Muscle performance is partially a consequence of its recent contractile history. Postactivation potentiation (PAP) can occur after muscle contractions and leads to enhanced neuromuscular performance. The purpose of this dissertation was to explain the relationship between muscle factors (twitch potentiation, TP) and neural factors (reflex potentiation, RP) contributing to overall PAP following a non-fatiguing volitional muscle contraction. The tibial nerves of fifteen resistance trained volunteers (eleven men, four women) were stimulated intermittently at supramaximal (Mmax) and submaximal (Hmax) intensities for 20 minutes on separate days under three conditions: rest (Control); after a after a 10 second maximum voluntary isometric contraction (MVIC) of the plantarflexors; and after a low frequency fatigue protocol prior to the MVIC. Plantarflexion isometric torque and rate of force development (RFD), and soleus and gastrocnemius EMG Hmax/Mmax ratios, were analyzed. Both experimental conditions resulted in TP at 10 seconds post-MVIC compared to the control condition. The two experimental conditions were not different for any measure. Torque and RFD at Hmax (overall PAP) were highest at 3 and 4.5 minutes post MVIC, respectively, but were not significantly different from the control condition. EMG values generally were insignificantly increased in the experimental conditions versus the control condition. Mmax torque and RFD significantly contributed to Hmax torque and RFD at 20 seconds, Hmax peak, and 20 minute post-MVIC time points. The soleus significantly contributed to Hmax torque at 20 seconds and 20 minutes post-MVIC, and Hmax RFD at 20 seconds, 4.5 minutes, and 20 minutes post-MVIC. The results of this study suggest that both muscle and neural factors play a significant role in overall PAP, and that neural factors may play a more meaningful role in RFD potentiation than torque potentiation.

The research presented in this thesis examined the issue of the compatibility of strength and endurance training within one training regime, termed concurrent training, in recreational cyclists. Various research designs used in the previous literature resulted in inconclusive findings. The overall aim of this thesis was therefore to examine, in three systematically designed studies, the effects of various components of concurrent training regimes on cycling efficiency and recovery, and to identify some of the mechanisms that may be responsible for the interference or impedance of strength and/or endurance adaptations.

The development of technology has created many platforms for entertainment, participatorycommunities and socialization online. One of the largest current platforms for live streamingis Twitch.tv with a focus on gaming and eSports. This is a male-dominated field wherewomen often face harassment and a non-welcoming community. This paper is a qualitativestudy of the negative communication towards female streamers on Twitch with a focus onthe context in which said communication takes place. The aim of the study is to understandthe circumstances in which negative communication occurs and how it changes dependingon context. The study takes a qualitative approach and analyses the content of six streamsfrom five different channels, as well the negative communication in their chat room. Theresults show that negative communication varies depending on the content as well as thenature of the community built around the channel.

The development of digital economies, digital environments and digital collaborative cultures has enabled entrepreneur-like content creation and distribution through digital platforms and new media. In recent years the profession of livestreamers has become increasingly more popular. This study attempts to find out the factors behind livestreamers value-creating processes as well as how these processes help them stay relevant in the future. To do this, we have conducted a couple of interviews with up-and-coming streamers. In addition to this we have also orchestrated several observations on some of the most successful streamers. In these observations we applied the use of the framework Business Model Canvas. The results from our completed data collection presents several different factors behind value creation in streaming.  The conclusion we made which was based on the analysis of our result are divided into four significant factors. These are interaction, motivation, marketing and external communication, as well as personality and competence. We hope that our findings can help define and explain the value-creating processes in streaming.

