Activité physique et remodelage osseux : étude chez une population de jeunes gymnastesPhysical exercise and bone turnover: a study in young girl gymnasts

Aims – Intensive exercise is known to improve the bone mass acquisition. One of the main explanations consists in the mechanical strains exerted on the skeleton. Little is known about the effects of physical exercise on the bone remodelling process.Methods and results – The bone remodelling rate evaluated in a group of young female (24 gymnasts and 21 controls), using a bone resorption marker, the CrossLaps peptides CTx. We measured in our subjects the bone mineral density at the whole body and at six regional sites. The bone density was statistically higher in the gymnasts compared to the controls at all the specific sites. The CTx level corrected by urinary creatinine was significantly higher in the gymnasts, reflecting a faster bone remodelling rate.Conclusion – Intensive physical activity could improve the bone mineral acquisition probably by a stimulation of the bone remodelling activity.     

Alimentation calcique et effet de l'entraînement physique sur l'os

Physical exercise is able to influence bone structure. In the principal part of cases, physical training results in an enhanced bone density when in any case overtraining could decrease bone density. Numerous factors are involved in the effect of physical training on bone, dietary calcium supply being one. Numerous epidemiological surveys have shown that the daily calcium supply in the French population is between 500 and 1,200 mg/24 hours. Thus part of the French population is under the recommended intake of 1,000 mg. It was proposed that physical training could improve calorie intake and consequently calcium supply. The main objective of this paper is the relationship between exercise and bone structure: second, literature is used to present the role of dietary calcium on bone structure. Finally, the data of a survey in a French population are used in order to define to what extent calcium dietary supply of different sports groups agree with the dietary recommended allowance. They report that calcium supply is influenced by the type of sport, strength trained atheletes enhance calcium intake while endurance trained atheletes present lower calcium intake.     

Cortisol, testostérone et rapport testostérone/cortisol au cours d''un trimestre scolaire chez des lutteurs de haut niveau comparés à des étudiants non sportifs

This study presents the saliva cortisol and testosterone levels in young high level wrestlers compared to those of students not involved in sporting activities. Measures were realised during the first school term (September to mid-December) at 3-week intervals. Hormonal levels revealed a higher degree of tiredness in sportsmen than in non-sportsmen. It also appeared that a 2-week resting period (All-Saint's Day at the end of October) permitted return to hormonal reference values at the beginning of the school year.     

Exercice physique, carence estrogénique, monoxyde d'azote et remodelage osseux

Summary

Objectives

The aim of this paper is to emphasize the possible relationships established between estrogens and physical exercise and concerning bone metabolism. Nitric oxide (NO) might play an important role in such relationships.

Topics

Cellular metabolism of NO, as well as NO effects upon osteoblasts and osteoclasts have been summarized. Several studies indicate that NO deficiency might be implicated in various vascular diseases observed in post-menopausal women. Other works also indicate that NO deficiency induced by cessation of ovarian activity might be responsible for osteopenia associated with this condition. Thus, decreased production of NO would be responsible both for post-menopausal osteoporosis as well as for osteopenia sometimes observed in amenorrheic athletes. Moreover osteoblastic response to mechanical stimulation might implicate estrogenic receptor(s). The role of these receptors in the regulation of NO synthesis is still unknown.     

Modification de la lipolyse du tissu adipeux après un entraînement en endurance chez des sujets obèses

This study investigates the effect of a 3 month endurance training on in vitro adipose tissue lipolysis in 13 obese men (body mass index: 36.9 ± 1.3 kg/m²). Training decreased body fat mass percentage (P < 0.05), without body weight change. Lipolytic effects of epinephrine, isoproterenol (β-adrenoceptor agonist) and dobutamine (β₁-adrenoceptor agonist) were significantly increased (P< 0.05). Antilipolytic effects of α₂-adrenoceptor and insulin were significantly decreased (P < 0.05). Endurance training in obese men enhances adipose tissue lipolysis through β-adrenergic pathway, and decreases antilipolytic activity.     

Fracture de fatigue de l'humérus. À propos de trois cas

Three cases of stress fractures of the humeral shaft are reported. The first, a complete spiroid fracture, was observed after a rope climbing exercise following an intensive training period. The two others, radiologically not so spectacular, occurred during the first weeks of this training. The three fractures represent the three different clinical stages. Intensive training and repetitive stress won over an otherwise wonderfully adapted bone structure. Treatment remains orthopaedic, even in the case of the spiroid fracture, with a perfect functional result.     

