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We investigated the strength of the association between oxidative stress, hypoxia inducible factor 1 (HIF-1 alpha) and acute hypoxic ventilatory response (AHVR) after hypoxic training in elite runners. Six elite runners were submitted to 18-day of "living high-training low" (LHTL) and six performed the same training in normoxia. AHVR was measured during an acute hypoxic test before and after training. Plasma levels of protein oxidation (AOPP), malondialdehydes and (HIF-1 alpha) mRNA in the leukocytes were measured before and after the acute hypoxic test. LHTL increased AHVR and amplified the responses of HIF-1 alpha mRNA and AOPP (Delta(AOPP)) to the acute hypoxic test. Furthermore, between PRE and POST, the changes in Delta(AOPP) were correlated with the changes in AHVR (r=0.69, P=0.01). The ventilatory acclimatization to hypoxia occurring in athletes after LHTL seems to be modulated by oxidative stress. Furthermore, LHTL induced a higher sensitivity of HIF-1 alpha mRNA to acute hypoxia in elite athletes.

The aim of this study was to determine the response of blood markers to acute hypoxia in high-level endurance athletes before training based on "living high-training low" model. Thirty endurance athletes performed a hypoxic cycling test and spent 3 h at rest in a simulated altitude of 3,000 m. At the end of the hypoxic cycling test, the quantity of the natural antisense transcript of HIF-1alpha mRNA (aHIF) transcript increased significantly (+37%, P = 0.024). After 3-h exposure, at a simulated altitude of 3,000 m, the amount of HIF-1alpha mRNA increased significantly (+57%, P = 0.012). Moreover, a large inter-subject range was observed in response to the hypoxic cycling test and to the prolonged hypoxic exposure: -133%/+79% and -82%/+653% for HIF-1alpha mRNA, 69%/+324% and -76%/+229% for aHIF. This study shows a large inter-variability of blood markers in elite athletes in response to acute hypoxic exposure corroborating previous observations made in other populations.

Resume: Dans cette etude 69 % des 80 sujets prenant des psychotropes (PM) presentaient des levures dans leur cavite buccale contre 45 % seulement chez une population temoin (PT) de 73 sujets. 90 % des levures sont des candidoses. Les localisations sont: L'etude de la presence des levures, les signes cliniques des candidoses et le debit salivaire montrent la complexite des interactions entre ces differents facteurs. Zusammenfassung: In dieser Studie wurden bei 69% von 80 Patienten (MG), die in psychotropischer Behandlung sind, Hefen in der Mundhohle beobachtet. Bei einer Kontrollgruppe (KG) von 73 Patienten wurden nur bei 45 % der Personen Hefen angetroffen. 90% der angetroffenen Hefen waren Candida-Arten. Sie wurden wie folgt lokalisiert: Die Untersuchung des Vorkommens der Hefen, der Speichelsekretionsrate und der klinischen Zeichen der Candidose zeigen, wie kompliziert das Zusammenspiel der verschiedenen Faktoren ist. Summary: In this study, 69 % of 80 subjects treated by neuro-psychotropic drugs (P. M.) presented yeasts in their oral cavity against only 45 % in 73 healthy subjects (P. T.). 90 % of the yeasts were Candida species. The localizations were: This study of the presence of yeasts, the clinical features of candidosis and the flow-rate of saliva show the complexity of interactions between these differents factors.

Whether direct exposure to different concentrations (0%, 13%, 100%) of oxygen may affect horse erythrocyte membrane fluidity (EMF) and fatty acid (FA) composition was studied during 1 (T60) and 2 h (T120) exposure. EMF was investigated at the head group level and hydrophobic core thanks to phosphorus nucleus 31 ( 31 P) nuclear magnetic resonance ( 31 P NMR) and electronic paramagnetic resonance (EPR) using two spin probes: 5-nitroxydestearic acid and 16-doxylstearic acid. Lipid structure of the membranes was studied by gas liquid chromatography. 4-Hydroxy2E-nonenal was also analyzed as a marker of lipid peroxidation. It increased at T120 13% and 100% oxygen whereas there were no significant changes in membrane dynamic or structure. Correlation was demonstrated between EMF and partial pressure of oxygen in the blood (PO2 ). In vitro high rate of oxygenation was efficient to induce lipid peroxidation but did not change membrane dynamics. This may be due to a low free radical production in vitro or to the high red blood cells antioxidant properties. © 2007 Elsevier B.V. All rights reserved.

Purpose: Altitude training is popular among athletes to augment oxygen delivery capabilities to tissues and to improve physical performance. Hypoxia inducible factor-1 (HIF-1) controls the expression of several genes' encoding involved in physiological responses towards reduced oxygen availability, in particular by increasing serum erythropoietin (EPO). It may be involved in the individual variability for erythropoietic markers and/or sea-level performance of athletes using altitude during their training. Therefore, we investigated whether, before training, evolutions of hif-1a and ahif (HIF-1a natural antisense) transcript amounts and HIF-1a protein quantities in leukocytes measured during an acute hypoxia normobaric test (3 h at 3000 m at rest) could allow to predict poor and good responders for hematological markers after a "living high-training low" protocol. Methods: Eighteen elite swimmers were divided into two groups that followed a 13-d training program: "living low-training low" (1200 m) (LL) or "living high (2500-3000 m)-training low (1200 m)" (LH). Results: During the initial hypoxia test, a strong interindividual variability in the amounts of HIF-1a mRNA, aHIF transcript, and HIF-1a protein was observed in athlete leukocytes (after vs before): -82%/+396%, -100%/+229%, and -100%/+633%, respectively. After the test, serum erythropoietin concentration was increased (11.2 ± 0.8 vs 9.8 ± 0.8 IU·L-1; +18%, P = 0.01). After the training protocol, total red cell volume (+7.6%, P = 0.04) and circulating hemoglobin amount (48.8 ± 2.8 vs 45.5 ± 3.0 mmol; i.e., +7.9%, P = 0.02) were significantly augmented in LH. Conclusion: We conclude that hif-1a gene expression quantification in leukocytes after a 3-h hypoxia test performed before training does not predict poor and good responder athletes to "living high-training low" model.

International audience; Energy expenditure (EE) is a major determinant of energy balance and body composition. The objectives of this paper were to review the contributing factors of the main components of daily EE (DEE) and the inter-individual variability in these components in non-obese (NOb), obese (Ob), and post-obese (POb) adolescents. Body composition especially fat-free mass (FFM), is the major determinant of the basal metabolic rate which contributes 50-70% of DEE, whereas fat mass (FM) is a significant factor only in obese subjects. Physical activity is the second main variation factor of DEE, whereas growth, the thermic effect of food, and thermoregulation are generally of marginal importance. The energy costs and EE associated with various sedentary and physical activities were assessed in NOb, Ob and POb subjects both in standardised and in free-living conditions. The inter-individual variability of DEE is high, even after adjustment for body composition, mainly because of great differences in time devoted to the various physical activities. DEE and EE associated with sleep and sedentary activities are significantly higher in Ob than in NOb, but not after adjustment for FFM. On the contrary, EE associated with physical activities is not significantly different between Ob and NOb adolescents, but 61% lower in Ob subjects after adjustment for body composition. Multidisciplinary weight-reduction programmes including moderate energy restriction and physical training result in great FM loss, maintenance of FFM, improvement of physical capacities, but reductions in organ and tissue metabolic rate and in EE associated with the various sedentary and physical activities, which may favour body weight regain in the less active POb subjects.

Pulmonary function was measured in 48 air divers (age range: 8–38 yr) and 56 control participants (age range: 8–34 yr). Static lung volumes, dynamic lung volumes and flows, and the pulmonary diffusing capacity for carbon monoxide were measured twice, 29 months apart. At both times the adult divers (>18 yr) had higher forced vital capacity, forced expiratory volume in 1 s and maximal expiratory flow rate at 50%, as well as lower pulmonary diffusing capacity for carbon monoxide, than did the adult controls. Whatever the age, mean annual changes in these parameters did not differ between groups. Our results indicate that there were no significant changes in pulmonary function in the young (8–12 yr), adolescent, or adult divers compared with healthy controls over the 29-month period. The mean annual changes in forced expiratory flow and volume, however, were negatively correlated with number of years of diving experience in adult divers and with maximal diving depth in adolescent (13–18 yr) divers (p < .05 and p < .001, respectively). Deep diving during the teenage years coupled with years of recreational diving might increase the risk of airway obstruction.

