Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Exercise Tolerance”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 55 records · Page 3Linked to original sources
PubMed2000

Determinants of exercise tolerance after acute myocardial infarction in older persons.

OBJECTIVES: Exercise tolerance is reduced with advancing age. Identification of potentially reversible determinants of the age-related decrement in exercise tolerance, which remain largely unexplored in older subjects and in patients recovering from a recent myocardial infarction (MI), may have useful therapeutic implications. The objective of this study was to identify the independent determinants of exercise tolerance in older patients with a recent MI. DESIGN, SETTING, AND PARTICIPANTS: Data is from baseline assessment of 265 post-MI patients (age range 45-85 years) enrolled in the Cardiac Rehabilitation in Advanced Age randomized, controlled trial. Patients with major comorbidities or severe MI complications were excluded from the trial. Exercise tolerance was determined from symptom-limited exercise testing and expressed as total work capacity (TWC, kg.m) or peak oxygen consumption (VO2peak, mL/kg/min). The associations between both TWC and VO2peak and baseline demographic, social, clinical, and neuropsychological variables and an index of health-related quality of life were determined with univariate and multivariate analysis. RESULTS: With univariate analysis, TWC decreased by 1285 kg.m per decade of increasing age between 45 and 85 years of age. With multivariate analysis, TWC decreased by 922 kg.m per decade. Increasing age (P < .001), female gender (P < .001), a small body surface area (P < .001), a low level of usual physical exercise before MI (P < .002), and the presence of post-MI depressive symptoms (P < .024) were independently associated with a lower TWC. The same factors, in addition to a small arm muscle area (P < .002), were also independently associated with a lower VO2peak. CONCLUSIONS: Age per se accounts for approximately 70% of the age-related decay in TWC or VO2peak. However, the inclusion of modifiable factors such as physical exercise and depression in the prediction model reinforces the importance of a multidimensional approach to the evaluation and treatment of older patients with a recent MI.

Age Factors↗
PubMed1995

Exercise-induced rise in arterial potassium is enhanced in patients with impaired exercise tolerance.

We assessed the changes in arterial potassium concentration during exercise and recovery in relation to exercise tolerance in patients with impaired exercise tolerance. Sixteen patients with cardiac disease were subjected to a cardiopulmonary exercise test on a cycle ergometer. Arterial potassium and lactate concentrations were measured every minute during and after exercise, and ventilatory threshold (VT) and lactate threshold (LT) were identified. Before exercise, arterial potassium concentration was 3.8 +/- 0.3 mEq/l. It increased to 4.1 +/- 0.3 mEq/l at LT (p < 0.002 versus at rest), to 4.2 +/- 0.3 mEq/l at VT, and to 4.8 +/- 0.5 mEq/l at peak exercise (p < 0.001 versus at LT, p < 0.001 versus at VT). At an exercise intensity equivalent to 30, 40, 50 or 60% of predicted maximum oxygen uptake, the increase in arterial potassium showed a negative and significant correlation with %LT (r = -0.62 approximately -0.72, p < 0.01 approximately 0.05) and %VT (r = -0.62 approximately -0.75, p < 0.001 approximately 0.05), where %LT and %VT represent the ratios of LT and VT to the predicted maximum oxygen uptake, respectively. There was a good correlation between the rate of fall in potassium concentration during recovery and its increase during exercise. It was concluded that in patients with impaired exercise tolerance, the greater the degree of exercise intolerance, the greater the increase in arterial potassium concentration during exercise, and the steeper the fall in potassium concentration during recovery. Because the rise in potassium concentration during exercise and its fall during recovery were greater when the exercise level exceeded the anaerobic threshold, exercise levels below the anaerobic threshold are recommended for patients with cardiac diseases.

Aged↗
PubMed1991

Prediction of maximum exercise tolerance in patients with COPD.

Exercise tolerance in patients with COPD is difficult to predict from measurements of lung function. We examined multiple physiologic and psychosocial variables in an attempt to predict exercise performance in a group of patients with COPD enrolled in a clinical trial of pulmonary rehabilitation. A total of 119 patients (FEV1 = 1.41 +/- 0.64 L) were divided randomly into either a study group (group A, n = 58) or validation group (group B, n = 61). Stepwise multiple regression in group A revealed that peak oxygen uptake (peak VO2) was predicted best by the following equation: Peak VO2 (L/min) = (0.0327 x DCO) + (0.0040 x MVV)-(0.0156 x peak-exercise VD/VT) + (0.0259 x resting VE) + 0.848; r = 0.90; SE = 0.233 L/min. This equation was then cross-validated in group B. It demonstrated excellent validity: measured peak VO2 (L/min) = (1.13 x predicted peak VO2)-0.0891; r = 0.90; SE = 0.239 L/min. We conclude that exercise tolerance was predicted reasonably well from measurements of lung function and gas exchange in this group of patients with COPD. However, the variability of the prediction would limit its usefulness in individual patients.

