SEARCH · PubMed Health

Results for “Exercise Tolerance”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources

PubMed1997

Effects of dihydrocodeine on chemosensitivity and exercise tolerance in patients with chronic heart failure.

OBJECTIVES: We sought to test the hypothesis that suppression of chemosensitivity (respiratory response to arterial blood gases) with dihydrocodeine may improve dyspnea and exercise tolerance in patients with chronic heart failure. BACKGROUND: Exertional dyspnea is a common limiting symptom in patients with chronic heart failure. The mechanisms underlying this symptom are not fully understood but may be related to increased ventilation caused, in part, by the augmentation of chemosensitivity. Suppression of chemosensitivity with mild opiates may thus improve this symptom as well as exercise tolerance. METHODS: Twelve men with chronic heart failure (mean [+/-SE] age 65.5 +/- 1.5 years, range 58 to 75; left ventricular ejection fraction 21.3 +/- 3.0%, range 8 to 39) received placebo or dihydrocodeine (1 mg/kg body weight) on two separate days in a randomized, double-blind design. One hour later, hypoxic and hypercapnic chemosensitivities were assessed using the transient inhalations of pure nitrogen and the rebreathing of 7% carbon dioxide in 93% oxygen, followed by treadmill cardiopulmonary exercise testing. The symptoms of dyspnea and fatigue during the exercise test were assessed using a modified Borg scale from 0 to 10. RESULTS: There was a significant fall in hypoxic and hypercapnic chemosensitivities with dihydrocodeine administration compared with placebo (0.447 +/- 0.096 vs. 0.746 +/- 0.104 liter/min per percent arterial oxygen saturation, p = 0.005; 2,480 +/- 0.234 vs. 2.966 +/- 0.283 liter/min per mm Hg, p = 0.01, respectively). Exercise duration was prolonged from 455 +/- 27 s on placebo to 512 +/- 27 s (p = 0.001) with dihydrocodeine, and peak oxygen consumption increased from 18.0 +/- 0.6 to 19.7 +/- 0.6 ml/kg per min (p = 0.002). The ventilatory response to exercise, characterized by the regression slope relating minute ventilation to carbon dioxide output, decreased from 34.19 +/- 2.35 to 30.85 +/- 1.91 (p = 0.01). With dihydrocodeine administration, the change in the modified Borg score for dyspnea was -0.80 (p = 0.003) at 6 min and -0.33 (p = 0.52) at peak exercise, whereas that for fatigue did not change significantly. Arterial oxygen saturation was maintained during exercise despite dihydrocodeine administration (99.3% at rest vs. 98.9% at peak exercise, p = 0.21). CONCLUSIONS: Augmented chemosensitivity is important in the pathophysiology of chronic heart failure. Its suppression with dihydrocodeine was associated with a reduction of exercise ventilation, an improvement in exercise tolerance and a decrease in breathlessness. Pharmacologic modulation of chemosensitivity may benefit patients with chronic heart failure and merits further investigation.

Aged↗

PubMed1977

Portable oxygen and exercise tolerance in patients with chronic hypoxic cor pulmonale.

Breathing 30% oxygen during exercise alleviated arterial hypoxaemia and reduced minute ventilation in patients with severe chronic bronchitis. A similar level of oxygen (2 or 4 litres of oxygen/minute) from nasal prongs also increased their exercise tolerance, as assessed by the distance that they could walk on the level in 12 minutes. Nevertheless, a single-blind controlled study showed that the effort of carrying their portable supply of liquid oxygen, in the Union Carbide Oxygen Walker, abolished this gain in exercise tolerance. The improvement in walking distance was restored when oxygen on exercise was provided by wheeling the oxygen walker on a light-weight shopping trolley.

Arteries↗

PubMed1987

Effects of the platelet inhibitor ticlopidine on exercise tolerance in stable angina pectoris.

