Jeanick Brisswalter

Influence of physical exercise on simple reaction time: effect of physical fitness.

The influence of physical fitness and energy expenditure on a simple reaction time task performed during exercise was investigated. Two groups of 10 subjects were used, one was composed of trained middle-distance runners and one of students who had no regular physical training. The subjects performed a simple reaction time task while pedalling on a cycloergometer at different relative power output corresponding to 20, 40, 60, and 80% of their own maximal aerobic power and immediately after exercise. During exercise, the results showed a decrease in cognitive performance for both groups whereas no significant effect was found after exercise. A significant effect of physical fitness on simple reaction time was noted during exercise. The data are interpreted in terms of optimization of performance focusing particularly on the relations between energy cost of the physical task and attentional demand.

SELECTIVE EFFECTS OF PHYSICAL EXERCISE ON CHOICE REACTION PROCESSES

The aim of the present study was to examine the effects of an exercise of moderate intensity (60% of maximal aerobic power) on specific information-processing mechanisms. 22 students completed 3 10-min. exercise bouts on a bicycle ergometer. Concomitantly, participants performed six manual choice-reaction tasks manipulating task variables (Signal Intensity, Stimulus–Response Compatibility, and Time Uncertainty) on two levels. Reaction tests, randomly ordered, were administered at rest and during exercise. A significant underadditive interaction between Time Uncertainty and exercise was found for the highest quartiles of the distribution of reaction times. No other interaction effects were obtained for the other variables. These results reasonably support that moderate aerobic exercise showed selective rather than general influences on information processing.

Effects of Ramadan intermittent fasting on middle-distance running performance in well-trained runners.

Objective:To assess whether Ramadan intermittent fasting (RIF) affects 5000-m running performance and physiological parameters classically associated with middle-distance performance. Design:Two experimental groups (Ramadan fasting, n = 9, vs control, n = 9) participated in 2 experimental sessions, one before RIF and the other at the last week of fasting. Setting:For each session, subjects completed 4 tests in the same order: a maximal running test, a maximal voluntary contraction (MVC) of knee extensor, 2 rectangular submaximal exercises on treadmill for 6 minutes at an intensity corresponding to the first ventilatory threshold (VT1), and a running performance test (5000 m). Participants:Eighteen, well-trained, middle-distance runners. Main Outcome Measures:Maximal oxygen consumption, MVC, running performance, running efficiency, submaximal &OV0312;O2 kinetics parameters (&OV0312;O2, &OV0312;O2b, time constant τ, and amplitude A1) and anthropometric parameters were recorded or calculated. Results:At the end of Ramadan fasting, a decrease in MVC was observed (−3.2%; P < 0.00001; η2, 0.80), associated with an increase in the time constant of oxygen kinetics (+51%; P < 0.00007; η2, 0.72) and a decrease in performance (−5%; P < 0.0007; η2, 0.51). No effect was observed on running efficiency or maximal aerobic power. Conclusions:These results suggest that Ramadan changes in muscular performance and oxygen kinetics could affect performance during middle-distance events and need to be considered to choose training protocols during RIF.

Le coût énergétique de la course à pied de durée prolongée: étude des paramètres d’influence