Resume Objectifs. – Le but de ce travail etait d’etudier la faisabilite d’une etude comparant deux protocoles d’electrostimulation du quadriceps apres chirurgie du ligament croise anterieur. Methodes. – Sept hommes sportifs, d’âge moyen 26 ans, ont ete tires au sort en deux groupes : un groupe de quatre patients stimules a 20 Hz et un groupe de trois patients stimules a 80 Hz. Tous les patients ont beneficie en postoperatoire d’une electrostimulation du quadriceps cinq fois par semaine pendant 12 semaines, en plus d’un programme standard de contractions volontaires. Le programme d’evaluation, avant et trois mois apres la chirurgie comprenait la mesure des elements suivants : peak torque du quadriceps et des ischio-jambiers a 90, 180 et 240°/seconde, force isometrique maximale a 75° du quadriceps et volumes musculaire et de la graisse sous-cutanee des cuisses, evalues par resonance magnetique. Resultats. – Apres 12 semaines de reeducation, le deficit du volume musculaire, cote opere par rapport au cote sain, variait entre 3 et 9 % pour le groupe 80 Hz et entre 1 et 2 % pour le groupe 20 Hz. Le deficit de la force quadricipitale, cote opere par rapport au cote sain, etait inferieur a 30 %, sauf pour deux patients du groupe 80 Hz en isocinetique. Il etait en isometrique, superieur a 30 % sauf pour deux patients du groupe 20 Hz. Conclusion. – La comparaison de deux protocoles d’electrostimulation apres plastie ligamentaire est possible avec une duree d’electrostimulation n’excedant pas quatre semaines.

The present study was performed to determine how equilibrated fluctuations in hydration affected the validity of bioelectrical impedance analysis (BIA) for body composition assessment. Total body water (TBW) expansion was induced by a 4 d endurance trial and the subsequent water loss was obtained over the recovery period. Twelve healthy men exercised on a cycle and treadmill alternately for 5 h/d over 4 d at moderate intensity. TBW, fat mass (FM) and fat-free mass (FFM) were assessed 3 d before the trial (control), and on the first and eighth day of recovery (R1 and R8 respectively). TBW was evaluated by 2H dilution (TBW2H) as a reference method and by BIA (TBWBIA) at 100 kHz at the same time. TBW2H increased significantly between the control day and R1 by 1·87 (sd 1·11) litres (P=0·005) and TBWBIA by 1·38 (sd 1·56) litres (P=0·009). Both values returned to the control level on R8. For each period, TBW2H and TBWBIA did not differ significantly and were correlated (r2 0·85, P=0·0004 for the control day; r2 0·63, P=0·03 for R1; r2 0·75, P=0·02 for R8). Plasma Na concentration and osmolality did not differ between the control day, R1 and R8. FFM gain (1208 (sd 1983) g) and FM loss (−1168 (sd 906) g) between the control day and R1 were followed by a FFM decrease (−624 (sd 1281) g) and a FM increase (860 (sd 1212) g) between R1 and R8. As expected, these FFM and FM changes were significantly correlated with TBW variations. The present results provide evidence that BIA may be a useful method for estimating TBW when fluid shifts are equilibrated and electrolyte concentrations are unchanged. However, it is not a valid technique for assessing FM and FFM under these conditions.

The aim was to evaluate the cardiodynamic adjustment during 4 days of prolonged exercises and to check if the plasma volume (PV) expansion which is observed generally during such events plays a role in this adaptation. Thirteen subjects exercised 5 hours per day on a cycle ergometer alternately with a treadmill for 4 days (D1 to D4) (6 x 50 min sessions per day). The individual cycle ergometer load and the treadmill speed were unchanged during each exercise session and throughout all the sessions, and corresponded to a moderate exercise intensity: 58 - 63 % of peak oxygen uptake (VO (2)peak). Heart rate (HR) was recorded every 15 s during each exercise session and VO (2) was measured from the expired air at the beginning and the end of each exercise session. Relative PV changes were measured from haematocrit and haemoglobin changes in the morning before the exercise bouts. No significant changes of VO (2) were observed between the first and the last exercise session i. e. for cycling: 2.1 +/- 0.2 l/min and for running: 2.4 +/- 0.3 l/min. Between the first and the last day, HR decreased from 143 to 129 bpm for cycle (p < 0.0001) and from 147 to 137 bpm (p = 0.01) for treadmill. As compared to D1, PV increased gradually from D2 (+ 1.8 % +/- 4.7 %) to D4 (+ 8.5 % +/- 4.7 %). The individual PV increases were significantly correlated with cycling HR decreases from D1 to D4 (r (2) = 0.40, p = 0.02). In conclusion, the 4 days' prolonged exercise induced a HR decrease during submaximal exercise without VO (2) drift. Here we suggested that this HR decline could be in part linked to the transient PV expansion.

Background: Energy intake at breakfast affects the performance of creativity tests, memory recall and voluntary physical endurance in children before lunch, and food craving during the whole day. Objective: To assess the adequacy of breakfast energy supply (BES) and energy expenditure (EE) in adolescents during a schoolday without or with 2 h of physical education lesson (PEL) in the morning. Design: Sixty adolescents (four groups of 14–16 boys and girls aged 12–16 y) participated in a cross-sectional study. Activity patterns and EE were determined by whole-body calorimetry during 36 h and in free-living conditions during 5 days using both a diary and the validated heart rate recording method. BES was determined by weighing individual foods. The pyloric energy flow was assessed using a model of fractional stomach emptying. Results: BES averaged 24.9% (s.d.=6.1) of daily EE in the four groups of subjects. It covered the mean morning EE on a schoolday without PEL, but not in a schoolday with 2 h of PEL in any group. When PEL took place from 8–10 am the cumulative EE exceeded the cumulative pyloric energy flow after 105–150 min, that is during the PEL session, and the energy deficit increased until lunch. With a light breakfast (BES−1 s.d.) energy deficiency happened after 90 min. Conclusion: The results stress the need for a heavy breakfast for children and adolescents on the days with PEL in the morning, and a carbohydrate rich snack at 10 am to improve attention, memory and willing participation in physical activities.

Background: Changes in lifestyle and increases in sedentary activities during recent decades have been shown to contribute to the prevalence of overweight in adolescents. Objectives: To determine the inter-individual variability and the day-to-day variations in daily energy expenditure (DEE) and activity pattern, and the energy costs and EE of the various activities of adolescents in free-living conditions. Design: Sixty adolescents (four groups of 14–16 boys or girls aged 12–16 y) participated in this cross-sectional study during spring or autumn. Activity patterns and EE were determined during five consecutive days, using both a diary and the heart rate recording method validated by whole-body calorimetry and laboratory tests. Results: Mean DEE increased significantly with age in boys, but not in girls. However, the physical activity level did not vary significantly with sex and age. Mean DEE was significantly higher in spring than in autumn in the 12.6-y-old subjects. It was also 21% higher during the free days than during the schooldays in the active subjects, but 7% lower in the sedentary subjects. The energy cost of 22 activities was determined. Time and energy devoted to moderate and sport activities exhibited great inter-individual variability. They were lower in girls than in boys and decreased with age. The increase in EE resulting from moderate and sport activities instead of sedentary activities ranged from 0.2 to 2.7 MJ/day over the week. Conclusion: The great variability in DEE of adolescents resulted mainly from differences in the nature, duration and intensity of physical activities during the free days.