Coronary blood flow might be reduced by platelet aggregates or by vasospasm induced by platelet-produced thromboxane A2. Therefore the effects of the platelet inhibitor ticlopidine (500 mg daily) on platelet function and on exercise tolerance were investigated in a double-blind placebo-controlled study in 38 middle-aged men with stable incapacitating angina pectoris. Before and after 4 and 8 weeks of treatment, exercise tests were performed in warm and cold environments. The in vitro platelet reactivity to ADP was determined at rest and the plasma levels of beta-thromboglobulin (BTG) and platelet factor 4 (PF4) were measured before and immediately after exercise. There were no signs of increased platelet activity at rest or after exercise as judged by the levels of BTG and PF4. Despite a potent inhibition of platelet reactivity to ADP in vitro during ticlopidine treatment, the exercise tolerance was reduced in exercise tests in both warm and cold environments and in daily life. Therefore platelet activity does not seem to play any significant role in exercise tolerance in the stable phase of angina pectoris.

Adult↗

PubMed1980

Extremely obese patients: improvements in exercise tolerance with physical training and weight loss.

The relationship between improvements in exercise tolerance and body weight was determined for 11 extremely obese patients (mean entry weight = 189kg) concomitantly participating in progressive physical training (walking-jogging) and severe caloric restriction (600kcal/day) to induce weight loss as part of a residential multidisciplinary rehabilitation program. Two standardized tests (treadmill mile-walk and graded-exhaustive) to quantitatively evaluate exercise performance were administered periodically. Significant weight reductions and improvements in exercise tolerance were observed, with measures of the latter occurring relatively sooner. Correlation coefficients between body weight and performance or physiologic response measures were extremely low, indicating widespread individual responsiveness to training and the probable separateness of training and dietary effects. A moderate inverse correlation was found between body weight and a simple measure of work performance: endurance time to volitional exhaustion (r = -0.45). Training programs of moderate rather than higher intensity, duration, and progression rate were used with this obese group. Such programs can be safely administered and will be well tolerated but therapists should recognize the inability to predict improvements in exercise performance on the basis of the current body weights of individual patients. The major application of results from standardized exercise tests, therefore, resides in direct reinforcement of patient progress.

Adult↗

PubMed1992

Food in chronic heart failure: improvement in central haemodynamics but deleterious effects on exercise tolerance.

Food has been known to have significant central haemodynamic effects for over half a century; it causes an increase in cardiac output and a fall in systemic vascular resistance. These changes are potentially desirable in patients with chronic heart failure but how they relate to exercise tolerance is unknown. This study was designed to examine the haemodynamic effects of food with changes in exercise capability in a group of patients with chronic heart failure. Fifteen patients with chronic heart failure and 10 normal control subjects were studied. They underwent treadmill exercise testing whilst fasting and after a standardized meal. Measurements were made of symptom-limited exercise tolerance, cardiac output, limb blood flow and respiratory gases. Superior mesenteric artery blood flow was measured fasting and postprandially only. Despite an increase in cardiac output, at rest and during exercise, which was not, however, as great as that in the control subjects, the symptom-limited exercise tolerance of the patients fell by 37 s postprandially (P < 0.05). Superior mesenteric artery blood flow increased postprandially by a mean of 133 ml.min-1 (P < 0.05) in the patients and 424 ml.min-1 (P < 0.01) in the control subjects. Calf blood flow increased in both groups during exercise, but there was no change in limb blood flow when comparisons were made between the fasting and postprandial states. The normal postprandial increase in oxygen consumption did not occur in the patients although their minute ventilation was higher than the control subjects (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1979

[Wolff-Parkinson-White syndrome. Correlation between the results of electrophysiological investigation and exercise tolerance testing on the electrical aspect of preexcitation].

Fourteen patients with permanent electrocardiographical features of the Wolff-Parkison-White syndrome in sinus rhythm referred for electrophysiological investigation also underwent maximal exercise tolerance tests. The working hypothesis was that in patients with the Wolff-Parkinson-White syndrome with accessory pathways of longer effective refractory periods than the normal pathway (group I) the delta wave should disappear on exercise, whilst in patients with accessory pathways with shorter refractory periods than the normal pathway (group II) the delta wave should persist. Of the 9 patients in group I,the delta wave regressed in 8 and persisted in 1 patient; of the 5 patients in group II, the delta wave persisted in 4 of them. Three patients had attacks of tachycardia during or just after the exercise tolerance test. These results suggest that the exercise tolerance test may help in the identification of patients with accessory pathways with long refractory periods, less susceptible to rapid ventricular rhythms should atrial fibrillation occur, and therefore with better prognoses.

