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PubMed2006

Relationship between maximal exercise capacity and walking capacity in adult hemiplegic stroke patients.

OBJECTIVE: To evaluate the relationship between maximal exercise capacity and walking capacity in hemiplegic stroke patients. DESIGN: An uncontrolled observational study was conducted in the physical medicine and rehabilitation unit in an academic hospital. Participants were 21 hemiplegic stroke patients (18 men, 3 women; age, 18-70 yrs) whose stroke occurred >3 mos before the study and who could walk independently with or without walking aids. Main outcome measures were peak oxygen uptake, workload, walking capacity, and motor impairment. RESULTS: There was a significant correlation between walking capacity (6-min-walk test) and both peak oxygen uptake (r=0.602, P=0.0032) and maximal power output (r=0.867, P<0.0001). CONCLUSIONS: Aerobic capacity and walking capacity are decreased in hemiplegic stroke patients and are correlated with each other. These results underscore the need for future studies, to confirm the role of fitness in relation to walking capacity, and to evaluate the benefit of integrating aerobic training into more traditional rehabilitation programs after stroke.

Adolescent↗
PubMed1989

Reduced exercise capacity of chronic obstructive pulmonary disease patients exercising with noseclip/mouthpiece.

A noseclip and low resistance mouthpiece are often used to monitor exhaled gases during exercise. Because otolaryngologic studies suggest that 50% of airway resistance is in the nose and mouth, it was hypothesized that patients with advanced chronic obstructive pulmonary disease might be artifactually limited by exercise testing with a noseclip and mouthpiece. Accordingly, 12 patients with stable chronic obstructive pulmonary disease performed identical symptom-limited supine bicycle exercise tests with and without noseclip and mouthpiece. Right-sided cardiac hemodynamic measurements, radionuclide ventriculography and arterial and mixed venous gas sampling were performed during each exercise test. Exhaled gases were analyzed during the noseclip/mouthpiece exercise. The order of exercise tests was alternated. Comparing exercises with and without a noseclip, there were significant reductions in exercise duration (397 +/- 270 vs 300 +/- 230 seconds, p less than 0.01), exercise oxygen consumption (780 +/- 279 vs 638 +/- 200 ml/min, p less than 0.01) and exercise cardiac output (8.4 +/- 2.7 vs 7.3 +/- 2.0 liters/min, p less than 0.05), an increase in right ventricular ejection fraction (0.39 +/- 0.08 vs 0.43 +/- 0.08, p less than 0.01) and no change in exercise heart rate (106 +/- 14 vs 106 +/- 14), right-sided cardiac pressures or arterial and mixed venous blood gases. These data suggest that a noseclip/mouthpiece can limit exercise tolerance in advanced chronic obstructive pulmonary disease patients. This limitation may result from decreased right-sided cardiac preload (venous return).

Adult↗
PubMed2001

Submaximal exercise capacity and maximal power output in polio subjects.

OBJECTIVES: To compare the submaximal exercise capacity of polio subjects with postpoliomyelitis syndrome (PPS) and without (non-PPS) with that of healthy control subjects, to investigate the relationship of this capacity with maximal short-term power and quadriceps strength, and to evaluate movement economy. DESIGN: Cross-sectional survey. SETTING: University hospital. PARTICIPANTS: Forty-three polio subjects (25 PPS, 18 non-PPS) and 12 control subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Power output, oxygen uptake, and heart rate were measured in an incremental submaximal cycle ergometry test. Maximal short-term power was measured in 5-second all-out efforts. Knee extensor strength was measured on a chair dynamometer. RESULTS: The mean submaximal power +/- standard deviation at 80% of heart rate reserve of 83.8 +/- 29.9 watts in the polio subjects was significantly less than the mean submaximal power of 142.1 +/- 30.4 watts in the control group. However, expressed as a percentage of the maximal short-term power, submaximal power did not differ between the groups. Strength and maximal short-term power correlated significantly (p < .005) with submaximal power (r = .64 and .76, respectively). The oxygen uptake was higher than theoretically expected for the given submaximal power output in polio subjects, and appeared to increase with increasing asymmetry in strength and power between legs. No differences were found between PPS and non-PPS subjects. CONCLUSION: The submaximal work capacity of polio subjects was severely reduced, mainly in association with the reduced muscle capacity. And, because of a reduced movement economy, their energy cost was elevated. Although muscle loads in activities such as walking and climbing stairs differ from cycling, they also may require elevated relative levels of effort, predisposing subjects to premature fatigue in sustained activity.

