Neural and muscular mechanisms of electrically induced fatigue in patients with spinal cord injury.

STUDY DESIGN: Intervention study. OBJECTIVES: The present study aimed at examining whether spinal and/or peripheral alterations are in the origin of neuromuscular fatigue development induced by intermittent neuromuscular electrical stimulation (NMES) in subjects with complete spinal cord injury (SCI). SETTING: Neurological Rehabilitation Center CMN Propara, Montpellier, France. METHODS: Thirteen volunteers with complete SCI participated in the study. The right triceps surae muscle was fatigued using a 30-Hz NMES protocol (2 s ON-2 s OFF) composed of three series of five trains. Spinal excitability (assessed by the H-reflex), muscle excitability (assessed by the M-wave), muscle contractile properties (assessed by mechanical response parameters) and torque evoked by NMES were tested before and after each five-train series. RESULTS: NMES-evoked torque significantly decreased throughout the protocol (P<0.001). This decrease was accompanied by a significant increase in M-wave amplitude (P<0.001), whereas H-reflex and the Hmax/Mmax ratio were not significantly modified. The amplitude of the mechanical response was significantly decreased at the end of the protocol (P<0.05). CONCLUSION: The results indicate significant fatigue development, which was attributed to impaired cross-bridge force-generating capacity, without modification of spinal excitability nor muscle excitability.

An innovative maintenance follow-up program after a first inpatient pulmonary rehabilitation.

Although the benefits of pulmonary rehabilitation (PR) have been demonstrated in patients with COPD, most studies suggest that short-term programs are insufficient to maintain the benefits beyond a post-discharge period of 6 months to 1 year. We were interested to evaluate the effects of an innovative maintenance intervention compared with a usual after-care. Forty moderate to severe COPD patients, who had just completed their first inpatient PR, were consecutively included in either a maintenance group (MG) or a standard after-care group. The maintenance program was coordinated within a health-care network including self-help associations, and offered weekly activities. We measured the 6-min walk distance (6MWD), the quality of life using the St George Respiratory Questionnaire (SGRQ), the dyspnea, the maximal workload and the health-care utilization. Data were collected at respiratory clinic admission and discharge, and at 6- and 12-month visits after the PR. After 12 months, we found statistically and clinically significant differences in favor of the MG in 6MWD (74 m; p < or = 0.01) and in the three domains of SGRQ: symptom (19%; p < or = 0.01), activity (27%; p < or = 0.01) and impact (32%; p < or = 0.01). The results showed no difference between groups in dyspnea and maximal workload. We also found that the number of days spent in hospital for respiratory disorders was significantly lower in the MG after 12 months (p < or = 0.03). The multidisciplinary management of COPD patients in the post-rehabilitation period within a health-care network including self-help associations seems to be an effective strategy for maintaining, and even improving, the benefits of a first initial structured program.

[What are the post-rehabilitation options for patients with COPD?]. / Quelles solutions pour l'après-réhabilitation des patients BPCO?

INTRODUCTION: The efficacy of pulmonary rehabilitation in the short term for patients with Chronic Obstructive Pulmonary Disease (COPD) is now clearly established. However, several studies have shown that these benefits last only for between 6 months to one year. On the basis of the current literature, the authors believe that a follow-up of rehabilitation "post-rehabilitation" is necessary not only to maintain benefits but also to reinforce them. STATE OF THE ART: We review studies that have focused specifically on post-rehabilitation and found a heterogeneity of tested solutions. As with conventional pulmonary rehabilitation, a multidisciplinary approach including physical activity, health education and psychosocial supports seem to be the key to successfully maintain rehabilitation's gains. PERSPECTIVES: Further randomised and controlled research will be needed to confirm the medical and economic effectiveness of this combination of intervention in patients with different severities of COPD. CONCLUSION: Individualised, objective and coordinated follow-up activities allow COPD patients to cope with the chronicity of their disease and the unpredictability of symptoms in the context of daily life.

Cortical motor output decreases after neuromuscular fatigue induced by electrical stimulation of the plantar flexor muscles.

