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.     

Enregistrements vidéos et moments de force mesurés sur cycloergomètre : étude du transfert d'énergie entre membre inférieur et manivelle à vitesse élevée

In the field of radiation measurements the energy transfering mechanism has not been described in the case of liquid scintillators containing naphtalene. However, now, this one is an usual component of scintillating solutions. The experiments related in this paper show that naphtalene acts like an intermediate and a secondary solvent. The transfer processes chain is not the same when the energy transfer from the solvent to the primary solute is slow or when it is rapid. The quenching law is still linear with regard to quencher concentration when the scintillator contains naphtalene. But the quenching constant of many quenchers is smaller than the one measured when naphtalene is absent.

Abstract

B oблacти иэмepeний иэлyхeния (дoэимeтpии) нe был oпиcaн мeхaниэм пepeдaхи знepгии для cлyхaeв, кoгдa жидкocтныe cцинтиллятopы coдepжaт. нaфтaлин. oднaкo тeпepь oн являeтcя oбыхным кoмпoнeнтoм cцинтиллиpyыщих pacтвopoв. Упoминaeмыe в зтox cтaтвe oпыты пoкaзывaют, хтo нaфтaлин дexcтвyeт, кaк пpoмeжyтoхныx и втopихныx pacтвopитeль. Цeпь пpoцeccoв пepeдaхи нe являeтcя oдинaкoвox в cлyхaях мeдлeннox или быcтpox пepeдaхи знepгии oт paтвopитeля к пepвихнoмy pacтвopoннoмy вeщeтвy. Пpи coдepжaнии нaфтaлинa в cцинтиллятope зaкoн тyшeния ocтaeтcя в линexнoм cooтнoшeнии c кoнцeнтpaциex ингибитopa. Ho кoнcтaнтa тyшeния мнoгих ингибитopoв нижe, хeм кoнcтaнтa пpи иэмepeниях, кoгдa нoгдa нaфтaлин oтcyтcтвycт.

Zusammenfassung

Auf dem Gebiete der Strahlungsmessungen ist der Energieübertragungs-mechanismus mit einem Naphtalingehalt noch nicht beschrieben worden. Dies ist jedoch nunmehr ein üblicher Bestandteil der Szintillator-lösungen. Die in diesem Beitrag beschriebenen Versuche zeigen, dass Naphtalin wie ein Zwischen- und ein Sekundär-Lösungsmittel wirkt. Die Kette der Übertragungsvorgänge ist nicht dieselbe bei einer langsamen Energieübertragung vom Lösungsmittel auf die gelöste Substanz wie bei einer schnellen Übertragung. Das Lchgesetz ist immer noch linear mit Bezug auf die Löschmittelkonzentration, wenn der Szintillator Naphtalin enthält. Die Löschkonstante vieler Löschmittel ist jedoch kleiner als bei Abwesenheit von Naphtalin gemessen.

Somatotypes et débit cardiaque chez les handballeurs d'élite

Objective – The aim of this research is to study the relationship between the cardiac output (CO) and the somatotype in elites handball players.Facts – The CO of endomorphs (ENDO) is significantly higher than mesomorphs (MESO) at rest (P < 0,01) and at 70% (P < 0,01). The QO presents a significant correlation with the fat free mass (FFM) in all the population of study (P < 0,001).Conclusion. – This study shows that the FFM could be considered as a determining factor of the variation of the CO between the ENDO and the MESO.     

Détermination de l'insulin-like growth factor-I, du lactate et du glucose par microdialyse musculaire au cours d'un exercice d'électrostimulation modéré

Introduction. – The impact of low intensity light neuromuscular electrostimulation (14 Hz, 30 mA) of the vastus lateralis was assessed through interstitial microdialysis measurement of free Insulin-Like Growth Factor-I, glucose and lactate during the stimulation (45 minutes) and recovery (40 minutes) periods in 3 healthy subjects.Results. – Muscular uptake of glucose was immediate, while delayed decrease of lactate production was observed. Free Insulin-Like Growth Factor-I was decreased during recovery.Conclusion. – These data suggest that a low intensity of neuromuscular electrostimulation determines a metabolic activation of the muscle. That activation spreads to the recovery period.     

Les lésions intra-articulaires et leur évolutivité au cours des ruptures récentes et anciennes du ligament croisé antérieur. Rapport préliminaire

