The main purpose of this thesis was to investigate the fit between four achievement goals, personal goal attributes and self-regulation strategies, and the generalisation of goal-strategy patterns to (1) different life domains (academic and physical activity settings), (2) two cultures (individualistic/the UK and collectivistic/Romania) and (3) over time, in two contexts (academic and sport university settings) in the UK. Additionally, differences between high level English and Romanian athletes in self-construals (individualism versus collectivism), achievement goals and self-regulation processes was investigated in one study. Method. The participants in the four studies of this thesis were: English university students (N = 591; study 1), English university athletes and exercise participants (N = 294 and N = 288, respectively; study 2), English and Romanian elite/sub-elite athletes (N = 91, N = 109 respectively; study 3a), Romanian university students involved in sport at elite and sub-elite levels (N = 196; study 3b), and English university student-athletes (N= 295; study 4). Three main questionnaires were used: the Achievement Goals Questionnaire (AGQ; Elliot & McGregor, 2001) (studies 1, 3b, and 4) and the Achievement Goals Questionnaire for Sport (AGQ-S; Conroy, Elliot & Hofer, 2003) (studies 2, 3ab and 4) measured four achievement goals in academic and sport settings, respectively (mastery-approach, mastery-avoidance, performance-approach and performance-avoidance goals); the third questionnaire, the Goal Systems Assessment Battery (GSAB; Karoly & Ruehlman, 1995) (all studies) required participants to state their most important personal goal, and measured two goal attributes (efficacy and value) and five self-regulation strategies used during goal pursuit (planning, self-monitoring, social comparison, self-reward and self-criticism). The fourth questionnaire, was the Self-Construal Scale-Revised (SCS-R; Hardin, 2006) which measured individualistic and collectivistic self-definitions in study 3a. Studies 1, 2 and 3a and 3b employed a correlational design, structural equation modelling analyses, and multivariate and univariate analyses of covariance (study 3a only), while study 4 employed a longitudinal design, latent growth curve analyses and structural equation modelling. Studies 1 and 2 Results. The goal-strategy models identified in education (study 1), sport and exercise (study 2) in the UK were very similar to each other, and consisted of both positive and negative paths (see figure A overleaf). Furthermore, in study 1, the total sample was divided into two samples according to the difficulty and specificity of personal goals: students in sample 1 (N = 325) set easy and vague goals, while students in sample 2 (N = 266) set difficult and specific goals. The model found in the total sample was tested again simultaneous in these two samples in order to ascertain the potential moderation effects of goal difficulty and specificity. As the model was invariant across groups it was concluded that personal goal difficulty/specificity was not a moderator of achievement goal relations with self-regulation processes. Finally, in study 2 Map relations with planning/self-monitoring was fully and partially mediated by goal efficacy and value in the sport and exercise domains, respectively. Study 3a and 3b Results. In study 3a, Romanian athletes had higher collectivistic self-construals than English athletes, while the two groups were similar in individualism. After controlling for collectivism, Romanian athletes, regardless of sport type (individual or team sport) had higher scores than English athletes on Pap and Pav goals, social comparison and self-motivation strategies (self-reward and self-criticism); and Romanian team sport athletes had higher scores on Map and planning/self-monitoring than their English counterparts. In study 3b the goal-strategy models identified in moderately competitive academic and physical activity settings in an individualistic West European culture (UK) were tested in highly competitive academic and elite sport settings in a collectivistic East European culture (Romania). The academic and sport domain models identified in Romania were similar to each other, and to those found in the UK. The following differences in model paths were noted in Romania: in the academic domain, four paths were not significant (Map and Mav to efficacy, efficacy to self-reward, and social comparison to self-criticism); and a new negative path was identified, from Map to social comparison; in the sport domain, five paths were not significant (Mav to efficacy, Pap to efficacy and social comparison, efficacy to reward and social comparison to self-criticism) and three new paths emerged, two positive paths, Pav to social comparison, and efficacy to planning/self-monitoring, and one negative path from efficacy to criticism. The positive path from Pav to social comparison (found in highly competitive sport settings) represents the most notable difference between the UK and Romanian models. Study 4 Results. The goal-strategy models identified in academic and sport contexts in studies 1 and 2 (described earlier) emerged again in these settings in study 4 (minus the path from efficacy to reward in both settings, and efficacy to criticism in academia) at three measurement times (start, middle and end of academic year/competitive season). Therefore, the model was stable over time. Unconditional growth curve analyses showed that, during one year, achievement goals and self-regulation processes followed different patterns of change: Map and Pav goals declined, while Pap and Mav goals were stable in education, and all goals declined in sport settings; goal commitment (a composite measure of goal efficacy and value) declined and planning/self-monitoring remained stable (in both settings); social