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.     

Suivi de l’entraînement de nageurs de haut niveau par questionnaire de fatigue, dosages hormonaux et variabilité de la fréquence cardiaqueTraining follow up by questionnaire fatigue, hormones and heart rate variability measurements

Introduction. – A short questionnaire of fatigue, urinary cortisol/cortisone ratio and heart rate variability were measured in 14 elite swimmers during heavy, light and moderate training periods.Results. – The questionnaire was strongly related to the variations of training and performance (r > 0.70). Correlations were lower with the hormonal ratio and insignificant with the heart rate variability.Conclusion. – The questionnaire and the hormonal ratio were good markers of the variations of training and performance contrary to the heart rate variability.     

Étude comparative de l'analyse spectrale de la fréquence cardiaque au cours de l'exercice sur ergocycle et de l'entraînement en judoHeart rate comparative study by spectral analysis between two exercises: ergocycle vs judo randori

Aim – Heart rate comparative study by spectral analysis between a 6 minutes judo randori et a 4 minutes ergocycle exercise at .Materials and methods – By ten male judokas, both time series were analyzed by short term Fourier transform (time/frequency analysis). Each 512 RR time series drawn from ECG was subdivided by Hanning windowing in 13 samples of 128 values (32 RR periods step). For each sample, both exercise types, means of the ten spectrograms have been computed, yielding two mean spectrograms for each sample.Results – 1) Despite a near maximal heart rate (HR) level between the two exercise types, the spectral energy computed from judo randori was significantly more important than ergocycle spectral energy. This phenomenon yields a qualitative effect of the exercise type (judo or ergocycle) on HRV. 2) the normalized spectral powers of low frequency and high frequency bands respectively, were not significantly different between both exercise types.Conclusion – The autonomie nervous control on HR would depend rather on exercise load than on exercise type.     

Influence de l''hydratation sur la sécrétion d''hormone de croissance induite par l''exerciceHydration influence on exercise-induced growth hormone secretion

Aim – Study was then to investigate hydration influence on exercise-induced GHh secretion.Methods and results – Seven healthy men underwent a submaximal rectangular cycling exercise for 30 minutes to 150 watts during two sessions. A first one without any water intake and a second one with ingestion of spring water corresponding to the volume of water lost during the first session. Plasma volume decrease was significantly higher during the first session (p < 0.05). Total GH secretion was significantly lower during this session (p < 0.05).Conclusion – A moderate dehydration decreases exercise-induced GH response. Thus, hypovolemia may exert a negative feed back on GH secretion, during exercise.     

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.     

Les effets indésirables de la créatine exogène: de la fiction à la réalité

Summary

Objectives

For the last six years the consumption of exogenous creatine monohydrate has been extended more and more. Despite numerous publications on the ergogenic effects of this naturally occurring substance, there is almost no information on the deleterious effects of this supplement. The objectives of this review are to point out facts which are often in contradiction with allegations introduced by the media.

Topics

In athletes, exogenous creatine supplements amount to 20 g per day during five days followed by 1 to 10 g per day, every day, for weeks, months, and even years. Usually consumers do not report side-effects, with the exception of body weight increase. However, gastro-intestinal disturbances and muscle cramps have been reported occasionally. Liver and kidney dysfunction have also been hypothesized but real facts are missing for this. From a theoretical point of view, exogenous creatine supplementation suppresses its hepatic synthesis (maximum 2 g per day for vegetarians). Its destination is mainly (95–98%) skeletal muscle and all excess is excreted in urine (on average 60% of the supplement). Scientific publications on the undesirable effects of exogenous creatine are almost non-existent, but newspapers and the media do not hesitate to publish false information or wrong interpretations based on one individual case of an individual with nephropathy who, later on, consumed creatine monohydrate. In addition, we did not find any side-effects on renal function after short-term (five days), medium-term (nine weeks) or long-term (up to five years) creatine supplementation in small cohorts of athletes.

Future prospects

We have no intention to validate or not the supplementation of exogenous creatine by athletes, but apparently there are no real deleterious effects on the body of healthy consumers. Nevertheless, one has to be careful about individual reactions when excess food are taken up. We are convinced that regular biological check-ups are needed to avoid any abnormal reaction under creatine supplementation.     

Correction de l’hypoxémie d’exercice chez le BPCO : variabilité des réponses, enjeux et problèmes posés dans le cadre de la réhabilitation respiratoire

Aim

To define in chronic obstructive pulmonary disease patients (COPD) moderately hypoxemic in resting conditions, if controlled acute oxygen supplementation was always able to increase exercise tolerance when partial oxygen saturation SpO₂ was corrected.

Results

In hyperoxia, endurance time (T_LIM) was significantly and consistently increased in 14 COPD (+68%) and decreased in seven others (–36%). These two subgroups exhibited no difference in resting values or in their disease severity. COPD with a decreased T_LIM under hyperoxic conditions had an abnormal response to O₂: unchanged cardiac output and ventilation, increased breathing frequency.