Resume Objectif. — Il sagissait d’etablir une revue des questions inherentes au probleme de l’evaluation du cout energetique de la course la pied de longue duree, afin d’identifier les differents parametres influencant sa mesure et son interpretation. Methodologie et validite . — Le cout energetique de la locomotion (marche, course, cyclisme…) est defini comme la quantite d’energie depensee par unite de distance parcourue. Calculee la partir de cette definition, la validite de celui-ci depend de la methode mise en œuvre pour mesurer la depense en energie. Dans l’intervalle precis de sa determination, c’est-la-dire entre 60 et 90 % de la consommation maximale d’oxygene (VO 2max ), le cout energetique represente une mesure valide du rapport entre la depense energetique et le travail produit par l’individu. Resultats et discussion. — De nombreuses donnees suggerent l’existence, chez des coureurs de longue distance, de variations du pouvoir de seconomiser en course, influencant l’ensemble des performances. Ajoute la ce facteur discriminant de la performance, un certain nombre de contraintes inherentes la l’effort de longue duree est classiquement releve. Parmi elles, les contraintes liees la la nature de l’environnement (denivele, vent, ambiance thermique, duree…) semblent exercer une influence non negligeable sur la valeur de la depense en energie. D’autres contraintes sont associees aux particularites propres la chaque individu (longueur des membres, expertise, entrainement…), et peuvent alterer le cout energetique pendant l’effort, et venir ainsi modifier les performances. l’evaluation de l’efficience de l’athlete la partir de la mesure du cout energetique necessite la connaissance prealable de l’ensemble des facteurs qui determinent les variations de ce parametre. Ces facteurs dependent des caracteristiques de l’athlete ainsi que la specificite de l’exercice pratique.

Optimization characteristics of walking with and without a load on the trunk of the body.

Previous work showed that subjects naturally adopt a walking speed which optimizes energy cost of locomotion and stability of stride; however, no studies have examined whether these criteria are affected by carrying an external load. The purpose of this study was to compare optimization characteristics during loaded or unloaded walking. Energy cost and stride characteristics were measured for 10 subjects with and without a load on the trunk of the body of 10% of the body weight during 4 sessions. The first 2 sessions represent free walking at 2.5, 3, 3.5, 4, 4.5, and 5 km · hr.−1. The last sessions represent free vs forced walking at constant speed (preferred frequency and ± 10 PF and ± 20% of preferred frequency). Results show an effect of load on energy cost of walking but no effect on the optimal speed for stability. Furthermore, when carrying a load the subject does not adopt systematically the speed that minimizes physiological cost. Our findings suggest the necessity to consider this effect to prevent gait disturbance and maintain the health benefits of walking.

Interactions entre les processus physiologiques et cognitifs: modèles théoriques et approche méthodologique

Resume Lanalyse des differents modeles explicatifs de levolution de la performance cognitive lors de la realisation dun effort physique indiquent que les resultats inconsistants releves dans lapproche experimentale sont lies ades ≪ effets pluriels et contradictoires ≫. Ces influences diverses sont determinees, en partie, par les caracteristiques objectives des tâches mais aussi par les representations des sujets. Il est donc important, a ce niveau, de proposer a chaque sujet un protocole standardise. Dans ce cadre experimental, aucune des hypotheses ne peut etre a priori rejetee, et la prevision des performances dans la tâche cognitive reste delicate car elle depend etroitement de facteurs individuels qui interviennent dans lactivite du sujet. La premiere hypothese suggere un effet de lactivation sur la performance cognitive medie par lexercice physique. Celui-ci semble etre complexe. Dune part il est difficile detablir une relation lineaire entre activation et effort physique, dautre part, les modeles multidimensionnels de lactivation integrent dans la relation entre exercice et processus cognitifs les effets indirects des traits de personnalite, ou encore de linvestissement des sujets. La seconde hypothese est issue du paradigme de la double tâche. Dans une situation ou le sujet realise deux tâches en meme temps, une tâche de pedalage et une tâche cognitive, les modeles experimentaux suggerent une degradation de la performance en fonction de la priorite accordee a lune ou lautre des tâches. Enfin leffet de lexercice peut egalement se traduire par ladoption par les sujets de strategies a risque privilegiant la vitesse de reponse au detriment de la justesse. Aussi, pour clarifier la diversite des resultats experimentaux, les futures recherches menees dans ce cadre devront considerer a priori les multiples biais methodologiques qui pourraient induire des interferences entre les differents modeles theoriques sous-jacents.