Adolescent↗

PubMed2002

Effect of growth hormone on exercise tolerance in children with cystic fibrosis.

PURPOSE: The effect of growth hormone (GH) treatment on exercise tolerance in children with cystic fibrosis was investigated. METHODS: 10 prepubertal children (mean +/- SD; age: 12.1 +/- 1.7 yr; height: 137.4 +/- 9.2 cm; body mass: 27.8 +/- 4.2 kg; forced expiratory volume in 1 s (FEV1): 68 +/- 22% predicted) were randomly assigned to either control period (CON, standard therapy) or recombinant human growth hormone (GH) period (additional GH treatment, 0.11-0.14 IU.kg-1, daily, s.c.) for the first 6 months, and then assigned to the other period for the next 6 months. At study entry and after each period, anthropometric data, pulmonary function, and exercise capacity (peak exercise capacity, .VO(2peak), and isokinetic muscle strength) were measured. RESULTS: Changes in height (+4.3 +/- 1.0 cm), total body mass (+2.2 +/- 0.8 kg), and lean body mass (LBM, +2.9 +/- 0.7 kg) were significantly higher (P < 0.01) after GH treatment compared with CON. Pulmonary function did not significantly change in either of the periods. In contrast to CON, GH treatment improved absolute .VO(2peak) (+19%, P < 0.01), peak ventilation (+14%, P < 0.01), and peak oxygen pulse (+18%, P < 0.01). Analysis of variance revealed that most of the changes (71%) in .VO(2peak) could be explained by those in LBM and FEV1 (P = 0.001). CONCLUSION: GH treatment clearly improved exercise tolerance, presumably resulting from the combined effects of GH on the muscular, cardiovascular, and pulmonary capacity.

Adolescent↗

PubMed1997

Proportional assist ventilation and exercise tolerance in subjects with COPD.

STUDY OBJECTIVE: This study determined whether proportional assist ventilation (PAV) applied during constant power submaximal exercise could enable individuals with severe but stable COPD to increase their exercise tolerance. DESIGN: Prospective controlled study having a randomized order of intervention. SETTING: Pulmonary function exercise laboratory. PARTICIPANTS: Ten subjects with severe stable COPD (mean [SD]: age=59 [6] years; FEV1=29 [7]% predicted; FEV1/FVC=33 [7]%; thoracic gas volume=201 [47]% predicted; diffusion of carbon monoxide=36 [10]% predicted; PaO2=76 [8] mm Hg; and PaCO2=41 [4] mm Hg). INTERVENTION: Each subject completed five sessions of cycling at 60 to 70% of their maximum power. The sessions differed only in the type of inspiratory assist: (1) baseline (airway pressure [Paw]=0 cm H2O); (2) proportional assist ventilation (PAV) (volume assist=6 [3] cm H2O/L, flow assist=3 [1] cm H2O/L/s); (3) continuous positive airway pressure (CPAP) (5 [2] cm H2O); (4) PAV+CPAP; and (5) sham (Paw=0 cm H2O). MEASUREMENTS AND RESULTS: Dyspnea was measured using a modified Borg scale. Subjects reached the same level of dyspnea during all sessions but only PAV+CPAP significantly (p<0.05) increased exercise tolerance (12.88 [8.74] min) vs the sham session (6.60 [3.12] min). Exercise time during the PAV and CPAP sessions was 7.10 [2.83] and 8.26 [5.54] min, respectively. Minute ventilation increased during exercise but only during PAV+CPAP was the end exercise minute ventilation greater than the unassisted baseline end exercise minute ventilation (36.2 [6.7] vs 26.6 [6.4] L/min, respectively; p<0.05). CONCLUSIONS: In this study, PAV+CPAP provided ventilatory assistance during cycle exercise sufficient to increase the endurance time. It is now appropriate to evaluate whether PAV+CPAP will facilitate exercise training.