Conclusion

This work shows that acute O₂ supplementation responses in COPD are not univocal, either on exercise tolerance or cardio-respiratory variables typically affected by hyperoxia.     

Le « syndrome des jambes lourdes » chez les athlètes surentraînés est-il le reflet de désordres hémorhéologiques ?Is the feeling of heavy legs in overtrained athletes related to impaired hemorheology?

Introduction. – The aim of this work is to evaluate if the feeling of heavy legs in athletes is correlated with overtraining syndrome-related hemorheological disturbances.Results. – The subjects who quoted the item: “I have the feeling of heavy legs” had higher plasma viscosity and higher red cell aggregation parameters. The overtraining score was correlated positively with plasma viscosity, and aggregability parameters. The feeling of heavy legs was correlated with plasma viscosity and aggregability.Conclusion. – These findings suggest that the feeling of heavy legs in overtrained athletes is related to overtraining syndrome-related hemorheologic disturbances, namely mild plasma hyperviscosity and mild erythrocyte hyperaggregability.     

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.     

Réponses corticotropes à un stress intense en fonction de l'entraînement chez deux souches de rats. Résultats préliminairesCorticotropic responses to acute stress according to exercise training in different rat strains: preliminary results

Aims – Determine the corticotropic responses to acute stress with or without prior exercise training and following the corticotropic phenotype of the rats.Methods and results – Lewis and SHR strains were selected for their opposite corticotropic responsiveness characteristics (high and low in SHR and Lewis strain, respectively). This study shows that exercise training induces opposite adrenal responses in SHR strain and in Lewis strain (which decrease increase its corticosterone concentration, respectively).Conclusion – This suggests that genetic may play an key role in pituitary-adrenal adaptations to exercise training.     

Intérêt du questionnaire de surentraînement de la Société française de médecine du sport lors d’un suivi de sportifsOvertraining questionnaire of Société française de médecine du sport for a continuous observation in a sport population

Aim. – Verify the sensibility of a standardised overtraining questionnaire during a weekly observation in a sport population.Methods and results. – The experiment was carried out in 12 athletes, 20–23 years old, students at the University in Licence STAPS, with a standardised overtraining questionnaire given every week during 8 weeks. Results were analysed individually and for the total population. Those showed that overtraining questionnaire could allow individualised training programs, and could provide some pertinent information on sleep quality and physical condition for each athlete. For the coach, the overtraining questionnaire permits to identify some fatigue state, consecutively to training variations. On the total population, the analysis of overtraining questionnaire showed some items more reliable than other.Conclusion. – This questionnaire was very interesting for coaches, allowing a good individualisation of the training program. Nevertheless, this questionnaire presents intricate statistical analysis when given at high frequency.     

Évolution des erreurs techniques et de quelques variables physiologiques pendant la course d'orientation

During orienteering, the accumulation of technical errors (TE) can be an important factor of handicap at the arrival. In the same conditions of championships, ten voluntary national runners (age: 29.2 ± 3 years, height: 176.8 ± 3.5 cm, body mass: 65.0 ±6.8) participed to the study. Firstly in laboratory the subjects performed a treadmill test in order to study their physical capacity (aerobic fitness and oxygen consumption). The initial speed (12 km·h⁻¹) increased by 1 km·h⁻¹ every 4 minutes. During the last minute of each step a blood sample (50 μl) was taken on a finger for lactate analyze (Kontron). Two days later the subjects participed in an orienteering race (OR) of four loops (Bi₁, B₂, B₃, B₄) stepping in a central point; the first and third loops (B₁, B3) were technical orienteering while the second and the fourth (B₂, B₄) were rough orienteering. During the race the heart rate (HR) was recorded by means of a Sport Tester PE 4 000. The nature, the number and the moment of TE were determined with the help of the map area of each subject and time keeping. During OR the subject's physical capacity (running speed, HR, lactates, carbohydrate) was evaluated when the runners arrived at the crossing point of the loops. The results give some evidence that the anaerobic threshold quickly is reached during technical orienteering (B₁) and stay at a level hihger than 4 mmoles.l⁻¹ during the whole field test, suggesting that the energy expenditure was very high. It is difficult to compare the physical capacity and the psychological behavior of the subjects during OR yet two distinctive critical pediods have been observed for TE in OR (B₃, B₄); nevertheless our study confirms that the number of TE (which is a picture of the mental performance) is linked to the decrease of the physical capacity. Indeed the increase of HR (HRmax-HRmin) during OR stabilized in the first three loops (B₁, B₂, B₃) at 25 beats, min⁻¹, then the increase of HR was about 31 beats.min⁻¹ in B4. This increase of HR (HRmax-HRmin), is due to the muscular fatigue, the subjects must have some rest and they run slowly because the carbohydrates decrease, excepted for the best runners. Thus the consequences of an insufficient warm-up in the first quarter of the race and/or supply of energetics substrates during the whole OR has been brought to attention.