake and MET (p = 0.013 and p = 0.024, respectively) and a prolonged respiratory exchange ratio (p = 0.022) in group 1 compared with group 2. MET was significantly influenced by SOD level (p = 0.035). CONCLUSIONS: Lower antioxidative protection and impaired relaxation decrease cardiopulmonary capacity in hypertensive patients.

Aged↗

PubMed1986

Effects of oral hypoglycemic agent methylpalmoxirate on exercise capacity of streptozocin diabetic rats.

The effect of the oral hypoglycemic agent methylpalmoxirate (methyl-2-tetradecylglycidate), a selective inhibitor of long-chain fatty acid oxidation, on the exercise capacity of diabetic rats was evaluated. Rats were made diabetic by injection of streptozocin (75 mg/kg i.p.), which was confirmed by 4+ glucosuria. Daily oral administration of 2.5 mg/kg for 5 days, or a single dose of 10 mg/kg, of methylpalmoxirate produced a slight, nonsignificant decrease in the ability of diabetic rats to perform strenuous exercise of an intensity that caused exhaustion in less than 30 min. The ability of diabetic rats to perform prolonged, moderately strenuous exercise of an intensity that could be maintained for more than 60 min was not affected by methylpalmoxirate treatment. Methylpalmoxirate normalized plasma glucose concentrations, with resting glucose levels reduced 71% compared with nontreated controls, and did not cause hypoglycemia during prolonged exercise to exhaustion. Hepatic glycogen content was significantly reduced in methylpalmoxirate-treated rats in the fed, resting state, and during exercise, suggesting that liver was forced to oxidize carbohydrate at the expense of carbohydrate storage. Blood ketone levels of methylpalmoxirate-treated rats were reduced by 82% at rest, and exercise-induced ketosis was prevented by drug treatment. Muscle glycogen concentration and the rate of muscle glycogen depletion during exercise were not altered by methylpalmoxirate. It appears that the liver is the major site of action of methylpalmoxirate in diabetic rats when given in low doses.

3-Hydroxybutyric Acid↗

PubMed1982

Acute and long-term effects of captopril on exercise cardiac performance and exercise capacity in congestive heart failure.

Although many studies have shown that captopril (CPT) provides acute hemodynamic improvement in patients with severe congestive heart failure (CHF) at rest, little information is available concerning exercise hemodynamic responses to CPT or the effect of this drug on exercise tolerance in CHF. Therefore, we evaluated the hemodynamic effects of CPT at rest and during upright bicycle exercise in 15 patients with stable CHF. CPT (25 to 50 mg) reduces both resting heart rate and mean arterial pressure (84 +/- 11 to 78 +/- 7 bpm, p less than 0.025 and 85 +/- 9 to 64 +/- mm Hg, p less than 0.001). Concomitantly, left ventricular filling pressure dropped dramatically (26 +/- 9 to 15 +/- 7 mm Hg, p less than 0.001), while cardiac and stroke indices rose (2.0 +/- 0.5 to 2.5 +/- 0.6 L/min/m2, p less than 0.001, and 25 +/- 8 to 33 +/- 7 ml/m2, p less than 0.001). Similar directional changes occurred during exercise, with heart rate, mean arterial pressure, and left ventricular filling pressure at maximum exercise being less (123 +/- 15 to 115 +/- 16 bpm, p less than 0.01; 93 +/- 17 to 86 +/- 14 mm Hg, p less than 0.05; and 35 +/- 10 to 30 11 mm Hg, p less than 0.001, respectively) after CPT ingestion. Peak exercise cardiac index rose slightly (3.6 +/- 0.7 to 3.9 +/- 0.6 L/min/m2) but not significantly. Six patients followed long term on CPT underwent elective recatheterization after 3 months. In these, the beneficial hemodynamic changes seen acutely persisted or further improvement was noted, both at rest and during exercise. Most impressively, peak exercise cardiac index rose from 3.6 +/- 0.7 to 4.6 +/- 1.0 L/min/m2 (p less than 0.05), and this was associated with an increase in exercise duration (8.0 +/- 2.2 to 11.5 +/- 1.4 minutes, p less than 0.05) and exercise work load (332 +/- 32 to 468 +/- 52 kp-m/min, p less than 0.05). These findings indicate that in patients with severe CHF, oral CPT provides markedly beneficial augmentation of cardiac function during activity as well as at rest; moreover, chronic CPT therapy substantially increases exercise capacity in this setting.

