Ventilatory response to exercise does not evidence electroencephalographical respiratory-related activation of the cortical premotor circuitry in healthy humans.

AIM: The neural structures responsible for the coupling between ventilatory control and pulmonary gas exchange during exercise have not been fully identified. Suprapontine mechanisms have been hypothesized but not formally evidenced. Because the involvement of a premotor circuitry in the compensation of inspiratory mechanical loads has recently been described, we looked for its implication in exercise-induced hyperpnea. METHODS: Electroencephalographical recordings were performed to identify inspiratory premotor potentials (iPPM) in eight physically fit normal men during cycling at 40 and 70% of their maximal oxygen consumption ((V)·O(2max) ). Relaxed pedalling (0 W) and voluntary sniff manoeuvres were used as negative and positive controls respectively. RESULTS: Voluntary sniffs were consistently associated with iPPMs. This was also the case with voluntarily augmented breathing at rest (in three subjects tested). During the exercise protocol, no respiratory-related activity was observed whilst performing bouts of relaxed pedalling. Exercise-induced hyperpnea was also not associated with iPPMs, except in one subject. CONCLUSION: We conclude that if there are cortical mechanisms involved in the ventilatory adaptation to exercise in physically fit humans, they are distinct from the premotor mechanisms activated by inspiratory load compensation.

[Physical activity and exercise training for patients with cystic fibrosis]. / Activité physique et réentraînement à l'effort du patient atteint de mucoviscidose.

In France patients with cystic fibrosis benefit from a multidisciplinary follow-up in Cystic Fibrosis Centres. In this follow-up, despite the numerous therapeutic benefits of exercise in this disease, little emphasis is placed on the promotion of physical activity. The aim of this article is to improve this aspect of management, giving advice from a working group of experts, based on the medical literature and clinical experience. These proposals include quantification of physical activity, evaluation of exercise, training and rehabilitation programs and finally, modification of behaviour to include physical activity in the overall cystic fibrosis treatment strategy. It is intended to set up multicentre studies to evaluate the impact of these proposals.

Multicentre trial evaluating alveolar NO fraction as a marker of asthma control and severity.

BACKGROUND: Exhaled NO can be partitioned in its bronchial and alveolar sources, and the latter may increase in the presence of recent asthmatic symptoms and in refractory asthma. The aim of this multicentre prospective study was to assess whether alveolar NO fraction and FE(NO) could be associated with the level of asthma control and severity both at the time of measurement and in the subsequent 3 months. METHODS: Asthma patients older than 10 years, nonsmokers, without recent exacerbation and under regular treatment, underwent exhaled NO measurement at multiple constant flows allowing its partition in alveolar (with correction for back-diffusion) and bronchial origins based on a two-compartment model of NO exchange; exhaled NO fraction at 50 ml/s (FE(NO,0.05)) was also recorded. On inclusion, severity was assessed using the four Global initiative for asthma (GINA) classes and control using Asthma Control Questionnaire (ACQ). Participants were followed-up for 12 weeks, control being assessed by short-ACQ on 1st, 4th, 8th and 12th week. RESULTS: Two-hundred patients [107 children and 93 adults, median age (25th; 75th percentile) 16 years (12; 38)], 165 receiving inhaled corticosteroid, were included in five centres. The two-compartment model was valid in 175/200 patients (87.5%). Alveolar NO and FE(NO,0.05) did not correlate to control on inclusion or follow-up (either with ACQ /short-ACQ values or their changes), nor was influenced by severity classes. Alveolar NO negatively correlated to MEF(25-75%) (rho = -0.22, P < 0.01). CONCLUSION: Alveolar and exhaled NO fractions are not indexes of control or severity in asthmatic children and adults under treatment.

Nandrolone excretion in sedentary vs physically trained young women.

