The influence of ventilatory control on heart rate variability in children     

Craig A. Williams  Philippe Lopes 《Journal of sports sciences》2013,31(5):407-415

The aim of this study was to determine the influence of breathing frequency and tidal volume on resting heart rate variability in children aged 9 years ( n = 29) and 16 years ( n = 19). Heart rate variability was measured in four conditions: (1) without the control of ventilation followed at random by (2) a fixed breathing frequency of 12 breaths· min -1 , (3) a breathing frequency of 12 breaths· min -1 but with a fixed tidal volume of 30% vital capacity and (4) a fixed breathing frequency of 6 breaths·min -1 and a tidal volume of 30% vital capacity. A total of 128 RR intervals (the time between two spikes in the heart rate) were detected and absolute high- and low-frequency spectral components were calculated using autoregressive modelling. The younger children were unable to control ventilation to achieve conditions 3 and 4; therefore, a 2 2 2 (group 2 condition) analysis of variance was used to analyse conditions 1 and 2. There were significant interactions between group and heart rate variability conditions for the low-frequency component and the ratio of low to high frequencies ( P ? 0.001). The main effect for condition showed that at 12 breaths· min -1 with no fixed tidal volume there was a significantly higher standard deviation of the RR interval, total power and high-frequency ( P ? 0.01) and lowfrequency spectral components ( P ? 0.05) than in the condition with no ventilatory control. Across the four breathing conditions for the older participants, the high-frequency spectral component was significantly higher in the condition at 6 breaths· min -1 with a fixed tidal volume than in that with no ventilatory control ( P ? 0.005); the ratio of high to low frequencies was significantly lower for the spontaneous condition than those performed at 12 breaths· min -1 ( P ? 0.001). The results provide evidence of the need for ventilatory control when assessing short-term resting heart rate variability in children.  相似文献   

Sequence-dependent rotation axis changes in tennis     

Clint Hansen  Caroline Martin  Nasser Rezzoug  Philippe Gorce  Benoit Bideau  Brice Isableu 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(3):411-423

The purpose of this study was to evaluate the role of rotation axes during a tennis serve. A motion capture system was used to evaluate the contribution of the potential axes of rotation (minimum inertia axis, shoulder-centre of mass axis and the shoulder-elbow axis) during the four discrete tennis serve phases (loading, cocking, acceleration and follow through). Ten ranked athletes (International Tennis Number 1–3) repeatedly performed a flat service aiming at a target on the other side of the net. The four serve phases are distinct and thus, each movement phase seems to be organised around specific rotation axes. The results showed that the limbs’ rotational axis does not necessarily coincide with the minimum inertia axis across the cocking phase of the tennis serve. Even though individual serving strategies were exposed, all participants showed an effect due to the cocking phase and changed the rotation axis during the task. Taken together, the results showed that despite inter-individual differences, nine out of 10 participants changed the rotation axis towards the minimum inertia and/or the mass axis in an endeavour to maximise external rotation of the shoulder to optimally prepare for the acceleration phase.  相似文献   

Does endurance training improve red blood cell aging and hemorheology in moderate-trained healthy individuals?     

Daniel A. Bizjak  Fabian Tomschi  Gunnar Bales  Elie Nader  Marc Romana  Philippe Connes  Wilhelm Bloch  Marijke Grau 《运动与健康科学(英文)》2020,9(6):595-603

ObjectiveTo examine the impact of a 6-week endurance training on red blood cell (RBC) aging and deformability of healthy participants to detect possible improved hemorheological and performance-related adaptations.MethodsA total of 31 participants (17 females and 14 males) performed a 6-week moderate training protocol (three 1-h running sessions per week at 70% of maximal heart rate). Blood was sampled before and after the training. RBCs from each participant were fractioned according to density and age into 4 RBC subfractions. Subfractions were examined for changes of RBC properties, including aging distribution, RBC deformability, RBC microparticles, and phosphatidylserine concentrations. RBC and plasma nitrite levels were measured as indicators of nitric oxide metabolism.ResultsAerobic performance, peak oxygen consumption, ventilatory thresholds, velocity at the aerobic–anaerobic threshold, and lactate at exhaustion improved after training. The relative amount of both young RBCs and old RBCs increased, and the amount of the main RBC fraction decreased. Phosphatidylserine externalization and RBC-derived microparticles decreased. Overall deformability expressed as shear stress required to achieve half-maximum deformation to theoretical maximal elongation index at infinite shear stress improved in unfractioned RBCs (p < 0.001). Nitrite decreased in total (p = 0.001), young (p < 0.001), main (p < 0.001), and old (p = 0.020) aged RBCs and in plasma (p = 0.002), but not in very old RBCs.ConclusionThese results indicate that non-endurance-trained healthy participants benefit from a regular moderate running training program because performance-related parameters improve and a younger RBC population with improved RBC properties is induced, which might support oxygen supply in the microcirculation.  相似文献   

