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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Effects of Resistance Training with Heat Stress on Muscle Mass, Strength and Performance

Drew, Sean January 2019 (has links)
Background: Recent research has demonstrated the presence of heat being an effective stimulus for increasing skeletal muscle and strength. The exposure of increased environmental temperature combined with resistance training has been shown to amplify muscle adaptation for hypertrophy and strength. However, research into the potential effects of using heat stress combined with resistance training to increase performance criteria, such as speed and agility, are minimal. Utilizing a hot environment coupled with an intense exercise regime has been considered as a potential aid for sport preparation given the evidence that heat stress has on promoting hypertrophy and strength. The desired result is to enhance athletic performance. Aim: The aim of this study was to examine if (a) performing resistance training in a hot environment for 10 weeks induces greater increases in muscle mass and (b) whether this combination improves performance in speed, agility and strength compared to resistance training in a standard temperate environment. Methods: 17 healthy male adults, who have undergone a consistent regime of resistance training in the six months leading up to the study, were distributed at random into two groups; (1) Intervention group (Heat n=8) training in 40°C and (2) control group (Con, n=9) training in 23°C. Each group would follow a 10-week resistance exercise protocol. To monitor time-course adaptations, lean body mass, speed, agility and strength were measured at baseline, week 5 and week 10. Results: Over the selected training period, there was no statistically significant difference observed between the two groups or time x group interaction, over the 10-week exercise duration with respect to lean body mass, speed, agility or strength. Conclusion: Compared to the resistance training regime in the standard temperature condition of 23°C (group two), training results suggest heat stress in the hot environment at 40°C (group one) had no effective stimulus in amplifying hypertrophic adaptations in skeletal muscle nor in increasing performance in speed, agility or strength. Certain hypothetical factors were implicated for heat stress being ineffective such as potential counter-productive aspects from heat exposure or flawed methodology. / Heat Effects on Adaptations to Resistance Training, Victoria University
32

Úbytek svalové hmoty - sarkopenie u seniorů / The decline in skeletal muscle mass - sarcopenia in seniors

KADEŘÁBKOVÁ, Hana January 2019 (has links)
As the age increases, the physical fitness of seniors decreases. This shows the fragility of their body. Managing everyday activities becomes increasingly more difficult for them. Result of this is reduced self-sufficiency of the seniors, which leads to reduced mobility and to the greater loss of muscle mass and higher dependence on professional care. Aging is accompanied by loss of muscle mass and muscle strength - sarcopenia. This is one of the main causes of geriatric fragility. Sarcopenia presents a serious health problem with both social and economic consequences. The term sarcopenia (from Greek words sarx - meaning flesh referring to muscle and penia - loss) was first used in 1989 by Irwin Rosenberg to describe the loss of muscle mass accompanying aging. Exactly defining the term sarcopenia has helped explain this gradual loss of muscle mass. Three objectives were set in the thesis. The first objective was to find out whether sarcopenia reduces the quality of life in the elderly. The second goal was to determine, which quality of life tests are suitable for testing sarcopenia and the last one was whether the SARC - F questionnaire predicts sarcopenia.Quantitative research was used for the empirical part of this work. Data collection was performed using a method of a questionnaire. These were standardized questionnaires aimed at assessing sarcopenia and quality of life. The research was carried out with a total of 77 respondents with sarcopenia and respondents without sarcopenia. The quantitative part of the research was statistically processed using the MS Excel computer program.
33

Caractérisation du métabolisme protéique musculaire au cours de l'obésité et lors de la perte de poids

