L'enfant diabétique à l'exercice : étude multiparamétrique

Methods and results – A multiparametric study was realised on insulinodependant diabetic children (n=11) and on control children (n=24) during linear incremental test on ergocycle, normalised with respect to their own maximal aerobic power. It consist in quantifying electromyographic signal of quadriceps muscle (total energy and mean power frequency of the signal), and cardiorespiratory variables (maximal oxygen consumption, heart rate) and metabolic variables (glycemia, lactatemia). Results showed no significant difference of cardiorespiratory changes and significant difference with metabolic changes between diabetic or control children. Changes in electromyographic variables exhibit different profiles between children but not between groups. A discriminant analysis realised on the set of mean power frequency profiles showed difference between diabetic or control children.Conclusion – Thus, electromyographic changes allowed to characterise exercise aptitude for diabetic children.     

Les bases génétiques et moléculaires de la performance et de l'adaptation à l'exercice physique

Objectives – This paper reviews the state of our knowledge on the genetic and molecular bases of performance and the response to exercise training, the theme of the inaugural conference of the XIXth annual meeting of the Société Française de Médecine du Sport held in Rennes in October 1999.Topics – The studies on the genetic bases of performance performed over the past 20 years suggest that 25 to 50% of interindividual differences observed in maximal and sub-maximal oxygen consumption as well as in other indicators of aerobic performance could be explained by genetic factors. For metabolic and histochemical properties of skeletal muscle, heritabilities ranging from 40 to 70% have been reported. Considerable interindividual differences are also observed in the cardiorespiratory, metabolic and morphologic adaptations to exercise training and results from twin and family studies suggest that these differences are also determined by genetic factors. Unlike many other complex traits such as hypertension or obesity, the search for candidate genes of performance is in its infancy. Only a few studies with candidate genes such as the angiotensin converting enzyme (ACE), the muscle specific creatine kinase (CKMM) or genes of mitochondrial DNA have reported positive results with indicators of aerobic performance.Conclusion – More studies are needed before any conclusion could be made about the role of these genes in performance and adaptation to exercise training. Although the molecular dissection of performance and adaptation to regular exercise is a complex task, considerable progress will probably be achieved in the next decade in our understanding of the molecular basis of these complex phenotypes.     

Infections ORL,immunodépression et stress liés à la pratique des activités physiques et sportives

Objectives – Understand the pathophysiology of upper respiratory tract infections (URTI), the most common ailment of elite athletes.Actualities – URTI likely develop as a consequence of local or systemic immunosuppression. Such a lowered protection may result both from training and from the stress associated to competitive sports. This literature review summarises the physiology of the immune system associated to the upper respiratory tract, then presents evidence supporting the impact of stress and training respectively on the immune system.Perspective – Better knowledge of the impact of high-level sport on the immune system may allow to adapt training and competition in order to avoid or limit the immunosuppression leading to an increased susceptibility to infections.