Aged↗

PubMed2005

Incremental prognostic value of dobutamine-atropine stress 99mTc-tetrofosmin myocardial perfusion imaging for predicting outcome in diabetic patients with limited exercise capacity.

PURPOSE: This study assessed the incremental value of dobutamine stress ( 99m)Tc-tetrofosmin single-photon emission computed tomography (SPECT) for the prediction of cardiac events in diabetic patients with limited exercise capacity. METHODS: The study population comprised 125 consecutive diabetic patients (mean age 61+/-9 years, 61% men) who were unable to perform an exercise test and underwent dobutamine ( 99m)Tc-tetrofosmin SPECT. Follow-up was successful in 124 (99%) patients. Three patients who underwent early revascularisation (within 60 days) were excluded. End-points during follow-up were cardiac death and non-fatal myocardial infarction. RESULTS: An abnormal scan (with the presence of reversible or fixed perfusion defects) was observed in 76 (63%) patients. During the follow-up (3.4+/-1.5 years), 36 patients died (19 cardiac deaths) and four patients had non-fatal myocardial infarction. Cardiac death occurred in one of 49 (2%) patients with a normal myocardial perfusion study and in 18 of 75 (24%) patients with an abnormal study (p<0.001). Abnormal scan was incremental to the clinical parameters in predicting cardiac death (chi(2)=48 vs 39, p<0.05) and hard cardiac events (chi(2)=50 vs 43, p<0.05). CONCLUSION: Dobutamine stress ( 99m)Tc-tetrofosmin SPECT provides prognostic information additional to clinical data for the prediction of cardiac death and hard cardiac events in diabetic patients unable to perform an exercise test.

Age Distribution↗

PubMedDate not supplied

Effects of Nebivolol on left ventricular function and exercise capacity in patients with non-ischaemic dilated cardiomyopathy. A randomised placebo-controlled study.

INTRODUCTION: This study assessed the effects of Nebivolol on left ventricular (LV) function and exercise capacity in patients with non-ischaemic dilated cardiomyopathy (NIDC). METHODS: After enrolment in this double-blind trial, 60 patients, aged 55 +/- 9.5 years, with angiographically proven NIDC, LV ejection fraction (EF) < 45%, NYHA class II-III, were randomised to either Nebivolol (target dose 5 mg) or placebo and were evaluated using echocardiography and exercise tests over 3 months. RESULTS: There were no baseline differences between the 2 groups regarding NYHA class, heart rate (HR), blood pressure (BP), LVEF or other echocardiographic variables. During follow-up, 4 patients in the Nebivolol and 5 in the placebo group discontinued treatment. After 3-months' treatment a significant decrease in NYHA class (p = 0.001), resting HR (p = 0.03), systolic and diastolic BP (both p < 0.001), left atrial diameter (p = 0.01) and LV end-systolic volume (p = 0.046), and an increase in LVEF (p = 0.01) were observed in the Nebivolol group compared to placebo. The atrial contribution to total LV filling (p = 0.007) and the pulmonary venous (PV) systolic wave velocity (p = 0.007) increased, whereas the atrial PV component decreased (p < 0.001) in the Nebivolol patients compared to placebo. Exercise duration decreased at 3 months (p = 0.01) compared to placebo, probably as a result of reduced maximal exercise HR (p < 0.001). CONCLUSIONS: Nebivolol is a safe and well-tolerated drug that improves NYHA class, systolic and diastolic LV function in NIDC patients, although it is associated with a lower maximal exercise duration at 3 months.

Adrenergic beta-Antagonists↗

PubMed2006

Reduced pulmonary function in children with the Fontan circulation affects their exercise capacity.