Masgrau, Aurélie 03 July 2012 (has links)
L'obésité - caractérisée par l'accumulation de lipides dans le tissu adipeux, puis dans les tissus périphériques tels que le foie et les muscles squelettiques - entraine des dysfonctionnements métaboliques de ces tissus. Sur le long terme, même s'il est fréquemment rapporté une augmentation de la masse maigre, l'obésité s'accompagne d'une perte de masse musculaire. La perte de poids a un impact positif sur les comorbidités associées à l'obésité. Toutefois, lorsqu'elle est induite par une restriction alimentaire, elle peut être associée à une perte demasse musculaire. L'association d'une activité physique à la restriction alimentaire peut limiter la perte de muscles. Sur le plan métabolique, la masse musculaire dépend essentiellement du renouvellement des protéines qui le composent. Aussi, l'objectif du travail de thèse a été de caractériser les modifications du métabolisme protéique musculaire, et particulièrement les modifications de la protéosynthèse, au cours du développement de l'obésité et pendant une perte de poids induite par un régime hypolipidique associé ou non à un exercice d'endurance. La première étude a permis de montrer qu'il existe deux phases distinctes lors du développement de l'obésité chez le rat. La première est associée à un gain de poids et de masse musculaire, associée à une augmentation de la vitesse de synthèse (FSR) des protéines myofibrillaires et mitochondriales spécifiquement dans le muscle glycolytique tibialis anterior, en postabsorptif. La seconde est associée à une stabilisation du poids, une réduction de la masse musculaire et à une diminution du FSR des protéines mitochondriales dans le tibialis anterior, alors même qu'une accumulation lipidique se produit dans ce muscle. Le muscle oxydatif soleus n'est pas affecté. La deuxième étude a montré qu'une restrictionlipidique isocalorique ou que la pratique d'un exercice en endurance régulier ne préviennent pas la perte de masse musculaire induite par l'obésité, contrairement à l'association des deux traitements. L'exercice seul ou associé au régime hyperlipidique stimule le FSR des protéinesmyofibrillaires dans le tibialis anterior, mais l'exercice ne stimule le FSR des protéines myofibrillaires et mitochondriales dans le muscle oxydatif soleus que lorsqu'il est associé à la restriction lipidique. En conclusion, ce travail a mis en évidence, d'une part, que la synthèseprotéique musculaire en postabsorptif et la masse musculaire sont différemment affectées en fonction du stade de développement de l'obésité et que, d'autre part, la synthèse protéique musculaire en postabsorptif est différemment affectée en fonction de la typologie musculaire. D'autre part, l'exercice a un impact bénéfique sur la masse musculaire et sur la protéosynthèse, mais cet effet "anabolisant" est limité par le régime hyperlipidiquehypersucré. Pour transposer ces données chez l'homme, une étude clinique qui porte sur l'effet de la perte de poids induite par chirurgie bariatrique sur le métabolisme protéique musculaire a été mise en place et est actuellement en cours. / Obesity - characterized by lipid accumulation in adipose tissue and in peripheral tissues such as liver and skeletal muscles - leads to metabolic dysfunction of these tissues. In the long term, although it is frequently reported an increase in lean mass, obesity is accompanied by a loss of muscle mass. Weight loss has a positive impact on comorbidities associated with obesity. However, when it was induced by dietary restriction, it may be associated with muscle mass loss. The association of physical activity to food restriction may limit muscle mass loss. Metabolically, muscle mass depends essentially on proteins turnover, i.e. protein synthesis and breakdown. Therefore, the aim of the thesis work was to characterize changes in muscle protein metabolism, especially changes in protein synthesis, during obesity development and weight loss induced by a low-fat-diet with or without endurance exercise. The first study has shown that there are two distinct phases in the development of obesity in rats. The first is associated with body weight and muscle mass gains and an increase in myofibrillar and mitochondrial proteins synthesis rate (FSR), specifically in glycolytic muscle tibialis anterior, in postabsorptive state. Oxidative muscle soleus was not affected. The second phase is associated with body weight stabilization, reduced muscle mass and a decrease in the mitochondrial proteins FSR in the tibialis anterior. The second study has shown that isocaloric low-fat-diet or the practice of regular endurance exercise do not prevent muscle mass loss induced by obesity, unlike the combination of both treatments. Exercise alone or associated with high-fat diet stimulates the FSR of myofibrillar proteins actin in tibialis anterior muscle, but exercise stimulates the FSR of myofibrillar and mitochondrial proteins in the oxidative muscle soleus only when it is associated with lipid restriction. In conclusion, this study has shown firstly that muscle protein synthesis in postabsorptive state and muscle mass are differently affected depending on the stage of obesity development, and, secondly that muscle protein synthesis in postabsorptive state is differently affected depending on muscle typology. On the other hand, exercise has a beneficial effect on muscle mass and protein synthesis, but this "anabolic" effect is limited by the high-fat, high-sucrose diet. To transpose these data in humans, a clinical study that examines the effect of weight loss induced by bariatric surgery on muscle protein metabolism has been established and is currently underway.
34

