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Biomedical subjects

T Reybrouck

Publications and source records attributed to T Reybrouck.

At least 37 records · Page 2Linked to original sources
PubMed1992

Evaluation of breath-by-breath measurement of respiratory gas exchange in pediatric exercise testing.

In adults, breath-by-breath analysis has been used for measuring respiratory gas exchange during exercise. The present study evaluates the validity and reproducibility of this method in children. In 21 patients with various types of congenital heart disease, steady state exercise testing was performed on a motor-driven treadmill. Based on simultaneous measurements of VO2, VCO2, VE and R, comparisons were made between the breath-by-breath and Douglas bag methods. No significant differences were found between both methods for any of the variables. In seven other patients the reproducibility of cardiorespiratory variables during exercise was assessed. No significant difference was found for the cardiorespiratory variables during any of the tests and the coefficients of variation were comparable to data obtained in adults. It is concluded that the breath-by-breath method for measuring respiratory values can be applied in children with an acceptable degree of validity and reproducibility.

Adolescent↗
PubMed1991

Cardiorespiratory exercise capacity after surgical closure of atrial septal defect is influenced by the age at surgery.

To study the influence of age at the time of the operation on long-term functional performance in children undergoing surgery for atrial septal defect (ASD) of the secundum type, exercise tolerance was assessed in 24 patients and values were compared with those of normal subjects. Patients were divided into two groups: 11 patients had surgery before the age of 5 years (group 1) and 13 patients had surgery at a later age (group 2). There were no significant differences between groups 1 and 2 with regard to the pulmonary-to-systemic flow ratio, pulmonary artery pressure, and the interval between surgery and exercise testing. Performance capacity was assessed by determination of the ventilatory threshold during submaximal exercise. The mean value for the ventilatory threshold in group 1 was normal (99.4 +/- 15.1% of the age-predicted normal value). In the children who were more than 5 years of age at the time of the operation, the ventilatory threshold was below normal (84.5 +/- 10.9% of the age-predicted normal value). Furthermore, in group 2 more patients (77%) had values that were below normal (below the 95% confidence limit of the age-predicted normal value) compared with group 1 (27%). It is concluded that functional performance capacity is better when surgical closure of ASD is performed in early childhood and before the age of 5 years rather than at a later age.

Adolescent↗
PubMed1990

Exercise therapy and hypocaloric diet in the treatment of obese children and adolescents.

Fourteen obese children and adolescents were treated with a combined therapy of low calorie diet and exercise and their progress compared to that of 11 obese children treated with diet only. Children treated with combination therapy were encouraged to perform aerobic exercises daily, for a period of time which was calculated to consume approximately 250 kcal per exercise session. After 4 months of therapy, a significantly (P less than 0.05) larger decrease of % overweight was observed in the group of children treated with diet and exercise (-25 +/- 13.5%) than in those treated with diet only (-15.8 +/- 10.5%). Treatment compliance was better in the group treated with diet and exercise than in the group which followed a low calorie diet only. We think that unsupervised exercise therapy can be successfully combined with a low calorie diet in the treatment of childhood obesity.

Adolescent↗
PubMed1989

Cardiorespiratory response to exercise in congenital complete atrioventricular block.

In 8 patients aged 8 to 17 years with congenital complete atrioventricular (AV) block, exercise testing was performed on a treadmill. Cardiorespiratory endurance performance was assessed by determination of the ventilatory threshold. The mean value for ventilatory threshold was significantly lower (p less than 0.005) than the normal mean value and averaged 76 +/- 16%, 75 +/- 17% and 75 +/- 16% of the predicted normal value in children of the same sex and comparable age, weight and height, respectively. The ventricular rate at rest varied from 36 to 56 beats/min and increased to a mean value of 106 +/- 25 on exercise. When expressed as a percentage of the normal value, the heart rate was subnormal (below the 95% confidence limit) in all patients, throughout different exercise levels. For the same exercise intensity the oxygen uptake, expressed as ml/min/kg, was significantly lower (p less than 0.02) in patients than in normal individuals. This suggests an inadequate hemodynamic adjustment to the relative exercise bradycardia and a higher than normal anaerobic/aerobic energy supply. Exercise testing was found to be useful in the assessment of congenital AV block, because the resting heart rate did not permit prediction of the relative exercise bradycardia or the degree of exercise intolerance.