Carbon Dioxide↗
PubMed1990

Exercise tolerance and alcohol intake. Blood pressure relation.

The relations of systolic and diastolic blood pressures to alcohol intake and exercise tolerance levels in 15,612 men and 3,855 women were investigated. Alcohol intake was assessed by questionnaire and stratified into seven levels for men and six for women according to the ounces of ethanol consumed per week. Exercise tolerance was determined by maximal treadmill exercise testing and was categorized into six age-specific by sex-specific levels. Both systolic and diastolic blood pressure were significantly related to both alcohol intake and exercise tolerance levels in both men and women. These relations, which were positive for alcohol and negative for exercise tolerance, remained after covariance adjustment for age, body mass index, and cigarette smoking. Alcohol intake was not significantly correlated with exercise tolerance. The relation of blood pressure to alcohol was not linear because the blood pressure of moderate consumers of alcohol tended to be slightly lower than that of nondrinkers. Higher blood pressure was found only in drinkers whose ethanol intake exceeded 9.5 ounces (approximately 285 ml or 19 drinks) per week. However, heavy drinkers in high exercise tolerance categories had no higher blood pressure than nondrinkers in low exercise tolerance groups. Exercise tolerance or physiological fitness appears to be important in quantifying the relation between alcohol intake and blood pressure and should be considered in describing this relation.

Adolescent↗
PubMed1988

Assessment of variability of exercise tolerance limited by breathlessness.

A sequence of questions was designed to quantify the within subject variation of exercise tolerance limited by breathlessness, to serve as a guide to variation in airflow limitation for epidemiological purposes. The questions seek answers about breathlessness in relation to various levels of attempted activity when the subjects are at their best and at their worst. The difference between exercise tolerance at best and exercise tolerance at worst (variation in exercise tolerance) was expressed on a scale ranging from 0 (no variation) to 6 (greatest variation). The effectiveness of these questions has been assessed in 68 patients with airflow limitation attending a chest clinic, by comparing the results with variation in peak expiratory flow rate (PEF). Variation in PEF was expressed as the standard deviation of the first 24 PEF recordings from each patient (equivalent to four days' recordings). There was a highly significant relation between the measure of variation in exercise tolerance obtained from the questionnaire and PEF variation, though each point on the scale of variation in exercise tolerance covered a wide range of variation in PEF. The questions give some guide to the variation in airflow limitation and in combination with other questions may be helpful in epidemiological studies.

Adolescent↗
PubMedDate not supplied

Research and commentary: Change in exercise tolerance, activity and sleep patterns, and quality of life in patients with cancer participating in a structured exercise program.

PURPOSE/OBJECTIVES: To investigate the feasibility of an exercise program patterned after a phase II cardiac rehabilitation program to improve selected physiologic and psychological parameters of health in patients with cancer. DESIGN: Prospective, repeated measures study. SETTING: Two major military medical centers in the southwestern United States. SAMPLE: 62 patients diagnosed with cancer within the previous two years. Ages ranged from 24-83 (meanX = 59). Half of the participants were male and half were female. Minorities made up 29% of the sample. Participants had a wide range of cancer diagnoses and all stages of cancer. Fifteen subjects were undergoing treatment when they enrolled in the study. More than half of the subjects exercised prior to their cancer diagnoses, but fewer than half were able to resume an exercise routine following their cancer diagnoses. METHODS: Subjects met two days each week for 12 weeks for exercise and education. MAIN RESEARCH VARIABLES: Exercise tolerance as measured with a graded exercise test, activity and sleep patterns as measured with a wrist actigraph, and quality of life (QOL) as measured with the Cancer Rehabilitation Evaluation System-Short Form. FINDINGS: Significant improvements were observed over time in exercise tolerance, selected activity and sleep patterns, and QOL among the 46 (74%) subjects who completed the program. CONCLUSIONS: Patients with various types and stages of cancer can safely exercise using a cardiac rehabilitation model and can realize significant improvements in exercise tolerance, selected activity and sleep patterns, and QOL. IMPLICATIONS FOR NURSING: Most people are aware that regular exercise is part of a healthy lifestyle. After cancer diagnosis and treatment, patients experience uncertainty regarding how to resume exercise or how to begin an exercise program as part of their rehabilitation. Participation in a structured exercise program can provide patients with a safe environment within which to exercise at an intensity appropriate to their individual needs.