Função e massa muscular em pacientes com doença pulmonar obstrutiva crônica

Sanchez, Fernanda Figueirôa [UNESP] 22 March 2007 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:23:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-03-22Bitstream added on 2014-06-13T18:50:44Z : No. of bitstreams: 1 sanchez_ff_dr_botfm.pdf: 1771868 bytes, checksum: 429488c50f3fd192853726c00c1fd7c1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A doença pulmonar obstrutiva crônica (DPOC) apresenta manifestações sistêmicas e, dentre entre elas, as alterações nutricionais são bastante evidentes. A perda de peso e o índice de massa do corpo (IMC) foram os primeiros indicadores do estado nutricional relacionados ao prognóstico em pacientes com DPOC. Entretanto, estudos recentes ressaltam a maior prevalência da depleção da massa magra do corpo (MMC) nestes pacientes. Embora algumas repercussões da depleção da MMC em pacientes com DPOC sejam conhecidas, as informações sobre a distribuição, mecanismos e características das alterações parecem contraditórios. Alguns estudos sustentam a idéia de que a fraqueza muscular é proporcional à perda de massa muscular. Por outro lado, os resultados de estudos recentes sugerem que as alterações qualitativas ou funcionais são mecanismos, adicionais à atrofia, envolvidos na disfunção muscular de pacientes com DPOC. Outro aspecto contraditório é o envolvimento de diferentes grupos musculares; alguns estudos mostram que a função dos músculos dos membros superiores (MMSS) encontra-se relativamente preservada enquanto outros sugerem a existência de fraqueza muscular generalizada. O impacto da disfunção muscular na endurance e na tolerância ao exercício também é controverso. Os objetivos deste estudo foram avaliar a prevalência e as repercussões da depleção da massa muscular sistêmica e localizada em pacientes com DPOC. Foram avaliados sessenta e dois pacientes com DPOC atendidos no Ambulatório de Pneumologia da Faculdade de Medicina de Botucatu – UNESP; vinte e seis pacientes (VEF1: 49,0±18,0%) com depleção de MMC e trinta e seis pacientes... / Chronic obstructive pulmonary disease (COPD) presents significant systemic manifestations and, among them, the nutritional alterations are very important. Loss of body weight and the body mass index (BMI) were the first indicators of the nutritional status related to the prognosis in patients with COPD. However, recent studies have shown the predominance of the fat-free mass (FFM) depletion in these patients. Although some consequences of FFM depletion are well known, information regarding the distribution, mechanism and characteristics of the modification remains unclear. Some researches support the idea that the muscular weakness is proportional to the loss of FFM. On the other hand, results of recent investigations suggest that either the qualitative or functional alterations are mechanisms, additional to the atrophy, involved in the muscular dysfunction in patients with COPD. Another controversial aspect is related to the involvement of different muscular groups; some findings show that the function of the upper-limb muscles are relatively preserved while others suggest the existence of generalized muscular weakness. The impact of the muscular dysfunction in the endurance function and in exercise tolerance is also controversial. The goals of this research were to evaluate the prevalence and the consequences of the systemic and peripheral FFM depletion in patients with COPD. Sixty-two patients with COPD attending to the respiratory outpatient clinic (Botucatu School of Medicine UNESP) were included in the study; twenty-six (FEV1: 49.0l18.0%) with FFM depletion and thirty-six (FEV1: 59.8l24.4%) without FFM depletion. The depletion was characterized by the presence of FFM index <15 kg/m2, for women, and <16 kg/m2, for men. Patients were, in average, 64.0l9.3 years old and 68% were male... (Complete abstract, access undermentioned eletronic address)
35