Aged↗

PubMed2002

Effect of atrial flutter on exercise tolerance in patients with grown-up congenital heart (GUCH).

OBJECTIVES: To assess the effect of atrial flutter (AFL) on exercise tolerance in patients with grown-up congenital heart (GUCH), exercise tests with modified Bruce protocol were performed in 20 patients aged 21 to 62 years with GUCH (11 females, 9 males) during symptomatic AFL and again 24 to 48 hours after DC conversion to sinus rhythm (SR). At the same time, cardiac function was assessed by means of transthoracic Doppler echocardiography. RESULTS: Mean exercise duration was significantly less during AFL (6.4 +/- 4.1 min) versus SR (10.9 +/- 3.7 min) (P <.001). Heart rate was faster at rest and peak exercise while in AFL (106 +/- 21 beats/min vs 77 +/- 14 beats/min, P <.001, and 157 +/- 31 beats/min vs 129 +/- 24 beats/min, P <.01, respectively). Systolic blood pressure was lower at peak exercise with AFL (112 +/- 25 mm Hg vs 137 +/- 24 mm Hg, P <.001), as was mean blood pressure increase (5.3 +/- 24.3 mm Hg vs 22.6 +/- 15.8 mm Hg) compared with SR (P <.01). Four of the 6 patients after Fontan surgery had a decrease of 16 mm Hg in systolic blood pressure at peak exercise when in AFL. The reasons for exercise termination during AFL were mainly breathlessness, chest pain, or presyncope, whereas in SR it was caused by fatigue. Echocardiography during AFL showed shorter isovolumic relaxation time (40 +/- 20 ms) compared with SR (50 +/- 20 ms) (P <.05). Ventricular long-axis excursion was reduced (left 1.0 +/- 0.3 cm vs 1.2 +/- 0.4 cm, septal 0.5 +/- 0.2 cm vs 0.7 +/- 0.3 cm, and right 0.7 +/- 0.2 cm vs 0.9 +/- 0.4 cm respectively, P <.001 for all), as were peak pulmonary and aortic flow velocities (85 +/- 30 cm/s vs 105 +/- 50 cm/s, P <.001, and 137 +/- 118 cm/s vs 143 +/- 114 cm/s, P <.02) compared with sinus rhythm. There was a close correlation between exercise duration and blood pressure increase (r = 0.6), left-sided long-axis excursion and blood pressure increase (r = 0.57), and between aortic flow velocity and right-sided long-axis excursion (r = 0.71). CONCLUSIONS: Atrial flutter causes dramatic reduction in exercise tolerance in patients with GUCH, and the combination of fast heart rate and hypotension may contribute to the development of presyncope, particularly in those with Fontan surgery. Marked improvement in effort tolerance and cardiac dynamics occurs after regaining SR. Thus, improving the quality of life in patients with GUCH requires maintaining SR.

Adult↗

PubMed1997

Highland mountain hiking and coronary artery disease: exercise tolerance and effects on left ventricular function.

Physical exercise has become a well-established concept in the secondary prevention of coronary artery disease. We investigated the exercise requirements of extensive highland mountain hiking (8.7 km, 470 m to 1220 m over sea level, average incline 8.5%, mean walking velocity < 3 km x h-1) in 11 regularly exercising male patients with history of MI and stable coronary artery disease (CAD; mean age +/- SD:61.0 +/- 3.9 yr) and 9 age-matched male healthy controls (CO; mean age +/- SD:61.2 +/- 5.0 yr). All subjects underwent continuous ECG monitoring; arterial blood pressure and blood lactate concentrations were measured several times during mountain hiking. Before and after exercise, cardiac dimensions and functions were assessed by two-dimensional echocardiography and Doppler echocardiography. The mean exercise levels for heart rate and blood lactate were compared with the corresponding data of a multistage upright cycle ergometry. Clinical manifestations of coronary insufficiency, left ventricular myocardial dysfunction, or cardiac arrhythmias > Lown IIIb were not observed in any case. No significant differences in left atrial and left ventricular dimensions and no changes in systolic left ventricular function compared with the preexercise values were found after the mountain hike tour. Doppler echocardiography demonstrated significant changes in diastolic left ventricular function in CAD, but not in CO. The peak exercise intensity during mountain hiking was equivalent to a workload of 100-125 W (1.25-1.5 W x kg-1 body weight) in a multistage upright cycle ergometry. Extensive highland mountain hiking may be a low risk alternative within the outpatient rehabilitation program for secondary prevention of CAD for MI patients with a cycle ergometric exercise tolerance > 1.5 W x kg-1 body weight.