AIM: Neuromuscular electrical stimulation (NMES) causes early onset of neuromuscular fatigue. Peripheral electrophysiological explorations suggest that supra-spinal alterations are involved through sensitive afferent pathways. As sensory input is projected over the primary somatosensory cortex (S1), S1 area involvement in inhibiting the central motor drive can be hypothesized. This study assessed cortical activity under a fatiguing NMES protocol at low frequency. METHODS: Twenty healthy males performed five NMES sequences of 17 trains over the plantar flexors (30 Hz, 4 s on/6 s off). Before and after each sequence, neuromuscular tests composed of maximal voluntary contractions (MVCs) were carried out. Cortical activity was assessed during MVCs with functional near-infrared spectroscopy over S1 and primary motor (M1) areas, through oxy- [HbO] and deoxy-haemoglobin [HbR] variation. Electrophysiological data (H-reflex during MVC, EMG activity and level of voluntary activation) were also recorded. RESULTS: MVC torque significantly decreased after the first 17 NMES trains (P < 0.001). The electrophysiological data were consistent with supra-spinal alterations. In addition, [HbO] declined significantly during the protocol over the S1 and M1 areas from the first 17 NMES trains (P < 0.01 and P < 0.001 respectively), while [HbR] increased (P < 0.05 and P < 0.01 respectively), indicating early decline in cortical activity over both primary cortical areas. CONCLUSIONS: The declining cortical activity over the M1 area is highly consistent with the electrophysiological findings and supports motor cortex involvement in the loss of force after a fatiguing NMES protocol. In addition, the declining cortical activity over the S1 area indicates that the decreased motor output from M1 is not due to increased S1 inhibitory activity.

Impaired skeletal muscle endurance related to physical inactivity and altered lung function in COPD patients.

STUDY OBJECTIVE: The aims of this work were to determine (1) whether patients with COPD have impaired skeletal muscle performance (ie, maximal strength and endurance) compared with healthy subjects, and (2) whether the level of physical activity, body composition, and lung function are related to skeletal muscle performance in COPD patients. METHODS: Seventeen COPD patients and eight healthy age-matched control subjects performed maximum voluntary contraction (MVC) of the quadriceps and an endurance test consisting of dynamic contractions of the quadriceps against 20% of MVC at an imposed regular pace until exhaustion. The endurance test duration determined the muscle "limit time" (Tlim). A score of physical activity (PA score) was obtained using an adapted physical activity questionnaire for the elderly, and body composition was measured by the bioelectrical impedance method. Symptom-limited oxygen uptake (VO2 sl) was also assessed in COPD patients using a maximal incremental exercise test. RESULTS: The results showed that Tlim and PA score were significantly decreased in COPD patients (p<0.05). Significant positive correlations were found in the COPD group between Tlim and the PA score (r=0.60; p<0.05), FEV1 (r=0.52; p<0.05), and PaO2 (r=0.63; p<0.05). The same results were found between the PA score and VO2 sl (r=0.57; p<0.05) and FEV1 (r=0.63; p<0.05). CONCLUSION: These findings indicate impaired skeletal muscle endurance in COPD patients related to altered lung function and associated physical inactivity.

Cardiorespiratory fitness evaluation by the shuttle test in asthmatic subjects during aerobic training.