Função e massa muscular em pacientes com doença pulmonar obstrutiva crônica /

Sanchez, Fernanda Figueirôa. January 2007 (has links)
Orientador: Irmã Godoy / Banca: Vitor Zuniga Dourado / Banca: José Alberto Neder / Banca: José Antônio Baddini Martinez / Banca: Sérgio Rupp Paiva / Resumo: A doença pulmonar obstrutiva crônica (DPOC) apresenta manifestações sistêmicas e, dentre entre elas, as alterações nutricionais são bastante evidentes. A perda de peso e o índice de massa do corpo (IMC) foram os primeiros indicadores do estado nutricional relacionados ao prognóstico em pacientes com DPOC. Entretanto, estudos recentes ressaltam a maior prevalência da depleção da massa magra do corpo (MMC) nestes pacientes. Embora algumas repercussões da depleção da MMC em pacientes com DPOC sejam conhecidas, as informações sobre a distribuição, mecanismos e características das alterações parecem contraditórios. Alguns estudos sustentam a idéia de que a fraqueza muscular é proporcional à perda de massa muscular. Por outro lado, os resultados de estudos recentes sugerem que as alterações qualitativas ou funcionais são mecanismos, adicionais à atrofia, envolvidos na disfunção muscular de pacientes com DPOC. Outro aspecto contraditório é o envolvimento de diferentes grupos musculares; alguns estudos mostram que a função dos músculos dos membros superiores (MMSS) encontra-se relativamente preservada enquanto outros sugerem a existência de fraqueza muscular generalizada. O impacto da disfunção muscular na endurance e na tolerância ao exercício também é controverso. Os objetivos deste estudo foram avaliar a prevalência e as repercussões da depleção da massa muscular sistêmica e localizada em pacientes com DPOC. Foram avaliados sessenta e dois pacientes com DPOC atendidos no Ambulatório de Pneumologia da Faculdade de Medicina de Botucatu - UNESP; vinte e seis pacientes (VEF1: 49,0±18,0%) com depleção de MMC e trinta e seis pacientes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Chronic obstructive pulmonary disease (COPD) presents significant systemic manifestations and, among them, the nutritional alterations are very important. Loss of body weight and the body mass index (BMI) were the first indicators of the nutritional status related to the prognosis in patients with COPD. However, recent studies have shown the predominance of the fat-free mass (FFM) depletion in these patients. Although some consequences of FFM depletion are well known, information regarding the distribution, mechanism and characteristics of the modification remains unclear. Some researches support the idea that the muscular weakness is proportional to the loss of FFM. On the other hand, results of recent investigations suggest that either the qualitative or functional alterations are mechanisms, additional to the atrophy, involved in the muscular dysfunction in patients with COPD. Another controversial aspect is related to the involvement of different muscular groups; some findings show that the function of the upper-limb muscles are relatively preserved while others suggest the existence of generalized muscular weakness. The impact of the muscular dysfunction in the endurance function and in exercise tolerance is also controversial. The goals of this research were to evaluate the prevalence and the consequences of the systemic and peripheral FFM depletion in patients with COPD. Sixty-two patients with COPD attending to the respiratory outpatient clinic (Botucatu School of Medicine UNESP) were included in the study; twenty-six (FEV1: 49.0l18.0%) with FFM depletion and thirty-six (FEV1: 59.8l24.4%) without FFM depletion. The depletion was characterized by the presence of FFM index <15 kg/m2, for women, and <16 kg/m2, for men. Patients were, in average, 64.0l9.3 years old and 68% were male... (Complete abstract, access undermentioned eletronic address) / Mestre
36