The purpose of this study is to determine the natural history of chronic injuries to the ligaments of the knee, by assessing the ligamentous and intra-articular lesions with arthroscopy. Functional instability, laxity and chondromalacia are graded according to special scores.Method: 54 patients with acute and 375 patients with chronic anterior cruciate deficient knees had a complete clinical statement of their symptoms, and an examination under anesthesia. An arthroscopic examination of the knee joint determined the intra-articular lesions. These data were compared with the time span between the initial sprain and the arthroscopy (4 days to more than 20 years, average 4.5 years). 92% are resulting from accidents in sports activities. All had initially an untreated hemarthrosis.Results: functional instability varies with time: in the first year, 40% were functionnally stable. Their number gradually disappeared, and the instability score increased in the following years. After 10 years, most of the patients had a feeling of insecurity, or giving way.Laxity equally increases in the first 2 years. It then settles and diminishes after 10 years, with the onset of osteoarthritis. The Lachman test and the anterior drawer followed the same evolution. The pivot shift test was almost always present: 90% in the first year, 100% there after. A jerk in external rotation was present in 30% in the first year, and its rate went up to 65% between 2 and 10 years.The meniscal lesions aggravate in frequency and their type changes with time. Initially, 55% of both medial and lateral menisci were intact. After 10 years, 35% of lateral menisci remained intact, but less than 10% of medial menisci. Repairable vertical peripheral tears were frequent in the first 2 years, and were then replaced by complex unrepairable tears.The lesions to the anterior cruciate were total for 50% (complete ruptures, disappearance of the ligament) and incomplete (partial tears, insertion on the posterior cruciate, stretched anterior cruciate) for 50%. Laxity was significantly more important in the first group, indicating that the ligament may keep some biomechanical effect on the control of the laxity, even if it is abnormal.Chondromalacia score was close to 0 in the first year and then increased regularly. The medial compartment was first damaged, then the patella, last the lateral compartment. At 10 years, 30% of the patients had an osteoarthritis of the 3 compartments, 10% kept normal cartilages of the joint. Meniscectomies, even partial, aggravated the onset of arthritis, but did not correlate with an increase of the laxity.In conclusion, osteoarthritis is the final term of anterior cruciate ruptures. The 22 years period is a key in their evolution, if the surgical treatment tries to stabilize the lesions before they become unrepairable. Both symptoms of instability, laxity and lesions aggravate. Laxity is related to the initial damage to the supporting structures of the knee, and the progressive stretching of the peripheral restraints which remained intact at first, due to the non-functionnal anterior cruciate. Unfortunately, there is no evidence that surgery prevents the knee from post-traumatic osteoarthritis. The therapeutic indications must still rely upon functional disability.     

Effet du déconditionnement suite à une chirurgie du genou sur l'aptitude aérobie

Introduction. – The object of this study consisted in analysing the changes in cardiorespiratory fitness of fourteen sportsmen having undergone a surgical operation following a lesion of the anterior cruciate ligament of the knee.Methods and results. – Two triangular and maximum tests starting from the upper limbs were carried out before and after the operation with 7 days of interval. The results showed that the operation followed by a few days of bed rest generates a fast and significant reduction in the maximum oxygen consumption (–7%, p < 0.05) and peak aerobic power (–8%, p < 0.05).Conclusion. – These results could encourage therapists to propose endurance training during rehabilitation protocols.     

Analyse de variables permettant la détermination du niveau d'un cycliste

Aims

We aimed to define a mathematical model allowing to foresee the level of a cyclist.

Methods

One hundred (and) six cyclists were classified according to their level and some of their physiological characteristics were measured with the threshold (4 mmol of lactate) and with the maximum values of their oxygen flow.

Results

To the threshold, power, lactatemy, age and size allow to foresee the level with an error rate of 27% ; to the maximum values, the criteria are development, flow in oxygen, lactatemy and age (error rate of 31%).

Conclusion

These results indicate that our mathematical model allows to envisage the level.     

Mise au point sur les positions d’évaluation isocinétique des muscles rotateurs de l’épaule

IntroductionThe isokinetic position of rotator muscles are numerous. A reference position is essential for reliable, reproductible and comparable assessment.Synthesis of factsThe position used must be close to the function while isolating the muscles to evaluate. The position must be comfortable, safe and reproducible, providing an invariable axis of movement.ConclusionTo evaluate the rotator muscles, now it is advisable to use: Davies's position in the pathological contexts, and the position in the supine position with a 90° abduction of the shoulder in sporting arm.     

Vieillissement et désaturation oxyhémoglobinée du sportif

A extreme athlete can be defined as an athlete able to exceed the limit of one function in such a way that failure of another function appears. For example extreme athletes in endurance events are able to exceed the normal limits of cardiac output but show a hemoglobin desaturation by the end of exhaustive exercise. Usually, these athletes have had a maximal oxygen uptake (O₂ max) greater than 65 ml·min⁻¹. The aim of this study was to determine whether hemoglobin desaturation occurs in master athletes and whether aging facilitates this phenomenon. Nine master athletes aged 62–75 participated to this study. They practised leisure cycling 5000 to 14000 km per year. Hemoglobin saturation was measured non-invasively using the transcutaneous method during both incremental exercise until exhaustion and constant load exercise at 70% and 90% of O₂ max for a 15 min period. We considered that there was a desaturation if SaO₂ decreased by 4%. During maximal incremental exercise we observed desaturation in six subjects. These results were confirmed during constant load exercise at 90% of O₂ max. It is interesting to note that one of the subjects, whose desaturation was 8% during incremental exercise, showed a desaturation of 16% at the 15th minute of constant load exercise at 90% O₂ max. In our master athletes this desaturation was observed for O₂ max and pulse oxygen values respectively equal to 1/2 and 2/3 of the values of young athletes. Aging thus seems to facilitate the mechanisms of athlete's desaturation. These mechanisms are highly speculative. One can, however, suspect the role of relative hypoventilation, a ventilation-perfusion inequality, and a diffusion limitation. A decrease of red blood cell transit time in the pulmonary capillary may also play a role, as there is a decrease in pulmonary capillary volume in master athletes over 60 years and that maximal cardiac output does not seem to decrease with age.     

