Azyklische Beinstreckbewegungen stellen mit der Erzeugung hoher Absprunggeschwindigkeiten in vielen Sportarten wesentliche Teilleistungen dar, die durch Gelenkleistungen der unteren Extremitäten limitiert werden. An maximal willentlich ausgeführten Beinstreckbewegungen mit dem Ziel größtmöglicher Endbeschleunigung des Körperschwerpunkts hat die kniestreckende Muskulatur den größten Anteil. Mit geeigneten Muskelparametern lässt sich das Kontraktionsverhalten und damit die mechanische Antriebsleistung von Muskeln unter verschiedenen Arbeitsbedingungen kennzeichnen und das Training wirksam steuern. In dieser Arbeit wurde ein Instrumentarium zur individuellen Bestimmung von Muskelparametern der Kraft-Geschwindigkeit-Längen-Relation für die Kniestrecker entwickelt. Dies beinhaltete ein isokinetisches Testprogramm das die von antagonistischen Einflüssen isolierte Kraftdiagnose der kniestreckenden Muskulatur gewährleistet. Mit den in den Tests erhobenen Eingangsdaten konnten mit einem wirklichkeitsnahen Geometriemodell, inverser Dynamik und einem Optimierungsverfahren plausible Muskelparameter, u. a. die maximale Muskelleistung, für sechs Kadersportler berechnet werden. Am Beispiel eines Strecksprungs ohne Sprunggelenkeinsatz wurde gezeigt, dass die berechneten Parameter zur muskelkraftgesteuerten Simulation in Muskel-Skelett-Modellen geeignet sind und so die Optimierung der sportlichen Technik unter Berücksichtigung der individuell limitierten Antriebsleistung im Kniegelenk möglich ist.

Made available in DSpace on 2016-12-08T15:59:06Z (GMT). No. of bitstreams: 1 Resumo Heiliane Fontana.pdf: 222602 bytes, checksum: 7b9629dbef6d399a129553dbf066ba26 (MD5) Previous issue date: 2015-05-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Embora as relações força-comprimento (F-C) e força-velocidade (F-V) de um músculo possam ser facilmente determinadas in-vitro, a determinação in-vivo é certamente mais complexa, e baseia-se frequentemente em medidas de torque e ângulo articular. Uma importante limitação dessa abordagem reside no fato de as mudanças de comprimento do fascículo muscular não se relacionarem de maneira simples às da unidade músculo-tendínea (UMT). Dessa forma, a investigação in-vivo da mecânica músculo-tendão torna-se necessária para a determinação da expressão dessas propriedades musculares no contexto do movimento humano. Neste trabalho, foi determinado, in-vivo, a relação F-C (Parte I) e a relação F-V (Parte II) nos níveis do fascículo e da UMT para contrações voluntárias do músculo vasto lateral (VL) em humanos. A relação F-C foi obtida para contrações máximas e submáximas e a relação F-V, para diferentes níveis de pré-contração do músculo. A fim de obter um melhor entendimento do fenômeno, o movimento de extensão de joelho foi analisado em diferentes amplitudes de acordo com características cinéticas e cinemáticas do mesmo. As coletas de dados envolveram medições sincronizadas de torque e ângulo de joelho, bem como arquitetura muscular e EMG do VL durante contrações isométricas (F-C) e isocinéticas (F-V) de extensores de joelho. Na Parte I, foi demonstrado que a quantidade de encurtamento dos fascículos em uma contração isométrica depende do comprimento da UMT/ ângulo articular, resultando em diferentes formatos para a relação F-C entre os níveis do fascículo e da UMT e entre contrações máximas e submáximas. As relações F-C para contrações submáximas foram determinadas a partir de níveis percentuais de força (como sugerido na literatura), mas, também, através de uma nova abordagem baseada em níveis percentuais de ativação (EMG). Com base na primeira abordagem, por definição, os picos de força para as relações F-C ocorrem em um comprimento muscular fixo, mas, devido a complacência da UMT, em comprimentos de fascículo maiores a medida que a força na UMT decresce. Contrariamente, na análise baseada em ativação, os picos de força ocorrem em um comprimento de fascículo constante, mas em comprimentos musculares menores a medida que a a força na UMT decresce. Este resultado sugere que o maior potencial de geração de força submáxima é obtido em comprimento de fascículo próximo ao definido como ótimo, ou seja, no comprimento onde a sobreposição dos miofilamentos