Muscular hypertrophic adaptations in high and low load training regimes : Eight weeks training intervention

Kalenius, Richard January 2017 (has links)
Aim The purpose of this study was to assess muscle hypertrophy outcomes from high and low load strength training routines performed to muscular fatiguein a unilateral design. Method 14 well-trained men and women (age 26.4 ±4.4 years, weight 79.9 ±10.7 kg, height 179.4 ±76 cm) volunteered to participate in eight weeks of fully supervised training two times per week. Subjects had their legs randomized to a HL protocol performing 3-5reps and LL protocol performing 20-25 reps. Training was performed in leg press and leg extension and all sets were performed until volitional failure. Subjects were measured for muscle thickness by ultrasound at mid and distal portion of vastus lateralis before and after the study. Paired sample t-test and independent sample t-test was used to establish differences in pre and post and between leg differences. Results Muscle thickness increased inHL: MID 8% p=0,002 and DIST 14% p=0.009, in LL: MID 7% p=0.004 and was unchanged at DIST 4% p=0.512. Total muscle thickness for both measurement sites combined increases significantly in both legs, HL: 9% p=0.001 and LL: 5% p=0.045. There were no between leg differences at MID (p=0.404) or DIST (p=0.989) after eight weeks. Conclusion We conclude that high and low load strength training performed unilaterally to volitional failure yields equal increases in muscle thickness after eight weeks for well-trained men and women. / <p>Kursen Projektarbete.</p>
37

Impact of Skeletal Muscle Mass Index, Intramuscular Adipose Tissue Content, and Visceral to Subcutaneous Adipose Tissue Area Ratio on Early Mortality of Living Donor Liver Transplantation / 生体肝移植における骨格筋量、筋肉内脂肪および内臓脂肪肥満の意義

Hamaguchi, Yuhei 24 July 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20620号 / 医博第4269号 / 新制||医||1023(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 坂井 義治, 教授 小西 靖彦, 教授 川口 義弥 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
38

Styrkeförluster vid åldrande? : En tvärsnittsstudie om eventuella skillnader i styrkeförluster hos äldre seniorer / Loss of strength with ageing? : A cross-sectional study on possible differences in strength losses in older seniors