Aged↗

PubMed2004

Effect of candesartan and verapamil on exercise tolerance in diastolic dysfunction.

Diastolic dysfunction may be exacerbated by increased systolic blood pressure (SBP) during exercise. Ang II may contribute to this process. We performed a randomized, double-blind, crossover study of two weeks of candesartan (16 mg) and verapamil (SR 160 mg). The 21 subjects were 64 +/- 10 years old with ejection fraction greater than 50%, no ischemia, mitral flow velocity E/A less than 1, normal resting SBP (< 150 mm Hg), and SBP greater than 200 mm Hg during exercise. Exercise tolerance was assessed using a Modified Bruce Protocol at baseline and after each two-week treatment period, separated by a two-week washout period. Quality of life (QOL) was assessed using the Minnesota Living with Heart Failure questionnaire. During exercise, Ang II levels increased from 29 +/- 18 to 33 +/- 18 pg/ml (P < 0.05). SBP during exercise was 213 +/- 9 mm Hg at baseline and similarly reduced by candesartan (198 +/- 18, P < 0.01) and verapamil (197 +/- 14, P < 0.01). With candesartan, exercise time increased from 793 +/- 182 seconds to 845 +/- 163 seconds (P < 0.05), and QOL improved from 11 +/- 14 to 5 +/- 6 (P < 0.05). In contrast, verapamil did not significantly improve exercise time or QOL. In patients with mild diastolic dysfunction at rest and a hypertensive response to exercise, both Ang II receptor blockade and verapamil blunted the hypertensive response to exercise. Ang II blockade increased exercise tolerance and improved QOL.

Antihypertensive Agents↗

PubMed2004

[Lung function and exercise tolerance after treatment with salmeterol or ipratropium bromide in chronic obstructive pulmonary disease].

The aim of this study was to compare the effects of 6 months therapy with salmeterol or ipratropium bromide on lung function (resting and dynamic parameters), exercise tolerance in patients with chronic obstructive pulmonary disease (COPD). In open, randomised study patients at visit 1 were included into trial, at visit 2 and, after 6 months therapy, at visit 3 lung function measured by a pressure body plethysmography, exercise tolerance was investigated by 6 minute walking test and dyspnoea was analysed by the means of Borg scale. We studied 24 patients (18 males, 6 females, range age 45-76 yrs, mean: 60.2+/-10.46) with stable COPD. 13 subjects (mean FEV1 = 63.61% predicted, SD = 15.66%) received salmeterol (2 x 50 microg/day) and 11 subjects (mean FEV1 = 62.52% predicted, SD = 12.39%) received ipratropium bromide (4 x 40 microg/day). There were no significant changes in lung function parameters (FEV1, VC, Rtot, TLC, RV and RV%TLC) after 6 months therapy with both drugs, but the treatment with salmeterol significantly improves exercise tolerance in 6 minute walking test (p=0.048) and Borg dyspnea ratings (p=0.008).

Aged↗

PubMed2001

Exercise tolerance and quality of life in elderly patients with chronic atrial fibrillation.