é máxima. Na Parte II dessa tese, a análise da relação F-V evidenciou que a velocidade de encurtamento do fascículo durante a extensão isocinética de joelho pode ser menor, semelhante ou maior do que a da UMT dependendo da velocidade articular e de qual parte do movimento é analisada. A velocidade de encurtamento da UMT aumenta sistematicamente com a velocidade articular, enquanto que os fascículos podem permanecer com velocidades constantes para uma grande amplitude de velocidade articular. Os resultados apontam para a crítica natureza da interação entre ângulo articular, força/ativação muscular, elementos elásticos e mecânica dos fascículos musculares e auxiliam na superação das restrições encontradas quando se relaciona e se aplica conhecimento obtido nos diferentes níveis organizacionais dos músculos. / Although there are no major difficulties in obtaining the force-length (F-L) and force-velocity (F-V) relationships in skeletal muscles in-vitro, obtaining them in-vivo is certainly much more complex, and is often based on joint torque and angle. A primary problem is that fascicle length changes are not associated in a simple manner with changes in the length of the whole muscle-tendon unit (MTU). Therefore, investigation on whole muscle tendon mechanics in-vivo is needed in order to elucidate the link between these mechanical properties and the muscle performance in the context of human movement. In this thesis work, we determined the in-vivo F-L relationship (Part I) and F-V relationship (Part II) at the fascicle and MTU levels for voluntary contractions of the human vastus lateralis muscle (VL). F-L relationships were obtained for maximal and submaximal contractions, and F-V relationships for different pre-load conditions. In order to obtain a better understanding of the phenomena, different ranges of the knee extension movement were identified for their kinematic or kinetic properties and were analyzed separately. Data collection involved synchronized measurements of knee extensor torque, knee angle, VL EMG and muscle architecture (fascicle length and pennation angle) during isometric (F-L) and isokinetic (F-V) knee extensor contractions. In Part I, we demonstrated that fascicles undergo different amounts of shortening depending on MTU length/ joint angle, which results in different shapes of the fascicle and muscle F-L relationship, and produces different F-L shapes for maximal and submaximal levels of activation. The submaximal fascicle F-L relationships were determined based on percentages of force (as typically done in the literature), but novel to the literature, also based on percentages of activation (EMG). In the force-based analysis, the peak forces of F-L relationships, by definition, must occur at the same muscle length, but because of muscle-tendon compliance, it occurs at increasing fascicle lengths with decreasing levels of force. In contrast, in the activation-based analysis, the peak occurred at similar fascicle lengths, but because of muscle compliance, at decreasing muscle lengths with decreasing levels of force. This result suggests that, in the activation-based analysis, the greatest force generating potential always occurs close to optimal fascicle lengths; that is the length at which sarcomeres present maximum myofilament overlap. In Part II, analysis of the F-V relationship showed that fascicle shortening velocities during maximum isokinetic knee extension exercises can be slower, equal or faster than the corresponding MTU shortening velocities, depending on the knee extensor speed and depending on which part of the knee extension curve is analyzed. MTU shortening velocities increase systematically with increasing speeds of knee extension. However, this observation is not made for fascicle shortening velocities, which, depending on the range and conditions analyzed, remain about constant across a large range of knee extensor speeds. The results of this thesis point to the critical nature of the interaction between joint angle, muscle force/activation, series elastic compliance, and fascicle mechanics and help to overcome the difficulties in relating and applying knowledge obtained at the different organizational levels of muscles.