Long term effects on respiratory function have been found in adult professional divers and have indicated the development of small-airway disease. The aim of this report was to investigate pulmonary lung function and breathing pattern of recreational divers, especially in young subjects. Pulmonary function was measured in 84 air divers (aged 8 - 38 years) and in a matched control group of 89 subjects (aged 8 - 34 years). Static lung volumes, dynamic lung volumes and flows, transfer factor for carbon monoxide (T(Lco) ), maximal static pressures and CO(2) rebreathing test were measured. We observed no significant differences for all lung function parameters between divers and non divers in children and adolescents. Adult air divers showed a significant decrease in T(Lco) in absolute values (5.74 vs 6.26 ml x min(-1) x mmHg(-1) x l(-1), p = 0.03) and normal values and no significant difference in % predicted (112 vs 119 %), a higher maximal inspiratory pressure at functional residual capacity (-92 vs -74 cm H(2)O, p < 0.05) and at residual volume (-108 vs -88 cm H(2)O, p < 0.05) than adult controls. Adult divers also had a decreased resting respiratory frequency (13 c x min (-1) vs 17 c x min (-1) respectively, p < 0.01) and a higher carbon dioxide threshold (52 mm Hg vs 49 mm Hg respectively, p < 0.05) than adult controls. No significant differences occurred between adults divers and non divers for obstruction parameters. In this study, no airway obstruction or transfer factor reduction was observed in young recreational divers. Lower CO(2) threshold and higher inspiratory pressure were obtained in adult recreational divers compared to controls.

Background : Pentane in exhaled gas is often used as an index of lipoperoxidation, but today, there is no standardization for its measurement. In this study, with our technical experience, we determined basal production of pentane in healthy subjects, and we evaluated variability of pentane flow 1 month later. Methods : 18 subjects inhaled hydrocarbon-free air (HCFA) in order to realize a lung washout. Ambient air and three samples (at T0, T10, T30 min) of expired gas were concentrated using a “trap-and-purge” procedure. For the analysis of pentane, an Al 2 O 3 /KCl plot column contained in a gas chromatograph equipped with a flame ionization detector was used. Results : After 10 min of washout, mean (±SD) exhalation rate of pentane was 1±0.6 pmol min −1 kg −1 . After 30 min of washout, mean (±SD) exhalation rate of pentane was 0.7±0.5 pmol min −1 kg −1 . No significant difference in pentane flow was shown 1 month later for eight subjects who repeated the protocol. Conclusion : With our results and data of the literature, exhalation rates of pentane from healthy adults appear to range between 0.3 and 2 pmol min −1 kg −1 . The variability of pentane flow 1 month later seems not very important.

Background: The onset of puberty is a period of rapid anatomical and physiological alterations expected to induce changes in metabolic rate and energy requirements of children. Aim of the study: To evaluate the changes in anthropometrical features, body composition, physical capacities, and energy expenditure (EE) of boys and girls during the period of onset of puberty. Methods: Sixteen children (8 boys and 8 girls were recruited in the same school-class and studied both at 10.4 and 12.8 years of age. Body composition was assessed by bioimpedance analysis. Peak oxygen uptake (peak VO2) was measured using an automated on-line system during exercising on a cycle ergometer. Energy expenditure (EE) was determined by whole-body indirect calorimetry over a 24-h period after a 12-h period of adaptation to the calorimeters. Volunteers followed the same activity programme that included four 15-min periods of exercise. Results: During the onset of puberty, boys and girls gained 4.7±2.1 kg.y−1 (P < 0.0003) fat-free mass (FFM), whereas fat mass gain was 1.0±1.2 kg.y−1 (P < 0.05) in girls and 0.20±0.66 kg.y−1 in boys (NS). Peak VO2 adjusted for differences in FFM was not significantly affected by gender or pubertal stage. However, adjusted external mechanical power performed at peak VO2 was higher in pubertal than in prepubertal children, by 40% (P < 0.0001) and 22% (P < 0.003) in boys and girls, respectively. It was also 17% (P < 0.0002) higher in pubertal boys than in pubertal girls. Daily and sleeping EE increased by 38% and 32% in boys and girls, respectively, during the 2.4-y period (P < 0.0001). Adjusted EEs were also significantly higher in pubertal than in prepubertal boys (P < 0.05 and P < 0.03), but not in girls. The main significant determinants of daily EE were FFM (r2=0.866, P < 0.0001), peak VO2 (r2=0.017, P < 0.04), and age (r2=0.014, P < 0.05). Tanner's stage was an additional determinant of sleeping EE (r2=0.025, P < 0.006). Conclusions: The increases in physical capacities and EE during the onset of puberty indicated clear gender differences, which could be explained mainly by alterations of body composition in boys and girls, and by changes in hormonal status in bouys. They also stressed the significant increase in energy requirements of children, especially boys, at an early stage of puberty.

Effects of progressive endurance training on energy expenditure (EE) were studied in thirteen elderly sedentary subjects (62.8 (sd 2.3) years) after 7 and 14 weeks of training. Daily EE (DEE) and energy cost of the various usual activities were measured over 48 h by whole-body indirect calorimetry. Free-living DEE (DEEFLC) was calculated from 7 d activity recordings and the energy costs of activities were measured in the calorimeters using the factorial method. DEEFLC did not vary significantly throughout the training period despite the additional energy cost of training sessions (0·60 (sd 0·15) MJ/d), because energy expended during free-living activities (EEACT) decreased by 4·8 (sd 7·1) % (P < 0·05) and 7·7 (sd 8·6) % (P < 0·01) after 7 and 14 weeks of training respectively. Measurements in the calorimeters showed that sleeping metabolic rate transiently increased by 4·6 (sd 3·2) % after 7 weeks of training (P < 0·001) and returned to its initial level after 14 weeks of training. BMR was 7·6 (sd 7·0)%(P < 0·01) and 4·1 (sd 6·1)% (P = NS) higher after 7 and 14 weeks of training respectively, than before training. Likewise, diet-induced thermogenesis increased from 3·7 (sd 2·5) to 7·2 (sd 2·8) % energy intake after 7 weeks of training (P < 0·05), and returned to its initial level after 14 weeks of training (4·2 (sd 2·6) % energy intake). Despite these changes, energy expended during activities and the corresponding DEE did not vary throughout the training period. It was concluded that: (1) DEEFLC remained constant throughout the training period due to a compensatory decrease in free-living EEACT; (2) progressive endurance training induced a transient increase in sleeping metabolic rate, BMR and diet-induced thermogenesis after 7 weeks which was not reflected in the energy expended during activities and DEE.

Based on a theoretical approach from world record running data, we have previously calculated that the most suitable duration for measuring maximal aerobic velocity (Vamax) by a field test was 5 min (Vamax(5)). The aim of this study was, therefore, to check this hypothesis on 48 men of various levels of physical fitness by comparing (Vmax(5)) with (Vamax) determined at the last step of a progressive treadmill exercise test when the subject felt exhausted (Vamax(t)) and during a test on a running track, behind a cyclist (following an established protocol) (Vamax(c)). For each test, (VO2max) was also measured by a direct method on a treadmill (VO2max(1)) and calculated by an equation for field tests (VO2max(5) and VO2max(c)). The Vamax(5) [17.1 (SD 2.2) km.h-1] and (Vamax(c)) [(18.2 (SD 2.4) km.h-1] were significantly higher than (Vamax(t)) [16.9 (SD 2.6) km.h-1; P < 0.001]. The (Vamax(t)) was strongly correlated with (Vamax(5)) (r = 0.94) and (Vamax(c)) (r = 0.95) (P < 0.001). The best identity and correlation between (Vamax(5)) and track performances were found in the runners (n = 9) with experience over a distance of 3,000 m. The VO2max(5) and (VO2max(c)) were higher than VO2max(t) (+ 5.0% and + 13.7%, respectively; P < 0.001) and VO2max(t) was highly correlated with Vamax(5) (r = 0.90; P < 0.001). These results suggest that the 5-min field test, easy to apply, provided precise information on Vamax and to a lesser degree on VO2max.

