Exercise Capacity In Children Research Articles

Exercise Capacity In Children With Chronic Fatigue Syndrome (CFS/ME)

Chronic Fatigue Syndrome (CFS/ME) is characterized by debilitating fatigue and affects physical and mental functioning. Several studies have been performed studying the exercise capacity of adults with CFS/ME. However no sties have been performed in children and adolescents with CFS/ME. PURPOSE To evaluate exercise capacity in children with chronic fatigue syndrome. METHODS We examined 17 consecutive patients (11 girls and 6 boys; mean age 14.9±3.46 years) diagnosed with CFS. Anthropometry and algometry was performed in all patients by the same pediatric physical therapist (RHE). Exercise capacity was measured using a graded exercise test on a bicycle ergometer to exhaustion and an expiratory gas analysis system. Muscle strength was assessed using a hand held dynamometer. RESULTS Children with CFS reached low-normal exercise capacity (VO2peak (L/min), Z-score of −0.31±1.10 SD) and lower peak power (Z-score of −0.73±1.21 SD) compared to controls. BP and heart rate at peak exercise was significantly lower compared to controls. Muscle strength of children with CFS was not significantly different compared to controls. Children with CFS have a tendency for increased joint motion (Z-score of 0.43±1.33) compared with controls. Skin extensibility (Z-score of 1.69±1.13) and algometry of children with CFS were significantly increased compared to controls. CONCLUSIONS VO2peak and Wmax were not significantly lower compared to controls. When exercise capacity was expressed in VO2peak/kg, children with CFS scored significantly lower, possibly caused by muscular atrophy and higher fat mass. Muscle strength was not significantly different in our patients compared to controls. Together with a normal VO2peak and low peak heart rate these findings indicate that the origin of fatigue is at a central level.

Oxygen uptake efficiency slope, a new submaximal parameter in evaluating exercise capacity in chronic heart failure patients

Background The oxygen uptake efficiency slope (OUES) is a new submaximal parameter which objectively predicts the maximal exercise capacity in children and healthy subjects. However, the usefulness of OUES in adult patients with and without advanced heart failure remains undetermined. The present study investigates the stability and the usefulness of OUES in adult cardiac patients with and without heart failure. Methods Forty-five patients with advanced heart failure (group A) and 35 patients with ischemic heart disease but normal left ventricular ejection fraction (group B) performed a maximal exercise test. PeakV O 2 and percentage of predicted peakV O 2 were markers of maximal exercise capacity, whereas OUES, ventilatory anaerobic threshold (VAT), and slope VE/V CO 2 were calculated as parameters of submaximal exercise. Results Group A patients had lower peakV O 2 ( P < .001), lower percentage of predicted peakV O 2 ( P = .001), lower VAT ( P < .05), steeper slope VE/VC O 2 ( P < .001), and lower OUES ( P < .02). Within group A, significant differences were found for VAT, slope VE/VC O 2, and OUES (all P < .01) between patients with peakV O 2 above and below 14 mL O 2/kg/min. Of all the submaximal parameters, VAT correlated best with peakV O 2 ( r =.814, P < .01) followed by OUES/kg ( r = .781, P < .01), and slope VE/VC O 2 ( r = −.492, P < .001). However, VAT could not be determined in 18 (23%) patients. Conclusions OUES remains stable over the entire exercise duration and is significantly correlated with peakV O 2 in adult cardiac patients with and without impaired LVEF. Therefore, OUES could be helpful to assess exercise performance in advanced heart failure patients unable to perform a maximal exercise test. Further studies are needed to confirm our hypothesis.

Characterization of left ventricular diastolic function by tissue Doppler imaging and clinical status in children with hypertrophic cardiomyopathy.