La recherche sur les loisirs sérieux dans le monde du divertissement web a fait l’objet de nombreux articles sans pour autant faire de parallèles conceptuels explicites. Les acteurs sociaux cherchent habituellement un équilibre durable entre activité professionnelle et loisir dilettante. Il existe une part de ces individus qui s’investissent sérieusement dans une activité ludique sans devenir professionnels. Notre recherche veut s’intéresser à ces individus en comprenant comment ces acteurs se démarquent sérieusement sans s’apparenter aux dilettantes et sans égaler le niveau des professionnels. Nous comprenons au travers de cette étude qu’il existe de multiples profils autour de 5 dimensions sérieuses. En effet, chaque participant interrogé s’identifie ou explique la raison pour laquelle chaque dimension lui semble plus logique qu’une autre. En parallèle, l’application de ces dimensions fait intervenir l’apparition des ressources sous forme de capitaux. Si l’agencement de toutes les dimensions peut créer des opportunités capitalistiques sérieuses ou professionnelles, notre étude montre qu’un acteur usant de loisir sérieux ne génère habituellement pas de capitaux substantiels permettant des transitions de carrière. En revanche, il peut espérer tirer des capitaux communautaires grâce aux fruits de ses efforts. Ses capitaux communautaires sont représentés par un rassemblement de spectateurs regardant son contenu, discutant avec lui et versant occasionnellement des compensations monétaires. Au terme de cette recherche, nous souhaitons montrer les motivations derrière les activités du loisir sérieux sur une plateforme participative tout en nous questionnant sur la place du streaming au Québec. Étant placés entre l’enclume et le marteau d’une majorité anglophone dans une petite région francophone, nous élaborons la conclusion que les streamers sérieux du Québec se munissent de dimensions sérieuses afin de contourner ce problème d’un public minoritairement francophone. / Research about serious leisure in the web leisure world has been subject to many articles without proper explicit bridges between the two. Social actors are usually looking for long term balance between a professional activity and a leisure dabble. There is a part of these individuals seriously investing themselves in an activity without becoming an actual professional. Our research wants to focus on those individuals while understanding how they stand out in a serious fashion without looking like other dabblers and without being as efficient as professionals. We understand through this study that there are multiple profiles revolving around 5 different serious dimensions, each interviewed participant identifies himself or explains the reason why each dimension seems more logical than another. At the same time, applying those same dimensions can create ressources in the shape of capitals. If the alignment of all those dimensions may create serious or professional capitalistic opportunities, our study shows that an actor using serious leisure don’t usually generates enough substantial capital to shift into a full time streamer professional. However, he can hope gaining communal capitals thanks to his efforts. Those communal capitals are represented as a crowd of spectators watching his content, chatting with him or occasionally offering monetary compensations. At the end of this research, we wish to show the motivations behind serious leisure activities on participative platform while questioning ourselves about the place of streaming in Quebec. As it is stuck between the hammer and the anvil of an English speaking majority in a restricted French speaking territory, we conclude that serious streamers from Quebec are soliciting serious dimensions helping them overcome this issue of a small French speaking community.