The aim of this work was to evaluate the effects of high altitude and low socioeconomic status (SES) on aerobic and anaerobic power in 11-yr-old Bolivian girls. At both high (3,600 m) and low (420 m) altitudes, low-SES groups of girls were compared to similarly aged, high-SES girls. At low altitude, low-SES girls were also compared with younger high-SES girls with the same anthropometric characteristics. Anthropometric data were similar between high-SES and low-SES girls at both altitudes, but low-SES girls showed a 9-mo growth delay. Maximal O2 uptake was significantly lower for low-SES girls at both altitudes. Values did not differ when expressed relative to body weight at high altitude for high-SES vs. low-SES girls (37.6 +/- 1.2 vs. 39.3 +/- 1.0 ml.min-1.kg body wt-1), but a difference persisted at low altitude between high- and low-SES girls (37.5 +/- 1.0 vs. 34.7 +/- 0.7 ml.min-1.kg body wt-1). Anaerobic power (Pmax, force-velocity test; Pwing, Wingate test) was reduced for low-SES girls at both altitudes, whatever the mode of expression. For a given SES, the relative anaerobic performances were lower at low altitude. At low altitude, low-SES girls developed lower anaerobic power than did younger high-SES girls with similar anthropometric characteristics. In conclusion, at both altitudes, the reduction of anaerobic performances observed in girls of low SES could not be totally explained by anthropometric factors. Structural and/or functional muscle alterations are suggested. Moreover, at low altitude, tropical and other factors may have contributed to differences in performance between low- and high-SES girls.

This study was designed to investigate the interaction of mild and localized cold exposure and hypoxia on pulmonary hemodynamics in chronic obstructive pulmonary disease (COPD). Nineteen patients with COPD were studied at sea level and seven at an altitude of 2,640 m. For all patients, pulmonary hemodynamic measurements were performed 10 min after insertion of a catheter in a femoral vein and following 10 min of cold exposure. Cold exposure was restricted to the forehead, and subjects breathed air at ambient temperature. Flow and temperature of air (1.5 L.s(-1), 5 degrees C) to the forehead were chosen to cool down the forehead skin to approximately 20 degrees C without discomfort for the subject. For the seven patients studied at high altitude, the same measurements were also performed after 5 min of oxygen supplementation with and without cold exposure. At sea level, an increase in pulmonary vascular resistance (PVR) during cold exposure was inversely related to the initial PaO2. In six severe hypoxic subjects (PaO2 < 50 mm Hg), PVR increased by 24%. At high altitude, PVR was significantly increased by 15%. After O2 supplementation, cold exposure did not induce an increase in PVR. We concluded that mild and localized cold exposure to the forehead only induced an increase in PVR in COPD patients with severe hypoxia. Moreover, in cold exposure responders, O2 supplementation negated the effect of cold exposure on pulmonary hemodynamics.

Resume L'objectif de cette etude etait d'apprehender les effets d'une pratique intensive precoce sur le potentiel aerobie de la fille prepubere et de montrer l'importance du choix de l'epreuve de laboratoire dans la mise en evidence des adaptations physiologiques consecutives a l'entrainement. La population etait composee de 14 jeunes filles prepuberes dont cinq sont originaires d'un club nautique (GN) et neuf, d'âge similaire (9 ans), constituaient le groupe controle (GC). Ces sujets ont participe a trois epreuves progressives maximales dont le but etait de determiner les possibilites maximales de consommation d'oxygene. Les deux premieres ont ete realisees sur banc de nage (VO 2 pic) au debut du programme d'entrainement et 1 an plus tard. La troisieme (VO 2 max) a ete realisee sur bicyclette ergometrique 5 mois apres le second test. Pendant toute la duree de l'etude, les nageuses s'entrainaient environ 10–12 heures par semaine (deux fois 1 h a lh30/j ; 5 jours par semaine) et parcouraient environ 15–20 km hebdomadaire. Aucune difference significative n'existait au debut du programme entre GN et GC concernant VO 2 pic (GN : 26 ± 4mL·min −1 kg −1 , GC : 25 ± 3 mL·min −1 kg −1 ). Cependant, apres 1 an de pratique intensive, VO 2 pic des nageuses etait tres superieure (+ 36 %) a celle du groupe controle (GN : 34 ± 5 mL·min −1 kg −1 , GC : 25 ± 4 mL·min −1 kg −1 , p s 2 max mesuree sur bicyclette ergometrique, apres 1 an et demi d'entrainement, n'etaient par contre qu'un peu plus elevees (+12%) pour GN que pour GC (GN : 46 ± 1 mL·min −1 kg −1 , GC : 41 ± 4 mL·min −1 kg −1 , p s 2 pic sont significativement inferieures a celles de VO 2 max (GN : p s p s

This study describes habitual physical activity (HPA) of Bolivian boys living at different altitudes and from different socioeconomic status. The boys were living at high altitude (HA) in La Paz (4000 m) and at low altitude (LA) in Santa Cruz (400 m). At both altitudes samples of 10- to 12-year-old boys were chosen from a relatively low socioeconomic status (LSES) and a relatively high socioeconomic status (HSES). At HA 19 boys from LSES and 10 boys from HSES were measured and at LA 14 boys from LSES and 13 boys from HSES. HPA was measured by 24-h heart rate (HR) monitoring. Also an interview was completed to recall the HPA. By comparing the registered HR data with the time they were asleep the mean HR during sleep was calculated (HRsleep). The maximal HR (HRmax) was measured from a maximal exercise test on a bicycle ergometer. Heart rate reserve (HRR = HRmax-HRsleep) was used to measure the mean level of physical activity of the subjects. The results show that HRsleep (= HRrest) in HA boys with 70 (+/- 6) beats/min was significantly lower (p < 0.05) than in LA boys with 77 (+/- 10) beats/min. HRmax was also significantly lower (p < 0.05) in HA boys (187 +/- 12 beats/min) compared to LA boys (195 +/- 8 beats/min). Because HA influences HRsleep and HRmax in the same way, HRR is not significantly different between boys of HA and LA. The mean heart rate over 24 h (HRmean) in HA boys (87 +/- 7 beats/min) was significantly lower than in LA boys (93 +/- 8 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

The aim of this paper was to analyze the effects of chronic hypoxia and socioeconomic level on blood lactate concentrations obtained after maximal exercise and a 30-s Wingate test in 145 Bolivian boys (mean age: 10.8 years). Among the boys studied at high altitude (HA) (La Paz, 3600m) and at low altitude (LA) (Santa Cruz de la Sierra, 420m), 23 (HAHSES) and 48 (LAHSES) were from a high socioeconomic status (HSES), and 44 (HALSES) and 30 (LALSES) from a low socioeconomic status (LSES). The pubertal development was evaluated by salivary testosterone level ([T]). Blood samples were collected from the earlobe for blood lactate determination 2 min after cessation of maximal exercise ([L]v) and of a 30-s Wingate test ([L]w). Results (means +/- SD) showed: (1) [T] was significantly lower at HA: HA (HSES + LSES): 139.0 +/- 46.6 vs LA (HSES + LSES) = 186.2 +/- 53.7 pmole.1-1 (p = 0.0001). There was no significant difference between HAHSES and HALSES but LALSES was significantly lower than LAHSES. When the four groups were pooled, significant positive correlations between [L] and [T] were found; (2) for a same level of socioeconomic conditions, [L]v and [L]w were significantly lower at HA: HAHSES = 4.9 +/- 1.5 vs LAHSES = 7.4 +/- 2.1 and HALSES = 4.8 +/- 1.4 vs LALSES = 6.3 +/- 1.5 mmole.l-1 for [L]v; HAHSES = 5.1 +/- 1.0 vs LAHSES = 6.2 +/- 1.4 and HALSES = 4.6 +/- 1.0 vs LALSES = 5.3 +/- 1.4 mmole.l-1 for [L]w; (3) except for [L]v at HA, the HSES boys exhibited higher [L]v and [L]w than the LSES children for a same altitude; (4) there were significant linear relationships between the power developed during the 30-s Wingate test and [L]w.(ABSTRACT TRUNCATED AT 250 WORDS)

To investigate the influence of androgens on muscle maturation during growth, guinea pigs were orchiectomized (CX) or sham operated (SO) at the end of weaning. Extensor digitorum longus (EDL) muscles were removed at weeks 4, 8, and 12 of postnatal development. According to their contractile and metabolic characteristics, four fiber types were distinguished, called I, IIa, IIbox, and IIbglyc. Muscle maturation consisted of a concomitant decrease in percentages of type IIa and IIbglyc fibers and increase in the percentage of IIbox fibers in both groups. At week 12, fiber distributions were not different between the two groups. Citrate synthase activity fell and phosphofructokinase and lactate dehydrogenase (LDH) activities rose from week 4 to week 12 and were the same in CX and SO. Muscular LDH subunits increased in SO and decreased in CX during this period. In conclusion, fiber type distribution and enzyme activities at puberty were not androgen dependent in guinea pig EDL muscle. Conversely, these hormones acted on LDH isozyme distribution through the enhancement of the most glycolytic LDH fractions.