Most children with functionally univentricular hearts nowadays are treated surgically by creating a total cavopulmonary connection. In the resulting Fontan circulation, the venous return and the pulmonary arterial bed are coupled in series, bypassing the heart. This gives the potential for interaction between the abnormal circulation and function of the lungs. In this study, we investigated the pattern of impairment of pulmonary function, and its relation to decreased exercise capacity. We performed spirometry in 33 (85 percent) of 39 eligible Norwegian children, aged from 8 to 16, with a total cavopulmonary connection, along with whole body plethysmography, the carbon monoxide single breath test, and a peak treadmill exercise test. The single breath test showed a mean corrected diffusing capacity of 66.5 percent of predicted, giving a z score of minus 2.88. The mean residual volume measured by whole body plethysmography was 146.8 percent, equivalent to a z score of 2.46, whereas the mean residual volume measured by the single breath test was 102.4 percent of predicted, this being the same as a z score of 0.43. The mean peak treadmill exercise test was 70.0 percent of predicted, equivalent with a z score of minus 3.07. Mean forced vital capacity was 85.7 percent of predicted, the equivalent z score being minus 0.92. Lung function correlated with the peak treadmill exercise test. We have shown, therefore, that children with the Fontan circulation have reduced diffusing capacity, possibly caused by the abnormal circulation through the lungs. The difference between residual volume measured by plethysmography and the single breath test implies trapping of air. The correlation of parameters for lung function with peak consumption of oxygen during exercise indicates that the abnormalities of pulmonary function may affect physical capacity.

Adolescent↗

PubMed1989

[Effectiveness of diltiazem in controlling ventricular response and improving exercise capacity in chronic atrial fibrillation. Double-blind, cross-over study].

Although digoxin is often the drug of choice to control the ventricular response in chronic atrial fibrillation, it fails to control exercise-induced increase in heart rate. The efficacy of diltiazem to control ventricular response and to improve cardiovascular performance during maximal exercise was investigated in 13 digitalized patients with chronic atrial fibrillation. A placebo controlled prospective randomized double-blind study, was preceded by open titration phase. During the diltiazem treatment phase, mean ventricular response diminished at rest (85 +/- 12 versus 107 +/- 19 during digoxin therapy and versus 101 +/- 18 during digoxin and placebo therapy; p less than 0.001), as well as during maximal exercise (142 +/- 13 versus 159 +/- 17 during digoxin treatment and versus 160 +/- 14 during digoxin plus placebo treatment; p less than 0.001). During exercise (50 W), in a subgroup of 7 patients, mean ventricular rate dropped: 109 +/- 19 versus 142 +/- 21 during digoxin treatment and versus 143 +/- 17 during digoxin plus placebo treatment; p less than 0.001). In all patients, the mean rate at rest decreased about 19.3 +/- 6.9% and at maximal exercise about 10.3 +/- 4.9%. In the subgroup of the 7 patients ventricular mean rate at a load of 50 W decreased about 23.6 +/- 7.9%. In all the patients, maximal exercise capacity improved: the MET mean value increased from 3.59 +/- 1.3 to 4.52 +/- 1.18 (p less than 0.001); the mean value of the maximum exercise (MEC), according to the Redfords formula, increased from 65 +/- 48 to 132 +/- 70 (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Fibrillation↗

PubMed1986

Influence of transdermal nitrates on exercise capacity in patients with stable angina.

Twenty patients completed a double-blind cross-over study to determine the influence of a transdermal preparation of Nitroglycerin on exercise performance in stable angina. Angiographically proven two or three vessel coronary disease was present in all. After a base-line exercise test the active device was titrated to efficacy or side effects and the number of patches thereafter remained constant (2-6 patches per day; mean 3.5). Patients were randomly allocated to active treatment or placebo, and further exercise tests were performed at 2 hours and 26 hours after application of the device. Patients were then crossed over after one days rest to the opposite treatment group, and exercise studies repeated. Two hours after application of transdermal nitroglycerin total exercise duration increased (mean 14.0 minutes) compared to placebo (12.5 minutes) and control (12.0 minutes) (p less than 0.05). This effect was maintained at 26 hours. Exercise time to anginal threshold (angina + 1.5 mm ST segment depression) was increased at 2 hours and 26 hours with active drug by 11% compared to placebo and by 22% in comparison to control. Double product of heart rate and blood pressure was not significantly different in treated and placebo groups. Oral nitroglycerin consumption assessed during the titration phase was reduced by 71%. It is concluded that transdermal nitroglycerin significantly increases exercise capacity in patients with stable angina, with an effect that is maintained over a 24-hour period using a single dose application.