Adult↗
PubMed2006

Exercise capacity is a predictor of cardiovascular events in patients with type 2 diabetes mellitus.

Peak exercise oxygen consumption (peak VO2), as measured by expired gas analysis, is an accurate, reproducible and reliable method for determining exercise capacity. In this study, a cohort of 468 patients with type 2 diabetes underwent graded exercise testing to measure peak VO2 at baseline; the cohort was followed for five years for the occurrence of cardiovascular disease (CVD) events. Patients who developed CVD events during the five-year follow-up period were found to have significantly lower baseline peak VO2, as compared to those who did not (p = 0.02). Analysis by gender showed that the mean peak VO2 in male patients who developed CVD events was significantly lower than the peak VO2 in those who did not (p < 0.03). Multiple Cox regression analysis also showed low peak VO2 to be an independent factor. In conclusion, patients with type 2 diabetes mellitus with reduced peak VO2 during exercise have a greater tendency to develop future CVD events.

Adult↗
PubMed1988

The effect of iron therapy on the exercise capacity of nonanemic iron-deficient adolescent runners.

Iron-deficiency anemia impairs exercise capacity, but whether nonanemic iron depletion decreases endurance performance is unclear. In 14 iron-deficient (serum ferritin level, less than 20 micrograms/L [less than 20 ng/L])nonanemic runners, hematologic and treadmill running values were followed up during a competitive season. Following a four-week control period, runners were treated for one month in a double-blind protocol with ferrous sulfate (975 mg/d) or placebo. During treatment, the mean ferritin level rose from 8.7 to 26.6 micrograms/L (8.7 to 26.6 ng/mL) in those patients taking iron and fell from 10.6 to 8.6 micrograms/L (10.7 to 8.6 ng/mL) in the placebo group. Treadmill endurance times improved significantly in the iron-treated runners compared with controls. Endurance time declined in all seven controls (range, 0.07 to 1.30 minutes), while six of seven iron-treated subjects improved their performance (range, 0.03 to 1.92 minutes). No significant differences in maximal or submaximal oxygen consumption, ventilation, or heart rate were observed between the groups except for a 4% increase in maximum oxygen consumption during placebo treatment. These data indicate that nonanemic iron deficiency impairs exercise performance but does not influence gas exchange or cardiac measures.

Adolescent↗
PubMed1983

Exercise capacity of the patients with myocardial infarction.

This study was conducted to investigate the functional capacity in postmyocardial infarction. Eighty-four multistage treadmill exercise tests were performed on 60 patients, none of whom had had any formal rehabilitation or regular exercise. There were 50 men and 10 women, ranging in age from 30 to 81 with an average age of 60. The time interval between the acute attack and the exercise test ranged from one month to 9 years. Even though severe infarction affects the exercise capacity for a long time after an acute attack, its effect on cardiac function was more obvious than that on physical capacity. Age was the most important determinant of physical capacity, and the slope of decreasing physical capacity with age in patients with infarct was the same as that in normal subjects. Cardiac function also decreased with age. However, during the early recovery phase, cardiac function was influenced by the severity of infarction and the influence of age could not be established. There was no significant correlation between early ambulation and physical capacity. The beneficial effects of early ambulation may be lost if physical activity is discontinued for some time after the acute attack. The physical capacity increased 2-3 years after the acute attack, but myocardial function did not change significantly.

Adult↗
PubMed1993

Effects of rHuEPO therapy on exercise capacity in hemodialysis patients with coronary artery disease.

