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Summary. The aim of this investigation was, first, to examine comparatively the changes infirst and second ventilatory thresholds (VT 1 and VT 2 ) and, secondly, to compare with peakoxygen uptake (V_ O 2 peak ) changes following high-intensity interval training (HIT) in prepubescentchildren. Eighteen prepubescent children (aged 10.1 0.7 years) performed an incrementalexhaustive exercise on a cycle ergometer with pulmonary gas exchange measurements beforeand after an 8-week period. During this period, nine children (five girls and four boys; initialV_ O 2 peak : 39.6 6.0 ml O 2 min 1 kg 1 ) took part in a HIT and nine other children (three girlsand six boys; initial V_ O 2 peak : 39.8 7.8 ml O 2 min 1 kg 1 ), considered as controls, were nottrained. After the training period, VT 1 ,VT 2 , and V_ O 2 peak were significantly (P < 0.01) improved(21%, 24%, and 14%, respectively) without significant changes in the control group. However,the changes in VT 1 (DVT1 ¼þ4.35 4.36 ml O 2 min 1 kg

The purpose of our investigation was to suggest a new approach to determine exercise intensities in master elderly athletes. Sixteen trained elderly men (63.0 +/- 2.9 years) and 8 trained elderly women (62.3 +/- 5.5 years), performed an exhaustive exercise test on a cycle ergometer. Rating of perceived exertion (RPE) and heart rate reserve (HRr) were determined at the first and second ventilatory thresholds (VT1 and VT2). There was no significant difference between genders in RPE and HRr, whatever the exercise intensity. RPE scores corresponded to 12.4 +/- 0.9 in men and 12.7 +/- 1.3 in women at VT1. At VT2, RPE was 15.2 +/- 0.8 and 15.3 +/- 1.1 in men and women, respectively. HR at VT1 corresponded to 59.3 +/- 7.0% in men and 59.5 +/- 5.1% in women, whereas at VT2, HR was measured at 80.5 +/- 6.4% and 79.5 +/- 5.9% HRr, in men and women, respectively. Because it is not practical to measure VT1 and VT2 in routine clinical practice, the present study indicated that, in trained older men and women, the RPE value of 12 - 13 and/or 60 % HRr might be used to detect the exercise intensity at VT1. An RPE score of 15 and/or 80 % HRr would appear to be good indexes in the prescription of exercise intensity at VT2.

To analyze the influence of step-duration protocol (1 vs. 3 min) on breathing strategy according to the physical fitness of healthy elderly subjects, this study compared the ventilatory responses and exercise tidal flow-volume loops (ETFVL) at the first and second ventilatory thresholds (VT1and VT2). Nineteen master athletes (mean age (± SD), 63.1 ± 3.2 y; [Formula: see text]O2 max, 41.5 mL·(min·kg)-1) and 8 untrained elderly subjects (age, 65.5 ± 2.3 y; [Formula: see text]O2 max, 25.8 mL·(min·kg)-1) performed 2 exhaustive exercise tests on a cycle ergometer. In untrained subjects, at VT1and VT2, no significant difference was measured in ventilatory responses and ETFVL between protocols. Master athletes, at VT2, presented a significantly higher [Formula: see text]CO2(P < 0.01), ventilation ([Formula: see text]E; P < 0.01), breathing frequency (fb; P < 0.05), tidal volume relative to inspiratory capatcity (Vt/IC) (P < 0.01),Vtrelative to forced vital capacity (Vt/FVC; P < 0.05), and lower inspiratory reserve volume relative to FVC (IRV/FVC; P < 0.01) during the 1 min protocol than during the 3 min protocol. Master athletes, at maximal exercise, expressed significantly higher [Formula: see text]CO2(P < 0.01) and dyspnea (P < 0.05) with the shorter protocol. We concluded that, in untrained subjects, neither incremental exercise test had an impact on respiratory responses during exercise. Nevertheless, in master athletes, breathing strategy seems to be protocol dependent. The short test induced higher mechanical ventilatory constraints and dyspneic feeling than the long protocol, which could be explained by a higher [Formula: see text]E itself linked to a greater [Formula: see text]CO2and a higher blood lactate concentration.Key words: exercise flow-volume loops, master athletes, submaximal exercise, mechanical ventilatory constraints.