comparison and self-motivation (a composite measure of self-reward and self-criticism) increased in education, while in sport the former was stable and the latter declined . Finally, associative growth curve models showed that in both domains: 1) temporal changes in Map were positively related to changes in goal commitment and planning/monitoring, and changes in the latter were associated with changes in self-motivation; 2) changes in Pap, social comparison and self-motivation were positively related; and 3) Mav changes were not related to changes in SR processes. Conclusion. This thesis advocates a conceptualisation of achievement goals as a dynamic, cyclical interplay between situated reasons, standards and self-regulated action; 2) an exploration of goal standards dimensions beyond the mastery-performance focus with the reason-standard complex; and 3) an expanded achievement motivation and self-regulation model, including the why (achievement goals), the what (personal goals/goal setting), and the how (self-regulated action), where the focus of enquiry is sifted from the correlates to the mechanisms of achievement goal effects.

Exercise intensity and its distribution is probably the most important and most heavily debated variable of endurance training. Training induces adaptation but also induces stress responses. Controlling the training-intensity distribution may provide a mechanism for balancing these two effects. It has been reported that elite endurance athletes train with a high volume and load, relative to the sport. These athletes spend the vast majority (>80%) of training time at relatively low intensities (lower than the lactate threshold, zone one), and therefore <20% of training time above the lactate threshold (zones two and three). Experimental studies support the beneficial effects of a high training volume in zone one, and show detrimental effects of replacing zone one training with training in zone two. This is likely due to enhanced recovery from training in zone one compared with training in zone two. The acute recovery following training sessions in zones two and three has been reported to not be different, but the recovery following training in zone one has been reported to be faster. Improvements in physiological adaptation and endurance performance have been reported to be greater following training programmes with higher exercise intensities. Therefore, it has been suggested that a polarised training model, which includes ~80% of training in zone one with ~20% of training in zone three is more beneficial than a threshold training model, with the majority of training in zone two. However, research into an optimal training-intensity distribution is limited. Therefore, the aims of this thesis were to assess the effectiveness of training-intensity distribution on the improvements in physiological adaptation, endurance performance and assess if manipulating training-intensity distribution had an effect on immune function. Study one revealed that the lactate threshold, the lactate turnpoint and maximal performance measures in swimming, cycling and running, assessed using the methods outlined in the study, are reproducible in trained endurance athletes. These tests can therefore be used by trained endurance athletes as part of a physiological testing programme to assess not only endurance performance, but also to demarcate training intensity zones for exercise intensity prescription and monitor moderate to large adaptations to training. Practitioners should take care when deciding on the duration between tests to test for adaptations from training, as adaptations need to be greater than these detected test-retest variations to be considered physiologically meaningful. To the best of the author’s knowledge, study two was the first study to have assessed training-intensity distribution in a group of multisport athletes. Training was monitored over a 6-month period, and testing took place every two months to assess the effect of the training on physiological adaptation. Although speculative due to the number of variables involved, the results suggest that a greater proportion of training time spent in zone one and a lower proportion of training time spent in zone two is beneficial to physiological adaptation. However, given the number of variables associated with assessing the training-intensity distribution in multisport athletes, it is not easy to draw conclusions as to the effectiveness of the training in the different disciplines on the key measures of adaptation in the different disciplines. Study two highlighted the need for future research to focus on experimental manipulation of training-intensity distribution and thus improve our understanding of its impact on the training-induced adaptations in endurance athletes. Study three manipulated the training-intensity distribution in trained endurance athletes in just one discipline, to reduce the number of variables involved. A polarised training model was compared to a threshold training model on the effectiveness to improve physiological adaptation and endurance performance. Results revealed that a polarised training model is recommended for trained cyclists wishing to maximally improve performance and physiological adaptation over a short-term (six week) training period. The first part of study four assessed the effect of a polarised and a threshold training model on immune function markers in trained cyclists. Both endurance training programmes had similar volume, and were sufficient to induce improvements in performance and physiological adaptation. However, despite likely differences in recovery, both training programmes had no effect on the proportion of low or high differentiated or senescent CD8+ or CD4+ T-cells in blood. Therefore, training adaptation was achieved at no cost to this particular aspect of immune