We investigated the effects of recombinant human erythropoietin (rHuEPO) therapy on exercise capacity by symptom-limited maximal treadmill exercise testing in 9 patients with coronary artery disease who were receiving maintenance hemodialysis. The initial hemoglobin concentration of 7.9 +/- 0.7 g/dl, (mean +/- S.D.) rose to 10.4 +/- 1.1 g/dl, (p < 0.01) after three months of rHuEPO therapy. The partial correction of renal anemia resulted in a significant increase in exercise duration (from 278 +/- 84 sec to 384 +/- 74 sec, p < 0.01) and maximum pressure-rate product (from 228.3 +/- 50.3 mmHg.bpm/10(2) to 262.8 +/- 40.4 mmHg.bpm/10(2), p < 0.01). The maximum exercise-induced ST segment depression significantly decreased after treatment (from 1.3 +/- 0.5 mm to 0.5 +/- 0.5 mm, p < 0.05). These results suggest that the improvement in maximum coronary oxygen supply exceeded the increased maximum myocardial oxygen requirements after the partial correction of renal anemia by rHuEPO therapy in hemodialysis patients with coronary artery disease.

Adult↗
PubMed1989

The influence of dialysis solution on the exercise capacity in patients on CAPD.

The present study was conducted to see whether the exercise capacity can be altered by intraperitoneal dialysis solution in patients on CAPD. Symptom-limited progressive treadmill tests with respiratory gas analysis were performed in patients on long-term CAPD, and exercise time (ET), maximal oxygen uptake (VO2 max) and ventilatory anaeorbic threshold (AT) were obtained. The treadmill tests were carried out before and after the drainage of 2-liters of dialysis solution. The dialysate bag with the fluid had either been carried by patients on their backs (test A) or been kept apart from their bodies (test B) during exercise, i.e. an apparent body weight in test B without the CAPD bag decreased by 2 kg as compared with the control. VO2max, AT or ET in test A did not change, whereas ET in the test B was prolonged after the drainage of dialysis solution (before: 437 +/- 170 sec, after: 479 +/- 158 sec, n = 10, p less than .01). No change was noted in VO2max or AT in test B. We conclude that the dialysis solution retained in the peritoneal cavity affects ET by acting as an extra-weight, although the solution has no influence on VO2max and AT.

Adult↗
PubMed1990

[Changes in exercise capacity and in induced ischemia with an oral dose of 5 isosorbide mononitrate in patients with stable angina pectoris].

In order to establish the effects of 5-isosorbide mononitrate on: the exercise capacity, the onset period of angina and ischemia along with the degree and on whether the duration time was prolonged up to 5 hours after the oral administration of 20 mg of this drug, we compare this drug against a placebo in a group of 15 patients with stable angina pectoris developed by effort who performed an exercise test using a bicycle ergometer. After the administration of 20 mg of 5-isosorbide mononitrate it was observed that onset time of angina (p less than 0.001), the onset time of ST decrease (p less than 0.002) and total time of exercise attained were significantly superior to those found in patients with placebo administration. Moreover, for the same degree of EKG ischemia (ST decrease) showed a superior exercise time was registered (p less than 0.002) after the administration of 5-isosorbide mononitrate (5-IM). Our results show that an oral dosage of 20 mg of 5-IM given to patients with stable angina pectoris increased the capacity and exercise tolerance delaying significantly the onset time of angina, the onset time of EKG ischemia and its decree induced by the effort up to 5 hours after its administration.

Administration, Oral↗
PubMedDate not supplied

A comparison of treadmill and arm-leg ergometry exercise testing for assessing exercise capacity in patients with peripheral arterial disease.