PURPOSE: The purpose of this study was to assess the validity of the 20-m shuttle test with 1-min stages (20-MST) to estimate maximal oxygen uptake (VO2 max) and its ability to register cardiorespiratory modifications over the course of an individualized aerobic training program for mild to moderately asthmatic children acclimatized to moderate altitude. METHODS: Forty-eight asthmatic subjects aged 12 to 17 years performed both a maximal incremental exercise test on a cycle ergometer and the 20-MST. Ten of the subjects were then randomly chosen and trained three times per week at their ventilatory threshold (Vth) intensity level for three months. Another group of ten asthmatic subjects served as control subjects. Training intensity was adjusted monthly; heart rate values at Vth were increased by the same proportion as the increase in Vo2 max as measured by the 20-MST. At the end of training, both groups were again evaluated with the two tests. The Vo2 max values by direct measurement and by the 20-MST were not significantly different for the entire population (46.5 +/- 1.6 vs 47.2 +/- 2.1 ml.min-1.kg-1). In addition, the two test results were in close agreement (r = 0.84; p < 0.01). After training, a sharp improvement in the direct Vo2 max (44.1 +/- 2.4 to 51.2 +/- 1.9 ml.min-1.kg-1) was noted in the training group as well as an increase in the Vth (25.6 +/- 1.9 to 32.1 +/- 3.4 ml.min-1.kg-1), the maximal power (152 +/- 7.1 to 185 +/- 3.8 W), and the maximal oxygen pulse (0.24 +/- 0.007 to 0.27 +/- 0.008 ml.beat-1.kg-1). CONCLUSION: The indirect measure confirmed these results: a simultaneous increase in VO2 max (43.7 +/- 2.5 to 53.8 +/- 2.1 ml.min-1.kg-1), maximal oxygen pulse (0.22 +/- 0.004 to 0.27 +/- 0.006 ml.beat-1.kg-1), and the number of stages completed (7 +/- 1.4 to 10.1 +/- 1.3) was observed. It was concluded that the 20-MST has sufficient validity to assess VO2 max and to register cardiorespiratory modifications over the course of individualized aerobic training programs in mild and moderately asthmatic children. It thus may be used to adjust training intensities during these programs.

Individualized aerobic and high intensity training for asthmatic children in an exercise readaptation program. Is training always helpful for better adaptation to exercise?

In order to define the role of individualized training intensity in a conditioning program for asthmatic children, we have trained seven asthmatics (age = 11.4 +/- 1.8 years) at their ventilatory threshold (VTh) intensity level for a three-month period (aerobic training) and at maximal intensity also for three months (high intensity training). VTh is the point at which a nonlinear increase of VE occurs. Another group of seven asthmatics (age = 11.4 +/- 1.5) served as control subjects. Cardiopulmonary fitness was determined on a cycle ergometer before and after each training session. This study demonstrated that aerobic training, correctly adapted to the child's physical ability, induces the following: (1) a rapid and marked cardiovascular fitness increase; and (2) a decrease in VE over a given work range so that VTh is increased. This is of great importance because hyperventilation is a major determinant of exercise-induced bronchospasm. In contrast, even if high intensity training is well tolerated in an indoor swimming pool, the long-term effects are unsuitable for asthmatic children because the decrease of VTh will involve an increase of hyperventilation, even when exercise is performed at submaximal intensity.

Addition of inspiratory resistance increases the amplitude of the slow component of O2 uptake kinetics.

The contribution of respiratory muscle work to the development of the O(2) consumption (Vo(2)) slow component is a point of controversy because it has been shown that the increased ventilation in hypoxia is not associated with a concomitant increase in Vo(2) slow component. The first purpose of this study was thus to test the hypothesis of a direct relationship between respiratory muscle work and Vo(2) slow component by manipulating inspiratory resistance. Because the conditions for a Vo(2) slow component specific to respiratory muscle can be reached during intense exercise, the second purpose was to determine whether respiratory muscles behave like limb muscles during heavy exercise. Ten trained subjects performed two 8-min constant-load heavy cycling exercises with and without a threshold valve in random order. Vo(2) was measured breath by breath by using a fast gas exchange analyzer, and the Vo(2) response was modeled after removal of the cardiodynamic phase by using two monoexponential functions. As anticipated, when total work was slightly increased with loaded inspiratory resistance, slight increases in base Vo(2), the primary phase amplitude, and peak Vo(2) were noted (14.2%, P < 0.01; 3.5%, P > 0.05; and 8.3%, P < 0.01, respectively). The bootstrap method revealed small coefficients of variation for the model parameter, including the slow-component amplitude and delay (15 and 19%, respectively), indicating an accurate determination for this critical parameter. The amplitude of the Vo(2) slow component displayed a 27% increase from 8.1 +/- 3.6 to 10.3 +/- 3.4 ml. min(-1). kg(-1) (P < 0.01) with the addition of inspiratory resistance. Taken together, this increase and the lack of any differences in minute volume and ventilatory parameters between the two experimental conditions suggest the occurrence of a Vo(2) slow component specific to the respiratory muscles in loaded condition.

Reduction of fat accumulation and lipid disorders by individualized light aerobic training in human immunodeficiency virus infected patients with lipodystrophy and/or dyslipidemia.