Adaptation, Psychological↗
PubMed2004

New strategies to improve exercise tolerance in chronic obstructive pulmonary disease.

Breathlessness is the most common symptom limiting exercise in patients with chronic obstructive pulmonary disease (COPD). Exercise training can improve both exercise tolerance and health status in these patients, intensity being of key importance. Nevertheless, in these patients extreme breathlessness and/or peripheral muscle fatigue may prevent patients from higher levels of intensity. In this review article the literature concerning the different ways to optimise exercise tolerance in patients with COPD, with the objective of enhancing the tolerance to higher exercise training intensity, is summarised. Continuous positive airway pressure and different modalities of noninvasive positive pressure ventilation (NPPV) may reduce breathlessness and increase exercise tolerance in these patients. Respiratory muscle unloading and reduction in intrinsic positive end-expiratory pressure have been considered among mechanisms underlying these effects. Nevertheless, the role of NPPV in pulmonary rehabilitation, if any, is still controversial. The addition of nocturnal domiciliary NPPV during a daily exercise programme in patients with severe COPD resulted in an improvement in exercise tolerance and quality of life. In patients with severe COPD application of electrical stimulation combined with active limb mobilisation significantly improved muscle strength, and interval training has been shown capable of inducing physiological training effects. Oxygen supplementation in patients who do not desaturate during exercise seems to be the most promising treatment, since it allows for higher exercise intensities and, therefore, superior training efficacy. In conclusion, further studies are needed to define the appropriate patients in order to generalise such interventions. The modalities discussed should be used as adjuncts to a well designed comprehensive respiratory rehabilitation programme.

Breathing Exercises↗
PubMed1995

Effects of L- and DL-carnitine on patients with impaired exercise tolerance.

We designed this study to determine whether orally administered L- and DL-carnitine can improve exercise tolerance in a group of patients with exercise intolerance. Nineteen patients with cardiac disease were randomly divided into 2 groups, an L-carnitine treatment group (n = 9) and a DL-carnitine treatment group (n = 10). Eight additional age-matched patients served as an untreated control group. Subjects in both carnitine treatment groups underwent cardiopulmonary exercise testing on a cycle ergometer in order to determine peak exercise time, peak oxygen uptake (VO2), lactate threshold (LT) and ventilatory threshold (VT) before and after the oral administration of 900 mg/day of L- or DL-carnitine for 2 weeks. Basal values of peak exercise time, peak VO2, LT and VT did not differ significantly among the 3 groups. Peak exercise time and peak VO2 tended to be increased in the L-carnitine treatment group, and tended to be decreased in the DL-carnitine treatment group. Both LT and VT (ml/kg/min) were significantly improved (LT: from 9.7 +/- 0.6 to 10.8 +/- 1.0, p < 0.05; VT: from 9.8 +/- 0.8 to 11.8 +/- 1.9, p < 0.02) by the administration of L-carnitine, while LT was significantly decreased (from 11.0 +/- 2.0 to 9.6 +/- 1.2, p < 0.05) and VT tended to be decreased by the administration of DL-carnitine (from 11.6 +/- 2.0 to 10.8 +/- 2.4). In the untreated control group, no significant changes were observed in the values of exercise tolerance between the 2 series of exercise testings. In neither group did carnitine modify hemodynamic parameters at rest or during exercise. In conclusion, this study demonstrated that L-carnitine increases and DL-carnitine decreases exercise tolerance in patients with impaired exercise tolerance.

Administration, Oral↗
PubMed2002

The effectiveness of a cardiac rehabilitation program on self-efficacy and exercise tolerance.

This study evaluates the effectiveness of graded physical exercise on self-efficacy and exercise tolerance among a group of cardiac patients (N = 43). These patients were aged from 41 years to 82 years (mean age = 63.5 years, SD = 10.0 years). Results of the study show that efficacy of physical activity was significantly associated with exercise tolerance. After a 3-month rehabilitation with graded physical exercise, both efficacy of activity and exercise tolerance were significantly enhanced. The enhancement was relatively independent of patients' gender, age, education, and diagnostic category. Limitations of the study are discussed and future research suggested.