PURPOSE: To compare the results of treadmill exercise testing (TM) to arm-leg ergometry testing (AL) in patients with peripheral arterial disease (PAD). METHODS: Twelve men and 8 women with PAD (mean age, 62 +/- 10 years) completed a treadmill test and an arm-leg ergometer exercise test. Oxygen uptake, heart rate, rate-pressure product (x10(-3)), ratings of claudication and perceived exertion, and power were measured. RESULTS: Peak oxygen uptake, heart rate, and rate-pressure product were similar between TM and AL. Exercise duration was longer and the peak power higher on the AL than on the TM. Claudication pain > or =3/4 was the reason for test termination in all subjects during TM test and in 13 subjects during AL. Nine patients discontinued due to severe claudication on both tests, but the pain occurred later in AL than TM. CONCLUSIONS: Although peak oxygen uptake was similar between the 2 exercise tests, patients with PAD exercised longer and to a higher peak power during the AL. These data suggest that the AL test may be used to evaluate peak exercise capacity in patients with PAD. The AL may also provide an alternate method for detecting PAD and coronary heart disease.

Aged↗
PubMed1999

Pulmonary gas exchange and exercise capacity in patients with systemic lupus erythematosus.

OBJECTIVE: Exercise tolerance is often reduced in patients with systemic lupus erythematosus (SLE). Mechanisms have been proposed but the underlying causes have not yet been elucidated. The study of pulmonary gas exchange during exercise may be helpful in revealing circulatory, ventilatory, and metabolic abnormalities. We hypothesized that in SLE, exercise aerobic capacity would be reduced due to chronic inactivity and poor muscle energetics. METHODS: Thirteen women with SLE and low disease activity were studied; 5 age matched subjects served as controls. Clinical examination, chest radiography, electrocardiogram, and pulmonary function test were all normal. Subjects underwent 1 min incremental cycle ergometer exercise to exhaustion. Oxygen uptake (VO2), CO2 output (VCO2), minute ventilation (VE), heart rate (HR), and arterial O2 saturation were monitored. Anaerobic threshold (AT), VO2/HR, deltaVO2/deltaWatt, respiratory rate (RR), Ti/Ttot, VE/VCO2, and breathing reserve (BR) were computed. RESULTS: At rest, patients exhibited high VE, respiratory alkalosis, and a wide alveolar-arterial O2 gradient [(A - a)O2] during 50% O2 breathing. Other indexes of respiratory function were within the normal range. In the 6 patients with SLE where pulmonary artery systolic pressure at Doppler echocardiography was measurable, mean level was in the upper limits of normal. During exercise, maximal aerobic capacity was reduced in all patients (VO2 peak, 1098+/-74 vs. 2150+/-160 ml/min, p<0.01; AT, 36 +/-3 vs. 48+/-3% predicted VO2 max, p<0.05). Ventilation adjusted for the metabolic demand (VE/VCO2 at AT) was increased (31+/-1 vs. 24+/-1; p<0.05). A normal breathing pattern was observed during all tests. No patient stopped exercising because of ventilatory limitation (i.e., they had normal breathing reserve). CONCLUSION: Reduced muscle aerobic capacity is common in SLE and is most likely because of peripheral muscle deconditioning. Increased ventilatory demand, secondary to diffuse interstitial lung disease, is not a significant contributor to the reduction in exercise tolerance.

Adult↗
PubMed2004

Test of the principle of initial value in rat genetic models of exercise capacity.

An inverse relationship between initial level of physical capacity and the magnitude of response to training is termed the principle of initial value. We tested the operation of this principle under experimental conditions of minimal genetic and environmental variation. Inbred rat strains previously identified as genetic models of low [Copenhagen (COP)] and high [Dark Agouti (DA)] intrinsic (untrained) exercise capacity were trained for 8 wk on a treadmill using two disparate protocols: 1) a relative mode where each rat exercised daily according to its initial capacity, and 2) an absolute mode where both strains received the same amount of training independent of initial capacity. Response to exercise was the change in running capacity as estimated by meters run to exhaustion before and after training. When trained with the relative mode, COP rats gained 88 m (+21%; NS) whereas DA rats increased distance run by 228 m (+36%; P < 0.001). When each strain trained with the same absolute amount of training, the COP strain showed essentially no change (-6 m, -2%) and the DA strain gained 325 m (+49%; P < 0.009). Differences in response to exercise between the COP and DA could not be explained by body mass differences, oxidative enzyme activity (citrate synthase or ATP), or spontaneous behavioral activity. Our data demonstrate that genetic factors causative of high response to exercise are not uniquely associated with genetic factors for low intrinsic capacity and thus are not in accord with the principle of initial value.