We investigated the effects of the menstrual cycle, oral contraception and physical training on exhaustive exercise-induced changes in the excretion of nandrolone metabolites [19-norandrosterone (19-NA), and 19-noretiocholanolone (19-NE)] in young women. Twenty-eight women were allocated to an untrained group (n=16) or a trained group (n=12), depending on their physical training background. The untrained group was composed of nine oral contraceptive users (OC+) and seven eumenorrheic women (OC-), while the trained group was entirely composed of OC+ subjects. Three laboratory sessions were conducted in a randomized order: a prolonged exercise test, a short-term exercise test and a control session. Urine specimens were collected before and 30, 60 and 90 min after the exercise test and at the same times of the day during the control session. Urinary concentrations of nandrolone metabolites were determined by gas chromatography coupled to mass spectrometry. Urinary concentrations of 19-NA and 19-NE ranged from undetectable levels to 1.14 and 0.47 ng/mL, respectively. Nandrolone excretion was not affected by the menstrual cycle phase (early follicular vs mid-luteal), prior physical training, oral contraception or acute physical exercise. Therefore, a urinary concentration of 2 ng/mL of 19-NA appears to be fair as the upper acceptable limit in doping control tests for female athletes.

[Respiratory function testing in infants: recommendations on normal values]. / EFR du nourrisson: le point sur les valeurs normales.

The present document is being produced on behalf of the French Society of the Physiology Task Force on standards for Infant Respiratory Function Testing whose aim is to provide guidelines for good laboratory practices according to the latest international recommendations. Application of such recommendations could be of particular value when attempting to develop standardized protocols in the scope of multi-centre trials. The first part resume these recommendations about apparatus, acquisition system and software for Infant Respiratory Function Testing. The second part focuses on physiological principles and practical considerations: calibration procedure, infant conditioning, tidal breathing measurements, and occlusion techniques for assessing passive respiratory mechanics, plethysmographic measurements of lung volume and airway resistance and forced expiratory flows measurements. The major problem when collecting lung function data is that of predicted values. Valid reference data, set up according to these recommendations, are, to date, still to be established. The last part of the document provides a review of the literature concerning infant respiratory function reference data and a resume of the most used of them. This document will clearly need to be updated regularly in response to advances in knowledge in this field.

[Cystic fibrosis: how to use pulmonary function tests]. / Mucoviscidose: du bon usage des explorations fonctionnelles respiratoires.

INTRODUCTION: Neonatal screening for cystic fibrosis (CF) leads to early dedicated specialist care for all patients. BACKGROUND: Pulmonary function tests (PFT) are mandatory for routine monitoring of CF patients. The aim of this article is to review the current guidelines for PFTs in CF, particularly the type of test, the age and the clinical status of the patient. VIEWPOINT: The regular use of spirometry is generally accepted. Many other tests are used but their clinical value in the routine follow-up of CF patients remains to be established. CONCLUSION: Further efforts should be made to evaluate the value of PFTs in CF, particularly in very young children.

Urinary and blood concentrations of beta2-agonists in trained subjects: comparison between routes of use.

We aimed to assess the plasma and urine concentrations of beta2-agonists and evaluate the difference between three routes of administration in trained adults in order to distinguish doping from prevention of exercise-induced asthma. Ten young healthy Caucasian male subjects received during a four treatment period study: 1) inhaled salbutamol (S(I)) 2 x 100 microg t.i.d. for 3 days, 2) inhaled formoterol (F(I)) 2 x 12 microg b.i.d. for 3 days, 3) a single subcutaneous injection of salbutamol (S(S)) 0.5 mg, and 4) salbutamol 2 x 2 mg t.i.d. orally for 3 days (S(O)). Blood samples were taken during the first and the third day of experimentation at baseline, 30 min, 1 h, 2 h, 4 h and 6 h after administration; additional blood samples were drawn at 15 min for S(I), S(S) and F(I) and at 12 h for F(I). Urinary samples were collected at baseline, 2 h, 4 h, 6 h and 12 h after administration. Urinary concentrations were 20 to almost 50 times higher after S(O) than after S(I). Mean urinary concentration after S(O) increased to above 800 ng.mL(-1) within the two hours and above 1000 ng.mL(-1) at 6 to 12 hours post-drug administration. Urinary concentrations after S(S) were maximal during the first 2 hours (mean: 340 +/- 172 ng.mL(-1)). Plasma concentrations were very low, whatever the routes of administration. Results showed that we could eliminate the use of S(I) (authorized) and S(S) administration when individual urinary concentrations are higher than 230 ng.mL(-1) and 615 ng.mL(-1), respectively. Therefore, at rest, the cut-off value used to discriminate therapeutic from doping salbutamol intake could be fixed at 250 ng.mL(-1) instead of the 1000 ng.mL(-1) still authorized by international committees.