BACKGROUND: The management of abdominal fat accumulation and metabolic disorders in HIV1-infected patients, by an aerobic training program, is considered. METHODS: Seventeen lipodystrophic and 2 dyslipidemic (without body modification) adults were studied before and after 4 months of training. The training load was individualized on a ventilatory threshold basis, determined during a maximal exercise test on cycle ergometer. Total (TAT), Visceral (VAT) and Subcutaneous Adipose Tissue (SAT) were assessed by CT-scan. Total (TC) and High Density Lipoprotein (HDL-C) Cholesterol, Triglycerides (TG), lactate (La), insulin and glucose were measured after a 12-hour-overnight fast. LDL, TC/HDL, TG/HDL, HOMA-insulin resistance index and coronary heart disease (CHD) relative risk (RR(CHD)) were calculated. RESULTS: Besides a significant improvement of aerobic fitness, trained patients exhibited a reduction in TAT (-12.8%, p < 0.001), specially at the visceral level (- 12%, p < 0.01) and in TC, TG and La (- 23%, - 43% and - 19% respectively, p < 0.01). HDL-C was increased (+ 6%, p < 0.01). All these effects were above changes that could be expected by a possible regression to the mean artefact. Both TC/HDL and TG/HDL were reduced (p < 0.01) and the estimated RR(CHD) decreased by approximately 13% (p < 0.01). No significant training effect was observed on the 9 available HOMAs. Significant correlations were found between changes in blood lipid values and baseline measures (r range - 0.55 to - 0.79, p < 0.05), indicating a larger improvement when baseline lipid parameters were higher. CONCLUSION: Aerobic training reduced visceral fat, lipid disorders, basal blood lactate and CHD markers in HIV patients. Training effects were particularly important for patients with marked dyslipidemia.

Anaerobic fitness in children with asthma: adaptation to maximal intermittent short exercise.

Nineteen asthmatic boys (aged 13.4 years, 25-75 percentile: 11.5-15.1 years) performed short bouts of maximal exercise (force-velocity test) to test their anaerobic fitness and tolerance of maximal anaerobic exercise. Fourteen healthy boys (aged 13.9 years, 25-75 percentile: 11.6-15.7 years) matched for anthropometric characteristics including lean body mass (LBM), pubertal stage, and weekly physical activity formed a control group. The maximal anaerobic power (W(ana)) was measured during the force-velocity test. The maximal oxygen uptake (V'(O2max)) was assessed during a standard graded exercise test. Pre- and post-exercise pulmonary function was measured by body plethysmography. The asthmatic children exhibited lower W(ana) than the control group (8.2 watt.kg(-1) LBM, 25-75 percentile: 7.55-10.6 vs. 11.3 watt.kg(-1) LBM, 25-75 percentile: 9.46-14.1; P = 0.01). V'(O2max) was also diminished in the asthmatic group (P = 0.01). Multiple stepwise regression models revealed that Tanner's score (P < 0.001) and the diagnosis of asthma (P < 0.01) were the best predictors of W(ana). In conclusion, a diminished anaerobic fitness could contribute to the overall exercise limitation in asthmatic children.

Wingate test performance in children with asthma: aerobic or anaerobic limitation?

To investigate the anaerobic capacity in children with bronchial asthma, eight male children with atopic asthma (age: 12 +/- 1.7 yr) and seven healthy control subjects (age: 12 +/- 1 yr) performed a 30-s all-out exercise test: the Wingate anaerobic test (WanT). Post-exercise plasma epinephrine (E), norepinephrine (NE), venous blood lactate (La), and blood pH levels were determined. Peak power (Ppeak), mean power (Pm), and total energy expenditure (Wtot) during the WanT were assessed. The relative importance of aerobic (WO2) and anaerobic (Wana) energy release during the WanT was also evaluated. In comparison with control subjects, the children with asthma exhibited lower Ppeak (W.kg-1): 6 +/- 1.14 vs 7.3 +/- 0.5, P < 0.05; lower Pm (W.kg-1): 4.7 +/- 0.8 vs 5.9 +/- 0.5, P < 0.05; and lower Wtot (Jg-1): 140.3 +/- 25 vs 176.9 +/- 19, P < 0.05. The relative contribution of WO2 (26%) and Wana (74%) to the Wtot was identical in both groups. Blood lactate and pH kinetics revealed significantly lower La values and less acidosis in the asthmatic group (P < 0.001). Lastly, E (pg.ml-1) concentrations were lower in the asthmatic group: 274.96 +/- 84.58 vs 901.28 +/- 604.76, P < 0.05. These results suggest a reduced anaerobic capacity in children with asthma. A diminished adrenergic response to exhausting exercise, leading to a decreased anaerobic glycolysis, could partly account for this phenomenon.