function. From these results and evidence from previous studies, it seems likely that athletes need to be overreached to induce any change in immune function following a period of intensified training. The second part of study four assessed the impact of an ironman triathlon race on Epstein-Barr virus (EBV) and Varicella-Zoster virus (VZV) antibody titres and the frequency of low and high differentiated and senescent blood T-cells in trained endurance athletes. Previous work has revealed that an ironman triathlon race increases the proportion of senescent CD4+ T cells and decreases the proportion of naive CD4+ T cells, and thus induces changes the immune space which could leave an individual at a greater risk of infection. This study however, did not find any changes in the proportions of these T cell subsets following an ironman triathlon race. The mean results of this study suggest that there is no relationship between EBV and VZV-specific antibody concentrations and the proportion of senescent, low and highly differientiated T cells. However, on analysis of individual subject data, it seems possible that subjects with a high antibody titre for EBV or VZV 3 wks before a competition might be more at risk of infection post race. A greater subject number would be needed in order to make a more conclusive statement about this relationship. The results of this thesis suggest that future research is required in the area of training-intensity distribution. Firstly, our understanding of the physiological mechanisms responsible for the effectiveness of a polarised training model in trained endurance athletes is limited, and thus studies should attempt to address this issue. Our current knowledge on the mechanisms underlying a blunted T cell response following strenous exercise is also limited. A change in the immune space to a greater proportion of senescent T cells and a lower proportion of naive T cells might contribute to this blunted response. In the current thesis however, the proportions of these T cell markers were unchanged following the training/racing interventions. It is possible that with a higher training load, there could be changes in these markers, and thus this is an exciting area that could have potential implications on athlete health. Finally, testing for antibody titres in endurance athletes is possibly an avenue to detect individuals at the greatest risk of infection if subjected to a large physical and/or mental stress. This could have implications on maintaining athlete health and therefore, allowing athletes to train consistently.

Cette thèse met en évidence deux systèmes d’éducation scolaire au sein d’une seule discipline d’enseignement (EPS) à travers une analyse comparée. Cette dernière consiste à faire ressortir les points convergents et divergents, à étudier les actes didactiques et de contextualisation et à analyser les spécificités des interactions didactiques dans les deux territoires. Tout cela est donc centré sur cette problématique d’étude : « Quels sont les effets de contexte spécifiques sur l’évolution des savoirs dans la classe et sur les conditions de leur transmission ? ». Les principaux résultats sont traités et analysés à deux niveaux : macro et micro. Pour le macro, il s’agit d’une analyse comparée des systèmes d’éducation scolaire et de l’organisation de l’EPS en Haïti et en Martinique selon différents éléments : l’organisation de la scolarité, les principales réformes éducatives, le profil pédagogique des enseignants des deux premiers cycles de l’école fondamentale et de l’école élémentaire, les programmes d’EPS et les activités physiques, sportives et artistiques (APSA) proposées. Pour le micro, il s’agit d’une analyse comparée qui s’appuie sur le curriculum déclaré (entretiens ante et post) et le curriculum réel (observations filmées). Ce travail de recueil de données est réalisé dans huit établissements scolaires pour un total de trente classes, seize par territoire. Les niveaux choisis sont les 1ère, 3e, 5e et 6e années fondamentales en Haïti et CP, CE2, CM1 et CM2 en Martinique. La distinction entre le niveau macro et celui du micro porte essentiellement sur le volet contextuel de notre étude. Ainsi, le macro s’intéresse aux effets du contexte et le micro aux effets de contexte. Ces deux niveaux distincts sont donc complémentaires. / This thesis highlights two systems of school education within a single discipline of teaching (PES) through a comparative analysis. This research shows the convergent and divergent, points to study teaching and contextualizing acts and analyse the specificities of didactic interaction in the two territories. All this is so focused on this issue of study: "what are the specific effects of context on the evolution of knowledge in the classroom and on the conditions of their transmission.The main results are processed and analysed at two levels: macro and micro. For the macro, it is a comparative analysis of systems of school education and the organization of the PE in Haiti and Martinique based on different elements: the organization of schooling, the major educational reforms, the educational profile of teachers of the first two cycles of the fundamental school and elementary school, PE programs and physical, sports and artistic activities proposed. For the micro, it is a comparative analysis based on the curriculum said (before and after interviews) and the real curriculum (filmed lessons).This work of data collection is done in eight schools for a total of thirty classes, sixteen by territory. The selected levels are the 1st, 3rd, 5th and 6th fundamental years in Haiti and CP, CE2, CM1 and CM2 in Martinique. The distinction between macro-level and micro-level focuses on the contextual component of our study Thus, the macro is interested in the effects of the context and the microphone to the effects of context.