L'aptitude physique: étude comparée chez l'homme et la femme

Comparison of male and female performance trends in athletics and swimming over the last decade shows that women tend to improve their results less rapidly than men. Does this divergence reflect unequal physical capacities? Measuring performance implies the determination of numerous (biological, psychological, sociological) elements. For most authors, physical capacities are decisive in explaining performance levels, as expressed by energetic and biochemical factors. The latter are analysed in this study in order to compare performances in both sexes. Energy expenditure may be assessed through the study of maximum aerobic power and aerobic endurance. During tests which required a significant amount of aerobic power, female were observed to be lower than male performances. These differences may be explained by the lower maximal oxygen uptake (O₂ max) in women. Absolute O₂ max values, expressed in 1·min⁻¹ are typically 30 to 50% higher in men than in women. Using the relative expression of O₂ max, in ml of oxygen per kg of body weight, the apparent sex difference in maximal aerobic power is reduced to approximately 20%. Thus, part of the sex difference in O₂ max is related to the difference in body size and weight. One factor known to influence O₂ max is relative body fat. If O₂ max is expressed relative to fat-free weight, the sex difference in O₂ max is further reduced and, in some cases, ceases to exist. A smaller heart size and a lower hemoglobin concentration are two factors which are proposed as a possible hypothesis to explain this variation. The sex differential in O₂ max between trained men and women was less than for untrained subjects. On the other hand, during exercise involving moderate speed, women displayed better endurance properties than men. This observation indicates that females depend upon aerobic energy turnover and fat combustion to a larger extent than males. A higher lipid contribution to energy metabolism was explained in women compared to men via the lower values of respiratory exchange ratios obtained in women for oxygen uptake values below 75 to 80% of maximal oxygen uptake.The biochemical component takes into consideration the strength characteristics are produced by muscle and the conditions under which thus strength is manifested, assessed through efficiency study. Men are usually stronger than women because they have more muscle mass. However, when muscular strength is expressed relative to lean body mass or to cross-sectional area of muscle, sexual differences are reduced significantly. Signifaicant differences in gross energy expenditure are apparent between men and women but when expressed in relation to body weight, the difference in energy cost is decreased. These differences are also dependent upon activity and training level.In general, women have a significantly lower capacity to perform physical work than men. The effects of physical fitness training do not alter these differences.     

Evolution des taux plasmatiques des LDH (lacticodeshydrogénase), CPK (créatine phosphokinase) et de la myoglobine à l'issue d'une course de 100 km et d'un triathlon

The elevation of plasma levels of lactate dehydrogense (LDH), creatine phosphokinase (CPK) and myoglobin under the effect of prolonged physical exercise is considered as a biochemical index of muscle cell destruction. These biochemical parameters were used to evaluate the comparative effects of a 100 km race and a triathlon of the same duration upon muscle function. Venous blood samples were drawn from 8 long distance runners (the 100 km race at Belvès) and 8 participants in the Nice triathlon (swim 3 km, cycle 120 km, run 32 km) before the events, at the end and 4 days after. Leg muscle function was evaluated, using an isokinetic dynamometer CYBEX II before both events and 4 days later.The results show significant increases in these three parameters at the end of the competitive events. The plasma levels observed were higher at the end of the 100 km run (CPK: 700 ± 200 VS 180 ± 90; LDH: 411 ± 30 VS 200 ± 5; myoglobin 1100 ± 100 VS 730 + 400). The measurements made 4 days after these sporting events with the CYBEX revealed no change in the maximal effort of leg extensors and flexors. However, a slight reduction in the duration of exertion at this maximal level was noted. Foru days after these events, the CPK levels remained above the resting level for both groups studied, whereas the myoglobin values returned to basal levels in the triathletes, and the LDH values were the same as those observed at rest for both populations. These findings suggest that for a physical exertion lasting between 9 h 8 min and 8 h 20 min, the 100 km race causes more muscular lesions than the triathlon. The reduced time of exertion at maximal effort during the recovery period noted for both groups is an index representing a perturbation of the muscle function capacity, in spite of the normalization of the two biochemical parameters, LDH and myoglobin. The persistence of the slightly elevated CPK values suggests that this parameter is a better index of muscular lesions during the recovery phase.