International audience; There is evidence that pulmonary arterial hypertension plays a major role in the occurrence of high altitude pulmonary edema (HAPE). We tested the hypothesis that the pulmonary arterial systolic pressure response to a challenge associated with hypoxia and mild exercise may be considered a predictive factor of HAPE. Pulmonary arterial systolic pressure was measured by Doppler echocardiography in 8 HAPE susceptible (HAPE-S) subjects and 8 HAPE resistant mountaineers (HAPE-R) during a hypoxic exercise challenge established by the French Association for Sport Medicine (Richalet's test). Pulmonary arterial systolic pressure during hypoxic exercise allowed a significant discrimination between the groups, although an overlap of values was observed. When expressed as individual variations from baseline to hypoxic exercise level however, we found a highly significant difference. No overlap was observed between HAPE-R (range: 6.7-18.5 mmHg) and HAPE-S (range: 19.2-30.4 mmHg) groups, with a cut-off value at 19 mmHg. Plasma Vascular Endothelial growth factor (VEGF) and malondialdehyde (MDA) increased in response to hypoxic exercise only in HAPE-S group. Individual increases in pulmonary arterial systolic pressure during hypoxic exercise from basal resting normoxic values seem relevant to estimate HAPE susceptibility when measured during the Richalet's test.

In the breath-hold model described by S. Godfrey and E. J. M. Campbell (Respir. Physiol. 5: 385–400, 1968), chemical and nonchemical stimuli are independent. Because these two factors are time dependent, the effect of each could not be measured by breath-holding time (BHT). The aim of this study is to dissociate chemical and nonchemical stimuli and to assess the effects of BHT and PCO2 on respiratory center output by measurement of occlusion pressure (P0.1) and mean inspiratory flow (VI). Nine well-trained divers (age 36.5 +/- 5.0 yr) took part in the study. Each subject had to hold his breath at 75% of vital capacity for 30, 50, and 70 s of BHT. Before each breath hold, the subject inspired successively two vital capacities of the same CO2-O2 gas mixture. P0.1 and VI were measured during the first reinspiration after the breath hold. For the same BHT, we observed good linear relationships between P0.1 or VI and alveolar PCO2. The slopes of these relationships increased with BHT. For alveolar PCO2 of > 50 Torr, P0.1 increased linearly with BHT. These results indicate that, during breath holding, chemical and nonchemical stimuli acted linearly on respiratory motoneuron activity, but they were not independent.

It has been shown that the antioxidant status was altered by the "live high-train low" (LHTL) method, however, no information is available regarding the antioxidant restoration during the recovery period.We tested the hypothesis that the antioxidant status is impaired by 18 days LHTL in elite athletes and remained altered after 14 days of recovery.Eleven elite cross-country skiers from the French Skiing Federation were submitted to 18-day endurance training. Six (hypoxic group; HG) trained at 1,200 m and lived in hypoxia (simulated altitude of 2,500 m-3,000 m-3,500 m) and 5 (control group; CG) trained and lived at 1,200 m. Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA), ferric reducing antioxidant power (FRAP), trolox equivalent antioxidant capacity (TEAC) lipid-soluble antioxidants (alpha-tocopherol, beta-carotene and lycopene) were measured at rest, before (PRE), the first day after (POST1) and again 2 weeks (POST14) after the training. Intakes of vitamins A and E were evaluated from the dietary recording.In POST1, FRAP and TEAC decreased in both groups, however, the TEAC decrease persisted in POST14 for HG only. Lycopene and beta-carotene decreased in POST1 for HG and remained lower in POST14. Finally, AOPP increased only for HG in POST1. The general decline of antioxidant status for both groups might result from insufficient intakes in vitamins A and E.This is the first study to show that the antioxidant status did not return to baseline 2 weeks after 18 days of LHTL training.

International audience; We investigated the impact of 13 days of "living high-training low" (LHTL) on the antioxidant/prooxidant balance in elite endurance swimmers. Eighteen elite swimmers from the French Swimming Federation were submitted to a 13-day endurance training and divided into two groups: one group trained at 1,200 m and lived in hypoxia (2,500-3,000 m simulated altitude) and the second group trained and lived at 1,200 m. The subjects performed an acute hypoxic test (10 min at 4,800 m) before and 1 day after the training period. Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA), ferric reducing antioxidant power (FRAP), and lipid-soluble antioxidants were measured before and after the 4,800 m tests. After the training, MDA and AOPP responses to the 4,800 m test were lower than before training for both groups (+10 vs. +2%; P = 0.01 for MDA and +80 vs. +14%; P = 0.01 for AOPP). Thirteen days of LHTL did not modify antioxidant status (FRAP and lipid-soluble antioxidants) despite intakes in vitamins A and E below the recommended daily allowances. The LHTL did not affect the antioxidant status in elite swimmers; however, the normoxic endurance training induced preconditioning mechanisms in response to the 4,800 m test.

International audience; BACKGROUND/OBJECTIVES: We previously demonstrated that acute exposure to hypoxia (3 h at 3000 m) increased oxidative stress markers. Thus, by using the 'living high-training low' (LHTL) method, we further hypothesized that intermittent hypoxia associated with endurance training alters the prooxidant/antioxidant balance. SUBJECTS/METHODS: Twelve elite athletes from the Athletic French Federation were subjected to 18-day endurance training. They were divided into two groups: one group (control group) trained at 1200 m and lived in hypoxia (2500-3000 m simulated altitude) and the second group trained and lived at 1200 m. The subjects performed an acute hypoxic test (10 min at 4800 m) before and immediately after the training. Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA), ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants normalized for triacylglycerols, and cholesterol and retinol were measured before and after the 4800 m tests. RESULTS: After the training, MDA and AOPP concentrations were decreased in response to the 4800 m test only for the control group. Eighteen days of LHTL induced a significant decrease of all antioxidant markers (FRAP, P=0.01; alpha-tocopherol, P=0.04; beta-carotene, P=0.01 and lycopene, P=0.02) for the runners. This imbalance between antioxidant and prooxidant might result from insufficient intakes in vitamins A and E. CONCLUSIONS: The LHTL model characterized by the association of aerobic exercises and intermittent resting hypoxia exposures decreased the antioxidant status whereas the normoxic endurance training induced preconditioning mechanisms in response to the 4800 m test.

We investigated whether acute hypoxic exposures could modify the pro-oxidant/antioxidant balance in elite endurance athletes, known to have efficient antioxidant status. Forty-one elite athletes were subjected to two hypoxic tests: one at an altitude of 4 800 m during 10-min of mild exercise (4 800 m test) and the second at rest for 3 h at an altitude of 3 000 m (3 000 m test). Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA), ferric reducing antioxidant power (FRAP) and lipid-soluble antioxidants were measured before and immediately after the 4 800 m test and at the end of the 3 000 m test. The 4 800 m and the 3 000 m tests induced a significant increase in the level of MDA and AOPP (+7.1% and +71.7% for 4 800 m test and +8.6% and +40.9% for 3 000 m test). The changes in plasma MDA and arterial oxygen saturations were significantly correlated (r=0.35) during the 3 000 m test. FRAP values (-13%) and alpha-tocopherol (-21%) were decreased following the 3 000 m test. However, following the 4 800 m test, only alpha-tocopherol was decreased (-16%). These results provide evidence that the highly-trained athletes do not have the antioxidant buffering capacity to counterbalance free radical over-production generated by acute hypoxic exposure, with or without mild exercise.