Performance stability in simultaneous tasks of pedalling and reaction time

The purpose of the study was to examine the within-subject variability in heart rate, pedal rate, choice reaction time, and error rate during simultaneous tasks of cycling and reaction time. Students in physical education classes exercised a 10-min. submaximal cycloergometer test at a relative power output corresponding to 60% of their own maximal aerobic power, in a replication procedure. Concomitantly, the subjects performed a 2-choice reaction time task from Min. 3 of the exercise bout. No significant differences (p>.05) were found between the individual means in the tests for the diverse parameters. The total intraindividual variability averaged 1.3% for heart rate, 2.2% for pedal rate, and 13.3% for choice reaction time. Because wide within-subject variability was observed (from 7.7 to 16.7%), the reliability of choice reaction time was low. These data suggest that it is necessary to quantify more accurately the intraindividual differences of reaction time measures for the interpretation of exercise-changes in cognitive functioning.

Use of Energy Cost and Variability in Stride Length to Assess an Optimal Running Adaptation

The aim of this study was to analyse how subjects running adaptation was affected after a training overload. 14 middle-distance runners were tested before and after a training protocol of 15 days conducted only at one training pace. The efficacy of this training protocol to improve energy cost of running was observed only at the training pace. This improvement was correlated with a particular systematic variation in stride length whereas no changes in stability of stride length were recorded. The data were interpreted in terms of specificity of training for which energy cost and stability of stride length could be considered criteria of an optimal adaptation to the training pace.

L'évaluation subjective de la condition physique et de la santé: effet de l'âge et du sexe

Resume Sujets et methodes Six cents sujets, repartis en six groupes de 100 en fonction de lâge (20–35 ans, 35–50 ans et 50–65 ans) et du sexe et qui pratiquent une activite physique hebdomadaire ou plurihebdomadaire ont rempli un questionnaire dautoevaluation de la sante et des dimensions constitutives de la condition physique modifie dapres Borg, Skinner et BarOr (1972). Resultats et discussion. - Les resultats obtenus ont permis de montrer un effet specifique de lâge et du sexe, dune part, sur le poids respectif des dimensions constitutives de la condition physique dans levaluation subjective de la condition physique et, dautre part, sur la relation entre condition physique percue et sante percue. Dans tous les groupes masculins, lendurance percue apparait etre la dimension constitutive de la condition physique la plus importante, alors que dans les groupes feminins cette dimension est predominante uniquement dans le groupe le plus jeune; pour les autres groupes, la souplesse percue represente la principale dimension de la condition physique percue. Par ailleurs, a partir de 50 ans uniquement, levaluation subjective de la condition physique est significativement correlee avec celle de la sante quel que soit le sexe (respectivement pour les hommes et les femmes: r = 0,74 et 0,65, p p

Coût attentionnel d'une tâche de pédalage en fonction de l'intensité de l'exercice

Resume Lobjectif de cette etude etait dobserver si le cout attentionnel lie au maintien dune frequence de pedalage variait en fonction de lintensite de lexercice. A cette fin, il a ete demande a huit sujets de pedaler sur une bicyclette ergometrique a une cadence de 60 tours par minute et a quatre intensites fixees a 50, 75, 100 ou 125 % de Pmax. La degradation de la tâche secondaire en condition de double tâche permettait devaluer le cout attentionnel. Celle-ci consistait a reagir le plus rapidement possible a leclairement dune diode en appuyant sur une presselle. Les resultats montrent que les sujets ont bien respecte la consigne de ne pas deteriorer la tâche principale en condition de double tâche dans la mesure ou ils ont maintenu la cadence de pedalage pour chaque intensite dexercice. Dans tous les cas, le temps de reaction simple (TRS) mesure a lexercice est plus important que celui mesure au repos. Neanmoins, aucune variation significative du TRS en fonction de lintensite de lexercice na ete observee. Lensemble des resultats confirme quune tâche locomotrice cyclique coute de lattention mais que laccumulation de la depense energetique liee a laugmentation de lintensite de lexercice ne saccompagne pas dune augmentation du cout attentionnel.