Adaptation, Physiological↗
PubMed1995

Pulmonary rehabilitation improves exercise capacity in older elderly patients with COPD.

Pulmonary rehabilitation has been shown to improve exercise capacity in patients with COPD. It has been suggested that this improvement applies to all age groups; however, to our knowledge, the effects of pulmonary rehabilitation on older elderly patients (> or = 75 years of age) have not been studied. We compared changes in 12-min walking distance (12MD) and self-assessment scores in 47 older elderly patients with moderate to severe COPD who completed inpatient or outpatient pulmonary rehabilitation with those achieved by 87 younger patients who participated in the same programs from 1987 to 1992. There were 28 older elderly individuals (mean +/- SEM, 78 +/- 1 years) in the outpatient group and 56 younger patients (64 +/- 1 years). There were no differences between older and younger outpatients with respect to FEV1, FEV1/FVC, maximum inspiratory pressure (PImax), baseline 12MD, or baseline self-assessment score. After outpatient pulmonary rehabilitation, 12MD and self-assessment scores improved significantly in both groups. Inpatients included 19 older elderly individuals (81 +/- 1 years) who were also similar to the 31 younger inpatients (64 +/- 1 years) in FEV1, FEV1/FVC, PImax, and baseline self-assessment score, but they tended to be more limited in terms of baseline 12MD (p = 0.09). After inpatient pulmonary rehabilitation, significant improvements in 12MD and self-assessment were seen in both groups. We conclude that comprehensive outpatient and inpatient pulmonary rehabilitation programs are as beneficial in older elderly patients with COPD as they are in younger patients with similar lung function abnormalities. Patients 75 years of age or older should be considered for comprehensive pulmonary rehabilitation.

Aged↗
PubMed2002

Effect of naloxone on perceived exertion and exercise capacity during maximal cycle ergometry.

We assessed the effects of naloxone, an opioid antagonist, on exercise capacity in 13 men and 5 women (mean age = 30.1 yr, range = 21-35 yr) during a 25 W/min incremental cycle ergometer test to exhaustion on different days during familiarization trial and then after 30 mg (iv bolus) of naloxone or placebo (Pl) in a double-blind, crossover design. Minute ventilation (Ve), O(2) consumption (Vo(2)), CO(2) production, and heart rate (HR) were monitored. Perceived exertion rating (0-10 scale) and venous samples for lactate were obtained each minute. Lactate and ventilatory thresholds were derived from lactate and gas-exchange data. Blood pressure was obtained before exercise, 5 min postinfusion, at maximum exercise, and 5 min postexercise. There were no control-Pl differences. The naloxone trial demonstrated decreased exercise time (96% Pl; P < 0.01), total cumulative work (96% Pl; P < 0.002), peak Vo(2) (94% Pl; P < 0.02), and HR (96% Pl; P < 0.01). Other variables were unchanged. HR and Ve were the same at the final common workload, but perceived exertion was higher (8.1 +/- 0.5 vs. 7.1 +/- 0.5) after naloxone than Pl (P < 0.01). The threshold for effort perception amplification occurred at approximately 60 +/- 4% of Pl peak Vo(2). Thus we conclude that peak work capacity was limited by perceived exertion, which can be attenuated by endogenous opioids rather than by physiological limits.

Adult↗
PubMed1994

Significance for exercise capacity of some electrocardiographic findings in racehorses.