The aim of this study was to investigate the development of exercise-induced hypoxemia (EIH defined as an exercise decrease > 4 % in oxygen arterial saturation, i. e. SaO (2) measured with a portable pulse oximeter) in twelve sportsmen and ten sportswomen (18.5 +/- 0.5 years) who were non-elite and not initially engaged in endurance sport or training. They followed a high-intensity interval-training program to improve V.O (2)max for eight weeks. The training running speeds were set at approximately 140 % V.O (2)max running speed up to 100 % 20-m maximal running speed. Pre- and post-training pulmonary gas exchanges and SaO (2) were measured during an incremental running field-test. After the training period, men and women increased their V.O (2)max (p < 0.001) by 10.0 % and 7.8 %, respectively. Nine subjects (seven men and two women) developed EIH. This phenomenon appeared even in sportsmen with low V.O (2)max from 45 ml x min (-1) x kg (-1) and seemed to be associated with inadequate hyperventilation induced by training: because only this hypoxemic group showed 1) a decrease in maximal ventilatory equivalent in O (2) (V.E/V.O (2), p < 0.01) although maximal ventilation increased (p < 0.01) with training, i. e. in EIH-subjects the ventilatory response increased less than the metabolic demand after the training program; 2) a significant relationship between SaO (2) at maximal workload and the matched V.E/V.O (2) (p < 0.05, r = 0.67) which strengthened a relative hypoventilation implication in EIH. In conclusion, in this field investigation the significant decrease in the minimum SaO (2) inducing the development of EIH after high-intensity interval-training indicates that changes in training conditions could be accompanied in approximately 40 % non-endurance sportive subjects by alterations in the degree of arterial oxyhemoglobin desaturation developing during exercise. 25;1

Resume Actuellement, il est bien reconnu que des sportifs d'endurance avec une forte consommation maximale d'oxygene ( V O 2 max ) peuvent presenter une hypoxemie induite par l'exercice. Le but de cette etude etait de determiner si un entrainement ameliorant la V O 2 max avait un impact sur l'apparition d'une hypoxemie d'exercice chez des sportifs ne pratiquant pas de sport d'endurance. Resultats – Sur 13 hommes et 11 femmes, apres 8 semaines d' interval-training , 7 sujets presentaient une hypoxemie d'exercice, 7 sujets presentaient une hypoxemie legere et 10 sujets ne presentaient pas d'hypoxemie lors d'un exercice progressif et maximal de course. Conclusion – Il semblerait qu'une courte periode d'entrainement induise l'apparition d'une hypoxemie d'exercice chez certains sportifs presentant des V O 2 max inferieures a 57 ml min –1 kg –1 .

International audience; The purpose of this study was to observe the effect of high intermittent exercise training on children's heart rate variability (HRV). Thirty-eight children (age 9.6 +/- 1.2 years) were divided into an intermittent (IT, n = 22) and a control group (CON, n = 16). At baseline and after a 7-week training period, HRV parameters, peak oxygen consumption (VO(2peak)) and maximal aerobic velocity (MAV) were assessed. Training consisted of three 30-min sessions composed by short maximal and supramaximal runs at velocities ranging from 100 up to 190% of MAV. HRV was computed in time and frequency domains. Training resulted in a significant increase in MAV and VO(2peak) in IT (P < 0.05) only without any significant change in HRV parameters for the two groups. Thus, 7 weeks of high intermittent exercise training allows to improve aerobic fitness. However, this modality of training was not sufficient enough to underline a possible effect on the heart rate autonomic regulation in children.

This work aimed to investigate accessory respiratory muscle oxygenation (RMO(2)) during exercise, using near-infrared spectroscopy, and to study relationships between RMO(2) kinetics and breathing parameters. Nineteen young males (19.3 +/- 1.5 years) performed a maximal incremental test on a cycle ergometer. Changes in breathing pattern were characterized by accelerated rise in the breathing frequency (f (Racc)), plateau of tidal volume (V (Tplateau)) and inflection point in the V. (E)/V (T) relationship (V. (E)/V (T inflection)). First and second ventilatory thresholds (VT1 and VT2) were also determined. RMO (2) kinetics were monitored by NIRS on the serratus anterior. During exercise, all subjects showed reduced RMO (2) (deoxygenation) with a breakdown (B-RMO(2)) at submaximal workload (86 % .VO(2max)). .VO(2) corresponding to B-RMO (2) and to f (Racc), V (Tplateau), .V(E)/V(T inflection), or VT2 were not different. Relationships were found between the .VO(2) at B-RMO(2) and the .VO(2) at f (Racc) (r = 0.88, p < 0.001), V (Tplateau) (r = 0.84, p < 0.001), V. (E)/V (T inflection) (r = 0.58, p < 0.05) or VT2 (r = 0.79, p < 0.001). The amplitude of RMO(2) at maximal workload was weakly related to .VO(2max) (r = 0.58, p < 0.05). B-RMO (2) seems to be due to the change in breathing pattern and especially to the important rise in breathing frequency at the VT2 exercise level. Moreover, subjects who exhibit higher .VO(2max) also exhibit a higher decrease in respiratory muscle oxygenation during exercise.