Exercise tolerance in heart transplant patients with altered pulmonary diffusion capacity.

To test whether orthotopic heart transplant (OHT) patients with low pulmonary diffusion capacity have a greater limitation to exercise than OHT patients with normal pulmonary diffusion capacity, we investigated cardiorespiratory responses and blood gases in two groups of OHT patients, one with low (LdG) and the other with normal pulmonary diffusion capacity (NdG), during a graded exercise test. The results showed 1) significantly reduced peak power (P < 0.05), peak oxygen uptake (VO2, P < 0.001), peak oxygen pulse (VO2/heart rate, P < 0.01), peak minute ventilation (VE, P < 0.05), and delta PaO2 (peak PaO2 - rest PaO2, P < 0.05) in LdG versus NdG; 2) a nonsignificant decrease in peak heart rate in LdG (P < 0.13, P = 24%); and 3) significant increases in peak respiratory equivalent for oxygen (VE/VO2, P < 0.05) and delta P(A-a)O2 (peak P(A-a)O2 - resting P(A-a)O2, P < 0.05) in LdG versus NdG. No significant difference was found for PaO2 and PaCO2 at rest or at peak exercise between the groups. A strong correlation was found between pulmonary diffusion capacity (TLCO/VA) and peak VO2 (r = 0.81, P < 0.01); that is, TLCO/VA explains 66% of the variance in peak VO2. We conclude that OHT patients with decreased pulmonary diffusion capacity have a lower exercise tolerance than patients with normal pulmonary diffusion capacity. However, because of the lack of exercise-induced hypoxemia, diffusion abnormalities are not the main limiting factor for exercise tolerance in the low diffusion group.

Influence of post-surgery time after cardiac transplantation on exercise responses.

Influence of post-surgery time after cardiac transplantation on exercise responses. Med. Sci. Sports Exerc., Vol. 28, No. 2, pp. 171-175, 1996. To test the hypothesis that exercise response changes with time after cardiac transplantation, we investigated the cardiorespiratory responses of nine orthotopic heart transplant patients (52.4 +/- 2 yr) during graded exercise tests (30 W.3 min-1) done at 1, 3, 6, 9 and 12 months post-surgery. At peak exercise, 1) oxygen uptake per kg of body weight (VO2), minute ventilation (VE) and oxygen pulse (O2 pulse) did not change significantly between 1 and 12 months postsurgery; 2) transplanted heart rate (HRt) and delta heart rate (peak exercise heart rate--resting heart rate) increased significantly over time (P < 0.01; P < 0.05) with a marked increase between 1 and 3 months (P < 0.05); and (3) a significant negative correlation existed between O2 pulse and HRt (r = -0.36, P < 0.05), whereas no correlation was found between delta heart rate and delta VO2 (peak exercise VO2- resting VO2, l.min-1). During submaximal exercise, HRt increased significantly over time (P < 0.001); VO2, VE, and O2 pulse showed no significant change; and the VO2-HRt relationship shifted toward higher values of HRt. We conclude that, in the absence of formal physical training, the exercise response of denervated transplanted heart increases in relation to post-surgery time but does not affect oxygen uptake at submaximal and peak levels of exercise.

Evaluation of quality of life in elderly healthy subjects after aerobic and/or mental training.

