[Pulmonary rehabilitation in chronic obstructive pulmonary disease]. / La réhabilitation pulmonaire dans la bronchopneumopathie chronique obstructive.

The current treatment of chronic obstructive pulmonary disease (COPD) patients must comprise, in addition to an optimal pharmacological treatment, a pulmonary rehabilitation, if possible multidisciplinary, and a program of post-rehabilitation in order to maintain the outcomes. Today pulmonary rehabilitation has proved to be effective in improving dyspnoea, exercise capacity and quality of life in COPD patients, and reducing the use of health services and thus the cost. In this article we want to present pulmonary rehabilitation, its indications and results, and the way by which it is held in the CHU of Liege.

[Exercise training in COPD]. / Le réentraînement à l'effort du patient BPCO.

Rehabilitation for patients with chronic obstructive pulmonary disease (COPD) is well established and widely accepted as a means of enhancing standard therapy in order to alleviate symptoms and optimize function. The primary goal of rehabilitation is to restore the patient to the highest possible level of independent function. There is, however, no consensus on the optimal training modalities. Both walking and cycling improve exercise performance; there is substantial evidence that lower extremity exercise training should be included in rehabilitation programs for patients with COPD.

[Doping in sports]. / Le dopage et le sport.

Doping consists in the use of artificial means or substances with the unique aim of improving performance despite adverse effects on health. Amphetamines stimulate the central nervous system by increasing motivation and vigilance. Often consumed in association with analgesics, they increase the fatigue threshold during prolonged or repeated exercise. Addiction and dependency to these substances are extremely rapid. Side-effects include insomnia, exhaustion, violence and can lead to serious heart diseases. By enhancing capacity for intensive training, anabolic steroids improve strength, alertness and speed. This action is often further strengthened by the use of growth hormones DHEA and IGF-1. Extremely high dosage is used and is in no way comparable with natural secretions or those necessary to re-balance an exhausted glandular system. During prolonged endurance exercise, doping aims at improving the circulation of oxygen in the blood and thus its availability to the muscles. Firstly, the blood haemoglobin concentration was increased by blood transfusions. At present the production of red blood cells is stimulated by repeated injections of exogenous erythropoietin. The extreme viscosity of the blood leads to a risk of vascular thromboses and high blood pressure and accentuates greatly and sometimes even fatally the possibility of brachycardia which is common with sportsmen.

Immunological status of competitive football players during the training season.

We investigated possible immunological changes in 15 professional football players before, during and after the sports season. We studied the leucocyte count as well as different functions such as T-lymphocyte proliferation, NK activity, chemotaxis and phagocytosis of neutrophils. Training and competitions did not produce any change in the total number of leucocytes but increased neutrophil counts and decreased T4 lymphocyte counts. We also observed a slight decrease of T-lymphocyte proliferation and a significant decrease of neutrophil functions. On the other hand, training and competitions did not induce significant changes in the number of NK cells nor in the total NK cytotoxic activity. The different change observed tended to normalize after the sports season. Our results suggest a predominant neutrophil function depression in football players during a training season which could partly explain the susceptibility of elite athletes to infections.

Changes in breath 13CO2/12CO2 during exercise of different intensities.

The measurement of breath 13CO2/12CO2 is commonly used during exercise to evaluate the oxidation rate of exogenous carbohydrates enriched in 13C. The aim of this study was to investigate whether exercise itself affects the 13C/12C ratio in expired air CO2 in relation to exercise intensity. The relative abundance of 13C and 12C in expired air CO2 was determined by isotoperatio mass spectrometry and expressed as delta 13C (in %o) by using Craig's formula and calibrated standards. Five healthy young men exercised on a treadmill after an overnight fast during > or = 105 min on four occasions and in a randomized order. Work rates were performed at approximately 30, 45, 60, and 75% of their maximal O2 uptake (VO2max). Delta 13C in expired air CO2 and respiratory exchange ratio (RER) were determined every 15 or 30 min during exercise. At 30 and 45% VO2max, a slight and not statistically significant increase in delta 13C was observed at 30 min. In contrast, at 60 75% VO2max, the rise was statistically significant and averaged 0.83 and 0.99%o, respectively. Average delta 13C (between 0 and 105 min) progressively increased with the intensity of exercise. Individual values of delta 13C and RER were positively correlated (r = 0.653, P = 0.002) as were values of delta 13C and endogenous carbohydrates utilized (r = 0.752, P < 0.001). Factitious or "pseudooxidation" of a 13C-enriched exogenous glucose load (indeed noningested) was calculated from the changes in expired air delta 13C. Over the whole period of exercise it was not statistically significant at 30 and 40% VO2max. However, over the first 60 min of exercise, such pseudooxidation of exogenous glucose was significant at 30 and 45% VO2max. In conclusion, by modifying the mix of endogenous substrates oxidized, exercise at 60% VO2max and above significantly increases the 13C/12C ratio in expired air CO2. At these intensities, this could lead to overestimation of the oxidation of 13C-labeled substrates given orally. At lower intensities of exercise, such overestimation is much smaller an affects mainly the values recorded during the initial part of the exercise bout.