[Methacholine challenge in young children: measurement of resistance by interruption]. / Test a la métacholine chez le jeune enfant: Mesure de la résistance par interruption.

The aims of this study were 1. To evaluate the measurement of resistance by interruption (Rint) of bronchoconstriction induced by inhalation of methacholine and 2. To determine a threshold of increase of resistance in young children to differentiate responders from non-responders. Forty-six children (mean age 5 [4.3-6.1] years) referred for methacholine challenge were tested by measurement of Rint and transcutaneous oxygen tension. A fall of 20% or more in oxygen tension from the baseline was used to define the responders. The children studied had a baseline Rint significantly higher than normal (0.84 [0.68-1.01] vs. 0.76 [0.60-0.90] kPa L(-1)s; p < 0.03). Forty-one children were responders and had an increase in Rint significantly different from the non-responders (p < 0/04). An increase in Rint of 35% distinguished responders from non-responders in young children with chronic cough. Interrupter resistance increases significantly during bronchial provocation in responding young children and may be used to measure the degree of bronchoconstriction.

Airway tone during exercise in healthy subjects: effects of salbutamol and ipratropium bromide.

In healthy subjects changes in airway calibre during exercise are conflicting and smaller than in asthmatics. Methodological differences could explain the discrepancies between the results obtained in healthy subjects. Therefore, our aim was to assess during exercise the changes in airway diameter and the effects of 200 microg salbutamol (SAL) or 40 microg ipratropium bromide (IPR) inhalations versus placebo (PLA), using spirometry and respiratory resistance (Rrs). Eight non-asthmatic subjects exercised 9 min at 70 % of their maximal aerobic power after inhalation of 200 microg SAL, 40 microg IPR, or PLA. Maximal flow-volume curves were obtained before and after inhalations, at 3 (E3) and 6 (E6) minutes of exercise, and during recovery. Rrs were measured by impulse oscillometry before and after inhalation, and immediately at the end of exercise. At rest, FEV (1) increased significantly after inhalation of SAL and IPR. Rrs decreased only after SAL. During exercise FEV (1) increased significantly from rest with SAL and IPR while forced mid expiratory flow (FEF (25 - 75)) increased significantly for all conditions. At E6 the rise of FEV (1) and FEF (25 - 75) were greater with SAL compared to PLA and IPR. In all conditions Rrs increased significantly immediately at the end of exercise as compared to rest but less than during flow-matched hyperpnea. It is concluded that a similar bronchodilation was observed during exercise with and without anticholinergic drug which suggests a withdrawal of parasympathetic control of airways during exercise in healthy subjects. Nevertheless, the bronchodilation observed during exercise is not maximal since it can be reinforced by beta (2)-mimetic drug.

Putative protective effect of inspiratory threshold loading against exercise-induced supraspinal diaphragm fatigue.

The present investigation was intended to assess the consequences of an inspiratory load on the diaphragm central component of fatigue during exercise. We recorded the motor potential evoked (MEP) by transcranial magnetic stimulation of the motor cortex in 10 subjects. The diaphragm and rectus femoris were studied before and 10, 20, and 40 min after two 16-min cycling exercise (E) trials requiring 55% of maximal oxygen uptake: 1) one with an inspiratory threshold load (E + ITL), corresponding to 10% of maximal inspiratory pressure; and 2) the other without the load (E). Dyspnea, heart rate, electromyographic activity of the sternocleidomastoid, and diaphragm work were significantly higher in E + ITL than in E. Neither trial affected the response to phrenic magnetic stimulation, which was performed 15 and 25 min postexercise, or the maximal inspiratory pressure (116 and 120 cm H(2)O before E and E + ITL, respectively, and 110 and 114 cm H(2)O at 30 min postexercise). Whereas the amplitude of the diaphragm MEP was unaffected by E + ITL (+2.1 +/- 29.4%), a significant decrease was observed 10 min after E compared with baseline (-37.1 +/- 22.3%) and compared with E + ITL. The MEP amplitude of rectus femoris remained unchanged with E and E + ITL. The recruitment of synergistic agonists during E + ITL may have normalized the major ventilatory stress and reset up the excitability of the diaphragm pathway.