Adult↗
PubMedDate not supplied

Influence of venous function on exercise tolerance in chronic heart failure.

PURPOSE: The clinical phase of chronic heart failure (HF) includes a marked decline in exercise tolerance, in part due to impaired skeletal muscle blood flow delivery. Interestingly, the role of the venous system on exercise tolerance in patients with HF has not received much attention, despite evidence of changes in venous structure and function. The purpose of this study was to examine the relationship between forearm arterial and venous function, and exercise tolerance in patients with HF and age-matched controls. METHODS: Vascular function and exercise tolerance was examined in 20 patients with HF (age 59 +/- 13 years) and 10 control subjects (age 51 +/- 16 years). Nondominant forearm arterial inflow, vascular resistance, venous capacitance, and venous outflow were evaluated at rest and after 5 minutes of upper arm occlusion, using strain gauge plethysmography. Exercise tolerance was measured as the maximum walking distance achieved on a 6-minute walking test. RESULTS: Maximum walking distance (HF: 178 +/- 65 m; controls: 562 +/- 136 m, P=.0001), and forearm vascular function after occlusion were significantly different between groups (forearm arterial inflow: HF 15.3 +/- 6; controls 22 +/- 6.7; forearm venous capacitance: HF 1.4 +/- 0.5; controls 2.0 +/- 0.4; forearm venous outflow: HF 24.5 +/- 9.4; controls: 33 +/- 10 mL x 100 mL tissue(-1) x min(-1); and forearm vascular resistance: HF 7.8 +/- 3; controls 4.6 +/- 1.4 U). Correlation analysis revealed significant associations between all forearm vascular measurements after occlusion and maximum walking distance. CONCLUSION: These data confirm previous studies indicating the importance of arterial reactivity on exercise tolerance in patients with HF. Additionally, the results suggest the importance of venous function as a contributing factor to exercise performance.

Adult↗
PubMed1998

[Training of inspiratory muscles in chronic obstructive lung disease. Its impact on functional changes and exercise tolerance].

The aim of this study was to evaluate the impact of inspiratory muscle training on lung function and exercise tolerance in patients with chronic obstructive pulmonary disease (COPD). Thirty-five patients with stable COPD were enrolled. We measured lung function variables and peak inspiratory and expiratory pressures (PImax and PEmax). Tests of progressive maximal exercise tolerance and stable submaximal exercise tolerance were administered. Two study groups were formed. Group A patients (n = 20) were enrolled in a respiratory muscle training program lasting four months. Group B (n = 15) was the control group. At the end of the study period the patients underwent testing similar to the first battery of tests. All showed moderate to severe obstruction with no significant differences between groups (FEV1: group A 37.6 +/- 13%, group B 36.6 +/- 12%; FVC: group A 80.4 +/- 15%, group B 80 +/- 12%). Nor were there any significant differences between the two groups in initial results of either maximal respiratory pressures or exercise tolerance. No lung function changes were observed in either group. PImax in group A increased significantly at the end of the study (from 54 +/- 9 to 78 +/- 16 cmH2O; p < 0.001); there were no changes in group B. No changes were seen in VO2max or ventilatory response and/or gasometry during exercise in any of the groups. The trained group, on the other hand, experienced a significant decrease in dyspnea evaluated on the Borg scale exercise in maximal (5.7 +/- 1.1 versus 4.7 +/- 1.2, p < 0.005) and submaximal (5.9 +/- 0.9 versus 4.9 +/- 1.3, p < 0.005) and an increase in time of submaximal exercise tolerance (5.5 +/- 2 versus 7 +/- 3 min, p < 0.05), changes that were not observed in the control group. Based on these results, and although specific training of inspiratory muscles does not appear to improve lung function in patients with COPD, it is accompanied by a decreased sense of dyspnea during exercise and greater tolerance.

Aged↗
PubMed1979

[Exercise tolerance of patients with artificial cardiac pacemakers (author's transl)].