BACKGROUND: Atrial fibrillation is the most common arrhythmia affecting the elderly. Although the risk of cardioembolic stroke is well defined, the effects of chronic atrial fibrillation on exercise tolerance and quality of life have been less well quantified. METHODS: We compared a group of 52 elderly patients with chronic atrial fibrillation to a group of 48 control patients in sinus rhythm. Each patient underwent an interview that incorporated the Short Form-36 Health Survey (SF-36) to quantify individual perceptions on quality of life. In addition each person underwent physiologic testing that included a Modified Bruce Protocol exercise tolerance test, 24-hour ambulatory monitor test, and an echocardiogram. RESULTS: Both groups were elderly, 77 vs 76 years of age (P=0.35). The two groups had similar ejection fractions, 55.4% vs 58.4% (P=0.10). The atrial fibrillation patients demonstrated a higher level of comorbidity based on the Charlson Comorbidity Index, 2.46 vs 1.57 (P=0.03). On formal exercise testing there was no statistical difference in exercise duration between the two groups 9.0 vs 10.1 minutes (P=0.24). Similarly the Physical Summary Score (PCS) and the Mental Summary Score (MCS) of the SF-36 quality of life survey did not demonstrate a statistical difference between the two groups. PCS: 43.0 vs 45.9 (P=0.24); MCS: 52.5 vs 55.7 (P=0.07). CONCLUSIONS: Despite a higher level of comorbidity, elderly, ambulatory patients with chronic atrial fibrillation demonstrate similar exercise tolerance and report similar quality of life to a group of age-matched control patients in sinus rhythm. There is a cohort of patients in chronic atrial fibrillation in whom a strategy of rate control and anticoagulation may be appropriate.

Aged↗

PubMed1998

Left ventricular function and exercise tolerance in patients with type II diabetes mellitus.

BACKGROUND: Left ventricular (LV) preload changes may alter exercise tolerance (ET), probably lessening activation of the Maestrini-Starling mechanism. Reduced LV filling (pre-load) during the diastolic phase, usually impaired in diabetic patients, could affect ventricular function. HYPOTHESIS: To evaluate the relationship between some echocardiographic LV function indices and ET, 24 patients (age 43-75 years, mean 54 +/- 13 years, Group A) with type II diabetes mellitus (DM), not suffering from other pathologies, and for whom the ergometric stress test (EST) resulted in an early interruption because of muscular fatigue and/or dyspnea, and 14 patients (age 38-70 years, mean 53 +/- 12 years, Group B) with type II DM and maximal ergometric stress test, used as control group, were studied. METHODS: The EST was performed by increasing the load by 25 W every 2 min; its duration was used as an ET index and correlated with clinical parameters of LV function obtained with M-mode, two-dimensional, and Doppler echocardiography. RESULTS: No patients in either Group A or Group B showed a high systolic blood pressure value at rest and/or an LV hypertrophy and/or an alteration of systolic functional indices. In neither group was there significant correlation between ET and duration of DM, basal heart rate, basal and max systolic blood pressure, and EF values. Linear regression analysis showed a significant correlation between Doppler parameters of the diastolic function and ET index in Group A, while there was no significant correlation in Group B. CONCLUSION: From these data we can deduce that in absence of left systolic ventricular dysfunction the impairment of LV relaxation in DM can influence exercise tolerance, probably by limiting activation of the contractile reserve.

Case-Control Studies↗

PubMed1986

Impairment of exercise tolerance due to broxyquinoline-brobenzoxaldine combination.

A case report of impaired exercise tolerance during administration of broxyquinoline-brobenzoxaldine combination in therapeutic doses is presented. The first author of this paper, a 28-year-old healthy male, volunteered as a subject for a prospective study on the neurotoxicity of halogenated hydroxyquinolines and took a course of broxyquinoline-brobenzoxaldine combination. The author, who is a karate enthusiast, observed impairment of exercise tolerance during the course of treatment with the drugs. A challenge course of treatment with the same drugs in the same doses produced similar effects. Since halogenated hydroxyquinolines are still used widely in many countries, such an adverse effect would be of practical relevance, particularly in asymptomatic cyst-passers of Entamoeba histolytica whose occupations involve physical labour.

Adult↗

PubMed1990

Relation between chest expansion, pulmonary function, and exercise tolerance in patients with ankylosing spondylitis.