Introdução: Os músculos da mastigação masseter, temporal, pterigóideo medial e pterigóideo lateral são componentes essenciais do sistema estomatognático. A mastigação decorre da movimentação destes músculos. Além da função fisiológica, os músculos da mastigação estão envolvidos na disfunção temporomandibular (DTM) que é importante causa de dor, sons articulares e função mandibular irregular ou limitada. As DTM representam a maior causa de dor não dental na região orofacial, sendo a causa muscular a mais prevalente. O conhecimento detalhado da composição estrutural e funcional dos músculos da mastigação é fundamental para a compreensão dos mecanismos da DTM muscular. Objetivos: Analisar a distribuição da expressão das isoformas de miosina (rápida e lenta) e, a quantidade de fibras híbridas nos músculos temporal e masseter em material de autópsia da 1a a 9a décadas. Casuística e métodos: Foram estudadas 37 amostras dos músculos temporal e masseter (20 amostras do sexo masculino e 17 do sexo feminino) de autópsias do Serviço de Verificação de Óbitos de São Paulo com intervalo pós-mortem de até 18 horas, de ambos os gêneros e com idades divididas por décadas (1a a 9a décadas). Resultados: Não houve diferença estatística significante na porcentagem de fibras rápidas, lentas e híbridas no músculo masseter e temporal quanto ao gênero, quanto à porcentagem de fibras rápidas e lentas na amostra total e nos grupos de jovens, adultos e idosos. Foi encontrada diferença estatisticamente significante apenas na porcentagem de fibras rápidas do grupo de idosos, onde o masseter apresentou maior número de fibras rápidas. Foi encontrada diferença significante entre os grupos estudados na porcentagem de fibras híbridas no músculo masseter, onde o grupo jovem apresentou mais fibras híbridas do que o adulto e este grupo mais que o grupo idoso. Também houve diferença significante entre os grupos estudados na porcentagem de fibras híbridas no músculo temporal, onde o grupo jovem apresentou mais fibras do que o grupo adulto e idoso. Conclusão: Ao longo das nove décadas a percentagem de fibras lentas foi similar a percentagem de fibras rápidas nos músculos masseter e temporal. Quando a análise foi realizada separadamente comparando-se os músculos masseter e temporal houve diferença estatística (p=0,023*) no grupo idoso com predomínio de fibras rápidas no músculo masseter. Observou-se fibras híbridas presentes desde a primeira década (1 mês de vida) persistindo até a nona década com predomínio no grupo jovem, presença decrescente ao longo das décadas no músculo masseter (p < 0,001*). No músculo temporal observou-se predomínio de fibras híbridas no grupo jovem em relação aos grupos adulto e idoso (p = 0,011*) / Introduction: The masticatory muscles: masseter, temporalis, medial pterygoid and lateral pterygoid are essential components in the estomatognatic system. The mastication occurs through the function of these muscles, which provide direct contact between the upper and inferior arcades. In addition to their fisiologic function, the maticatory muscles are involved in the temporomandibular disfunction (TMD), which is an important cause of the pain, joint sounds and irregular or limited mandibular function .The TMD are seen as a distinct subgroup of reumatologic.and skeletal muscle disorders. They are the main cause of non dental pain in the orofacial area, being the muscular etiology as the most prevalent. The detailed understanding of structural and functional composition of the masticatory muscles is paramount to comprehend TMD due to muscle disorder. Objective: To analyze the muscle fiber type distribution concerning fast and slow myosin expression, and the amount of hybrid fibers in temporalis and masseter muscles in autopsy samples from 1st to 9th decades of age. Casuistics and methods: Tirthy seven temporalis and masseter muscles samples were studied (20 from male and 17 from female) from Serviço de Verificação de Óbitos of São Paulo. The specimens were divided by gender and ages. The samples were collected up to 18 hours post-mortem. Results: The percentage of slow muscle fiber in masseter and temporalis muscles were similar to the percentage of fast muscle fibers, when the samples were analyzed in the totality. However, when they were grouped in three different subgourp of ages: yound, adult and old, elder subjects presented more fast than slow muscle fibers in masseter. There was no significant gender difference in masseter and temporalis muscles concerning fast and slow muscle fiber distribution. Significant difference of hybrid fiber distribution was observed among the young, adult and old groups. Young subjects presented more hybrid fibers than adult, who presented more than elder subjects in masseter. In temporalis, hybrid fibers were more observed within young group than adult or elder group. The presence of hybrid fiber was confirmed with the immunostaining of a single muscle fiber. Conclusion: Slow and fast muscle fiber distribution is similar in both masseter and temporalis muscles in both gender subjects along the nine decades of age. However, when the samples was grouped in three subgroup of ages, fast muscle fibers significantly predominate (p=0.023) in masseter among the old group. Hybrid fibers were observed through out the first to nineth decade of age. The frequency of hybrid fibers decreased significantly (p<0.001) with aging in masseter. In contrast, hybrid fibers were more observed among young than adult or old groups (p=0.011) in temporalis

Lack of Improvement in Insulin Responsiveness in the Metabolic Syndrome after Resistance Training Only May Be Due to Fewer Muscle Slow-Twitch Fibers and Decreased Activation of AMPK Ten non-diabetic subjects (fi Ten non-diabetic subjects (five males, five females) with the Metabolic Syndrome underwent eight weeks of supervised strength training. Training consisted of five weekly sessions. A brief orientation period was followed by two blocks of progressively increasing intensity training. Nine control subjects were trained at the same time following the same protocols. At the completion of training, strength and VO[sub]2[/sub]max increased by 10% in both groups, but body composition and body weight had not changed. Insulin responsiveness, quantified using a three hour euglycemic clamp procedure, did not improve in the insulin resistant Metabolic Syndrome subjects, but increased significantly (13%) in the control group. Control subjects had significantly more slow-twitch muscle fibers at baseline (50% vs. 36%). The fiber composition was not changed in either group by training. Expression of GLUT4, the principle insulin-responsive glucose transporter, increased significantly in both groups (39% in Metabolic Syndrome subjects, 76% in the control group). The muscle mitochondrial biogenesis pathway reflected by AMPK total expression and activation, and the muscle hypertrophy pathway as indicated by mTOR expression and activation were increased in both groups. Even though total AMPK and total mTOR increased about 40% in both groups, the change in activated phospho-AMPK was greater in the control group (38% vs. 8%), and the activated phospho-mTOR increased more in the Metabolic Syndrome group (50% vs. 25%). Since AMPK is predominantly expressed in slow-twitch muscle fibers and mTOR is expressed at higher levels in fast-twitch fibers, these data may reflect the difference in fiber composition between the two groups. Strength training resulted in qualitatively similar effects on muscle remodeling in persons at low risk or high risk for diabetes, but greater activation of AMPK was associated with increased insulin responsiveness. In Metabolic Syndrome subjects, resistance training alone activated muscle hypertrophy pathways and increased muscle GLUT4 expression, but did not improve insulin responsiveness.