Cette thèse est basée sur le constat du manque d’activité physique (AP) chez les adolescents : environ 80% de cette tranche d’âge n’atteint pas les 60min quotidiennes recommandées. Cette situation aux conséquences sanitaires importantes, impacte davantage les jeunes les plus vulnérables comme les adolescents obèses et ceux issus de familles de position sociale et économique défavorisée. Deux études visant à promouvoir l’AP auprès de ces publics ont été menées : des mesures objectives de l’AP avant, pendant et après des interventions ont été réalisées dans deux contextes de prise en charge différents. L’objectif de la première étude était de tester la faisabilité et l’impact d’un programme d’AP à destination d’adolescents issus de milieux défavorisés en impliquant également un de leur parent. 18 parents et 22 adolescents ont participé au programme 1 parent – 1 ado. Il comportait deux fois deux heures d’AP par semaine pendant onze semaines pour chacun des groupes participants. Les niveaux d’AP ainsi que plusieurs paramètres anthropométriques, physiologiques et psychologiques ont été recueillis. Tous les participants ont suivi les onze semaines d’intervention. Les analyses ont montré que le seuil de 60 min d’AP quotidienne était atteint, uniquement pendant la durée du programme pour les adolescents. Celui de 30 min pour les parents l’était à tous les temps de mesures. Des analyses complémentaires ont révélé 1) des effets de la prise en charge sur l’AP modulés par l'âge chez les adolescents et par l'assiduité chez les parents, 2) une diminution de l’amotivation pour les adolescents les plus assidus et 3) une augmentation du bien-être pour les adolescents. Les résultats de cette étude pilote ont mis en évidence la faisabilité et l'efficacité d'un tel programme qui pourrait maintenant être déployé sous la forme d'un essai randomisé incluant un groupe contrôle.L’objectif de la deuxième étude était de tester les effets d’une prise en charge pluridisciplinaire de 10 mois sur l’indice de masse corporelle (IMC) et les niveaux d’AP d’adolescents obèses (21 garçons et 41 filles âgés de 14 ans avec un IMC de 33 kg/m²) dans un centre de Soins de Suite et de Réadaptation (SSR). Le rôle modulateur du climat parental et de la motivation de l’adolescent sur l’efficacité de la prise en charge a été évalué. Les résultats indiquent un effet positif de la prise en charge avec une diminution de l’IMC et une augmentation de l’AP au cours de la cure et quatre mois après. De type curvilinéaire, la perte de poids est forte en début de cure puis se stabilise à la fin. Le climat parental semble jouer un rôle facilitateur lors de cette amélioration, notamment par le père, lorsqu’il est perçu comme étant plus chaleureux, plus impliqué et soutenant davantage l’autonomie. Ces programmes de promotion de l’AP génèrent des résultats prometteurs sur les niveaux d’AP des adolescents. Cependant, l’étude des déterminants du maintien des changements obtenus pendant les interventions doit être poursuivie. / This thesis is based on the observation of the lack of physical activity (PA) in adolescents: approximately 80% of this age group does not reach the recommended daily 60 minutes. This situation and its important health consequences, has a greater impact on the most vulnerable young people, such as obese adolescents and those from socioeconomically disadvantaged families. Two studies aiming at promoting PA to these audiences were conducted: objective measures of PA before, during and after interventions were performed in two different PA program settings.The goal of the first study was to test the feasibility and the impact of a PA program for adolescents from disadvantaged backgrounds. For each adolescent, one of their parents was also involved. Thus, 18 parents and 22 adolescents participated in the “1 parent - 1 adolescent” program. Two hours of PA twice a week during eleven weeks were proposed for each of the participating groups. PA levels and several anthropometric, physiological and psychological parameters were collected. All participants followed the eleven weeks of intervention. The analyzes showed that the daily 60-min AP threshold was reached only during the program for adolescents. The daily 30 min for parents was reached at all measurements times of. Additional analyzes revealed 1) that program efficacy on PA level was modulated by age for adolescents and by attendance rate for parents, 2) a decreased of amotivation for the most assiduous adolescents, and 3) an increase in well-being for adolescents. The results of this pilot study highlighted the feasibility and effectiveness of such a program, which could now be deployed in the form of a randomized trial including a control group.The goal of the second study was to test the effects of 10-month multidisciplinary residential weight