Blood mononuclear cells mobilization and cytokines secretion during prolonged exercises.

This study was designed to compare the effects of three prolonged exercises varying in their intensity and duration, on blood mononuclear cell mobilization and cytokine secretion (IL1(1)-IL(2)). Seven healthy subjects underwent three effort trials (45 % VO(2)max during 4 h - 60% VO(2)max during 3 h - 75 % VO(2)max during 2 h) at one-month intervals. Blood samples were drawn before, different times during exercise and also after exercise. Prolonged exercises induced a transient increase in blood mononuclear cells which occurred across all intensity levels. We also observed a significant increase in plasma IL(1) level during exercise which correlates with the exercise intensity. The mean IL(1) level increased up to 2.5 times after the three proposed exercises (p <0.05). Plasma IL(2) level decreased at the end of prolonged exercises irrespective of the exercise intensity. No correlation was observed between blood mononuclear count and cytokine determination. Our data suggest that blood mononuclear cells mobilization is associated but not correlated with alterations of cytokine levels.

Exogenous glucose oxidation during exercise in relation to the power output.

In order to study the influence of the power output on the oxidation rate of exogenous glucose and on the contribution of the various substrates to the energy demand, we combined the use of artificially enriched 13C-glucose with classical indirect calorimetry during uphill treadmill exercise. Six young male healthy subjects underwent three exercise bouts, in a randomized order and at least two weeks apart, at a low (45% VO2max, 1822 +/- 194 ml O2/min for 4 hours), moderate (60% VO2max, 2582 +/- 226 ml O2/min for 3 hours), and high intensity (75% VO2max, 3036 +/- 287 ml O2/min for 2 hours). After 10 min of exercise, each subject ingested 100 g of artificially 13C-labelled glucose dissolved in 400 ml of water. Over the four hours of the exercise at 45% VO2max, the amount of exogenous glucose oxidized was 89.5 +/- 5.9 g from the 100 g ingested. In all exercise bouts, the oxidation of exogenous glucose already began during the first 30 min after ingestion and peaked at 120 min. The maximum oxidation rates averaged 0.64 +/- 0.07, 0.75 +/- 0.04, and 0.63 +/- 0.08 g/min, and the mean amounts of exogenous glucose oxidized over the first two hours averaged 51.7 +/- 8.0, 61.5 +/- 6.6 and 50.9 +/- 8.45 g, at 45, 60 and 75% VO2max respectively. The contribution of the oxidation of exogenous glucose to the total energy supply progressively decreased when the power output increased, from 19.6 to 12.2%. In the meantime, the contribution of total carbohydrates (exogenous+endogenous) progressively increased from 55.1 to 77.8% while the contribution of lipids decreased from 35.5 to 16.6%. In conclusion, exogenous glucose ingested during exercise is largely oxidized and strongly contributes to the energy supply. The oxidation rate first increases with the power output, but levels off or even decreases at high intensity exercise.

Effect of prolonged exercise on neutrophil myeloperoxidase secretion.

This study was designed to compare the effects of three prolonged exercises on plasma myeloperoxidase concentrations, used as marker of neutrophil degranulation. Seven healthy subjects underwent three effort trials (45% VO2max during 4 h, 60% VO2max during 3 h, 75% VO2max during 2 h) at one-month intervals. Blood samples were collected before, during and after exercise. Myeloperoxidase levels were measured by radioimmunoassay. We observed a significant increase in myeloperoxidase concentration (+85%) at the end of our three prolonged exercises (p < 0.05). This myeloperoxidase increase was not correlated with the modification of neutrophil count, suggesting that neutrophil degranulation is independent of their mobilisation.

Availability of glucose ingested during muscle exercise performed under acipimox-induced lipolysis blockade.