In order to determine their exercise tolerance, 20 patients with artificial ventricular demand pacemakers below the age of seventy were studied by bicycle ergometry. Only 30% of the patients showed a normal exercise tolerance according to the criteria by Kaltenbach, while 70% stopped the test prematurely because of leg fatigue, dyspnoe or chest pain. In terms of their exercise tolerance, there was no difference between patients who developed normal sinus rhythm or rapid atrial fibrillation during the exercise and those who remained at the fixed pacemaker rate throughout the test. It is concluded, therefore, that the exercise tolerance of pacemaker-patients is not only limited by the fixed heart rate but mainly by the underlying heart disease (coronary heart disease, cardiomyopathy, hypertensive heart disease etc.) and the general physical condition of the patients. In an age-matched control group of 20 patients 50% showed a normal exercise tolerance and the duration of exercise in this group was only slightly longer (21%) than in the pacemaker-group.

Aged↗
PubMed2006

Exercise tolerance and physical activity levels in children referred to a weight reduction clinic.

The aim of this study was to investigate exercise tolerance and physical activity levels in children with exogenous obesity. Measures included BMI, waist circumference, exercise tolerance and self reported physical activity. Exercise tolerance was measured by the Modified Balke Treadmill Protocol and results were compared to normal values. Physical activity levels were assessed by measuring energy expended in regular activities each week over the past year and number of hours spent watching TV/video using an adaptation of the 'Modifiable Activity Questionnaire for Adolescents'. Details on transport to school were also obtained. Forty five children between September 2002 and June 2004 were assessed. This group comprised of 25 girls and 20 boys with mean ages (standard deviation) of 11.9 +/- 3.0 years and 13.7 +/- 2.5 years respectively. Exercise tolerance as a percentage of normal was below minimal levels in 64% girls and 75% boys. Energy expended in regular activity was less than the minimal recommendation in 80% girls and 65% boys. Seventy six percent of girls and 70% of boys spent 2 hours or more per day watching television and 40% of girls and 70% of boys walked to school. The low levels of activity and exercise tolerance need to be addressed in the managemeni of children with obesity

Ambulatory Care Facilities↗
PubMed1985

Verapamil-induced improvement in left ventricular diastolic filling and increased exercise tolerance in patients with hypertrophic cardiomyopathy: short- and long-term effects.

Verapamil improves exercise tolerance and decreases symptoms in many patients with hypertrophic cardiomyopathy. The mechanisms responsible for these effects are not completely understood, although previous studies indicate that verapamil enhances left ventricular relaxation and diastolic filling in such patients. To investigate the association between changes in left ventricular filling and exercise tolerance after verapamil, we studied 55 patients with hypertrophic cardiomyopathy by radionuclide angiography and graded treadmill testing before and after 1 to 4 weeks of therapy with orally administered verapamil, 320 to 640 mg/d. The verapamil-induced increase in peak left ventricular filling rate at rest (from 3.1 +/- 1.3 to 3.7 +/- 1.3 end-diastolic volumes/sec; p less than .001) was associated with an increase in exercise tolerance (from 5.9 +/- 3.6 to 8.7 +/- 4.7 min; p less than .001); exercise capacity increased in 34 of 43 patients (79%) manifesting an increase in peak filling rate but only one of 12 patients (8%) with unchanged or decreased peak filling rate (p less than .001). This initial trend persisted in 25 patients studied after 1 year of therapy; 11 of 16 patients (69%) with a persistent increase in peak filling rate had persistent improvement in exercise tolerance relative to preverapamil values, compared with only one of nine patients (11%) in whom peak filling rate was unchanged or decreased relative to preverapamil levels (p less than .02). Verapamil withdrawal after 1 to 2 years in 24 patients resulted in reduction in peak filling rate (p less than .001) and was associated with deterioration in exercise tolerance in 17 patients (71%). Hence, verapamil-induced changes in left ventricular peak filling rate were associated significantly with objective symptomatic improvement. These data support the concept that enhanced left ventricular diastolic filling is an important mechanism contributing to the clinical improvement experienced by many patients with hypertrophic cardiomyopathy during therapy with verapamil.

Adolescent↗
PubMed1987

Assessment of exercise tolerance of cardiac patients by bicycle, treadmill and treadmill plus isometric exercise with and without nifedipine.