reduction program on body mass index (BMI) and PA levels of obese adolescents (21 boys and 41 girls aged 14 years with a BMI of 33 kg / m²). The modulating role of parental climate and motivation of the adolescent on the effectiveness of the care was evaluated. The results indicated a positive effect of the program with a decrease in BMI and an increase in PA during the course of treatment and four months after. With a curvilinear shape, the weight loss was strong at the beginning of the cure and then stabilized at the end. The parental climate seemed to play a facilitating role in this improvement, especially by the father, when he was perceived as being warmer, more involved and more supportive of autonomy. These PA promotion programs generate promising results on adolescent PA levels. However, the study of the determinants of the maintenance of changes during interventions must be continued.

Previous studies targeting youth participation in physical activity have argued that self-motivation is the main key to increasing participation. However, few studies have focused specifically on the role of structural factors in prompting youth participation in physical activity. The structure may include people, and institutions that are introducing, providing and facilitating physical activity to youth. Therefore, this study focuses on the role of the structure surrounding youth. The study takes youth in Saudi Arabia aged 15-24 as its subjects in order to examine the use of three online social networks (OSNs), i.e., Facebook, Twitter, and Instagram, for communication and exchange of resources and the influence on participation of key decision makers such as home (parents and siblings), school (Ministry of Education and PE teachers), physical activity and sports clubs (General Authority of Sports [GAS]), and friends. The study uses mixed methods and follows the social network structural theory to examine how the exchange of resources (e.g., information, emotional support, financial support, and facilities and services) takes place between agent and structure. The main findings are that the structure plays a role in influencing participation among Saudi youth. Friends are of great influence, as they occupy the longest hours of youth time both at school, where friends interact in person, and outside of school, where friends communicate through OSNs. An Islamic and conservative society prevails in Saudi Arabia, where 99 per cent of the population is Muslim. Therefore, in addition to the structural factors noted above, religion is also investigated. Indeed, Islam drives motivation in this large conservative group as individuals learn to obey and implement the religious advice and Islamic teachings of the prophet Mohammed (peace be upon him), including those messages with relation to becoming a healthy and strong Muslim. Finally, the study also focuses on the participation of Saudi female youth in physical activity. Due to cultural reasons preventing women from participating in physical activity as freely and equally as their male peers in the country, Saudi Arabia has seen an increasing percentage of obese women. The main aim of this research is to understand the relationship between agency and structure and thereby to identify the role of structure in increasing the participation of youth in physical activity. The research question (How do OSNs facilitate Saudi youth participation in physical activity?) investigates the relationship between agency and structure to delineate the pattern of information exchange regarding resources for involvement in physical activity. Through the use of mixed methods including face-to-face interviews, online survey and digital ethnography, the researcher investigates how youth social networks function both offline and online. The study concludes that decision makers in the field of physical activity participation in Saudi Arabia vary in their level of encouragement, influence and communication. Family members do not seem to communicate with youth via online platforms, but they do play a crucial role in offline social networks. Private institutions are becoming very active in OSNs, and public institutions are following the trend, albeit at a slower pace. The study shows that physical activity facilitators in Saudi Arabia are still failing to effectively reach youth and encourage them to participate in physical activity. Various policies need to be reviewed and enhanced if the public institutions do indeed want to reach more youth and benefit youth and the community, including the female youth, who make up more than half of the population. The study shows that the way to develop these policies is to communicate with youth via OSNs and to provide youth with more facilities, venues and services in the country that are suitable for both genders.