This study investigated the percentage of carbohydrate utilization than can be accounted for by glucose ingested during exercise performed after the ingestion of the potent lipolysis inhibitor Acipimox. Six healthy male volunteers exercised for 3 h on a treadmill at about 45% of their maximal oxygen uptake, 75 min after having ingested 250 mg of Acipimox. After 15-min adaptation to exercise, they ingested either glucose dissolved in water, 50 g at time 0 min and 25 g at time 60 and 120 min (glucose, G) or sweetened water (control, C). Naturally labelled [13C]glucose was used to follow the conversion of the ingested glucose to expired-air CO2. Acipimox inhibited lipolysis in a similar manner in both experimental conditions. This was reflected by an almost complete suppression of the exercise-induced increase in plasma free fatty acid and glycerol and by an almost constant rate of lipid oxidation. Total carbohydrate oxidation evaluated by indirect calorimetry, was similar in both experimental conditions [C, 182, (SEM 21); G, 194 (SEM 16) g.3 h-1], as was lipid oxidation [C, 57 (SEM 6); G, 61 (SEM 3) g.3 h-1]. Exogenous glucose oxidation during exercise G, calculated by the changes in 13C:12C ratio of expired air CO2, averaged 66 (SEM 5) g.3 h-1 (19% of the total energy requirement). Consequently, endogenous carbohydrate utilization was significantly smaller after glucose than after placebo ingestion: 128 (SEM 18) versus 182 (SEM 21) g.3 h-1, respectively (P < 0.05). Symptoms of intense fatigue and leg cramps observed with intake of sweet placebo were absent with glucose ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Fructose utilization during exercise in men: rapid conversion of ingested fructose to circulating glucose.

The aim of the present study was to compare the metabolic fate of repeated doses of fructose or glucose ingested every 30 min during long-duration moderate-intensity exercise in men. Healthy volunteers exercised for 3 h on a treadmill at 45% of their maximal oxygen consumption rate. "Naturally labeled" [13C]glucose or [13C]fructose was given orally at 25-g doses every 30 min (total feeding: 150 g; n = 6 in each group). Substrate utilization was evaluated by indirect calorimetry, and exogenous sugar oxidation was measured by isotope ratio mass spectrometry on expired CO2. Results were corrected for baseline drift in 13C/12C ratio in expired air due to exercise alone. Fructose conversion to plasma glucose was measured combining gas chromatography and isotope ratio mass spectrometry. Most of the ingested glucose was oxidized: 81 +/- 4 vs. 57 +/- 2 g/3 h for fructose (2P < 0.005). Exogenous glucose covered 20.8 +/- 1.4% of the total energy need (+/- 6.7 MJ) compared with 14.0 +/- 0.6% for fructose (2P < 0.005). The contribution of total carbohydrates was significantly higher and that of lipids significantly lower with glucose than with fructose. The blood glucose response was similar in both protocols. From 90 to 180 min, 55-60% of circulating glucose was derived from ingested fructose. In conclusion, when ingested repeatedly during moderate-intensity prolonged exercise, fructose is metabolically less available than glucose, despite a high rate of conversion to circulating glucose.

Endogenous substrate oxidation during exercise and variations in breath 13CO2/12CO2.

This study attempted to induce a major shift in the utilization of endogenous substrates during exercise in men by the use of a potent inhibitor of adipose tissue lipolysis, Acipimox, and to see to what extent this affects the 13C/12C ratio in expired air CO2. Six healthy volunteers exercised for 3 h on a treadmill at approximately 45% of their maximum O2 uptake, 75 min after having ingested either a placebo or 250 mg Acipimox. The rise in plasma free fatty acids and glycerol was almost totally prevented by Acipimox, and no significant rise in the utilization of lipids, evaluated by indirect calorimetry, was observed. Total carbohydrate oxidation averaged 128 +/- 17 (placebo) and 182 +/- 21 g/3 h (Acipimox). Conversely, total lipid oxidation was 84 +/- 5 (placebo) and 57 +/- 6 g/3 h (Acipimox; P < 0.01). Under placebo, changes in expired air CO2 delta 13C were minimal, with only a 0.49/1000 significant rise at 30 min. In contrast, under Acipimox, the rise in expired air CO2 delta 13C averaged 1/1000 and was significant throughout the 3-h exercise bout; in these conditions calculation of a "pseudooxidation" of an exogenous sugar naturally or artificially enriched in 13C, but not ingested, would have given an erroneous value of 19.8 +/- 2.6 g/3 h. Thus under conditions of extreme changes in endogenous substrate utilization, an appropriate control experiment is mandatory when studying exogenous substrate oxidation by 13C-labeled substrates and isotope-ratio mass spectrometry measurements on expired air CO2.

[Plasma histamine and exercise-induced bronchospasm]. / Histamine plasmatique et bronchospasme d'effort.

The pathogenesis of bronchospasm of effort is not yet elucidated and it is probable that is determined by multiple factors. In this study we have tested the role of mastocytes in taking as an index of their activation the fluctuation of plasma histamine levels during repeated exercise tests. We will show that asthmatic subjects who develop bronchospasm on effort have a significant rise (times 3) in their level of serum histamine whilst normal subjects don't show much change. Furthermore in a repeated effort test we have observed a strict parallelism between the occurrence of bronchospasm of effort and a rise in plasma histamine levels. These different observations enable us to consider that the activation of mastocytes and the liberation of mediators which follow play an important role in the pathogenesis of bronchospasm of effort.