Conventional transmitral Doppler indices are unreliable in assessing clinical status in patients with hypertrophic cardiomyopathy (HCM) because they are affected by loading conditions. This study sought to determine whether tissue Doppler velocities are predictive of adverse clinical outcomes including death, cardiac arrest, ventricular tachycardia (VT), significant cardiac symptoms, and exercise capacity in children with HCM. We studied 80 consecutive children (median age 12 years, median follow-up 26 months) evaluated at 1 hospital from January 1999 to August 2003 compared with 80 age- and gender-matched controls. Patients underwent echocardiography, ambulatory Holter monitoring, and upright exercise testing. Children with HCM had significantly decreased early diastolic tissue Doppler velocities at the lateral mitral (13.2 versus 19.3 cm/s), tricuspid (13.3 versus 16.3 cm/s), and septal (9.4 versus 13.5 cm/s) annuli compared with controls (P<0.001 for each comparison). By forward stepwise regression analysis, early transmitral left ventricular filling velocity (E)/septal Ea ratio predicted death, cardiac arrest, or VT (r=0.610, R2=0.37, P<0.001). Peak oxygen consumption (VO2) was most predictive of children who developed symptoms (r=0.427, R2=0.182, P<0.001). Peak VO2 correlated inversely with E/Ea septal ratio (r=-0.740, P<0.01). Transmitral E/septal Ea ratio predicts children with HCM who are at risk of adverse clinical outcomes including death, cardiac arrest, VT, and significant cardiac symptoms. Peak VO2 correlated with peak exercise capacity in HCM patients.

Exercise capacity in children with hypertrophic cardiomyopathy and its relation to diastolic left ventricular function

Left ventricular diastolic impairment is often seen in children with hypertrophic cardiomyopathy regardless of left ventricular outflow tract obstruction. Such impairment in diastolic filling is related to the presence of symptoms and exercise impairment.

Peripheral muscle weakness and exercise capacity in children with cystic fibrosis.

Exercise intolerance in cystic fibrosis (CF) is attributed to diminished nutritional and pulmonary function. We studied the pathophysiology of such intolerance in relation to muscle force and fat-free mass (FFM), in 15 children with moderately severe symptoms of CF (FEV1 < 80% predicted and/or weight for age < -1 SD of reference median), 13 children with mild symptoms of CF (FEV1 and weight above these thresholds), and 13 healthy controls. Cycle maximal workload (Wmax) and V O2max were assessed. Maximal peripheral muscle force was measured, and FFM was calculated from skinfolds. Patients with mild CF, as compared with matched controls, had lower values of Wmax per kilogram of FFM (3.9 +/- 0.5 versus 4.6 +/- 0.3 W/kg [mean +/- SD], respectively; difference = 0.7 [95% CI = 0.4 to 1.1]), and diminished maximal muscle force (2.7 +/- 0.4 kN versus 3.1 +/- 0.7 kN; difference = 0.44 [95% CI = 0.03 to 0.87]), but similar V O2max. Patients with moderate CF had lower FFM, muscle force, and exercise tolerance than did the other groups. Oxygen cost of work was elevated in both groups of CF patients. Muscle force showed a strong positive correlation with Wmax in patients and controls, with disproportionately lower regression slopes in the CF patients. In children with CF, muscle force is decreased and associated with diminished maximal work load, even in the absence of diminished pulmonary or nutritional status.

Pulmonary dysfunction and reduced exercise capacity in patients with myelomeningocele