Le suivi et la compréhension des états de stress et de récupération des sportifs est un enjeu majeur, notamment dans le cadre de périodisations complètes de l’entraînement. Un déséquilibre mal maîtrisé entre le stress et la récupération peut induire une fatigue voire un épuisement psychologique et physiologique du sportif. Il en découlera des conséquences néfastes sur le bien-être et la santé de la personne mais également sur la performance individuelle et collective. Ces conséquences sont complexes et impliquent des dimensions environnementales, sociales, psychologiques et physiologiques non-spécifiques. Enfin, ces symptômes sont soumis à des variations intra et interindividuelles importantes rendant le diagnostic d’autant plus complexe à établir. En s’appuyant sur plusieurs suivis de sportifs en pôle « Espoir », ce travail de recherche montre l’évolution de variables psychologiques et physiologiques intervenant dans la réponse au stress chez le sportif. Ces travaux permettent également de mettre en évidence des variables prédictives des états de stress et de récupération. Enfin, nous démontrons que les états de stress et de récupération des sportifs impactent les états émotionnels au niveau intra et interindividuel. / Monitoring stress and recovery states is a key issue, especially in high performance sport. An imbalance between stress and recovery can induce fatigue, psychological and physiological exhaustion. Thus, negative consequences on well-being, health and individual and collective performance can be experienced. These consequences are complex as they stem from non-specific environmental, social, psychological and physiological dimensions. These phenomena are subject to important intra-individual and inter-individual variations, which make a diagnosis hard to establish. Based on a several followings of athletes from high performance structures, this research shows the evolution of psychological and physiological variables intervening as a response to stress. From these studies, some predictive variables also showed up in predicting stress and recovery states. Finally, we made evidence of the impact of athletes’ stress and recovery states on emotional states, on the intra and inter-individual levels.

L’organisation biologique, du niveau moléculaire jusqu’au niveau des performances de l’organisme. La locomotion est une fonction neurophysiologique hautement intégrée illustrant un tel processus multi-échelle. Le déclin des performances de locomotion avec l’âge, comme la vitesse maximale, a été observé pour de nombreuses espèces, aussi bien en captivité qu’en milieu naturel. Cependant, ces descriptions restent souvent succinctes, sans précision sur la progression de ces performances au cours du vieillissement. Dans ces travaux, nous utilisons une équation bi-phasique pour décrire la relation entre performance de locomotion et âge sur l’ensemble de la durée de la vie pour Caenorhabditis elegans, Mus domesticus, Canis familiaris, Equus caballus et Homo sapiens. Les performances maximales de locomotion se révèlent être des bio-marqueurs robustes pour suivre la progression des performances sur l’ensemble de la durée de vie des animaux, permettant ainsi d’estimer le pic physiologique et le début du déclin des performances. De plus, dans tous les cas, nous remarquons que la forme de progression des performances maximales selon l’âge est similaire et conservée d’une espèce à l’autre ; seule varie la pente dans le temps, dépendant de l’espèce et la performance mesurée. L’observation des performances selon le genre ne montre pas de différence dans la forme de l’enveloppe. Néanmoins, elle révèle des écarts variables dans les performances maximales entre femelles et mâles selon les espèces. Enfin, les conditions thermiques affectent les performances maximales de locomotion, mais la forme de l’enveloppe reste aussi préservée. Nous avons ensuite étudié le développement et l’expansion de cette dynamique au cours du siècle dernier pour les performances athlétiques maximales d’Homo sapiens. Cette étude révèle que la forme s’est progressivement précisée au cours du temps en s’étendant à tous les âges et suivant homothétiquement la progression des records du monde. Néanmoins, la progression semble ralentir au cours des dernières décennies, laissant présager l’atteinte possible des limites biologiques d’Homo sapiens. Ces travaux offrent de nouvelles perspectives sur l’utilité des approches comparatives et l’utilisation d’un bio-marqueur comme les performances de locomotion pour