Administration, Topical↗

PubMed1991

Left and right ventricular systolic function and exercise capacity with coronary artery disease.

This prospective study of symptom-limited supine ergometry was conducted to determine the contributions of right ventricular (RV) and left ventricular (LV) systolic function to the exercise capacity of a cohort of patients with coronary artery disease (CAD). Patients with unstable angina, angiographically proven CAD (n = 53) and stable symptoms after medical therapy or angioplasty were included. Documented myocardial infarction (greater than or equal to 2 weeks before exercise) was present in 43 of 53 patients. Angina was the limiting symptom in 11 of 53; the other 42 stopped exercise with dyspnea or fatigue, or both. Oxygen consumption was measured on-line during exercise with a metabolic cart. RV ejection fraction and LV ejection fraction were measured by validated methods from gated blood pool radionuclide ventriculography. There were weak but statistically significant correlations between exercise oxygen consumption and exercise RV ejection fraction (r = 0.30, p less than 0.05) and between exercise oxygen consumption and exercise LV ejection fraction (r = 0.38, p less than 0.01). Multivariate regression analysis, including exercise RV ejection fraction, exercise LV ejection fraction and exercise heart rate versus exercise oxygen consumption revealed a better relation (r = 0.48, p less than 0.005) than any variable in univariate regression. The values of RV and LV ejection fraction at rest did not correlate significantly (r = 0.2, difference not significant), but the exercise values did correlate weakly (r = 0.41, p less than 0.01). The reserve of LV ejection fraction, defined as exercise minus rest value, correlated weakly with exercise oxygen consumption (r = 0.32, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗

PubMed1983

A new oral slow release form of isosorbide dinitrate. Effect on the hemodynamics and exercise capacity of patients with angina.

To assess the bioavailability of a new oral and slow release form of isosorbide dinitrate (ISDN-SR), we evaluated 12 patients with confirmed coronary artery disease, chronic stable angina pectoris and abnormal maximal exercise tests (angina-limited and associated with greater than or equal to 0.1 mV ST displacement). Each patient was known to have an increased exercise time after 0.4 mg of sublingual nitroglycerin. Patient responses to exercise on the treadmill at two, four, six, and eight hours after the double-blind administration of 40 mg of ISDN-SR were compared to an identical placebo. It is concluded that 40 mg of this slow release form of isosorbide dinitrate is bioavailable for at least eight hours as demonstrated by significantly improved exercise capacity of the majority (64 percent) of angina patients in this study, each of whom demonstrated anginal limitation to exercise and favorable responses to 0.4 mg of sublingual nitroglycerin.

Administration, Oral↗

PubMed1994

Absence of effect on exercise capacity of 12-weeks treatment with ramipril in patients with moderate congestive heart failure. Ramipril Study Group.

Pharmacological therapy in cases of chronic congestive heart failure (CHF) is usually evaluated by maximal exercise time. To assess the effect of an angiotensin converting enzyme inhibitor, ramipril, 223 patients with moderate CHF were studied in 24 centres in four Nordic countries in a randomized, double-blind, placebo-controlled, parallel group design. The study drug was titrated from 1.25 mg to a maximum of 10 mg once daily (o.d) over a period of 4 weeks (mean dose 8 mg). A symptom-limited bicycle exercise test, starting at 30 watts and increasing by 10 watts.min-1, was used to evaluate exercise capacity. Reproducible tests were required at baseline, and the test was repeated after 4, 8 and 12 weeks of treatment. Seven deaths were recorded in the placebo group and one death in the ramipril group. A total of 195 patients completed 12 weeks of treatment (placebo group n = 91, ramipril group n = 104). The groups had similar baseline characteristics. Maximal exercise time was increased by mean (SD) 35 s (9) and 41 s (8) in the placebo and ramipril groups, respectively. The adjusted difference between the groups at 12 weeks was 9 s (12) (ns). A significant decrease in blood pressure and rate-pressure product at rest and at end of exercise was obtained by ramipril as compared with placebo. Significantly fewer patients deteriorated in NYHA class from baseline to 12 weeks of ramipril treatment compared to placebo (P = 0.012). Concomitant medication for CHF increased significantly in the placebo group as compared with ramipril-treated patients (P = 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Output, Low↗