Adolescent↗
PubMed1989

Habitual level of physical activity and cardiorespiratory endurance capacity in children.

A total of 257 healthy children (140 boys, 117 girls) varying in age from 5.7 to 18.5 years underwent graded exercise tests on a treadmill. Cardiorespiratory endurance capacity was assessed by determination of the ventilatory threshold, which was defined as the highest exercise intensity before a disproportionate increase occurred in pulmonary ventilation (VE) relative to oxygen uptake (VO2). The purpose of the present study was to investigate the relationship between the habitual level of physical activity (HLPA) and the cardiorespiratory endurance capacity in children. The HLPA was assessed by a standardized questionnaire. In boys and girls HLPA increased gradually with advancing age. For the group as a whole, the boys reached the highest values for HLPA. The most active boys reached the highest value for ventilatory threshold and the lowest value was found in the less active ones, except for the age span of 12-16 years. It is concluded that more active boys showed a higher cardiorespiratory endurance capacity, as assessed by the ventilatory threshold, compared to less active ones, except during puberty. It can be postulated that during puberty this effect may be overruled by the influence of other more dominant growth-related factors. In girls, because HLPA was rather low, there was no discriminative effect of HLPA on exercise performance, as would be expected.

Adolescent↗
PubMed1988

Cardiorespiratory exercise testing after venous switch operation in children with complete transposition of the great arteries.

In 14 children who underwent a venous switch operation for complete transposition of the great arteries, exercise testing was performed 3 to 15 years (mean 8) after the operation. Exercise performance capacity was assessed by the determination of the ventilatory threshold during exercise and by the oxygen uptake (VO2) reached at a heart rate of 170 beats/min (VO2,170). The ventilatory threshold was defined as the highest oxygen uptake (VO2) at which the pulmonary ventilation (VE) stops to increase linearly when related to VO2. During exercise above this threshold a disproportionate increase in VE relative to VO2 is observed. The mean ventilatory threshold was significantly lower (p less than 0.01) than the normal mean value and averaged 72 +/- 15%, 67 +/- 15% and 70 +/- 13% of the predicted normal value for children of comparable age, weight and height, respectively. The mean value for VO2,170 also was significantly lower (p less than 0.05) than the normal mean value for children of comparable age, weight and height, and averaged 81 +/- 20%, 81 +/- 18% and 80 +/- 18%, respectively. Compared with normal control subjects of the same sex and age, the ventilatory threshold was surpassed sooner (p less than 0.001) and reached after 2 +/- 1 min instead of the 4 +/- 1 min required by the controls. In nearly half of the patients, a lower than normal (i.e. below the 95% confidence limit) heart rate response to exercise was observed. Theoretically, this could be interpreted as indicating a normal or high physical performance capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1987

Cardiorespiratory function during exercise in obese children.

Fifteen obese children, aged 4 to 16 years and ranging in body weight from 27.3 to 95 kg (median 67.5) and percentage overweight from 22 to 127% (median 40), underwent graded exercise testing on a treadmill and were compared with healthy peers of comparable age. Cardiorespiratory performance capacity was assessed by determination of the ventilatory threshold. This was defined as the highest oxygen uptake at which the pulmonary ventilation stops to increase linearly with increasing exercise intensity. The ventilatory threshold, expressed as ml O2/min/kg, was significantly (p less than 0.05) lower than in normal children and averaged 70.6 +/- 13.5% of the normal mean value, matched for age. The habitual level of physical activity, assessed by a questionnaire, was 27% lower (p less than 0.01) in the obese children compared to healthy controls. As the ventilatory threshold was strikingly lower and also exceeded sooner in the majority of the obese children, compared with normal controls, it may be assumed that obese children avoid moderate or strenuous exercise, because of the higher degree of effort needed. This may contribute to the maintenance of overweight.

Adolescent↗
PubMed1986

Ventilatory anaerobic threshold for evaluating exercise performance in children with congenital left-to-right intracardiac shunt.