Effect of osmolality on availability of glucose ingested during prolonged exercise in humans.

The aim of this study was to investigate whether the osmolality of a glucose solution, ingested at the beginning of a prolonged exercise bout, affects exogenous glucose disposal. We investigated the hormonal and metabolic response to a 50-g glucose load dissolved in either 200 (protocol A), 400 (protocol B), or 600 (protocol C) ml of water and given orally 15 min after adaptation to exercise in five healthy male volunteers. Naturally labeled [13C]glucose was used to follow the conversion of the ingested glucose to expired-air CO2. Total carbohydrate oxidation (indirect calorimetry) was similar in the three protocols (A, 237 +/- 20; B, 258 +/- 17; C, 276 +/- 20 g/4 h), as was lipid oxidation (A, 128 +/- 4; B, 132 +/- 15; C, 124 +/- 12 g/4 h). Exogenous glucose oxidation rates were similar under the three experimental conditions, and the total amount of exogenous glucose utilized was slightly, but not significantly, increased with the more diluted solution (A, 42.6 +/- 4.4; B, 43.4 +/- 4.1; C, 48.7 +/- 7.2 g/4 h). The blood glucose response was similar in the three protocols. Thus, within the range investigated, the osmolality of the glucose solution ingested had no significant influence either on its oxidation (which was 86-98% of the load ingested) or on the utilization of endogenous carbohydrate, lipid, or protein stores.

[Adaptation to sports by insulin-treated diabetics]. / Adaptations au sport du diabétique traité par insuline.

Performing muscular exercise regularly is generally recommended to diabetics; indeed, exercise increases muscle insulin sensitivity, helps fighting overweight and, at least partly, tends to correct plasma lipids abnormalities, thus contributing to limit the development of atherosclerosis. Moreover, the practice of sport is beneficial from a psychological point of view, because, thanks to it, diabetic patients can match, even surpass, "the others" and overcome what they often consider as a disability. However, diabetes--especially type 1, insulin dependent, diabetes--deeply modifies the metabolic adaptations to muscular exercise; consequently, exercise must be performed only in good metabolic control conditions, for avoiding a worsening of ketonaemia. In adequately controlled diabetics, muscular exercise can be beneficial by reducing blood glucose levels; it can also lead to hypoglycaemia occurring during or after the exercise bout. In order to reduce the risk of exercise-induced hypoglycaemia, diabetics have to know how to modify three essential parameters of their treatment: (1) increase carbohydrate intake before, during or after exercise; (2) reduce the dose of the insulin acting during exercise, and this in relation to the usual doses and to exercise intensity; (3) under some circumstances, modify the site of insulin injection according to the type of exercise performed. Taking into account these parameters, some general rules can be assessed, which are to be adapted to every particular situation; the use of home blood glucose monitoring before and after exercise is not only useful but sometimes mandatory.(ABSTRACT TRUNCATED AT 250 WORDS)

Tocopherol mobilization during intensive exercise.

This work shows that the level of plasma tocopherol (vitamin E) which has free radical scavenging properties rises significantly during intensive exercise. It is proposed that mobilization of tocopherol could help to prevent lipoperoxidation phenomena occurring in exercising skeletal muscle. A hypothetical mechanism relating to a lipolysis effect is discussed to explain this mobilization.

Bone mineral content and physical activity.

The purpose of this study was to estimate the effects of intense and regular physical activity on locomotor system modifications. Tennis, with its unilateral solicitations, allows a more precise examination of specific localized development. Ten professional tennis players were compared with sedentary age-matched students. Muscular modifications were observed, mainly in the forearm circumference. The dominant side forearm circumference was 13% larger than the opposite side. Asymmetry was less in the upper arm and insignificant in the thorax and vertebra. Deep modifications in bone mineral content (BMC) were investigated by isotopic techniques, based on differential photon attenuation in bone and soft tissue of the forearm. Bone density was markedly increased in professional tennis players. Even in the nondominant side, radius BMC was 1.18 g HA/cm, 15% higher than in sedentary control students. The difference was yet larger in the dominant mid-radius, reaching 1.47 g HA/cm. The same differences were observed for the ulna and involved both cortical and trabecular bone. In the control group of sedentary students, no significant difference was noted between the two upper limbs. This study clearly demonstrates the positive correlation between exercise and bone mineralization. The precise mechanical constraints optimizing the favorable effect in the most efficient way should be studied.