Thirty three patients with definite ankylosing spondylitis (AS) were examined to establish the relation between restriction of chest expansion, limitation of lung function, and working capacity or exercise tolerance. As in previous studies there was a significant association between chest expansion and lung vital capacity. There was also a significant association between vital capacity and exercise tolerance as measured by a subject's maximum oxygen capacity (VO2max). Both vital capacity and VO2max were expressed as a percentage of predicted normal values using patients' height before disease. In this study chest expansion did not have a significant effect on exercise tolerance. The results suggested that patients who took a modest amount of exercise regularly could maintain a satisfactory work capacity despite very restricted spinal and chest wall mobility. It is recommended that greater emphasis should be given to encouraging patients with AS to maintain cardiorespiratory fitness as well as spinal mobility.

Adult↗

PubMed2005

Skeletal muscle phenotype is associated with exercise tolerance in patients with peripheral arterial disease.

OBJECTIVE: To better understand the association between skeletal muscle and exercise intolerance in peripheral arterial disease (PAD), we assessed treadmill-walking performance and gastrocnemius muscle phenotype in healthy control subjects and in patients with PAD. We hypothesized that gastrocnemius muscle characteristics would be altered in PAD compared with control subjects and that exercise tolerance in patients PAD would be related to muscle phenotype. METHODS: Sixteen patients with PAD and intermittent claudication and 13 healthy controls of the same age participated. Each subject completed a graded treadmill-walking test and underwent a resting muscle biopsy. Muscle biopsy samples were obtained from the medial gastrocnemius muscle of the most ischemic limb in PAD and a limb chosen at random in controls. Samples were analyzed for fiber type and cross-sectional area, capillary-to-fiber ratio, the number of capillaries in contact with each fiber type, and the optical density of glycogen within each fiber by using histochemical procedures. Total muscle glycogen content was determined biochemically. RESULTS: Exercise capacity measured on the incremental walking test in the PAD group was only 30% to 40% of that observed in controls. The PAD group had a lower proportion of type I muscle fibers (P < .05), fewer capillaries per muscle fiber (P < .05), and tended to have smaller fiber areas (P = .08). The relative area of type I fibers, the capillary-to-fiber ratio, capillary contacts with type I and IIa fibers, and the optical density of glycogen in type I fibers were all positively correlated with exercise tolerance in the PAD group (P < .05) but not controls. CONCLUSIONS: These data suggest that muscle phenotype is altered in PAD and that such alterations are associated with the exercise intolerance in these patients. In light of these findings, therapies such as resistance training or electrical stimulation that target skeletal muscle in PAD may prove beneficial, and further investigation of such therapies is warranted.

Biopsy, Needle↗

PubMed1992

Exercise tolerance and working capacity after valve replacement.

Between 1978 and 1987, 1270 patients who survived single aortic or mitral valve replacement at the Rehabilitation Center in Bad Krozingen, Germany, underwent a comprehensive rehabilitation program. The preoperative diagnosis was isolated aortic stenosis in 425, isolated aortic regurgitation in 159, mixed aortic lesion in 211, isolated mitral stenosis in 208, isolated mitral insufficiency in 137 and mixed mitral lesion in 130 cases. Follow up examinations were carried out one and six months after surgery, and at yearly intervals thereafter. Exercise testing was performed with an electrically braked bicycle ergometer in the supine position, and the load was increased by 25 or 50 watts every two minutes until fatigue, severe angina, more than 0.3 mV ST-segment depression, or 80% of the age predicted maximum heart rate was achieved. Patients after aortic valve replacement had a better exercise performance one month after operation than did those after mitral valve replacement. Those with mitral stenosis showed more severe impairment of exercise tolerance than did the mitral insufficiency group. There was a steady increase in exercise tolerance between one and six months postoperatively, both in patients with aortic and those with mitral valve replacement, but the difference in performance between the two groups was still present (72% versus 57% of normal). The results of univariate and multivariate analyses showed that the preoperative employment status was the most important factor for postoperative return to work, followed by gender (male > female), exercise tolerance and valualar lesion (aortic > mitral).(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