Intermittent hypoxic exposure with exercise training is based on the assumption that brief exposure to hypoxia is sufficient to induce beneficial muscular adaptations mediated via hypoxia-inducible transcription factors (HIF). We previously demonstrated (Mounier et al. Med Sci Sports Exerc 38:1410-1417, 2006) that leukocytes respond to hypoxia with a marked inter-individual variability in HIF-1alpha mRNA. This study compared the effects of 3 weeks of intermittent hypoxic training on hif gene expression in both skeletal muscle and leukocytes. Male endurance athletes (n = 19) were divided into an Intermittent Hypoxic Exposure group (IHE) and a Normoxic Training group (NT) with each group following a similar 3-week exercise training program. After training, the amount of HIF-1alpha mRNA in muscle decreased only in IHE group (-24.7%, P0.05) whereas it remained unchanged in leukocytes in both groups. The levels of vEGF(121) and vEGF(165) mRNA in skeletal muscle increased significantly after training only in the NT group (+82.5%, P0.05 for vEGF(121); +41.2%, P0.05 for vEGF(165)). In leukocytes, only the IHE group showed a significant change in vEGF(165) (-28.2%, P0.05). The significant decrease in HIF-1alpha mRNA in skeletal muscle after hypoxic training suggests that transcriptional and post-transcriptional regulations of the hif-1alpha gene are different in muscle and leukocytes.

This study was done to determine the extent to which body composition accounts for differences in anaerobic characteristics between 12-year-old girls and boys. Peak leg power (PP), mean leg power (MP), percent body fat, fat free mass (FFM), and lean thigh volume (LTV) were determined by various tests. Pubertal stages and salivary testosterone concentration (in boys) were used to assess sexual maturation. Laboratory anaerobic indices were compared with performances in two running tests. Blood samples were taken for lactate determination. Absolute PP and MP outputs were similar in both sexes and were better correlated with LTV in girls, whereas in boys both PP and MP were highly correlated with FFM. Although nonsignificant gender difference in lean tissue was observed, PP and MP when corrected for LTV were significantly greater in boys than in girls. Factors other than the amount of lean muscle mass should be considered in explaining the gender differences in PP and MP in early pubertal children.

The aim of this study was to investigate in a placebo-controlled field study the effect of a (n - 3)-vitamin supplementation on erythrocyte membrane fluidity (EMF), oxidant/antioxidant markers and plasmatic ω3/ω6 fatty acid ratio (FAR) in 12 eventing horses. Venous blood was sampled at rest before (PRE) and after (POST) a three week treatment period with either the supplement (group S, n = 6) or a placebo (group P, n = 6) as well as after 15 min (POST E15′) and 24 h (POST E24h) after a standardised exercise test. The following markers were analysed: EMF, plasma antioxidant capacity of water and lipid soluble components, ascorbic acid, uric acid (UA), glutathione (reduced: GSH, oxidised: GSSG), vitamin E (Vit E), β-carotene, glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity, selenium, copper (Cu), zinc (Zn), oxidised proteins (Protox), lipid peroxides (Pool) and FAR. EMF did not differ between group S and P after treatment, but GPx remained unchanged in group S whereas it decreased in group P and plasma Cu/Zn ratio remained unchanged whereas it increased in group P. FAR were significantly increased in group S. Exercise induced a significant decrease of EMF (POST vs. E24h) in both groups, but which was significantly lower at E15′ in group S than in group P. Exercise induced a significant increase of UA and ACW (POST vs. E15′) and Protox (POST vs. E24h) in both groups. An exercise-related decrease in GSH and Pool (POST vs. E15′) was found in group P, whereas Vit E and FAR (POST vs. E24h) significantly decreased in both groups. The study showed that exercise induced a decrease in EMF in horses associated with changes of blood oxidative balance. The (ω-3)-vitamin supplementation tested improved the oxidative balance poorly but delayed the exercise-induced decrease of EMF and increased the FAR.

Summary Reasons for performing study: Fatty acid supplementation could modulate erythrocyte membrane fluidity in horses at rest and during exercise, but information is lacking on the effect of exercise. Objectives: To assess the effect of exercise with, and without, an oral antioxidant supplementation enriched with n-3 fatty acids on erythrocyte membrane fluidity (EMF) and fatty acid composition in eventing horses. Methods: Twelve healthy and regularly trained horses were divided randomly into 2 groups: group S received an oral antioxidant cocktail enriched in n-3 fatty acid (alphatocopherol, eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) whereas group P was placebotreated. At the end of 4 weeks, all horses performed a standardised exercise test (ET) under field conditions. Venous blood was sampled before starting treatment (T0), immediately before (T1) as well as 15 mins (T2) and 24 h (T3) after ET. Spin labelled (16-DOXYL-stearic acid) red blood cell membranes were characterised using the relaxation correlation time (Tc in inverse proportion to EMF). Fatty acid composition (%) of the membrane was determined by gas-liquid chromatography. Results: Supplementation (group S) did not induce changes in EMF (T1 vs. T0) but significant changes in membrane composition were observed and there were increases in n-3 polyunsaturated fatty acid PUFA, n-3/n-6 ratio, and total n3 fatty acids. Exercise (T2 vs. T1) induced a significant decrease of EMF in group P (Tc: +19%, P

The aim was to investigate the effects of acute exercise under hypoxic condition and the repetition of such exercise in a 'living low-training high' training on the antioxidant/prooxidant balance.Randomized, repeated measures design.Faculté de Médecine, Clermont-Ferrand, France.Fourteen runners were randomly divided into two groups. A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training.A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training. The first hypoxic group (HG, n=8) carried out these sessions under hypoxia (3000 m simulated altitude) and the second normoxic group (NG, n=6) in normoxia. In control period, the runners were submitted to two incremental cycling tests performed in normoxia and under hypoxia (simulated altitude of 3000 m). Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA) and lipid oxidizability, ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants (alpha-tocopherol and beta-carotene) normalized for triacyglycerols and cholesterol were measured before and after the two incremental tests and at rest before and after training.No significant changes of MDA and AOPP level were observed after normoxic exercise, whereas hypoxic exercise induced a 56% rise of MDA and a 44% rise of AOPP. Plasma level of MDA and arterial oxygen hemoglobin desaturations after the acute both exercises were highly correlated (r=0.73). alpha-Tocopherol normalized for cholesterol and triacyglycerols increased only after hypoxic exercise (10-12%, P0.01). After training, FRAP resting values (-21%, P0.05) and alpha-tocopherol/triacyglycerols ratio (-24%, P0.05) were diminished for HG, whereas NG values remained unchanged.Intense exercise and hypoxia exposure may have a cumulative effect on oxidative stress. As a consequence, the repetition of such exercise characterizing the 'living low-training high' model has weakened the antioxidant capacities of the athletes.International Olympic Committee and the Direction Régionale de la Jeunesse et des Sports de la Région Auvergne.

In different circumstances such as infant malnutrition, old age or chronic disease, decline of muscular strength, particularly anaerobic power, is shown. In this context, our laboratory, has demonstrated a decrease in anaerobic glycolytic power in pre-pubertal Bolivian children living at low and high altitude and suffering from marginal protein malnutrition. To bring molecular support to the relationship between protein malnutrition and anaerobic glycolytic metabolism, we studied the impact of prolonged protein malnutrition on lactate metabolism in different muscles of growing rats. Lactate dehydrogenase (LDH), monocarboxylate transporters (MCT1, MCT4) and membrane protein CD147 were chosen as specific markers of anaerobic glycolytic metabolism. Two groups of 10 weaning male rats were fed for 10 weeks either ad libitum with a well-balanced diet containing 18% protein or an isocaloric-diet containing 8% protein. LDH activity and mRNA amounts of LDH isoforms, MCT, CD147 were measured. Protein deprivation during rat growth induced a decrease of LDH specific activity in skeletal muscles (mean value of −41%), accompanied by isoform distribution modifications in soleus, but not in glycolytic muscles (extensor digitorum longus (EDL) or plantaris). A reduction in mRNA amounts encoding the LDH A and B subunits was observed in EDL. A decrease in LDH B mRNA amounts was monitored in plantaris, whereas no modification in both LDH isoform mRNA quantities was observed in soleus. MCT1 mRNA quantities were decreased in EDL but MCT4 mRNA quantities remained stable. CD147 mRNA amounts were unchanged except for EDL with a 42% increase. The global decreases of LDH activity, LDH and MCT gene expressions in growing rat skeletal muscles support the observed alterations of lactate metabolism associated with lowered muscular anaerobic performances in protein malnutrition.