The ventilatory response to graded treadmill exercise was studied in 50 children with congenital heart disease (CHD), a left-to-right intracardiac shunt, and compared to that of age and sex-matched healthy children. In all these children, a breakpoint in the minute ventilation (VE) in relation to increasing oxygen uptake (VO2) was detected. Because of the reported coincidence of the nonlinear increase in VE and lactate with increasing VO2, this threshold has been named "ventilatory anaerobic threshold" (VAT), expressed in ml O2 X min-1 X kg-1. VAT correlated well with VO2 (ml X min-1 X kg-1), reached at a heart rate of 170/min (VO2,170). Compared to normal children, however, a significantly (p less than 0.05) larger percentage (56%) of the patients showed a subnormal value (below the 95% confidence limit) for VAT than for VO2,170 (28%). Furthermore, when expressed as a percentage of the mean normal value, the mean VAT (89 +/- 14.4% SD) was significantly (p less than 0.05) lower than the mean VO2,170 (103 +/- 17.2%). VAT (ml O2 X min-1) correlated significantly with body weight and height, even after adjusting for age, and with the percentiles of body weight and height. VAT constitutes a useful noninvasive criterion for evaluating exercise performance in children with CHD, at least those forms with a left-to-right intracardiac shunt, and it is significantly more sensitive than the VO2,170 in detecting decreased cardiorespiratory endurance capacity.

Adolescent↗
PubMed1986

Exercise testing after correction of tetralogy of Fallot: the fallacy of a reduced heart rate response.

Thirty-nine patients, 5 to 19 years of age, were studied 1 to 10.5 years (mean 4.5) after surgical correction of tetralogy of Fallot (TF). In 32 of them the results of an exercise performance test based on heart rate response to submaximal exercise (VO2, 170 [bpm]) was compared with another index of physical performance capacity, which is independent from heart rate: the ventilatory threshold. In patients operated for TF, the mean heart rate during exercise was significantly lower than that corresponding to the same level of exercise in normal children (p less than 0.001) and their mean VO2, 170 was normal. Theoretically, these findings could be interpreted as indicating a normal or high physical performance capacity. By contrast, the ventilatory threshold was significantly lower than that in normal children: it averaged 89.3 +/- 15.7%, 79.7 +/- 14.4%, and 88.5 +/- 15.8% of the mean value in normal children matched for age, weight, and height, respectively. More patients had a subnormal value for ventilatory threshold than for VO2, 170: 58% had a ventilatory threshold below the 95% confidence limits for age-matched normal individuals and 75% had a subnormal value when compared to weight-matched normal children. For VO2, 170, these values were 39% and 34%, respectively (p less than 0.05). We recommend the evaluation of the exercise performance capacity in patients operated for TF not only by measuring heart rate response and VO2, 170 which may be misleading because of relative bradycardia, but also by analyzing gas exchange and determining the ventilatory threshold.

Adolescent↗
PubMed1986

Ventilatory threshold measurement to evaluate maximal endurance performance.

The ventilatory (anaerobic) threshold during short-term exercise has been defined as the O2 uptake (VO2) immediately below the VO2 at which pulmonary ventilation (VE) increases disproportionally relative to VO2 and the ventilatory threshold for long-term exercise as the VO2 immediately below the VO2 at which the VE continues to increase with time rather than attain a steady state. Maximal endurance performance was determined by measurement of the maximal endurance time during treadmill runs at 90%, and 70% of the previously determined VO2 max. The purpose of the present study was to investigate how maximal endurance performance was related to both ventilatory thresholds and to VO2max, and to select which variable best explained maximal endurance performance. The subjects were 11 healthy males. Maximal endurance performance was significantly correlated with the ventilatory threshold for long-term exercise and VO2max. A stepwise multiple regression analysis indicated that maximal endurance performance was best predicted by the ventilatory threshold for long-term exercise. Combination of variables could not improve the prediction. It is concluded that the ventilatory threshold for long-term exercise better explains maximal endurance performance than VO2max or the ventilatory threshold during short-term exercise.

Adult↗
PubMed1985

Ventilatory anaerobic threshold in healthy children. Age and sex differences.