This study proposed different techniques of mental rehabilitation to healthy elderly subjects in order to assess the results in terms of subjectively perceived changes in quality of life. Thirty-two elderly subjects (60-76 years) were assigned to one of the four groups: aerobic training, mental training, combined aerobic and mental training and a control group. Before and after 2 months of training, all subjects took two memory tests. After training, a French validated questionnaire of quality of life was administered individually. Memory parameters such as logical memory (P<0.05), paired associated learning (P=0.05) and memory quotient (P=0.01) were enhanced in all groups except the control group, but in terms of quality of life all the elderly subjects were dissatisfied. VO(2max) and ventilatory threshold were significantly improved in the two groups who were engaged in a physical training program (AT and AMT) and these improvements were associated with a better quality of life in the domain of functional life. Association of the two techniques did not enhance the results for cognitive function. In conclusion, despite objective improvement in cognitive function, all subjects reported dissatisfaction in terms of improvement in quality of life, whatever their assigned group. Nevertheless, an improvement in quality of life was acknowledged after aerobic training for the physical component of functional life.

A BASIC software program to estimate cardiac output and alveolar ventilation.

This software program adds two very interesting data to the usual results of exercise testing: an estimation of cardiac output according to the most recent validations and a reliable estimation of alveolar ventilation. The main advantage of this additional ventilatory and cardiovascular information using the same data: end-tidal PCO2.

Effects of drafting on energy expenditure in in-line skating.

AIM: The purpose of this study was to measure the effects of drafting on energy expenditure in in-line skating, and to investigate whether the "benefit of drafting", i.e. the decrease in energy expenditure, was different between two velocities and two distances separating the two skaters. METHODS: Eight recreational in-line skaters performed six exercises of 6 min, at 2 velocities (V(1) = 5.51+/-0.45 m x sec(-1); V(2) = 7.01+/-0.67 m x sec(-1)) in 3 conditions (ND = without drafting; D(1)=0.74-0.87 m "close"; D(2) = 1.19-1.36 m "far"). Collection of expired gas was carried out using a breath-by-breath portable gas analyser K4(b2) and the distance between the skaters was measured by video analysis. RESULTS: The skaters' energy expenditure was reduced in all drafting conditions; between D(1) and ND by 9.6+/-4.4% at V(1) and by 2.7+/-3.3% at V(2); between D(2) and ND by 8.8+/-6.0% at V(1) and by 4.2+/-4.8% at V(2). This reduction was significantly (p<0.05) more important at V(1) than V(2) and no differences were observed between D(1) and D(2). CONCLUSION: In in-line skating, the technical difficulties for drafting efficiently, especially while cornering, resulted in a reduced "benefit of drafting" at high velocity than in other sports. Moreover, the need for the subject to adjust their own cycle frequency to that of the lead skater while drafting "close" would explain partly that there were no significant differences between drafting at D(1) and D(2). These results suggest that the drafting technique should be emphasized in training, especially in non-skilled skaters at high velocities and when cornering.

[Physiopathological bases for retraining programs of asthma patients: adjustment to rehabilitation]. / Les bases physiopathologiques du ré-entraînement à l'effort des asthmatiques. Des adaptations à la réadaptation.

Despite current discussions promoting physical and sports activities in asthmatics, no studies have yet been done on the possible pathophysiological justifications for rehabilitation by sports programs. Consequently asthmatics are retrained in an empirical fashion and the assessment of these programs is subjective. The aim of this article is thus to review the different studies concerning the adjustment of asthmatics to muscular exercise and to deduce from these what could or should be the pathophysiological objectives of reconditioning protocols. The principal ideas which emerge from this study derive from three fundamental facts: 1) the training of asthmatics should be based on an individual approach since clinical severity leads to very unequal adaptations during muscular exercise; 2) it is advisable to strive against the declining physical fitness of the asthmatics, which is responsible for the accelerated functional deterioration, disturbances of psychomotor development and an increased risk of exercise-induce asthma; 3) the decrease of excessive exercise hyperventilation is, from the evidence, the greatest priority among the pathophysiological objectives, because hyperventilation is a principal cause implicated in the disturbance of cardiovascular adjustments to effort by heart-lung interaction.

[Effects of individualized aerobic training in the readaptation of the asthmatic child to exercise]. / Effets d'un entraînement individualisé de type aérobie dans la réadaptation à l'effort de l'enfant asthmatique.