Blessures musculotendineuses à répétition survenant sur un terrain métabolique perturbé : à propos d'une observation de maladie de Gilbert chez un sprinter de niveau national

Gilbert's disease is a constitutional disorder of bilirubin glycosilation in the liver. Physical exercise increases free bilirubin in blood, and the disturbance of the liver's metabolic activity could be the origin of muscular and tendon injuries. The diagnosis of Gilbert's disease is made through biological tests, which are necessary as prevention can obviate critical situations. Other metabolic constitutional disorders could be responsible for similar situations, therefore in cases of frequent muscular and tendon injuries, accurate biological investigations must be made.     

Taux sériques du propeptide aminoterminal du procollagène III chez des sportifs soumis à un entraînement régulier

Serum Procollagen III N-terminal Propeptide (PIIINP), a marker of bone matrix turnover, was measured in 36 sportsmen undergoing intensive training, including 23 adolescent gymnasts. All values are within the range of control values for age, suggesting that PIIINP is not modified by intensive training.     

Fécondité féminine et activité physique intense et répétéeFemale fertility and intensive physical activity

Aims – To estimate the effects of intensive physical activity on female fertility.Current knowledge – Since twenty to thirty years ago, women have regularly participated in intense physical sports. The first Olympic Marathon for women took place at Los Angeles (United-States) in 1984 and many clinical studies concerning the incidence of menstrual disturbances among sportswomen, were concomitant of the dramatic increase in female participation in endurance sports, either as recreational or professional sportswomen. Most of these studies were focused on secondary amenorrhea. Later, etiological studies have shown that a range of disturbances, from an apparently normal menstrual cycle, irregular menstruation, oligomenorrhea to the complete blockage of the ovarian function were observed.Points of views and plans – It is very likely that the physiological process leading to menstrual troubles among sportswomen include disturbances of GnRH pulsatility at hypothalamic level. It has been shown that a session of training at an intensity greater than 60% during at least 40 min leads to the secretion of neuromediators able to interfere with GnRH pulsatility. Repetitiveness of daily sessions of training (i.e., more than five sessions a week) associated with marginal energy intake or strictly vegetarian food may contribute to disturb the hypothalamo-pituitary-ovarian axis in female athletes.     

Comparaison de l'oxydation de glucose, d'un mélange de glucose et de fructose, et de saccharose ingérés en bolus ou en doses fractionnées au cours de l'exercice

The purpose of this study was to compare the oxidation rates ofisocaloric amounts of glucose (G), of a mixture of glucose and fructose (G+F), and of sucrose (S) ingested during prolonged exercise (120 min, 58 % V0₂max). The mode of ingestion, that is in a bolus at the onset of exercise or in fractionated doses during the exercise, was also investigated. Six young male subjects ingested a placebo (P), 100 g of G, 50 g of G + 50 g of F, or 95 g of S (13 % concentration) in fractionated doses during exercise, and 100 g of G and 50 g of G + 50 g of F in a bolus at the beginning of exercise. Blood samples were taken before and during the last minute of exercise period. Ingestion of carbohydrates (CHO) does not influence the blood glucose and insulin levels, but decreases by 50% the response of plasma free fatty acid concentration. During the 120-min exercise period, the amounts of ingested carbohydrates which were oxidized were similar for G (53 ± 5 g), G+F (57 ± 6 g) and S (50 ± 7 g). Exogenous CHO oxidation contributed to increasing the total CHO utilization (from 181 to 200 g/120 min) and to reducing fat oxidation (from 86 to 72 g/120 min). Ingestion of CHO as a bolus at the beginning of exercise does not influence G oxidation (58 ± 6 g) but significantly increased the oxidation of the mixture G+F (67 ± 6), probably by favoring fructose utilization which requires a delay. From a practical viewpoint, these results show that the oxidation of S, which is the most widely available oligosaccharide, is similar to that of G or a mixture of G+F. Moreover, in order to maximize exogenous CHO oxidation during exercise, CHO should be ingested early in the exercise period, and not in fractionated doses throughout the exercise period.     

Influence d’une compétition de rugby sur le taux de cortisol salivaireInfluence of an international rugby mah upon the concentration of salivary cortisol

Introduction – Measure the influence of a sporting event (in this case an international rugby match) upon the concentration of salivary cortisol.Synthesis of facts – In order to take our study to a successful conclusion, we took salivary samples from the players during the event as well as at the time of a rest day. These concentrations are measured thanks to a radio immunoassay technique. The sporting event  has resulted in a 75% cortisol level rise. This increase reflects both a physiological and a psychological response to a stressful stimulation. The value of the cortisol before the event is also higher (85%) than the one measured at the same time of day during the rest day.Conclusion – This result shows that the sporting event has a positive correlation with the level of the salivary cortisol that it is to say a cognitive anticipation of the subjects.     