To evaluate pulmonary function and exercise capacity in children with myelomeningocele. Prospective evaluation in a randomly selected cohort of 12 subjects (10 to 17 years of age) with myelomeningocele and 12 control subjects matched for age, sex, and arm span. Spirometry, lung volumes, maximum respiratory pressures, maximum oxygen expenditure during arm ergometry, and anaerobic threshold were measured. Mean total lung capacity and fractional lung volumes were significantly lower in case subjects than control subjects. Eleven subjects (92%) had a reduced forced vital capacity; seven (58%) had restrictive disease as evidenced by reductions in total lung capacity with normal or increased forced expiratory volume in 1 second/forced vital capacity ratio. Nine subjects (75%) had respiratory muscle weakness as evidenced by reduced maximum respiratory pressures or a low maximum voluntary ventilation. Exercise capacity was reduced as evidenced by a lower maximum oxygen consumption at peak exercise (13.8 +/- 4.8 vs 21.3 +/- 7.5 ml/min per kilogram of body weight; p < 0.02) and a lower anaerobic threshold (12.4 +/- 5.1 vs 17.3 +/- 4.2 ml/min per kilogram; p < 0.01) than the control group. Though the majority of subjects with myelomeningocele had a significant degree of restrictive disease, respiratory muscle weakness, or both, only one subject had pulmonary symptoms during exercise. Though most subjects with myelomeningocele had a significant degree of restrictive lung disease, respiratory muscle weakness, or both, exercise capacity was mostly limited by arm weakness. Skeletal muscle weakness may mask the symptoms of an underlying pulmonary abnormality, which may not be evident unless a pathologic cause of increased ventilation is present. Pulmonary function testing is suggested to screen for these abnormalities.

Reliability of subjective estimates of exercise capacity after total repair of tetralogy of Fallot.

Sixty-nine patients (age 10 +/- 3.5 years, median 9.7 years) operated on for tetralogy of Fallot, underwent exercise testing 5.1 +/- 2.5 years after total correction. Aerobic capacity was assessed by the ventilatory threshold method. After the exercise test, parents completed a validated standardized questionnaire to evaluate the habitual level of physical activity of their child. They were then asked to place their child into one of three groups, describing their child's activity level, compared to normals (below average, average and above average). In the average and above-average groups, 73% and 65% of the patients were misclassified when compared to objective exercise testing. However, in the below-average group, no misclassifications were found. Subjective estimates of activity level, and consequently exercise tolerance, were poorly associated with objective measurements of exercise performance in these patient groups. Our results question the reliability of self-reported estimates of physical activity level and consequently exercise capacity in children after surgical correction of tetralogy of Fallot.

Myocardial perfusion, function and exercise tolerance after the arterial switch operation

Objectives. This study was conducted to determine the prevalence of myocardial perfusion abnormalities at rest and exercise and to assess exercise capacity in children after the arterial switch operation.Background. There have been sporadic reports of myocardial ischemia or sudden death in children after the arterial switch operation for transposition of the great arteries, possibly related to inadequate coronary perfusion due to kinking or stenosis of the translocated coronary arteries.Methods. Myocardial perfusion at rest and peak exercise was assessed using the scintigraphic agent technetium-99m methoxyisobutyl isonitrile (sestamibi). Exercise capacity was determined with a modified Brace protocol. Ambulatory etectrocardiographic (ECG) Holter monitoring was performed. Ventricular function, contractility and wall motion were assessed echocardiographically.Results. Twenty-three children (aged 4.2 to 7.9 years) underwent evaluation. Abnormalities were found on the rest perfusion scans in 22 children (95.6%). The left ventricular myocardium was divided into 13 segments for analysis. Of 299 rest segments, 225 (75.3%) were normal, 11 (3.7%) showed mild defects, 45 (15%) moderate defects and 18 (6%) severe defects at rest. At peak exercise, 237 segments (79.3%) were normal, 24 (8%) showed mild defects, 33 (11%) moderate defects and 5 (1.7%) severe defects. Compared with rest studies, myocardial perfusion grade at exercise was unchanged in 246 segments (82.3%), improved in 42 (14%) and worsened in 11 (3.7%). All patients had normal exercise tolerance without symptoms or ischemic ECG changes. No ventricular tachycardia was seen on Holter monitoring. All patients had a shortening fraction ≥27%. Left ventricular contractility was normal in 12 children in whom it was assessed. Regional wall motion was normal in 17 children with adequate echocardiographic images for this analysis.Conclusions. Myocardial perfusion scan abnormalities assessed by technetium-99m sestamibi are common after an arterial switch operation. These abnormalities are of uncertain clinical significance and generally lessen with exercise. The normal exercise tolerance without symptoms or ECG changes suggests that myocardial perfusion is adequate during the physiologic stress of exercise in children up to 8 years after an arterial switch operation.