Various cardiorespiratory and metabolic indices were assessed during treadmill exercise in Thoroughbred and Standardbred racehorses with T wave changes in 4 or more leads on the electrocardiogram or second-degree atrio-ventricular (AV) block, and in horses that had no abnormalities on clinical examination, resting electrocardiography or upper respiratory tract endoscopy. No significant differences in heart rate, plasma lactate concentration, arterial blood gases, oxygen uptake, run time, peak velocity, or blood and red cell volumes were found between normal horses and horses with T wave changes or second-degree AV block. These results indicate that some electrocardiographic findings that are considered by some clinicians to indicate cardiac dysfunction, may have little effect on exercise capacity.

Animals↗
PubMed1993

Triiodothyronine, beta-adrenergic receptors, agonist responses, and exercise capacity.

Although thyroid hormone excess results in increased beta-adrenergic receptor density or agonist responses in some cells of experimental animals, the role of these effects in contributing to clinical manifestations of hyperthyroidism in human subjects is unclear. To shed further light on this issue, we characterized the effect of 2 weeks of excess triiodothyronine administration on cardiac and metabolic responses to graded-dose isoproterenol infusion, skeletal muscle beta-adrenergic receptor density, and physiologic determinants of exercise capacity in young healthy subjects. The slope of the heart rate response to isoproterenol was 36% greater (p < 0.05) after triiodothyronine administration. In addition, beta-adrenergic receptor density was increased (p < 0.01) in all types of skeletal muscle fibers. Maximal oxygen uptake during treadmill exercise declined 5% (p < 0.001) after triiodothyronine administration because of a decrease in the arteriovenous oxygen difference (p < 0.05). The plasma lactate response to submaximal exercise was 25% greater (p < 0.01) in the hyperthyroid state. These effects were paralleled by a decrement in skeletal muscle oxidative capacity and a decrease in cross-sectional area of type 2A skeletal myocytes. Thus, thyroid hormone excess enhances cardiac beta-adrenergic sensitivity under in vivo conditions in human subjects. Nevertheless, exercise capacity is diminished in the hyperthyroid state, an effect that may be related to reduced skeletal muscle oxidative capacity and type 2A fiber atrophy.

Adult↗
PubMed2002

Angiotensin-converting enzyme genotype modulates pulmonary function and exercise capacity in treated patients with congestive stable heart failure.

BACKGROUND: The gene encoding ACE exhibits an insertion/deletion polymorphism resulting in 3 genotypes (DD, ID, and II), which affects serum and tissue ACE activity as well as other vasoactive substances. Pulmonary function is frequently abnormal in patients with congestive heart failure (CHF), the mechanism of which has not been completely characterized. ACE inhibition has been shown to improve diffusion across the alveolar-capillary membrane and to improve exercise capacity and gas exchange in CHF. The aim of the current study was to determine if ACE genotype is associated with altered pulmonary function and exercise intolerance in patients with treated CHF. METHODS AND RESULTS: Fifty-seven patients (stratified according to ACE genotype as 17 DD, 28 ID, 12 II) with ischemic and dilated cardiomyopathy, left ventricular ejection fraction (LVEF) <35%, and <10 pack-years of smoking history were studied. All patients were receiving standard therapy for left ventricular systolic dysfunction. Pulmonary function, LVEF, serum ACE, plasma angiotensin II, atrial natriuretic peptide, and brain natriuretic peptide were measured at baseline. Peak VO2 and gas exchange measurements were assessed with graded exercise. Resting LVEF was similar among the genotype groups (25% to 28%), and no differences were observed in diastolic function or pulmonary artery pressures (P>0.05). Mean peak VO2 and forced vital capacity (% Pred) were significantly reduced (P<0.05), whereas mean serum ACE activity and plasma angiotensin II concentration were highest in DD homozygotes. Subjects homozygous for the D-allele also demonstrated higher mean ventilatory equivalents for carbon dioxide (VE/VCO2) during exercise (P<0.05). CONCLUSIONS: ACE DD genotype is associated with decreased exercise tolerance in CHF, possibly mediated by altered pulmonary function. Pharmacological strategies effecting more complete inhibition of serum and tissue ACE and/or potentiation of bradykinin may improve exercise capacity in patients with CHF and ACE DD genotype.

Angiotensin II↗