Reproducibility of cardiac output measurements by Doppler echocardiography in prepubertal children and adults

The aim of this study was to examine reproducibility of stroke volume and cardiac output measurements by Doppler echocardiography during submaximal and maximal exercise in adults and children. Fourteen healthy children (8 girls and 6 boys aged 10.9 +/- 0.9yr) and eleven healthy young adults (1 female and 10 males aged 22.3 +/- 3.8 yr) underwent a progressive maximal upright cycle test until exhaustion with estimation of stroke volume and cardiac output by Doppler echocardiography on two separate occasions (one week apart). Maximal oxygen uptake and maximal heart rate were not significantly different between both tests in the children and adults indicating that similar exhaustive efforts were achieved at each test. No significant differences for mean values of stroke volume and cardiac output were observed at rest in the children and whatever the exercise intensity in the children and adults. No significant differences were observed between values of root mean square (precision and precision of error) in both groups. Thus we demonstrated that stroke volume and cardiac output values obtained by Doppler echocardiography at rest and during submaximal and maximal exercise were reproducible on test-retest measurements in children and adults.

Effect of gender in response to an aerobic training programme in prepubertal children

The aim of the present study was to investigate the gender effect of an endurance training programme on the maximal oxygen uptake (VO2max) of prepubertal children. The subjects comprised eighty-five 10-11-y-old prepubertal children: 35 (17 girls, 18 boys; EG) were involved in a 13-wk running training programme and 50 (22 girls, 28 boys; CG) served as a control group. Each subject carried out a continuous and progressive cycle ergometer test before and after the 13-wk study period under the same conditions and procedures. Oxygen consumption, carbon dioxide, ventilation and heart rate (HR) were continuously monitored during the test. The training programme consisted of interval and continuous long-distance running (frequency: 3 times a week, duration: 1 h per session, intensity: higher than 80% of maximal HR). V02max significantly increased after the training programme for EG (before = 42.3 +/- 7.7, after = 45.3 +/- 7.5 ml x min(-1) x kg(-1), p < 0.01), while no alterations were noticed for CG (before = 43.1 +/- 6.7, after = 42.6 +/- 7.6 ml x min(-1) x kg(-1), p < 0.01). Such an increase was higher in the girls (+9.1%) than the boys (+4.6%). The lower initial fitness of the girls could explain this, however, because a significant relationship was found between the percentage of VO2max increase after training and the initial VO2max. The present longitudinal study shows that maximal oxygen uptake can increase in prepubertal children after an aerobic training programme and that such an increase is of the same order in boys and girls when the initial aerobic fitness is taken into account.

[Study of the reproducibility of cardiac output measurement during exercise in pre-pubertal children by doppler echocardiography and CO2 inhalation]

Non-invasive measurement of the cardiac output is essential in investigations of healthy children. However, the data concerning the reproducibility of the measurements are very limited. The aim of this study was to assess the reproducibility of the measurement of cardiac output during exercise by Doppler echocardiography and reinhalation of CO2 (extrapolation method). Fourteen pre-pubertal children underwent two similar tests at increasingly intense levels of exercise. The cardiac output was measured at rest and during the last minute of each stepwise increment of exercise. The results show no difference between the cardiac outputs of the two tests, whichever method was used and at all levels of exercise. They also demonstrate a better reproducibility of cardiac output measurement by Doppler echocardiography (coefficient of variation: 7.5% at rest and 5.2% at maximal effort) compared with reinhalation of CO2 (coefficient of variation: 16.8% at rest and 11.7% at maximal effort). Both methods showed better reproducibility on exercise, resulting from smaller variations in heart rate and stroke volume on effort than at rest. The authors conclude that Doppler echocardiography is very accurate and its simplicity makes it the method of choice in pre-pubertal children for measuring cardiac output during exercise.

