[Basics of exercise physiology: from Fick principle to the athlete's heart]. / Bases de la physiologie de l'exercice : du principe de Fick au cœur d'athlète.

Physical activity is undeniably associated with numerous health benefits. However, performance of high intensity and/or high-volume exercise poses a significant physiological challenge to the cardiovascular and respiratory systems, which must undergo several adaptations to meet the increased metabolic demands of the organism. Repeated and prolonged exposure to training leads to long-term cardiac remodeling aimed at optimizing the efficiency of the work performed by the heart during exertion. This article discusses some of the fundamental mechanisms of cardiovascular physiology during exercise including adaptive responses to acute bouts of exercise and longer term structural and functional characteristics of the athlete's heart.

L'exercice physique est indéniablement associé à de nombreux bénéfices pour la santé. La réalisation d'un effort représente un défi physiologique important pour le système cardiovasculaire et respiratoire, qui doivent entreprendre plusieurs adaptations permettant l'augmentation du débit cardiaque afin de palier l'augmentation des demandes métaboliques de l'organisme. L'exposition répétée et prolongée à l'entraînement induit à long terme un remodelage cardiaque optimisant l'efficience du système cardiovasculaire à l'effort. Dans cet article, nous analysons certains des mécanismes de base de la physiologie cardiovasculaire à l'effort, en passant des adaptations survenant lors d'un effort, pour finalement discuter des adaptations structurelles et fonctionnelles qui caractérisent le cœur d'athlète.

[Hypoxic tests and prediction of high altitude illnesses]. / Tests hypoxiques et prédictiondes pathologies liées à l'altitude.

More and more travelers are exposed to high altitude, for example, 176'000 trekkers/climbers were registered in Nepal in 2017. Individual predispositions, a history of altitude illness, the existence of risk factors and/or comorbidities increase the risk of developing specific altitude-related diseases that are potentially life threatening. Nevertheless, the prediction of these diseases remains difficult, especially in subjects without prior exposure to high altitude. In this context different altitude simulation tests have been developed. Their indication, practice and validity are summarized in this article.

De plus en plus de voyageurs s'exposent à la haute altitude, par exemple 176 000 trekkers/alpinistes ont été enregistrés au Népal en 2017. Des prédispositions individuelles, des antécédents de maladies d'altitude, l'existence de facteurs de risque et/ou comorbidités augmentent le risque de développer des maladies spécifiques liées à l'altitude qui sont potentiellement mortelles. Néanmoins, la prédiction de ces maladies reste difficile, notamment chez des sujets sans exposition préalable à la haute altitude. Dans ce contexte, différents tests de simulation à l'altitude ont été développés. Leurs indication, pratique et validité sont résumées dans cet article.

Validity and reliability of maximal-strength assessment of knee flexors and extensors using elastic bands.

CONTEXT: In the field of sport rehabilitation, an easy, valid, and reliable assessment of maximal strength is crucial for efficient muscle rehabilitation. Classically, it is performed on fitness equipment that is not necessary available in the field. Thera-Band has developed elastic bands with different resistances depending on the color of the band and on the percentage of its stretch. This may allow testing maximal strength. OBJECTIVE: To determine validity and reliability of maximal-strength assessment of knee flexors and extensors using elastic bands. DESIGN: Reliability and validity study. PARTICIPANTS: 22 healthy participants (31.3 ± 7.0 y, 175.5 ± 8.5 cm, 70.7 ± 12.9 kg). INTERVENTION: Participants performed 2 maximal-strength assessments, separated by 7 d, of the knee flexors and extensors using elastic bands. After the 2nd trial, a maximal concentric isokinetic test at 60°/s was performed. MAIN OUTCOME MEASURES: Correlations between 1-repetition maximum using elastic bands and peak torque on an isokinetic dynamometer were used to determine the validity of the proposed method, while ICC, CV, and SEM were used to determine reliability between the 1st and 2nd trials. RESULTS: The validity of the proposed method was found to be very high (r = .93 for both knee flexors and extensors). The relative reliability was found to be very high (ICC = .98 and .99 for knee flexors and extensors, respectively), while absolute reliability was also very satisfying (CV = 3.44% and 2.33%; SEM = 1.70 and 2.16 kg for knee flexors and extensors, respectively). CONCLUSIONS: Thera-Band is a valid and reliable alternative to the use of fitness equipment to test maximal strength of the knee flexors and extensors in healthy subjects. The ease of use, accessibility, and low cost of elastic bands should allow regular assessment during the rehabilitation process.

Electric bicycles as a new active transportation modality to promote health.

UNLABELLED: Electrically assisted bicycles (EAB) are an emerging transportation modality favored for environmental reasons. Some physical effort is required to activate the supporting engine, making it a potential active commuting option. PURPOSE: We hypothesized that using an EAB in a hilly city allows sedentary subjects to commute comfortably, while providing a sufficient effort for health-enhancing purposes. METHODS: Sedentary subjects performed four different trips at a self-selected pace: walking 1.7 km uphill from the train station to the hospital (WALK), biking 5.1 km from the lower part of town to the hospital with a regular bike (BIKE), or EAB at two different power assistance settings (EAB high, EAB std). HR, oxygen consumption, and need to shower were recorded. RESULTS: Eighteen sedentary subjects (12 female, 6 male) age 36 ± 10 yr were included, with V·O 2max of 39.4 ± 5.4 mL·min(-1)·kg(-1). Time to complete the course was 22 (WALK), 19 (EAB high), 21 (EAB std), and 30 (BIKE) min. Mean %V·O 2max was 59.0%, 54.9%, 65.7%, and 72.8%. Mean %HRmax was 71.5%, 74.5%, 80.3%, and 84.0%. There was no significant difference between WALK and EAB high, but all other comparisons were different (P < 0.05). Two subjects needed to shower after EAB high, 3 needed to shower after WALK, 8 needed to shower after EAB std, and all 18 needed to shower after BIKE. WALK and EAB high elicited 6.5 and 6.1 METs (no difference), whereas it was 7.3 and 8.2 for EAB std and BIKE. CONCLUSIONS: EAB is a comfortable and ecological transportation modality, helping sedentary people commute to work and meet physical activity guidelines. Subjects appreciated ease of use and mild effort needed to activate the engine support climbing hills, without the need to shower at work. EAB can be promoted in a challenging urban environment to promote physical activity and mitigate pollution issues.