There have been few works studying the effects of training in asthmatics and there does not yet exist any study utilising the idea of the individualization of training. This is why the aim of this study was to assess the value of the effects of individualised aerobic training on cardio-respiratory aptitude in the asthmatic child. This study was carried out on two populations of asthmatics, swimmers and non-swimmers matched for age, height, degree of bronchial obstruction during a remission and baseline of physical fitness. Each child in the swimming group was trained to a metabolic level corresponding to the ventilatory threshold. After a period of 3 months a second cardio-respiratory evaluation was carried out. A clear cut improvement (20%) of VO2 max was observed as well as a proportional elevation of the ventilatory threshold in the swimming group. The VE max, the VT max, the VT/Timax, the FC max and the maximal oxygen uptake were also recorded. On the other hand aerobic training seems to be without effect on resting pulmonary function, even if the clinical state of the children improved. In conclusion this study shows that aerobic training closely adapted to the level of each child, obtains an important and rapid gain in cardio-respiratory fitness which leads to a better exercise adaptation. In addition the progression of the ventilatory threshold implies an increased capacity for work without the appearance of hyperventilation. This enables an understanding of how aerobic training is generally accompanied in the asthmatic with a better respiratory comfort and argues in favour of the perfect efficacy of this type of reconditioning in the re-adaptation to effort in these patients.

[Value of individualized rehabilitation at the ventilatory threshold level in moderately severe chronic obstructive pulmonary disease]. / Intérêt du réentraînement à l'effort individualisé, au niveau du seuil ventilatoire, au cours de la bronchopneumopathie chronique obstructive de sévérité modérée.

In order to study the efficiency of individual training programs at the ventilatory threshold level, twenty COPD patients were randomized into two groups and studied over a two-month period. At the start, during, and at the end of the study all subjects performed incremental exercise tests. The trained group (59.60 SEM +/- 2.75 years) walked four times a week at the heart rate corresponding to the metabolic level of ventilatory threshold. The other group served as controls (58.2 +/- 1.80 years). A marked increase in the symptom-limited oxygen consumption (+/- 25%) (p < 0.01), the maximal ventilation (+20%) (p < 0.01), and the ventilatory threshold (+19%) (p < 0.05) was found in the trained group. No modification was recorded in the control group. The ventilatory pattern at submaximal intensities expressed in percentage of the initial oxygen consumption showed significant differences between groups, the trained-group ventilation decreased at 50% and 75% VO2 sl (p < 0.05). The breathing frequency also decreased at 50% and 75% VO2 sl (p > 0.05). Moreover, we observed an increase in the oxygen pulse at 50% VO2 sl (p < 0.05). In conclusion, this study demonstrates that individualized training at the ventilatory threshold level increases exercise tolerance and produces better ventilatory comfort in COPD patients.

[Evolution of bronchial hyperreactivity during post-exercise asthma]. / Evolution de l'hyperréactivité bronchique au cours de l'asthme post-exercice.

The occurrence of a late reaction following exercise induced asthma is questionable and its relationship with the non specific bronchial hyperreactivity is poorly known. In this study, nine patients (age 15-21 years) underwent an exercise challenge in order to (a) determine the incidence of immediate and late phase reaction and (b) analyse the modifications of non specific bronchial hyperreactivity. Study design was a follow; day-3: determination of bronchial responsiveness to metacholine; day 0: control day with FEV1 measurements every hour for 11 hours; day 1: exercise challenge followed by a careful observation of change in FEV1; day 2: new determination of bronchial responsiveness to metacholine. An immediate exercise induced bronchial obstruction was observed in 5 patients. A late phase reaction (6th hour) with a fall of FEV1 equal to or more than 20% has been demonstrated in two patients. For the former, the change in FEV1 did not differ from the value of the control day. For the second, the FEV1 changed spontaneously during the control day so that decreases of FEV1 during control and challenge days were parallel. Thus, no late phase reaction were observed (F = 0.46; ns). There was no modification of bronchial responsiveness to metacholine (pre-exercise: 1,784 +/- 1,970 [SD]; post-exercise 1,827 +/- 2,231 micrograms [SD]). The lack of true late phase reaction when the post-exercise change in FEV1 is compared to the one of a control day and the absence of modification of non specific bronchial hyperreactivity weaken the hypothesis of an inflammatory mechanism of exercise induced asthma.