We assessed expiratory airflow limitation (expFL) in 18 healthy prepubescent children (6 girls and 12 boys, 10.1 ± 0.3 years old), and examined how it might modulate regulation of tidal volume (VT) during exercise. The children performed a maximal incremental exercise on a cycle ergometer, preceded and followed by pulmonary function tests. Throughout exercise, breathing flow-volume loops were plotted into the maximal flow-volume loop (MFVL) measured at rest. End-expiratory and end-inspiratory lung volumes were estimated by measuring expiratory reserve volume relative to forced vital capacity (ERV/FVC), and inspiratory reserve volume relative to forced vital capacity (IRV/FVC), respectively. The expFL, expressed as a percentage of VT, was defined as the part of the tidal breath meeting the boundary of the MFVL. Ten children (FL) presented an expFL at peak exercise (range, 16–78% of VT), and the remaining 8 constituted a nonflow-limited group (NFL). At peak exercise, FL presented a higher IRV/FVC and lower ERV/FVC (P

We investigated the effects of short duration running training on resting and exercise lung function in healthy prepubescent children. One trained group (TrG) (n = 9; three girls and six boys; age = 9.7 +/- 0.9 year) participated in 8 weeks of high-intensity intermittent running training and was compared to a control group (ContG) (n = 9; four girls and five boys; age = 10.3 +/- 0.7 year). Before and after the 8-week period, the children performed pulmonary function tests and an incremental exercise test on a cycle ergometer. After the 8-week period, no change was found in pulmonary function in ContG. Conversely, an increase in forced vital capacity (FVC) (+7 +/- 4% ; P = 0.026), forced expiratory volume in one second (+11 +/- 6% ; P = 0.025), peak expiratory flows (+17 +/- 4% ; P = 0.005), maximal expiratory flows at 50% (+16 +/- 10% ; P = 0.019) and 75% (+15 +/- 8% ; P = 0.006) of FVC were reported in TrG. At peak exercise, TrG displayed higher values of peak oxygen consumption (+15 +/- 4% ; P < 0.001), minute ventilation (+16 +/- 5% ; P = 0.033) and tidal volume (+15 +/- 5% ; P = 0.019) after training. At sub-maximal exercise, ventilatory response to exercise DeltaV(E)/DeltaV(CO(2)) was lower (P = 0.017) in TrG after training, associated with reduced end-tidal partial oxygen pressure (P < 0.05) and higher end-tidal partial carbon dioxide pressure (P = 0.026). Lower deadspace volume relative to tidal volume was found at each stage of exercise in TrG after training (P < 0.05). Eight weeks of high-intensity intermittent running training enhanced resting pulmonary function and led to deeper exercise ventilation reflecting a better effectiveness in prepubescent children. 94

We studied mechanical ventilatory constraints in 13 aerobically trained (Tr) and 11 untrained (UT) prepubescent children by plotting the exercise flow-volume (F-V) loops within the maximal F-V loop (MFVL) measured at rest. The MFVL allowed to determine forced vital capacity (FVC) and maximal expiratory flows. Expiratory and inspiratory reserve volumes relative to FVC (ERV/FVC and IRV/FVC, respectively) were measured during a progressive exercise test until exhaustion. Breathing reserve (BR) and expiratory flow limitation (expFL), expressed in percentage of tidal volume (Vt) and defined as the part of the tidal breath meeting the boundary of the MFVL, were measured. Higher FVC and maximal expiratory flows were found in Tr than UT ( P < 0.05) at rest. Our results have shown that during exercise, excepting one subject, all Tr regulated their Vt within FVC similarly during exercise, by breathing at low lung volume at the beginning of exercise followed breathing at high lung volume at strenuous exercise. In UT, ERV/FVC and IRV/FVC were regulated during exercise in many ways. The proportion of children who presented an expFL was nearly the same in both groups (∼70% with a range of 14 to 65% of Vt), and no significant difference was found during exercise concerning expFL. However, higher ventilation (V̇e), ERV/FVC, and dyspnea associated with lower BR, IRV/FVC, and SaO2 were reported at peak power in Tr than UT ( P < 0.05). These results suggest that, because of their higher V̇e level, trained children presented higher ventilatory constraints than untrained. These may influence negatively the SaO2 level and dyspnea during strenuous exercise.