The slow component of O2 uptake kinetics during high-intensity exercise in trained and untrained prepubertal children

The aim of the present study was to investigate the O2 uptake slow component in prepubertal children of different aerobic capacity during high intensity exercise. Twenty-three (12 well-trained, T and 11 untrained, U subjects) 10-13 year old prepubertal children took part in 3 tests: one incremental test to determine the maximal aerobic power (PMA) and anaerobic threshold (LAT); two constant-power tests performed at intensities corresponding to 80%LAT and 90%PMA. Oxygen uptake (VO2), heart rate, ventilation (VE) and lactate ([L]s) were evaluated during each test. A monoexponential + linear term model (starting after phase 1) was used to assess VO2 kinetics during both constant-power tests. Our results showed that a slow component, represented by the linear coefficient (S) of the mathematical model, was present during the 90%PMA test only (S = 0.86 +/- 0.48 ml x min(-2) x kg(-1) for the whole population). No relationships were found between either S and VE or [L]s, showing that, at least in prepubertal children, these factors play a minor role in the explanation for the VO2 slow component. The slow component contributed approximately to the same amount of the total VO2 response in both groups (T: 21.4 +/- 8.0, U: 19.3 +/- 3.9%, ns). In conclusion, as previously described in adults, our data demonstrated the existence of a slow component in prepubertal children during high-intensity exercise. Moreover, this slow component was similar in trained and untrained children, exercising at the same relative intensity.

Parotidectomy: a plastic approach

Three disadvantages are frequent after parotidectomy: a scar affecting the neck, a deep hollow between the sternocleidomastoid muscle and the mandible (the larger the resection is, the deeper is the hollow), and a sweat secretion. These disadvantages can be prevented or reduced by using four simple procedures: (1) using a facelift incision; (2) using a very simple and original "trick," by displacing outward the posterior belly of the digastric muscle; (3) using a flap with an upper pedicle taken from the sternocleidomastoid muscle; and (4) using a double free graft, taken from the superficial and deep temporal fascias. These two grafts lay down on the net constituted by the preceding flaps. They line the skin, thus blocking the wrong innervation.

Effect of long-term intensive endurance training on left ventricular structure and diastolic function in prepubertal children

In children, the fact that cardiac anatomy and function, particularly during the diastolic phase, can adapt to endurance training is still uncertain. Therefore, this study was undertaken to evaluate the effect of a long-term intensive endurance swimming program on the cardiac structure and function of 10-11 year old children. The population consisted of 9 children who belonged to a local youth swimming team (S) and 11 recruited from a primary school to serve as a control group (C). The swimmers had been training on average 10 to 12 h x wk(-1) for at least 2 years. All the subjects were examined by M-mode, 2-dimensional and pulsed-wave Doppler analyses according to standard procedures recommended by the American Society of Echocardiography. Investigations were carried out at rest with the subjects in a supine position. The results showed that highly trained children exhibited significantly higher left ventricular (LV) internal diameter (S: 41.6+/-1.6, C: 39.0+/-2.2 mm/m(1/3) surface area, p<0.01) and LV mass (S: 68+/-7, C: 59+/-5 g/m2 SA, p<0.01). There were, however, no differences between S and C for chamber wall thickness (posterior wall S: 5.2+/-0.6, C: 5.3+/-0.6 mm/m(1/3) SA; septum S: 5.8+/-0.3, C: 5.8+/-0.4 mm/m(1/3) SA), LV systolic function parameters (ejection fraction S: 77.1+/-0.3, C: 77.7+/-0.4%; shortening fraction S: 38.9+/-3.0, C: 39.7+/-4.1%) and the diastolic function parameters, estimated from LV inflow velocitometry (E wave S: 1.04+/-0.12, C: 1.07+/-0.16 m/s; A wave S: 0.45+/-0.10, C: 0.55+/-0.11 m/s). Finally, transaortic Doppler examinations demonstrated similar resting cardiac output (Qc) between both groups (S: 3.76+/-0.81, C: 3.90+/-0.67 l x min(-1)). However, Qc were obtained with significantly lower heart rates (S: 69+/-7, C: 83+/-14 beat x min(-1), P<0.01) and higher stroke volumes (S: 55.2+/-8.0, C: 47.5+/-8.5 ml, P<0.05) in S when compared to C. Thus, these findings strongly suggest that, as has been shown before in adults, several cardiac adaptations (including resting bradycardia, increased stroke volume and enlarged left ventricular internal dimensions) can occur in prepubertal children as a result of intensive endurance training. However, our results did not demonstrate any effects of such training during prepuberty on both diastolic and systolic functions parameters.

