Nitric oxide response in exhaled air during an incremental exhaustive exercise.

This study examines the response of the exhaled nitric oxide (NO) concentration (CNO) and the exhaled NO output (VNO) during incremental exercise and during recovery in six sedentary women, seven sedentary men, and eight trained men. The protocol consisted of increasing the exercise intensity by 30 W every 3 min until exhaustion, followed by 5 min of recovery. Minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production, heart rate, CNO, and VNO were measured continuously. The CNO in exhaled air decreased significantly provided that the exercise intensity exceeded 65% of the peak VO2. It reached similar values, at exhaustion, in all three groups. The VNO increased proportionally with exercise intensity up to exhaustion and decreased rapidly during recovery. At exhaustion, the mean values were significantly higher for trained men than for sedentary men and sedentary women. During exercise, VNO correlates well with VO2, carbon dioxide production, VE, and heart rate. For the same submaximal intensity, and thus a given VO2 and probably a similar cardiac output, VNO appeared to be similar in all three groups, even if the VE was different. These results suggest that, during exercise, VNO is mainly related to the magnitude of aerobic metabolism and that this relationship is not affected by gender differences or by noticeable differences in the level of physical training.

Acute mountain sickness relates to sea-level partial pressure of oxygen.

The aim of this study was to clarify the relationships between acute mountain sickness (AMS), studied during an expedition in the Andes, and some physiological parameters determined before the expedition, i.e. biometrical characteristics of the subjects [maximal oxygen consumption (VO2max), body fat content, body mass index], functional pulmonary tests (forced vital capacity, forced expiratory volume at the first second), ventilatory or cardiac responses measured at 4,500 m [hypoxic ventilatory responses (HVR) 4,500 and hypoxic cardiac responses (HCR) 4,500, respectively), cold pressor responses. To achieve this objective, 11 subjects were firstly submitted to a hypobaric poïkilocapnic hypoxic test (589 hPa, 4,500 m) at rest and during exercise to study minute volume, respiratory frequency, end tidal partial pressure of O2 (PETO2) and CO2, HVR 4,500, HCR 4,500 and to a cold pressor test of the hand (5 min in 5 degrees C cold water) to study heart rate, blood pressure and skin temperature changes. The AMS was assessed daily by questionnaire during a 12-day expedition in the Andes following both Hackett's method and Environmental Symptoms Questionnaire (modified ESQ II). Maximal AMS-Hackett score, maximal AMS-ESQ score and mean AMS-ESQ score were defined. The quantifications of AMS following the two methods were correlated. No significant relationships were observed between mean AMS-ESQ score and the biometrical characteristics of the subjects, the functional pulmonary tests, HVR 4,500, HCR 4,500 or the cold pressor responses. However, it appeared that the mean AMS-ESQ score was correlated with PETO2 measured at rest and during exercise (50% VO2max) both in hypoxia and normoxia. A closer linear relationship was observed during the exercise in normoxia (r = -0.92, P < 0.0001). These results could suggest that AMS was related to a relative alveolar hypoventilation more in relation to breathing pattern than HVR.

[Changes in plasma lipoproteins in adolescents with trisomy 21 in response to a physical endurance test]. / Variations des lipoprotéines plasmatiques chez des adolescents trisomiques 21 en réponse à un test d'endurance physique.

In a previous study, the authors recorded a free fatty acids (FFA) concentration decrease in 11 Down's Syndrome (DS) subjects after an incremental maximal exercise until exhaustion. The aim of this study was to determine if lipid metabolism parameters in a group of DS subjects could be changed after an endurance training period prior to a sustained physical exercise test. After an "adapted" exercise programme, 6 healthy DS subjects, 4 boys and 2 girls aged from 16 to 22 years, performed a sustained exercise lasting 40 minutes on an cycle ergometer. They also compared their values with those taken from the data of laboratory for similarly aged normal subjects. The results of this trial indicate: (a) at rest: (i) a lipid metabolism that included normal level of triglycerides (Trig), but low level of total cholesterol (TC), (ii) a pathological pattern of lipoproteins: low level in high density lipoprotein (HDL), and high level in pré beta very low density lipoprotein (VLDL); (b) after an "adapted" exercise programme period concluding with a final test: (i) an approximate adjustment to normal lipid profiles: rise in HDL and fall in VLDL (ii) a rise of free fatty acids (FFA) between the start and the end of the test. It is noted that physical activity of an endurance type appears to have a favourable long term effect on some manifestations of this genetic disease and that, consequently, such endurance training may be promoted.

Discrimination between cross-country and downhill skiers by pulmonary and local 31PNMR evaluations.