PubMed1983

Effects of travel across time zones (jet-lag) on exercise capacity and performance.

Eighty-one healthy male soldiers, aged 18-34, were studied for 5 d before and 5 d after an eastward deployment across six time zones to determine the effects of translocation on exercise capacity and performance. Fatigue, weakness, headache, sleepiness, irritability, and other commonly reported symptoms occurred in the majority of subjects. Most, but not all, of the symptoms were diminished or absent by the fifth day following the translocation. Cardiorespiratory function and perception of effort during both submaximal and maximal treadmill exercise were unaffected. Isometric strength of the upper torso, legs, and trunk extensor muscles also was not changed. Dynamic strength and endurance of elbow flexors declined significantly. Dynamic knee extensor strength and endurance scores exhibited a progressive decrement prior to translocation and were inconsistent suggesting that the stress of repetitive testing outweighed any jet-lag effects on performance capacity. Performance times for a 270 m sprint were increased for the first 4 d following translocation as were times for a 2.8 km run on the second and third days and for a 110 m lift and carry on the third day after deployment. Times for a 6.5 m rope climb did not change. These findings indicate that certain symptoms and physiological capacities are affected as a result of multiple time zone translocation. However, the specific mechanisms involved, the factors influencing the magnitude of any physiological alterations, and the ultimate impact of these capacity changes on actual physical performance remain to be clarified.

Adaptation, Physiological↗

PubMed1980

Preoperative exercise capacity in symptomatic patients with aortic regurgitation as a predictor of postoperative left ventricular function and long-term prognosis.

Forty-five symptomatic patients with aortic regurgitation underwent graded treadmill exercise testing before operation. Twenty-seven patients (group A) could not complete stage I of the National Institutes of Health exercise protocol because of limiting symptoms (exercise duration less than or equal to 22.5 minutes); 18 patients (group B) completed this stage without limiting symptoms (exercise duration > 22.5 minutes). Patients in group A had higher resting pulmonary capillary wedge pressures (mean 19 vs 13 mm Hg, p < 0.05) and left ventricular (LV) end-diastolic pressures (mean 24 vs 16 mm Hg, p < 0.05) than those in group B, but did not differ with respect to LV systolic dimension or fractional shortening by echocardiography or LV ejection fraction at rest or during exercise by radionuclide cineangiography. Among 32 patients with subnormal preoperative LV fractional shortening on echo, nine of 17 in group A and 0 of 15 in group B have died (p < 0.01); seven of the nine deaths were from late congestive heart failure. Group A patients also had less decrease postoperatively in LV diastolic size by echocardiography (mean decrease 8 vs 23 mm, p < 0.001) and less increase postoperatively in LV ejection fraction during exercise by radionuclide cineangiography (mean increase 11% vs 23%, p 0.05) than group B patients. No group A patient and 60% of group B patients had normal exercise ejection fractions postoperatively (p < 0.01). The differences in postoperative mortality and function were not predicted by the differences in preoperative hemodynamics between the two groups. Thus, exercise capacity is imprecise in assessing preoperative LV function in symptomatic patients with aortic regurgitation, but is useful in predicting long-term survival after operation and reversibility of LV dilatation and systolic dysfunction.

Adult↗

PubMed2005

Impact of the exercise mode on exercise capacity: bicycle testing revisited.