Azyklische Beinstreckbewegungen stellen mit der Erzeugung hoher Absprunggeschwindigkeiten in vielen Sportarten wesentliche Teilleistungen dar, die durch Gelenkleistungen der unteren Extremitäten limitiert werden. An maximal willentlich ausgeführten Beinstreckbewegungen mit dem Ziel größtmöglicher Endbeschleunigung des Körperschwerpunkts hat die kniestreckende Muskulatur den größten Anteil. Mit geeigneten Muskelparametern lässt sich das Kontraktionsverhalten und damit die mechanische Antriebsleistung von Muskeln unter verschiedenen Arbeitsbedingungen kennzeichnen und das Training wirksam steuern. In dieser Arbeit wurde ein Instrumentarium zur individuellen Bestimmung von Muskelparametern der Kraft-Geschwindigkeit-Längen-Relation für die Kniestrecker entwickelt. Dies beinhaltete ein isokinetisches Testprogramm das die von antagonistischen Einflüssen isolierte Kraftdiagnose der kniestreckenden Muskulatur gewährleistet. Mit den in den Tests erhobenen Eingangsdaten konnten mit einem wirklichkeitsnahen Geometriemodell, inverser Dynamik und einem Optimierungsverfahren plausible Muskelparameter, u. a. die maximale Muskelleistung, für sechs Kadersportler berechnet werden. Am Beispiel eines Strecksprungs ohne Sprunggelenkeinsatz wurde gezeigt, dass die berechneten Parameter zur muskelkraftgesteuerten Simulation in Muskel-Skelett-Modellen geeignet sind und so die Optimierung der sportlichen Technik unter Berücksichtigung der individuell limitierten Antriebsleistung im Kniegelenk möglich ist.

Background: Evaluation of power-force-velocity profiles in ballistic push-offs and in sprint movements are beneficial to enhance sport performance. There have only been a few studies investigating force-velocity profiles in rotational movements and there have not been any studies conducted on golf specific rotational movements. There is a lack of isoinertial power assessment protocols which can relate to golf swing performance. For this reason, 1080 Quantum was used for testing which is a machine able to measure power, force and velocity in several different resistance modes. Aim: The aim was to study the reliability of three golf specific rotational tests and to assess the reliable test’s validity. The secondary aim was to study the isoinertial force-velocity and power relationship in tests that assessed acceptable test-retest reliability and acceptable construct validity. Methods: Twelve high level golfers (handicap -1.5±1.2), 8 men and 4 women performed the tests with five different loads; 2 kg, 6 kg, 10 kg, 14 kg and 18kg with three golf specific rotational movements in a motorized cable machine (1080 Quantum, Sweden). The three new tests utilized were: full body rotational test (FBRT), thorax rotational test (TRT) and pelvis rotational test (PRT). Data gathered was used to study golfer’s individual force-velocity profile and to assess construct validity of the reliable tests against previously recorded normal-swing driver clubhead speed (CHSnormal), and maximum-swing driver clubhead speed (CHSmax). Construct validity was based on á priori stated hypothesizes, and data were analyzed with Spearman’s correlation coefficient (rs). Intraclass correlation coefficient (ICC) and coefficient of variation (CV) was used to assess test-retest reliability of FBRT, TRT and PRT. Results: In the reliability assessment, the highest peak power (PP) (ICC, 0.968, 95% CI (0.889- 0.991)), corresponding peak force (PF) (ICC, 0.993, 95% CI (0.96- 0.998)) and corresponding peak velocity (PV) (ICC 0.773, 95% CI (0.17- 0.936)) was only found to be acceptable in FBRT. Construct validity assessment of FBRT was not found acceptable in either of the resistances. The calculated average slopes indicated a velocity dominant force-velocity profile for women and a force dominant for men. Conclusion: The study demonstrated that only the FBRT assessed acceptable test-retest reliability for measuring force, velocity and power. Based on our hypothesizes FBRT is not a valid indicator of golf performance on either resistance, however it had a significant moderate to good correlation with CHSmax and with CHSnormal at all resistances apart from 2 kg. FBRT should not be applied as a test, nor to be used for the calculation of the force- velocity profile since it is not valid, even though it is reliable. since it is not valid, even though it is reliable. As a result, FBRT could only be used for exercise and needs further development to improve its validity. / <p>While only my name is featured on the title page of this thesis, it reached its final stage with the guidance and support of many others. I thank my primary supervisor, Ann Bremander and James Parker whom, with their professional guidance, helped complete this thesis.</p>