suivre les dynamiques sur l’ensemble de la durée de vie à différentes échelles. Elles apportent aussi un regard novateur sur la progression des performances avec l’âge, en intégrant à la fois les processus de développement et de vieillissement, permettant ainsi de préciser les pics physiologiques et la forme des progressions des performances sur toute la durée de la vie. / Aging is a complex, multi-scale process that affects all levels of biological organization from molecular structure to individual behavior. Locomotion is a highly integrated neurophysiological function that illustrates this process. The functional decline in locomotion with age has been described in a wide-range of species, both domestic and wild, and appears as a common aspect of senescence among animals. However, in most cases these descriptions remain incomplete and the dynamics of age-related changes are poorly understood. Here, we use a conceptual feature to describe age-related changes in locomotor performances for Caenorhabditis elegans, Mus domesticus, Canis familiaris, Equus caballus and Homo sapiens. We show that measurements of locomotor performance are consistent biomarkers of age-related changes, with a well preserved pattern regardless of the type of effort or duration. We also show that age-related pattern for locomotor performance are modulated by gender and environment. Nevertheless, in every case, the pattern remains similar and very well preserved. The second part of this work introduces the concept of phenotypic expansion and focuses on the expansion of the age-related pattern for Homo sapiens during the last century. Since the first edition of modern Olympic Games in 1896, athletes have consistently improved previous records, echoing scientific and industrial progress. Their data constitute privileged and accurate biomarkers, as sport performances reflect highly integrated neuro-physiological traits based on complex multifactorial interactions. Following the progression of the world records, the age-related pattern expanded gradually during the 20th century. However, the last decades show a slow-down in the expansion, following again the recent asymptotic levelling off of world records, which no longer supports the historical motto “Citius, Altius, Fortius”. This work provides new insights about the utility of an age-based comparative approach to provide a thorough understanding of aging processes and also for gaining insights into aging at different levels of biological organization and in an evolutionary perspective.

L’objectif majeur de cette thèse a été d’appréhender les conséquences de la comparaison sociale sur l’auto-évaluation implicite et explicite en termes de prudence, les affects et les comportements à risque. Les participants ont été exposés à un standard de comparaison prudent (standard haut) ou imprudent (standard bas) en matière d’alcool. Les résultats montrent que les sujets confrontés au standard haut se perçoivent implicitement plus imprudents et ressentent plus d’anxiété que les sujets exposés au standard bas. En revanche, le standard de comparaison n’influence pas l’auto-évaluation explicite et les comportements contrôlés. Ces résultats témoignent en faveur d’une dissociation entre les processus automatiques (implicites) et contrôlés (explicites) en jeu dans la comparaison sociale. Au niveau appliqué, nos données suggèrent que dans une campagne de prévention il serait potentiellement plus efficace de mettre en scène un standard prudent plutôt que de montrer un preneur de risque. / The main goal of this PhD research was to study the consequences of social comparison on implicit and explicit self-evaluation in terms of cautiousness, on affect and on risk-taking behavior. In a series of studies, participants were exposed to a comparison standard who displayed either cautious (high standard) or reckless (low standard) drinking behavior. Results show that participants confronted with the high standard implicitly perceive themselves as more reckless and experience higher levels of anxiety than participants exposed to the low standard. On the other hand, the comparison standard does not influence explicit self-evaluation and controlled behaviors. These results indicate that there might be a dissociation between automatic (implicit) and controlled (explicit) processes involved in social comparison. On an applied level, regarding alcohol prevention campaigns, our findings suggest that it could be more effective to show a cautious standard rather than a reckless one.