STUDY OBJECTIVE: To test the performance of a tool designed to estimate functional capacity in order to select a bicycle ramp protocol yielding a test duration from 8 to 12 min in healthy individuals, and to assess differences in exercise responses between bicycle and treadmill tests. PARTICIPANTS AND MEASURES: Forty-one healthy and physically active volunteers (10 women; median age, 37 years; interquartile range [IQR], 29.5 to 41 years) performed an individualized ramp exercise protocol on a bicycle ergometer and a treadmill in random order. Prior to testing, the Veterans Specific Activity Questionnaire (VSAQ) combined with a modified variant of the VSAQ nomogram (metabolic equivalents [METs] derived from VSAQ and age with the modified nomogram, resulting in METs nomogram) was used to estimate exercise capacity and to select the treadmill protocol. The corresponding bicycle work capacity nomogram (in watts) was derived by the following equation: (METs nomogram - 1) x body weight/3.486. RESULTS: Using treadmill tests, all 41 participants (100%) achieved maximal exercise from 8 to 12 min, as compared to 33 participants (80%) for the bicycle tests (p = 0.003). Peak oxygen uptake (V(O2)) [bicycle: median, 49.7 mL/kg/min (IQR, 45.4 to 56.6 mL/kg/min); vs treadmill: median, 53.1 mL/kg/min (IQR, 47.3 to 57.7 mL/kg/min; p < 0.0001)] was lower using the bicycle compared to the treadmill. However, the difference in peak V(O2) values between the two exercise modes was lower (2.6 mL/kg/min; IQR, 1.1 to 4.3 mL/kg/min), corresponding to 4.6% (IQR, 2.4 to 8.5%) of the lower of both values than reported in previous studies, and seven participants (17%) even achieved a higher peak V(O2) using the bicycle. CONCLUSIONS: A modified version of the VSAQ can be effectively used to select appropriate ramp rates for exercise testing using a bicycle ergometer in healthy individuals. Differences in maximal responses are less than those previously reported, suggesting that the bicycle ergometer is an appropriate alternative to the treadmill test in healthy volunteers.

Activities of Daily Living↗

PubMed2000

Polymorphisms of the beta(2)-adrenergic receptor determine exercise capacity in patients with heart failure.

The beta(2)-adrenergic receptor (beta(2)AR) exists in multiple polymorphic forms with different characteristics. Their relevance to heart failure (HF) physiology is unknown. Cardiopulmonary exercise testing was performed on 232 compensated HF patients with a defined beta(2)AR genotype. Patients with the uncommon Ile164 polymorphism had a lower peak VO(2) (15.0+/-0.9 mL. kg(-1). min(-1)) than did patients with Thr164 (17.9+/-0.9 mL. kg(-1). min(-1), P<0.0001). The percentage achieved of predicted peak VO(2) was also lower in patients with Ile164 (62. 3+/-4.5% versus 71.5+/-5.1%, P=0.045). The relative risk of a patient having a VO(2) </=14 mL. kg(-1). min(-1) who had Ile164 was 8.0 (P=0.009). Catheterization-based invasive exercise testing revealed depressed changes in the exercise-induced cardiac index, systemic vascular resistance, stroke volume, and VO(2) in patients with Ile164. The polymorphisms at position 16 also impacted exercise capacity: peak VO(2) for Arg16 versus Gly16 was 17.0+/-0.8 versus 15. 6+/-0.5 mL. kg(-1). min(-1), respectively (P=0.03). Because the polymorphisms at loci 16 and 27 can occur together, 4 homozygous combinations exist. Patients with Arg16/Glu27 had the highest percentage achieved of predicted peak VO(2) (75. 7+/-6.4%), whereas those with Gly16/Gln27 had the lowest (55.3+/-2. 8%, P=0.0032). The above findings were not confounded by baseline clinical characteristics, including beta-blocker usage. We conclude that the beta(2)AR polymorphisms Ile164, Gly16, and the combination of Gly16 and Gln27 are associated with depressed exercise performance in HF and represent a genetically determined factor in the pathophysiology of HF.

Alleles↗