Seventeen post-myocardial infarction patients experiencing angina on effort performed 6 different exercise tests until they reached symptom-limited maximal level, 3 after placebo and 3 after oral administration of 10 mg of the Calcium antagonist, nifedipine, in a randomized, double blind, cross-over controlled study. Four of the tests were conventional bicycle and treadmill tests with stepwise increasing load. In 2 of the tests an isometric exercise of carrying a weight averaging 6 kg and corresponding to about 30% of maximal grip strength was added to the treadmill walking. When the exercise was stopped because of moderately severe angina, the product of heart rate and systolic blood pressure did not show any statistically significant difference between the tests. However, in the treadmill plus isometric test the work time was shorter and the slope of the treadmill was less than in the treadmill test. The difference was caused partly by non-cardiac factors, namely fatigue of the hand muscles. In routine exercise tests of coronary patients the addition of an isometric to a dynamic load did not give substantially more information than dynamic exercise alone. Nifedipine caused a modest increase of exercise tolerance in all tests, the increase being greatest in the treadmill plus isometric test. The increase in exercise tolerance was seen also in patients receiving beta-blocking agent.

Aged↗
PubMed1983

Exercise parameters for the prediction of post-training increase in exercise tolerance in patient with stable angina pectoris.

Twenty cases with effort angina underwent exercise training for a mean follow-up period of 38 weeks. Various parameters were investigated to clarify whether or not such parameters can be used to predict an increase in exercise tolerance of patients with effort angina. The increase of exercise tolerance after training was found to be related to a reduction of the myocardial oxygen demand at a given external work load. The maximal heart rate (max HR) the maximal systolic blood pressure (max SBP) and the maximal rate-pressure product (max RPP) could not predict the post-training increase in exercise tolerance. Before training, the maximal oxygen intake (VO2max) was found to be lower, and the HR/VO2max and the SBP/VO2max were higher in the group (11 patients) which showed a good response to the exercise program (effective group) than those in the group (9 patients) which did not (unchanged group). Before training, the HR/VO2max and the SBP/VO2max in the effective group were also higher than those of 96 healthy adults. On the other hand, the HR/VO2max and the SBP/VO2max in the unchanged group were not different from those of the healthy adults throughout the training. It is useful to compare the values of the HR/VO2max and the SBP/VO2max of patients with effort angina to those of healthy adults for the prediction of post-training increase in exercise tolerance.

Angina Pectoris↗
PubMedDate not supplied

Effect of once weekly pulmonary rehabilitation on exercise tolerance in patients with chronic lung disease.

BACKGROUND: Pulmonary rehabilitation (PR) programmes improve exercise tolerance and reduce breathlessness in patients with chronic obstructive pulmonary disease. AIM: A retrospective audit was undertaken to assess the effectiveness of the pulmonary rehabilitation programme at Belfast City Hospital (BCH). METHODS: Data from 74 patients who completed a six-week PR programme were reviewed. Exercise tolerance was assessed by the shuttle walk test (SWT), and breathlessness by the BORG scale. Paired t-tests were used for within group analysis. RESULTS: The mean (SD) exercise tolerance assessed by the SWT improved significantly as did duration of individual exercises. Patients were able to exercise more without increasing their breathlessness or heart rate. CONCLUSIONS: This paper highlights the effect of PR on exercise tolerance and breathlessness in patients with chronic lung disease. The results compare favourably with published literature where more frequently supervised exercise sessions were provided.

Exercise Tolerance↗
PubMed1980

The role of nutritional status, airway obstruction, hypoxia, and abnormalities in serum lipid composition in limiting exercise tolerance in children with cystic fibrosis.

Previous work has shown that impaired exercise tolerance in children with cystic fibrosis (C.F.) is related to the severity of airway obstruction without elucidating the possible roles of hypoxia or malnutrition. It has been suggested that poor nutrition leads to abnormalities in serum fatty acids composition, which may lead to tissue hypoxia. We investigated the roles of hypoxia, pulmonary mechanics, nutritional status, and serum fatty acid composition in limiting exercise tolerance in C.F. In 20 children with C.F., exercise tolerance, while breathing air and while breathing oxygen, was evaluated on a cycle ergometer and compared to pulmonary function tests, anthropometric data, serum lipid compostition, and clinical condition. The mean percent work expected from height (Wmax) was 75, and was unchanged by O2. Wmax correlated significantly with the degree of respiratory impairement, the discrepancy between height and weight, and the clinical score but not serum fatty acid composition. Where measured, no child at any time had an elevated end tidal CO2(PetCO2). We conclude that nutritional status and airway obstruction are closely correlated with exercise tolerance in C.F. and that, unlike the case in adults with chronic obstructive pulmonary disease, exercise-limiting dyspnea occurs in the presence of a normal PetCO2.

Adolescent↗