International audience; The aim of this study was to analyze the effects of a 7-week interval-training program on different aspects of physical fitness in children who were 8-11 years old. Forty-six boys and 54 girls (9.7 +/- 0.8 years) were divided into an experimental group and a control group. The 2 groups performed selected tests from the European physical fitness test battery before and after training. Training consisted of 2 specific 30-minute sessions per week of short high-intensity, intermittent-running aerobic exercises at velocities ranging from 100-130% of maximal aerobic speed. After training, the experimental group demonstrated a significant improvement in the standing broad jump (9.6%, p < 0.001, F = 12.9) and 20-meter shuttle run (5.4%, p < 0.001, F = 14.4), whereas for the control group, no significant changes were observed. It was concluded that a high-intensity, intermittent-running program improved children's aerobic performance and explosive strength.

Exercise-induced arterial hypoxemia (EIAH) is a recognized phenomenon in highly trained adults. Like adult athletes, prepubescent trained children may develop high-level metabolic demand but with a limited lung capacity in comparison with adults. The purpose of this investigation was to search for evidence of EIAH in prepubescent trained children. Twenty-four prepubescent (age: 10.3 +/- 0.2 y) trained children (10.0 +/- 0.7 h of weekly physical activity) performed pulmonary function tests and a graded maximal exercise test on a cycle ergometer. EIAH was defined as a drop of at least 4% from resting level arterial oxygen saturation (Sao(2)) measured by pulse oximetry. EIAH was observed in seven children. Forced vital capacity (FVC), ventilatory response to exercise (Delta(E)/Deltaco(2)), and breathing reserve at maximal exercise were significantly lower, whereas tidal volume relative to FVC was higher in hypoxemic children than in nonhypoxemic children; weekly physical activity and maximal oxygen uptake were similar. Moreover, positive relationships were found between Sao(2) at maximal exercise and breathing reserve (r = 0.56; p < 0.05) or volume relative to FVC (r = 0.70; p < 0.01). EIAH may occur in prepubescent trained children with a relatively low maximal oxygen uptake (42 mL. min(-1). kg(-1)); however, the mechanisms remain unclear and need to be investigated more accurately. 55

Les enfants pre-puberes entraines peuvent atteindre de hauts niveaux de demande metabolique malgre une taille pulmonaire limitee en comparaison avec l’adulte. Le but de cette investigation etait d’etudier l’evolution de la saturation arterielle en oxygene (Sao2) au cours de l’exercice chez des enfants pre-puberes entraines pour determiner si une hypoxemie induite par l’exercice (HIE) peut exister dans ce type de population. 24 enfants sportifs pre-puberes (âge = 10,3 ± 0,2 ans) ont realise un examen spirometrique et un exercice progressif et exhaustif sur ergocycle. La Sao2 etaient mesuree par oxymetrie de pouls. 7 enfants presentaient une HIE lors du test d’exercice, soit une chute d’au moins 4 % de la Sao2 par rapport au repos. La capacite vitale forcee (CVF) et la reserve ventilatoire a l’exercice maximal (RV) etaient inferieures chez les sujets hypoxemiques (P < 0,05). Cependant, la ventilation et les pressions partielles de fin d’expiration en oxygene et en dioxyde de carbone n’etaient pas differentes entre les deux groupes a l’exercice maximal. En conclusion, la HIE peut apparaitre chez l’enfant sportif pre-pubere a partir de valeurs de Vo2max relativement basses (42 ml.min-1.kg-1). Les faibles valeurs de CVF semblent impliquees dans ce phenomene cependant, le role de la ventilation reste flou.