Effect of intensive swimming training on lung volumes, airway resistance and on the maximal expiratory flow-volume relationship in prepubertal girls

The aim of the present study was to analyse the effect of 1 year of intensive swimming training on lung volumes, airway resistance and on the flow-volume relationship in prepubertal girls. Five girls [9.3 (0.5) years old] performing vigorous swimming training for 12 h a week were compared with a control group of 11 girls [9.3 (0.5) years old] who participated in various sport activities for 2 h per week. Static lung volumes, maximal expiratory flows (MEF) at 75, 50 and 25% of vital capacity, 1-s forced expiratory volume (FEV1.0) and airway resistance (R(aw)) were measured by means of conventional body plethysmograph techniques. Prior to the training period there were no significant differences between the two groups for any of the parameters studied. Moreover, for both groups, all parameters were within the normal range for children of the corresponding age. After 1 year of training, vital capacity (VC), total lung capacity (TLC) and functional residual capacity (FRC) were larger (P < 0.05) in the girl swimmers than in the control group, while physical development in terms of height and weight was similar. FEV1.0 (P < 0.01), MEF25, MEF50 (P < 0.05) and MEF75 as well as the ratio MEF50/TLC (P < 0.05) had increased in the girl swimmers but were unchanged in the control group. R(aw) tended to be lower in the girl swimmers and higher in the control group. The results indicate that intensive swimming training prepuberty enhances static and dynamic lung volumes and improves the conductive properties of both the large and the small airways. As to the causative mechanism, it can be speculated that at prepuberty intensive swimming training promotes isotropic lung growth by harmonizing the development of the airways and of alveolar lung spaces.

Effect of long-term intense swimming training on the upper body peak oxygen uptake of prepubertal girls

The purpose of the present investigation was to determine the effect of a long-term intense swimming programme on the aerobic potential of prepubertal girls. Five girls [GS, aged 9.3 (SD 0.5) years] participated in a 40-month intense training period. The girls trained on average 10-12 h*week(-1), approximately 1 h-1.5 h twice a day, 5 days each week. Nine girls [CG aged 9.3 (SD 0.4) years] who were engaged in various activities (on average 1-4 h*week(-1)), but not in sports involving upper body muscle mass, served as the control group. All the children completed, on a special swim bench, an incremental maximal exercise prior to (pretest) and after (post-test) the swimming programme. Biometric parameters and the peak oxygen uptake (VO(2peak)) were determined using the same procedure at the pre- and post-test sessions. There was no significant difference between the two groups for any of the variables at the beginning of the study. The biometric characteristics remained similar at the post-test session, indicating that intense swimming training early in life has no influence on the physical growth of prepubertal children. The VO(2peak) expressed in absolute values, however, increased over a year in GS and CG by 38 percent and 13 percent, respectively. The improvement in CG VO(2peak) was related to normal growth and development while that of GS was much higher (P<0.01) than would have been expected due to growth factors alone. The reason for such an improvement could be attributed to an increase in the stroke volume and/or in the difference of the arteriovenous concentration of oxygen since the maximal O(2) pulse was different between CG and GS only at the post-test. Moreover, it increased after 10 months only in GS (delta maximal O(2) pulse: GS 1.09, P<0.01; CG 0.27 NS, ml.beat(-1)). Thus, the results of this study show that physiological adaptations can occur in prepubertal children as a consequence of intense physical training.