Ce travail de thèse s'est intéressé à l'étude des facteurs permettant d'expliquer les performances fonctionnelles des membres inférieurs des personnes âgées. Dans une première étude, nous avons montré que la puissance maximale (Pmax) ainsi que sa composante appelée la vitesse optimale (Vopt) obtenues lors d'un test de force-vitesse des extenseurs du genou, sont des facteurs déterminants de la performance fonctionnelle des personnes âgées évaluées sur 3 tests : marche sur 6m, se relever et s'assoir 5 fois de suite à partir d'une chaise et monter 6 marches d'escalier. Ainsi, plus une personne possède une Pmax et une Vopt élevées, plus ses performances lors de tests fonctionnels seront élevées. De plus, la Vopt étant considérée comme une évaluation indirecte du pourcentage de fibres rapides, les sujets ayant les plus grandes valeurs de Vopt sont les plus performantes aux tests fonctionnels. La deuxième étude a mesuré et comparé l'activité électromyographique (EMG) du quadriceps lors des tests de contraction isométrique volontaire maximal (IMVC), de détermination de la puissance maximale et des tests fonctionnels cités cidessus. La mesure du signal EMG au cours de ces différents tests a permis de déterminer dans quelle mesure le type de tâche induit une activation maximale ou non. Les personnes âgées montrent une capacité à davantage activer leurs quadriceps lors des tests de de contraction concentrique plutôt qu'isométrique ou excentrique. Les tests utilisant l'IMVC comparé aux tests de détermination de la puissance et de monté de marche, et de lever de chaise ne seraient pas les tests les plus appropriés pour mesurer les capacités maximales d'activation neuromusculaires chez la personne âgée. Il ressort de ces résultats une amélioration du testing de la personne âgée et des orientations pour la réhabilitation / This work has focused on the study of factors that explain the functionals performances of the lower limbs of the elderly. In a first study we showed that the maximum power (Pmax) and its component called the optimal speed (Vopt) obtained during a test of force-velocity of the knee extensors, are important determinants of functional performance elderly evaluated on three tests: walking on 6m, sit to stand 5 times from a chair and climbing 5 stairs. The more a person has a high Pmax and Vopt, the more its performance during functional tests will be. In addition, Vopt is considered an indirect assessment of the percentage of fast fibers; subjects with the highest values of Vopt are best performers during functional tests. The second study measured and compared the electromyographic (EMG) activity of the quadriceps when tested for isometric maximum voluntary contraction (IMVC), determination of maximum power and functional tests mentioned above. Measurement of EMG signal during these tests was used to determine to what extent the type of task induced a maximum activation or not. Older people show a greater ability to activate their quadriceps muscles when tested for concentric contraction rather than isometric or eccentric contractions. Tests using the IMVC compared to tests for determining the power, sit-tostand and stairs climbing would not be the most appropriate tests to measure the maximum neuromuscular activation capacity in the elderly. From these results improved testing of the elderly and guidelines for rehabilitation are proposed

Aim  The purposes of this study were to investigate if the load-velocity (L-V) profile parameters – force capacity and efficiency - differ between swimmers of different performance level, and to investigate if efficiency is the key performance indicator between international elite and national elite level swimmers.  Method  Fifty-four swimmers (27 female and 27 male) of either regional level, national elite or international elite level, participated in this study. The swimmers performed three 25 m semi- tethered maximum effort swims with ascending loads (1 kg, 5% and 10% of body mass). Mean velocity during three stroke cycles mid-effort was calculated and plotted as a function of the external added load. A linear regression was established, expressing the relationship between load and velocity, with the intercepts between the axes and the regression line being defined as the theoretical maximum velocity (V0) and load (force capacity, L0). The slope of the regression line (slopeLV) serves as an index of efficiency. Results A statistically significant difference was found between the three performance levels for all L- V profile variables for front crawl: V0 (F [2, 51] = 7.76, p&lt;0.001), L0 (F [2, 51] = 5.18, p=0.009), and slopeLV (F [2, 51] = 3.36, p=0.043). A paired t-test revealed no difference in slopeLV between matched international elite and national elite level swimmers (t [9] = 1.42, p=0.188), but a near significant difference in L0 (t [9] = 2.11, p=0.064) . Both slopeLV and L0 for front crawl had a strong correlation with personal best in 100 m front crawl (PB100). Conclusion Efficiency was not found to be the key performance indicator between matched international elite and national elite swimmers in this study, and neither was force capacity. Nevertheless, a significant difference in all front crawl L-V profile parameters was found between performance level groups, but post hoc analyses indicated no difference between adjacent performance levels neither in L0 nor slopeLV. There was however a strong correlation between both slopeLV, and L0, to the swimmers’ PB100. All these findings imply that efficiency and force capacity seem to be of equal importance for high performance, but swimmers use different strategies to reach the high swim velocity. / Longitudinal development of performance determining factors in swimming (NIH)