Hallgren, Hampus, Brostedt, Carl-Mikael January 2023 (has links)
Bakgrund: Äldre personer, 65 år och uppåt, bör vara fysiskt aktiva för ett hälsosammare och längre liv. Forskning har visat att muskelmassa och styrka minskar exponentiellt snabbare efter år 60 och muskelatrofi sker främst av typ 2 muskelfibrer. En minskad mängd muskelmassa är hos äldre starkt korrelerat med funktionsnedsättning, vilket resulterar i att regelbunden styrketräning därmed är en effektiv metod för att motverka sarkopeni hos äldre individer. Syfte: Syftet med studien var att studera kraftskillnader mellan olika åldersgrupper hos seniorer uppmätt på prestations-anpassat utomhusgym. Metod: Studien var en kvantitativ tvärsnittsstudie. Totalt deltog 35 personer, 21 kvinnor och 14 män, som fick utföra fysiska maxtester på labb och utomhusgym. Resultat: Mann Whitney U-testet visade skillnader i maxstyrka mellan män och kvinnor 65+ i alla statiska maxtester, på 0.001-nivån. Vid könsuppdelning av åldersgrupperna var det en skillnad mellan männen på 0.05-nivån i roddrag, p=0.039, och bänkpress, p=0.028. Spearmans korrelationstest visade ett negativt samband på 0.01-nivån, p=0.005 mellan ålder och STS r = -0,466. Slutsats: Konklusionen av vår studie är att det inte fanns någon betydande skillnad i maxstyrka mellan åldersgrupperna 65-75 och 75+. Det fanns en skillnad i maxstyrka mellan män och kvinnor över 65 år. Vid könsuppdelning av åldersgrupperna fanns det en skillnad i maxstyrka mellan män 65-75 och män 75+ i roddrag och bänkpress, men hos kvinnor fanns det ingen skillnad i maxstyrka mellan åldersgrupperna 65-75 och 75+. Utifrån resultaten i vår studie kan därmed slutsatsen dras att både äldre män och kvinnor behöver styrketräna för att behålla styrka vid åldrande. / Background: Older people, aged 65 and over, should be physically active for a healthier and longer life. Research has shown that muscle mass and strength decrease exponentially faster after the age of 60 and muscle atrophy occurs mainly in type 2 muscle fibres. A reduced amount of muscle mass in older people is strongly correlated with disability, resulting in regular strength training being an effective method to counteract sarcopenia in older individuals. Purpose: The purpose of the study was to study strength differences between different age groups in seniors measured in a performance-adapted outdoor gym. Method: The study was a quantitative cross-sectional study. A total of 35 participants, 21 women and 14 men, were asked to perform physical max tests in the lab and outdoor gym. Results: The Mann Whitney U test showed differences in maximum strength between men and women 65+ in all static max tests, at the 0.001 level. When splitting the age groups by gender, there was a difference between men at the 0.05 level in the rowingpull, p=0.039, and benchpress, p=0.028. Spearman's correlation test showed a negative correlation at the 0.01 level, p=0.005 between age and STS r = -0.466. Conclusion: The conclusion of our study is that there was no significant difference in maximum strength between the 65-75 and 75+ age groups. There was a difference in maximum strength between men and women over 65 years of age. When dividing the age groups by gender, there was a difference in maximum strength between men 65-75 and men 75+ in the rowing pull and bench press, but in women there was no difference in maximum strength between the age groups 65-75 and 75+. Based on the results of our study, it can therefore be concluded that both older men and women need strength training to maintain strength during aging.
39

Efeito da suplementação com leucina sobre a resposta atrófica da musculatura esquelética induzida pelo uso de dexametasona / Effects of leucine supplementation on skeletal muscle atrophy dexamethasone-induced

Zanchi, Nelo Eidy 06 April 2011 (has links)
A dexametasona (DEXA) é um potente agente imunossupressor e antiinflamatório, mas apresenta importantes efeitos colaterais, tais como a atrofia muscular e a resistência à ação da insulina nos músculos esqueléticos. Neste contexto, a suplementação com leucina poderia representar uma estratégia nutricional terapêutica capaz de limitar os efeitos colaterais do tratamento com DEXA. Neste estudo, foram investigados os efeitos da suplementação com leucina em baixas e altas doses sobre a massa muscular, força muscular, assim como vários marcadores metabólicos que estão sob controle da insulina em ratos com restrição calórica e em ratos tratados com DEXA. Como a resposta da suplementação com leucina pode também estar ligada à forma de administração desse aminoácido, realizamos experimentos com leucina administradas via gavagem (bolus) versus leucina diluída no bebedouro dos animais. A suplementação com leucina demonstrou preservar a massa muscular, a força muscular voluntária média e a homeostasia da glicose em animais sob restrição calórica, mas este efeito foi observado apenas com a leucina suplementada em baixas concentrações/doses. Este efeito da leucina sobre a massa muscular esteve associado com a expressão de genes envolvidos no remodelamento da musculatura esquelética. Quanto ao efeito da leucina sobre a homeostasia da glicose, um efeito benéfico do aminoácido foi observado com a suplementação em baixas doses, o qual foi evidenciado pelos dados metabólicos avaliados. No entanto, sob tratamento com DEXA, a suplementação com leucina agravou o estado \"diabetogênico\" dos animais. Por último, a via de administração da leucina influenciou significativamente a resposta a este aminoácido, onde a suplementação via gavagem mostrou-se menos prejudicial do que a suplementação com leucina diluída nos bebedouros, ao menos em relação ao aspecto diabetogênico causado pelo tratamento concomitante com DEXA / Dexamethasone (DEXA) is a potent immunosupressor and anti-inflammatory agent but presents side effects such as muscle atrophy and insulin resistance in skeletal muscles. In this context, leucine supplementation may represent a way to limit the DEXA side effects. In this study, we investigated the effects of a low and a high dose of leucine on muscle mass, on muscle strength as well as on several metabolic markers that are under insulin control in energy-restricted and DEXA-treated rats. Since leucine response may also be linked to the way of administration of this amino acid, we performed experiments with leucine given in a gavage versus leucine given in drinking water way. Leucine supplementation was found to spare muscle mass, voluntary medium strength and glucose homeostasis in energy restricted animals but the effect was observed only with the low dose/concentration of leucine. The leucine effect on muscle mass was associated with expression of genes involved in muscle remodeling. However, under DEXA treatment, leucine supplementation was found to aggravate the diabetogenic state. Lastly, the route of leucine administration was found to significantly influence this variable to this amino acid, where leucine supplemented via gavage demonstrated to be less deleterious than supplemented diluted in the water drink, concomitantly with DEXA treatment
40