The purpose of the present study was to correlate data on calf muscle metabolism using 31P nuclear magnetic resonance spectroscopy with measurements of whole body maximal oxygen consumption and maximal power output, and to determine whether the combination of these data could be used to predict athletic ability. Experiments were performed in a 2.35 Tesla, 35 cm diameter electromagnet on the leg muscle of sedentary human subjects (N = 6) and groups of athletes trained for endurance (cross-country skiers, N = 7) or strength performance (downhill skiers, N = 5). The exercise protocol consisted of successive plantar flexions performed at graded fractions of the maximal voluntary contraction (MVC). The results obtained from NMR investigation (changes in content of inorganic phosphate: Pi, phosphocreatine: PC and muscle ATP, and intracellular pH) were then compared with those of maximal O2 consumption (VO2max) and maximal power (MP). When the data on athletes were compared with those obtained on sedentary subjects, the curves illustrating the relationship between the imposed load and the Pi/PC ratio were significantly shifted toward high output power for a given Pi/PC value. It also appeared from this study that specific training in force development (downhill skiing) induced a slighter decrease in PC level than for endurance (cross-country skiers) despite improvement in physical performance. A slight but significant intracellular acidification was observed in the muscles of sedentary subjects and downhill skiers for contraction at, respectively, 50% and 80% of MVC, but not in the skeletal muscles of cross-country skiers.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle bioenergetics in skiers: studies using NMR spectroscopy.

Sedentary human subjects (n = 6) and two homogeneous groups of athletes, trained for down-hill skiing (n = 5) and cross-country skiing (n = 7), were subjected to cardiorespiratory testing and to evaluation of the bioenergetics of calf muscles by means of Phosphorus Nuclear Magnetic Resonance Spectroscopy. The exercise consisted of successive plantar flexions performed at graded fractions of the maximal voluntary contraction force. It appears from this study that the decrease in phosphocreatine level induced by exercise at 80% of maximal voluntary contraction, was smaller in the muscles of athletes who trained for cross-country skiing, than in the muscles of down-hill skiers and control subjects. Intracellular acidosis was virtually absent in cross-country athletes. The rate of restitution of phosphocreatine, after the exercise, was higher in both groups of skiers, compared to sedentary subjects. The maximal oxygen consumption and the maximal alactic power were higher in athletes than in sedentary subjects. NMR data and mechanical measurements are used in consideration with functional systemic indexes to characterize the capabilities of skiers.

Individuality of breathing patterns during hypoxia and exercise.

Breathing was recorded via a pulsed ultrasonic flowmeter in 11 healthy subjects, at rest and during steady-state exercise (at 50% of their maximal O2 consumption) at both sea level (200 m) and simulated altitude (4,500 m in a hypobaric chamber). The pattern of breathing was quantified breath by breath in terms of classical respiratory variables (tidal volume and inspiratory and expiratory times), and the shape of the entire airflow profile was quantified by harmonic analysis. Statistical tests were used to compare the within-individual with the between-individual variations. In comparing the sea level vs. altitude rest (16% increase in ventilation) and sea level vs. altitude exercise (40% increase in ventilation) airflow profiles, we found a significantly greater resemblance within the individual than between individuals. Comparisons of sea level rest and exercise (295% increase in ventilation) and altitude rest and exercise (375% increase in ventilation) revealed no similarity within individuals. Despite airflow profile changes between rest and exercise, it is still possible to attest to a diversity of flow profile between individuals during exercise. Hypoxia at rest or during exercise does not alter the phenomenon of the individuality of breathing patterns.

Biochemical changes and catecholamine responses in Down's syndrome adolescents in relation to incremental maximal exercise.

The aim of this study was to determine biological responses in Down's syndrome subjects for an incremental exercise lasting 10 min. After a training programme specially adapted for children and adolescents with mental handicaps, 11 healthy Down's syndrome subjects, seven boys and four girls aged from 15 to 20 years, performed a progressive exercise until exhaustion on an ergometric bicycle. The results were compared with those taken from the literature for similar aged normal subjects. The results in our series of Down's syndrome subjects showed: (a) no differences in haematologic parameters, except for a high concentration of uric acid at rest which did not increase after the test; (b) a lower blood lactate level than in maximal exercise for this age range; (c) a late mobilization of FFA; and (d) a slightly lower maximal value of catecholamines. These results may suggest a reduced sympathetic response to maximal exercise.

Physical aptitudes to exertion in children with Down's syndrome.

The individual with Down's syndrome is characterized by apathy towards physical exercise. Ten untrained subjects with Down's syndrome and a control group have been tested at rest and after exercise on a bicycle ergometer. In subjects with Down's syndrome, the authors have observed: (a) a lower orthostatic index at rest; (b) a lower indirect maximal oxygen consumption; (c) a shorter performance time and a lower maximal workload; (d) a higher urinary catecholamines excretion; (e) a blood pressure which did not rise regularly with the workload increment. It is concluded that, in subjects with Down's syndrome, the low level of physical fitness is not only explained by lack of motivation but also by physiological impairments.