Book reviews     

Robert F. Lawson  David Nyberg  Philippe C. Duchastel  Paul Ramsden  Wolfgang Wilhelm  Jan Sadlak  Erich Leitner  Ronald K. Goodenow  Katherine Iverson  Arthur Liebman 《Higher Education》1978,7(3):373-388

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On passion and sports fans: a look at football     

Vallerand RJ  Ntoumanis N  Philippe FL  Lavigne GL  Carbonneau N  Bonneville A  Lagacé-Labonté C  Maliha G 《Journal of sports sciences》2008,26(12):1279-1293

The purpose of the present research was to test the applicability of the Dualistic Model of Passion (Vallerand et al., 2003) to being a sport (football) fan. Three studies provided support for this dualistic conceptualization of passion. Study 1 showed that harmonious passion was positively associated with adaptive behaviours (e.g. celebrate the team's victory), whereas obsessive passion was positively associated with maladaptive behaviours (e.g. risking losing one's job to go to a game). Study 2 used a short Passion Scale and showed that harmonious passion was positively related to the positive affective life of fans during the 2006 FIFA World Cup, psychological health (self-esteem and life satisfaction), and public displays of adaptive behaviours (e.g. celebrate the team's victory into the streets), whereas obsessive passion was predictive of maladaptive affective life (e.g. hating opposing teams' fans) and behaviours (e.g. mocking opposing teams' fans). Finally, Study 3 examined the role of obsessive passion as a predictor of partner's conflict that in turn undermined partner's relationship satisfaction. Overall, the present results provided support for the Dualistic Model of Passion. The conceptual and applied implications of the findings are discussed.  相似文献   

Self-belief does make a difference: a reciprocal effects model of the causal ordering of physical self-concept and gymnastics performance   总被引：2，自引：0，他引：2  

Marsh HW  Chanal JP  Sarrazin PG 《Journal of sports sciences》2006,24(1):101-111

A large body of research in support of the reciprocal effects model of causal ordering demonstrates that prior academic self-concept predicts subsequent academic achievement beyond what can be explained in terms of prior achievement. Here we evaluate the generalizability of this support for the reciprocal effects model to a physical activity context in which achievement is reflected in gymnastics skills on a standardized gymnastics performance test evaluated by expert judges. Based on the responses of 376 adolescents collected at the start (T1) and end (T2) of a gymnastics training programme, there is support for a reciprocal effects model in which there are significant paths leading from both T1 gymnastics self-concept to T2 gymnastics skills and from T1 gymnastics skills to T2 self-concept. Although there were gender and age effects (girls and older participants had better gymnastics skills, boys had higher self-concepts), multiple group structural equation models indicated that support for the reciprocal effects model generalized over responses by boys and girls. In summary, self-concept and performance are both determinants and consequences of each other.  相似文献   

Text illustration. Is an art–there is no doubt about it     

Philippe C. Duchastel 《Performance Improvement》1983,22(4):3-5

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Le football des nations. Des terrains de jeuaux communautés imaginées     

Philippe Vonnard 《Soccer & Society》2017,18(7):1080-1082

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Cognitive design for instructional design     

Philippe C. Duchastel 《Instructional Science》1990,19(6):437-444

There is strong interest in the field of instructional design in building expert systems that can provide advice to inexperienced instructional designers. This paper questions whether the expert systems model to advice-giving is in fact appropriate for a design process such as instructional design. An alternate approach based on case-based reasoning and the critic approach to advice-giving is considered to be better adapted to the cognitive needs of this task. The cognitive constraints of the task are used to orient the design of an instructional design workbench. The concept of an ID workbench illustrates the direct application of cognitive science to a complex practical task in the area of design.  相似文献   

Neutrality and impartiality in public education: the French investment in philosophy,teaching about religions,and moral and civic education     

Philippe Gaudin 《British Journal of Religious Education》2017,39(1):93-106

In France, there is no religious education in state schools. ‘Convictional education’ appeared by drawing its perimeter around three educational subjects: philosophy, teaching about religions, and moral and civic education. Today, the French school is facing new challenges in a highly secularised society on which religion is laying new claims. As an institution, it is not neutral insofar as it proceeds from a political philosophy that evolved from the French Revolution. It is within the operative framework of this philosophy and with specific teaching practices that it intends to combine unity and plurality within itself.  相似文献