Le conflit fémoro-acétabulaire (femoroacetabular impingement, FAI) est une pathologie mécanique de la hanche qui peut causer des douleurs et limitations fonctionnelles. Le but de cette thèse était d’étudier la fonction musculaire au niveau de la hanche chez des patients présentant un FAI symptomatique. La fonction musculaire de la hanche a été évaluée, dans un premier temps, chez des patients avant qu’ils ne subissent une opération. Ces patients démontraient un déficit de force qui pourrait être expliqué par de l’inhibition musculaire. Cependant, ce déficit de force n’était pas associé à une plus grande fatigabilité musculaire. Dans un deuxième temps, les altérations de force musculaire ont été évaluées chez des patients ayant subi une arthroscopie de la hanche. Après l’opération, les patients récupéraient un niveau de force normal au niveau de tous les groupes musculaires de la hanche excepté les fléchisseurs. Le cas d’un joueur de hockey sur glace ayant subi une chirurgie ouverte aux deux hanches pour traiter un FAI bilatéral a aussi été décrit. On a démontré que la déhiscence de la bandelette iléo-tibiale pouvait survenir après chirurgie, empêcher l’augmentation de force musculaire des abducteurs de la hanche, et retarder la reprise du sport. Enfin, un protocole d’évaluation du taux de développement de la force normalisé, variable permettant d’estimer l’inhibition musculaire de la hanche, a été proposé chez des sujets sains. La fiabilité et reproductibilité des résultats ont été montrées au niveau des adducteurs, rotateurs externes, et fléchisseurs de la hanche. Ces résultats montrent que ces patients ont une fonction musculaire altérée au niveau de la hanche, qui est toutefois récupéré après une opération. / Femoroacetabular impingement (FAI) is a pathomechanical process of the hip joint, which could lead to hip pain and functional disability. Aim of this thesis was to investigate hip muscle function in patients with a symptomatic FAI. Hip muscle function was first investigated before patients underwent any surgical treatment for managing FAI. It was shown that they present with reduced hip muscle strength (i.e., muscle weakness), probably due to hip muscle inhibition. Nevertheless, hip muscle weakness was not associated with exaggerated hip muscle fatigue. Hip muscle strength recovery was then evaluated in a series of patients after hip arthroscopy to treat FAI. These patients demonstrated a good recovery for all hip muscle groups, except for hip flexors. The case of a professional ice hockey player who underwent bilateral hip open surgeries for treating bilateral FAI was also documented. This report showed that iliotibial band dehiscence could occur after hip open surgery, thereby preventing hip abductor strength increase during rehabilitation and delaying the return to sport. In addition, the assessment of the rate of force development scaling factor for the hip muscles was evaluated in a group of healthy adults. This parameter seems to be promising for the evaluation of hip muscle inhibition. The testing protocol was feasible and reproducible for hip adductors, external rotators and flexors. Taken as a whole, these findings show that patients with symptomatic FAI demonstrate an impaired hip muscle function, which is however mainly resolved after surgical treatment.

Physical inactivity and disconnection from natural environments threatens human health. However, research has demonstrated that natural environments potentially support health-enhancing physical activity which could confer greater physical and mental health benefits than physical activity in other types of environment. This thesis approached the study of physical activity in natural environments through three related pieces of research. Firstly, an experimental study was carried out to explore how the presence of litter in beach environments affected psychophysiological responses to exercise. Responses to exercise did not differ in littered and clean conditions but there was evidence that order effects influenced findings. Visual attention to the two scenes differed, but did not mediate differences in psychophysiological responses. Secondly, analysis of a national dataset was undertaken to explore the form and quantity of physical activity conducted within natural environments in England. A series of linear regressions revealed that higher-intensity physical activities occurred in countryside environments, but more total energy expenditure occurred in coastal environments. Thirdly, a quantitative content analysis of brochures which promote recreational walking in natural environments was conducted which investigated their use of persuasive behavioural messages. These brochures omitted behavioural techniques which may be effective at motivating inactive individuals to walk. Extending this, an online survey tested whether improving brochure content heightened intentions to walk in natural environments. By designing content based on the theory of planned behaviour, the intentions of inactive individuals to undertake walking in natural environments were increased. The findings from this thesis demonstrate that the protection of natural environments is vital for preserving and promoting active recreation and could contribute to population-level increases in physical activity with theory-based promotion in the future.