Aptitude physique des porteurs du trait drépanocytaire

In order to obtain informations about the exercise capacity, the functional tolerance and the cardiorespiratory response to exercise of sickle cell trait subjects (HbAS) compared to those of normal subjects (HbAA), two groups of six male adults formed into pairs HbAS-HbAA have performed a triangular Exercise Test (corresponding to a gradually maximal exercise of average duration) and a Square-Wave Endurance Exercise Test (SWEET 45 corresponding to a severe exercise of long duration) after an interval of 24 h. The exercise capacity of HbAS was equal to that of normal subjects and their functional tolerance of performed exercises was good. The cardiorespiratory response of the two groups was identical for the gradually maximal exercise of average duration. But it was different for the severe exercise of long duration. During this type of exercise, the ventilation (V˙E l. min⁻¹) and heart rate (HR b. min⁻¹) of HbAS subjects were more important than those of normal subjects whereas their oxygen uptake (V˙O₂ ml. kg⁻¹. min⁻¹) was weaker. These results suggest that the physical fitness of HbAS is normal in regard to V˙O₂ max but it is limited in regard to endurance because of a decrease of their oxygen transport related to their hemoglobinopathy.     

Effets du repas précompétitif sur la perception de l'effort et sur la glycémie lors d'un exercice de pédalage

The first purpose of the present study was to investigate the effect of three different preexercise meals on perceived exertion and glycaemia during a one-hour bicycle exercise at 80% VO₂ max. The second purpose of this study was to determine the relationship between glycaemia and perceived exertion. Eight athletes (age: 24.6 ± 2.7 years, weight: 78.0 ±6.8 kg, height: 182.6 ± 9.9 cm) completed three assessment sessions, each being preceeded by one of the following meals, ingested 3 h before exercise: 400 mL of water, 400 mL of water and 75 g of glucose, and 100 mL of water and 375 g of potatoes. The subjects 'perceived exertion were measured at times 6, 15, 30, 45, 60 min and glycaemia at 0, 30, 60 min of the exercise. The results showed that perceived exertion (RPE and ETL) of each meal increased as a function of time (P <- 0.05) whereas glycaemia did not differ except for the glucose meal between 30 min and 1 h(P < 0.02). There was no significant difference in ratings of perceived exertion among any meal whereas glycaemia was different between the three conditions only at the beginning and the middle of the exercises (P < 0.04 and P < 0.02, respectively). Moreover, the vectorial angles between the variables ofperceived exertion and the glycaemia are close to 90 °. These results would suggest that perceived exertion does not seem to be affected by the three preexercise meals used in our study. Perceived exertion is not correlated to glycaemia changes during one-hour high intensity exercise. The results would, therefore, suggest that glycaemia is not a contributor signal of perceived exertion in this study. It seems that physiological factors other than glycaemia may have mediated the perceptual intensity at exhaustion. The respiratory-metabolic signals of exertion which are most pronounced at high relative exercise intensity are suggested to influence the perceptual signal of exertion.     

Flight crew physical fitness: a baseline analysis

INTRODUCTION: The purpose of this pilot study was to determine whether flight crew personnel are physically fit in comparison to published standards for the average American adult. SETTING: The study group consisted of pilots, paramedics and nurses in two similarly configured and geographically located rotor-wing air medical transport programs. METHODS: A physical fitness assessment of flight crew members was conducted. The results were compared with published standards for average adult males and females (AVG). Percentage of fat in body composition (FM%), aerobic fitness (VO2MAX), muscular endurance (ME), muscular strength (MS) and flexibility (FL) measurements were obtained using accepted testing methods. RESULTS: The study population consisted of 29 male and 21 female individuals. The following were their mean scores. Males averaged: pFAT = 19% (AVG = 20.0%); VO2MAX = 41.0 (AVG = 42.5); ME = 37.0 (AVG = 28.5); MS = 125.0 (AVG = 86.5); FL = 5.2 (AVG = 1.4); Females averaged: pFAT = 28.0% (AVG = 26.5%); VO2MAX (AVG = 34.0); ME = 27.0 (AVG = 21.0); MS = 83.0 (AVG = 76.5); FL = 4.5 (AVG = 3.4). CONCLUSION: These baseline data suggest the study population of air medical flight crew was physically fit compared to the average American adult.