Etude des relations os/muscle et projet de courbes de référence de la densité minérale osseuse et de la composition corporelle chez l’homme jeune : étude multicentrique française / Relationships between bone/muscle and project of reference curves of bone mineral density and body composition in young men : french multicenter study

Sutter, Thibault 24 May 2018 (has links)
Notre objectif à court terme est d’établir des courbes de référence Française de la densité osseuse (DMO) et de la composition corporelle masculine une fois que nous aurons toutes les données issues de tous les centres. Nous avons donc réalisé deux études préliminaires dans le cadre de ce projet dont les objectifs sont les suivants :A) Etudier les déterminants de la DMO corps entier mais aussi spécifiques de site osseux en lien avec les mesures de composition corporelle, de force musculaire et de l’activité physique chez l’homme jeune B) Cross-calibration in vitro des paramètres de densité osseuse et de composition corporelle mesurés par l’absorptiométrie bi-photonique à rayons X (DXA) afin d’établir les facteurs correctifs à appliquer in vivo dans le cadre de notre projet de courbe de référence chez l’homme jeune.Grâce à la DXA, notre étude a confirmé que la masse maigre était le facteur le plus important associé aux paramètres de la DMO sur tous les sites osseux étudiés et que la masse grasse avait un impact négatif sur la DMO. Aucune association n'a été trouvée entre activité physique et DMO. La force de préhension était significativement mais modérément corrélée avec la DMO. Concernant la cross-calibration, les résultats ont montré que l’oscillation des résultats entre les différents DXA des centres est un sujet de préoccupation pour les études multicentriques et en particulier pour l’évaluation de la composition corporelle. La cross-calibration nous a permis de calculer les facteurs correctifs à appliquer sur les données issues des centres impliqués. Afin de limiter ces variations, il serait souhaitable de mettre au point un fantôme corps entier standard qui serait utilisé pour les études multicentriques. / Our short-term goal is to establish French reference curves of bone mineral density (BMD) and body composition once we have data from all centers. We have therefore carried out two preliminary studies for this project whose objectives are as follows: A) To study the determinants of whole body BMD but also bone site specific in relation to measurements of body composition, muscle strength and physical activity in young men B) Cross-calibration in vitro of bone mineral density and body composition parameters measured by dual energy X-ray absorptiometry (DXA) in order to establish in vivo the correction factors to be used in our baseline project in young men. Using DXA, our study confirmed that lean mass was the most important factor associated with BMD parameters at all bone sites and fat mass had a negative impact on BMD. Grip strength was significantly but moderately correlated with BMD at all sites. No association was found between physical activity and BMD. Regarding cross-calibration, the results showed that the oscillation of the results between the different DXA centers is a problem for multicenter studies and in particular for the evaluation of body composition. Cross-calibration allowed us to calculate the corrective factors to be applied to the data from the centers involved. In order to limit these variations, it would be desirable to develop a standard whole-body phantom that would be used for multicentre studies.

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