The ventilatory anaerobic threshold (VAT) during graded exercise was defined as the oxygen uptake (VO2) immediately below the exercise intensity at which pulmonary ventilation increased disproportionally relative to VO2. Since VAT is considered to be a sensitive and noninvasive measure for evaluating cardiorespiratory endurance performance, the purpose of the present study was to determine normal values in children. We examined 257 healthy children (140 boys and 117 girls) varying in age from 5.7 to 18.5 years, during treadmill exercise. The data were analyzed in relation to sex and age. In boys the lowest VO2max (ml X min-1 X kg-1) was found in the youngest age group (5-6 year). In girls, on the other hand, no significant increase occurred with age. For VAT, expressed as ml O2 X min-1 X kg-1 or as a percent of VO2max, a significant decrease was found in boys and girls with age. This suggests an increase in lactacid anaerobic capacity during growth. In contrast to observations in adults, only low correlations were found between VO2max and VAT (r = 0.28 in boys and r = 0.52 in girls), which suggests that the development of the underlying physiological mechanism does not occur at the same rate in growing children. These data provide normal values for VAT that can be used for clinical exercise testing in the pediatric age group.

Adolescent↗
PubMed1984

The effects of beta blockers on exercise capacity and on training response in elderly subjects.

Treatment of 8 hypertensive elderly subjects with atenolol or with labetalol did not affect exercise performance, except after the development of circulatory congestion in 1 patient. Treatment with beta blockers did not alter the response to an exercise training programme in 15 elderly patients with ischaemic heart disease, as compared with 11 patients without such treatment.

Aged↗
PubMed1983

Ventilatory thresholds during short- and long-term exercise.

The ventilatory (anaerobic) threshold for short-term exercise was defined as the work rate or O2 uptake (VO2) immediately below the work rate at which ventilation increased disproportionately relative to work rate or VO2, and the ventilatory threshold for long-term exercise as the work rate or VO2 immediately below the work rate at which ventilation continued to increase with time rather than attain a steady state. The purpose of the present study was to investigate how both thresholds relate to each other and how they relate to other measures of physical performance capacity. The subjects were eight healthy males, 20-53 yr of age. Maximal performance capacity was estimated by measurements of maximal O2 uptake (VO2 max) and by endurance performance during a 12-min distance run. A high interrelationship was found between the two thresholds (r = 0.84), and each threshold expressed in VO2 (ml X min-1 X kg-1) correlated highly with VO2 max (r = 0.87 and r = 0.75, for short-term and long-term exercise, respectively). When the two thresholds were expressed as a percentage of VO2 max, neither threshold showed a significant relationship with VO2 max. Endurance performance was significantly correlated with both the ventilatory threshold for short-term and long-term exercise (r = 0.73 and 0.82, respectively). A stepwise multiple regression analysis indicated that the distance run in 12 min was best predicted by VO2 max (R2 = 0.66) or the ventilatory threshold for long-term exercise (R2 = 0.63). It is concluded that the ventilatory threshold for long-term exercise is a more specific measure to explain running performance than is the threshold during graded exercise.

Adult↗
PubMed1982

Anaerobic threshold for long-term exercise and maximal exercise performance.

The anaerobic threshold during graded exercise (GXT, AT1) was determined as the exercise level initiating a curvilinear increase in ventilation (VE), and during prolonged exercise (PXT, 40 min, AT2) as the maximal exercise level where still a steady state for VE can be reached. Subjects were 8 healthy males, 20 to 53 years of age. Maximal exercise capacity was estimated by means of 1) VO2 max 2) max time on bicycle ergometer at 200 Watts and 3) maximal distance run within 12 min (Cooper test). VO2 max was significantly related to AT1, GXT (r = 0.85, 0.01 less than p less than 0.001) and to AT2, PXT (r = 0.75, 0.05 less than p less than 0.01). Also a significant correlation was found between the endurance exercise capacity (= 200 Watts) and both AT1 (r = 0.80; 0.05 less than p less than 0.01) and AT2 (r = 0.84; 0.01 less than p less than 0.001). Finally only AT2 was significantly correlated with the Cooper test (r = 0.81; 0.01 less than p less than 0.001), no significant relationship was found for AT1 (r = 0.68; p less than 0.05). In conclusion AT1 reached the highest correlation with a short maximal exercise test such as VO2 max, in contrast to AT2, which showed the highest correlation with endurance exercise such as Cooper test or maximal exercise time at 200 Watts.

Adult↗