International audience; Measuring physical workload in occupational medicine is fundamental for risk prevention. An indirect measurement of total and relative energy expenditure (EE) from heart rate (HR) is widely used but it has never been validated. The aim of this study was to validate this HR-estimated energy expenditure (HREEE) method against whole-body indirect calorimetry. Twenty-four-hour HR and EE values were recorded continuously in a calorimetric chambers for 52 adult males and females (19-65 years). An 8-h working period was retained, comprising several exercise sessions on a cycloergometer at intensities up to 65% of the peak rate of oxygen uptake. HREEE was calculated with reference to cardiac reserve. A corrected HREEE (CHREEE) was also calculated with a modification to the lowest value of cardiac reserve. Both values were further compared to established methods: the flex-HR method, and the use of a 3rd order polynomial relationship to estimate total and relative EE. No significant difference was found in total EE when measured in a calorimetric chamber or estimated from CHREEE for the working period. A perfect linear and identity relationship was found between CHREEE and energy reserve values for intensities ranging from 15% to 65%. Relative physical workload can be accurately assessed from HR recordings when expressed in CHREEE between 15% to 65%, and EE can be accurately estimated using the CHREEE method.

Lactate dehydrogenase (LDH) is a tetramer made up of two different subunits A and B. In cellular models, severe hypoxia increases LDH A gene expression whereas LDH B gene does not exhibit any regulation. The aim of our work was to characterise LDH expression in different tissues of rats bred at high altitude. For this purpose, we chose a Sprague-Dawley rat strain adapted to chronic hypoxia in La Paz (3700 m), Bolivia. Two normoxic control groups were bred at low altitude in Clermont-Ferrand (350 m), France, one group was ad libitum with free access to food and water as was the hypoxic one, and the second normoxic group was nourished with the food intakes measured for the animals from La Paz. We measured total LDH specific activity, isoform distribution and LDH A and B mRNA amounts in three skeletal muscles (soleus, extensor digitorum longus (EDL), plantaris), heart and brain. Our study demonstrates that, unlike what has been shown in cellular models under severe hypoxia, LDH A gene is not systematically up-regulated in tissues of rats living at high altitude. Furthermore, chronic hypoxia limits LDH B gene transcription or its mRNA stability in both soleus and EDL. These regulations occur at various molecular levels like gene transcription, mRNA stabilisation or translation and protein stability, depending on the tissue studied, and are partly attributed to caloric restriction provoked by high altitude. These data provide insight into LDH gene expression underlying the diverse and complex tissue-specific response to chronic hypoxia.

In Bolivia, malnutrition in children is a major health problem that may be caused by inadequate protein, energy, and micronutrient intake; exposure to bacterial and parasitic infections; and life in a multistress environment (high altitude, cold, cosmic radiation, low ambient humidity). However, no data on protein absorption and utilization at high altitude were available. Therefore, we evaluated the effect of altitude on protein metabolism in Bolivian children. We measured protein utilization using leucine labeled with a stable isotope ((13)C) in two groups of healthy prepubertal children matched for age. Group 1 (n = 10) was examined at high altitude (HA) in La Paz (3600 m), and group 2 (n = 10) at low altitude (LA) in Santa Cruz (420 m). The nutritional status did not differ between groups but, as was to be expected, the HA group had higher hemoglobin concentration than the LA group. The children consumed casein that was intrinsically labeled with L-(1-(13)C) leucine and expired (13)CO(2) was analyzed. Samples of expired air were measured by isotope ratio mass spectrometer in Clermont-Ferrand. It was found that cumulative leucine oxidation ((13)CO(2)) at 300 min after ingestion was 19.7 +/- 4.9% at HA and 25.2 +/- 3.2% at LA. These results showed that protein absorption and/or utilization is significantly affected by altitude.

The purpose of this study was to determine whether an ultra-endurance event is a strong stimulus to increase albumin synthesis involved in the process of intravascular albumin mass increase associated with transient hypervolemia.The albumin synthetic rate was measured in six young men, 3 d before (C) and on the 1st (R1) and 8th (R8) days of the recovery from an ultra-endurance trial (5 h daily for 4 d). Albumin fractional (FSR) and absolute (ASR) synthetic rate were determined using a primed-constant infusion of [1(-13) C] leucine. Plasma volume (PV) using Evans Blue dye dilution and total body water (TBW) using bioelectrical impedance analysis were measured on C, R1, and R8.On R1 as compared with C: 1). PV (+23.3 +/- 3.2%; Por= 0.001) and TBW (+4.2 +/- 0.8%; Por= 0.01) expanded; 2). FSR and ASR both increased from 5.36 +/- 0.46 to 6.86 +/- 0.62%.24 h (+ 29.0 +/- 7.1%; Por= 0.01) and from 103 +/- 10 to 153 +/- 19 mg.kg body weight (-1).24 h (-1) (+47.5 +/- 6.8%; Por= 0.01); and 3). plasma albumin and protein masses increased (Por= 0.05) from 1.92 +/- 0.08 to 2.22 +/- 0.14 g.kg body weight (-1) (i.e., +15.3 +/- 4.9%) and from 3.15 +/- 0.18 to 3.56 +/- 0.21 g.kg body weight (-1) (+13.3 +/- 3.9%), respectively. By R8, all these parameters had returned to their control levels except for albumin mass (1.73 +/- 0.08 g.kg body weight(-1), which was lower than C ( Por= 0.05).The increase in the albumin synthetic rate the day after an ultra-endurance trial is a major event associated with a greater circulating protein mass. The impact of exercise on albumin synthesis has disappeared 8 d later, as did PV and total protein mass expansion.

The aim of this study was to determine the influence of prolonged exercise repeated for 4 days on sleeping heart rate (SHR) and metabolic rate (SMR). Eleven young untrained men exercised at moderate intensity 5 hrs daily for 4 days, alternately on a cycle ergometer (57.0 ± 1.3% [Formula: see text]) and a treadmill (64.7 ± 1.6% [Formula: see text]). They spent the night prior to the exercise period (control, C) and the 4 nights following exercise days (N1 to N4) in room calorimeters for the measurement of SHR, SMR, and respiratory quotient (RQ) from midnight until 6 a.m. Every morning, before the exercise bouts, plasma-free epinephrine (E) and norepinephrine (NE) levels were measured. After exercise, all SHR values were significantly higher than at C level (52 ± 1 bpm, p

International audience; The purpose of this study was to compare the effects of two protocols of electrical stimulation combined with voluntary contractions on the recovery of thigh muscles after anterior cruciate ligament (ACL) surgery. Ten sportsmen with a mean age of 26 yrs were randomly assigned into two groups: a 80 Hz stimulated group (5 patients) and a 20 Hz stimulated group (5 patients). All patients received electrical stimulation of the quadriceps femoris, five days a week, for 12 weeks, and had a standard program of voluntary contractions. Muscle and fat volumes of the thigh were assessed using MRI before surgery and after 12 weeks of rehabilitation. Quadriceps and hamstring muscle strength were evaluated by isokinetic measurements. Twelve weeks after surgery, the quadriceps peak torque deficit in the operated limb with respect to the non operated limb at 180 degrees /s and 240 degrees /s was significantly (p < 0.05) less in the 20 Hz group than in the 80 Hz group. This difference was not confirmed when comparing the pre-surgery quadriceps peak torque of the operated limb with the post-surgery one. Subcutaneous fat volume was increased for the two groups at the post-surgery test. This increase was significantly (p < 0.05) greater for the 80 Hz group. Thigh muscle volume deficit was not significantly different between the two groups.