Psychedelics are a subset of hallucinogenic drugs that exert their characteristic effects through agonist activity at the serotonin receptor 2A (5-HT2A). In this study, I aimed to characterize the modulatory role of the metabotropic glutamate subtype 2 receptor (mGluR2) in the 5-HT2A-specific rodent model of hallucinogenic action, head-twitch response (HTR). Secondly, I aimed to explore if 5-HT2A agonist-induced deficits in prepulse inhibition (PPI) of the startle response, an additional model of hallucinogenic action, could be produced in mice. Though 5-HT2A agonist-induced PPI deficits, which represent interruptions in normal sensorimotor gating, have been described in both rats and humans, attempts to translate this behavior to mice are rare. In contrast to prior gene knockout studies suggesting the mGluR2 is necessary for 5-HT2A agonist-induced HTR, mGluR2 knockout (Grm2-/-) mice still displayed HTR upon administration of the psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI). Additionally, DOI and lysergic acid diethylamide (LSD) produced unexpected improvements in PPI in male 126S6/Sv wild-type mice, depending on the experimental protocol used and the origin of the animals. Sex differences were observed as DOI-induced improvements in PPI were present in female 129S6/Sv mice of the same origin and tested with the same protocol as their male counterparts; this effect in females was absent in 5-HT2A knockout (Htr2a-/-) mice. The results of this study shed light on issues with replicability and reproducibility in science, the importance of highlighting the origin and background of animal subjects, and potential sex differences in hallucinogenic drug action.

The fast-skeletal-muscle-fiber-specific expression of the troponin I(fast) (TnIfast) gene is driven by an Intronic Regulatory Element (IRE) located within the first intron of the gene. The IRE is a 148 bp transcriptional enhancer that contains several known and suspected cis-regulatory elements. These include the E-box, the closely-spaced MEF2 site and CACT box, the CACC site, and the CAGG element. Previous loss-of-function studies performed using the quail TnIfast IRE suggest that its activity depended on the MEF2 and CACT elements. The goal of my thesis research was to determine whether the MEF2 and CACT sites were not only necessary, but also sufficient, to support IRE activity. I prepared head-to-tail multimers of a 27-bp IRE segment that consisted largely of the near-adjacent MEF2 and CACT elements and did not contain any other known/suspected elements. These multimers were cloned upstream of a reporter gene consisting of the minimal promoter of the quail TnIfast gene linked to sequences encoding human placental alkaline phosphatase. The transcriptional capabilities of the constructs were assessed by gene transfer into the mouse soleus muscle in vivo by intramuscular injection/electroporation, and histochemical analysis of reporter enzyme plap expression including quantitative microdensitometry. I found that expression of these constructs was readily detectable and that it was markedly reduced by prior mutation of the CACT and, especially, of the MEF2 sites. These data indicate that the short DNA segment containing MEF2 and CACT elements is sufficient to drive expression in skeletal muscle and confirms the functional importance of these specific elements. / Although constructs containing the wild-type IRE 27-bp region were expressed, there was little preferential expression in fast fibers, in contrast to expression driven by the complete 148-bp IRE. Thus my results indicate that the MEF2 and CACT elements are not sufficient to drive fast fiber-type-specific expression, and suggest that additional elements outside of the 27-bp region tested are also necessary for fiber-type-specificity.

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