The objectives of the study were to determine: (1) daily energy expenditure (EE) of athletic and non-athletic adolescents of both sexes in free-living conditions; (2) day-to-day variations in daily EE during 1 week; (3) energy costs of the main activities; and (4) the effect of usual activity on EE during sleep, seated and miscellaneous activities. Fifty adolescents (four groups of eleven to fifteen boys or girls aged 16–19 years) participated in the study. Body composition was measured by the skinfold-thickness method, and VO2max and external mechanical power (EMP) by a direct method (respiratory gas exchanges) on a cycloergometer. Daily EE and partial EE in free-living conditions were computed from heart-rate (HR) recordings during seven consecutive days using individual prediction equations established from the data obtained during a 24 h period spent in whole-body calorimeters with similar activities. Fat-free mass (FFM), VO2max, EMP, daily EE and EE during sleep were significantly higher in athletic than in non-athletic subjects. After adjustment for FFM, VO2max, EMP, daily EE and EE during exercise were still higher in athletic than in non-athletic adolescents (P

OBJECTIVE: To address whether: (1) bioelectrical impedance analysis (BIA) can provide precise and accurate estimates of total body water (TBW) and extracellular water (ECW) in healthy elderly subjects, that display age-induced changes in body composition, (2) BIA models are improved by introducing variables related to geometrical body-shape and osmolarity. DESIGN: Cross-validation of available BIA models and models developed in the study. SUBJECTS: 58 healthy elderly subjects (31 women, 27 men, 66.8±4.7 y, mean±s.d.) MEASUREMENTS: BIA at 5, 50 and 100 kHz, 18O labelled water measurements of TBW, Br measurements of ECW, anthropometric variables, plasma osmolarity. RESULTS: Published BIA models for estimating TBW, entail various degrees of bias. Precise models (SEE of the models 0.8 L at 100 kHz, 1.0 L at 50 kHz) involving height2/resistance, weight, gender, circumferences and plasma osmolarity were established with data from 30 subjects chosen at random. Cross-validation of an independent group (n=28) showed no bias (−1.5±3.2 L at 100 kHz, −1.4±3.2 L at 50 kHz, P=NS). CONCLUSION: We conclude that BIA models with increased accuracy and precision for predicting ECW and TBW can be derived in healthy elderly subjects. Repeated measures had a mean difference of 0.2±1.2 L.

Pickering, Gisèle P., Nicole Fellmann, Béatrice Morio, Patrick Ritz, Aimé Amonchot, Michel Vermorel, and Jean Coudert. Effects of endurance training on the cardiovascular system and water compartments in elderly subjects. J. Appl. Physiol. 83(4): 1300–1306, 1997.—The effects of endurance training on the water compartments and the cardiovascular system were determined in 10 elderly subjects [age 62 ± 2 yr, pretraining maximal oxygen consumption (V˙o 2 max)/kg = 25 ± 2 ml ⋅ min−1 ⋅ kg−1body wt]. They trained on a cycloergometer 3 times/wk for 16 wk (50–80%V˙o 2 max, then 80–85%V˙o 2 max). They were checked at 8 wk, 16 wk, and 4 mo after detraining. Training improvedV˙o 2 max (+16%) and induced plasma volume expansion (+11%). No change in total body water, extracellular fluid, interstitial and intracellular fluid volumes, fat-free mass, and body weight was detected in this small sample with training. Body fat mass decreased (−2.1 ± 2.2 kg). Echocardiography at rest showed increased fractional shortening and ejection fraction and decreased left ventricular end-systolic dimension ( P < 0.05). Blood volume expansion correlates with cardiac contractility and has an impact on cardiac function. These improvements are precarious, however, and are completely lost after 4 mo of detraining, when elderly subjects lose the constraints and the social stimulation of the imposed protocol.

The aim of the study was to determine if a decrease in serum insulin-like growth factor I (Igf-I) levels under marginal malnutrition is responsible for the lower physical performance of girls of a low socio-economic status (LSES). Girls were selected after physical examination (Tanner's stage 1) and anthropometric measurements (height, body mass or mb, body mass index or BMI = mb height2). Lean body mass mb,1 was measured after skinfold thickness determination; serum IGE-I, by radioimmunoassay; maximal O2 consumption, (VO2max), directly during incremental exercise up to exhaustion; and maximal aerobic power (Wmax), using the force-velocity test. LSES girls (n = 31) had been malnourished in the past and, currently, were suffering from marginal malnutrition: they were smaller (135.2 +/- 5.5 vs 146.1 +/- 4.3 cm), lighter (31.7 +/- 3.9 vs 37.6 +/- 5.0 kg), exhibited a lower mb,1 (24.2 +/- 2.5 vs 27.5 +/- 3.0 kg) but same BMI compared with HSES (high socio-economic status) girls (n = 32). Igf-I levels (27.7 +/- 7.9 vs 34.1 +/- 6.5 nmol.1(-1), VO2max (45.26 +/- 4.72 vs 50.74 +/- 6.02 ml. min-1.kg-1 LBM) and Wmax (6.00 +/- 1.15 vs 8.70 +/- 1.53 W.kg-1 mb,1 were lower in LSES girls. Moreover, the differences in every parameter were not the consequence of the younger age (10.8 +/- 0.9 vs 11.2 +/- 0.6 years) of the LSES girls. Our results provide evidence that the lower Wmax of undernourished prepubertal girls was partly the consequence of alterations in muscle function at the qualitative level, as a result of a decrease in Igf-I levels. Conversely, under normal nutritional conditions, anthropometric characteristics only are explicatory factors for physical performances.

We have previously observed that 11-year-old children of low socio-economic status (LSES) showed a delayed physical growth of approximately 2 years and developed lower normalized short-term power output than children of high socio-economic status (HSES) of the same age. In contrast, maximal oxygen uptake\((\dot VO_{2max} )\) per unit of fat free mass was no different in either group. The aim of this study was to evaluate the effect of anthropometric characteristics between HSES and LSES prepubertal children in aerobic and anaerobic performance. To compare children of the same body dimensions, 11-year-old boys (n = 30) and girls (n = 31) of LSES and 9-year-old boys (n = 21) and girls (n = 27) of HSES were studied. Anthropometric measurements,\(\dot VO_{2max} \) (direct test), maximal anaerobic power (Pmax, force-velocity test) and mean anaerobic power (\(\bar P\), Wingate test) were determined. In these children having the same body dimensions: mean\(\dot VO_{2max} \) were the same in LSES and HSES children [1.2 (SD 0.2)1-min−1];Pmax and\(\bar P\) were lower in LSES subjects [154.0 (SD 33.2) vs 174.6 (SD 38.4) W and 116.3 (SD 23.3) vs 128.2 (SD 28.0) W, respectively]; the linear relationships between\(\dot VO_{2max} \) and fat free mass were the same in LSES and HSES boys but, in the girls, the LSES group had lower values. For anaerobic performance, the relationships were significantly different: the slopes were the same but LSES values for the both sexes were lower. These results would suggest that factors other than differences in body dimensions alone were responsible for the lower performance of LSES girls and boys. Cultural factors and motor learning, structural and functional alterations of muscle induced by marginal malnutrition have been discussed.

The aim of the study was to investigate the inter-relationships between pituitary-adrenal hormones and catecholamines during a prolonged competition over 6 days. Plasma adrenocorticotropic hormone (ACTH), cortisol (C), beta-endorphin (beta EP), free and sulphated adrenaline (A) and noradrenaline (NA) were measured in 11 volunteer male subjects during a national Nordic-ski race (323 km). Blood samples were obtained before the competition in the evening as control (D0), and before and after each day's racing (D1-D6). The mean daily heart rate (fc) was calculated from fc values recorded every minute during the race. The results showed the following: changes in mean fc [from 147 (SEM 3) to 156 (SEM 3) beats.min-1 according to the day] were not significant during the race. Diurnal variations in ACTH, beta EP and C were no longer apparent after the race: evening levels were higher than their respective D0 values during the race, except on D3 when there was a lack of response to exercise in the three hormones. Unlike ACTH and beta EP, pre- and postexercise C values on D1 and D2 were higher than those on the subsequent days (P less than 0.001). In contrast, there was a progressive accumulation of A and NA in pre- and postrace concentrations which reached a plateau in about 4 days. Positive correlations between exercise responses in ACTH, C and beta EP were found especially on D3 and D6 (P less than 0.001) but there were no significant correlations between catecholamines and the other three hormones. Thus, prolonged competition over 6 days evoked different control mechanisms for hormones of the pituitary-adrenal axis and catecholamines.(ABSTRACT TRUNCATED AT 250 WORDS)