Background: The incidence of anterior cruciate ligament (ACL) –injury is 3-5 times greater in female athletes compared to male athletes. This may be partially attributed to lower levels of hamstring-quadriceps co-contraction in females with subsequent knee kinematics that increases risk of ACL-injury. Finding training methods that improves co-contraction and increases knee stability is important. Objectives: To evaluate the effects of a new device on hamstring-quadriceps co-contraction and to investigate if training with the device can alter knee kinematics in female athletes. Study design: Controlled experimental study design with repeated measures. Method: Twenty soccer and floor ball athletes were measured with electromyography (EMG) for hamstring-quadriceps co-contraction while performing squats with and without the device. Thirteen athletes also underwent three-dimensional kinematic analyses, measuring knee abduction angles (at initial ground contact and peak angle) during a drop jump, before and after a six week intervention period with the device. Friedman’s test and Wilcoxon signed rank test was used to assess differences and effect sizes (ES) were calculated. Results: Co-contraction was consistently larger on the device (medial side: p<0.001, ES=0.88; lateral side: p<0.001, ES=0.80) and the ratio of medial-to-lateral co-contraction increased (p=0.001, ES=0.79). In the kinematic analysis low adherence rates amongst our subjects meant that the effects of the device on kinematics could not be measured. Conclusion: Performing squats with the new training device stimulates increased hamstring-quadriceps co-contraction and increases the ratio of medial-to-lateral co-contraction. The effects of the device on knee kinematics have yet to be determined.

L'objectif de ce travail était d'une part de développer des méthodes numériques permettant d'estimer de manière satisfaisante les moments résultant, agoniste et antagoniste développés autour d'une articulation et, d'autre part, d'appliquer ces méthodes à l'analyse de la coordination pluri-articulaire d'un mouvement de piétinement. Le problème de la dynamique inverse est résolu à l'aide d'une méthode d'optimisation statique des accélérations qui permet d'estimer les moments résultants en accord avec toutes les mesures cinématiques et dynamiques, tout en respectant les conditions d'équilibre mécanique de chaque segment. Les moments musculaires agoniste et antagoniste sont estimés en conditions dynamiques à l'aide d'une méthode qui comprend une étape de calibration isométrique et une procédure d'optimisation numérique qui utilise les données cinématiques, dynamiques et électromyographiques en entrée. Le modèle tient compte du comportement mécanique des muscles et de leur fonction anatomique pour obtenir une estimation physiologiquement réaliste des moments et un indice de co-contraction fiable a chaque instant du mouvement. Ces modèles sont appliqués à l'étude de la coordination pluri-articulaire d'un mouvement de piétinement, perturbé par le port d'un système élastique à l'articulation du genou. La redondance du système musculo-squelettique permet de gérer localement la perturbation en accroissant la participation des muscles extenseurs au contrôle de la cinématique du genou. Cette stratégie permet de conserver la même cinématique du mouvement et ainsi préserve l'équilibre dynamique du piétinement.

No description available.

The shoulder is one of the most complex joints in the body. It has a large range of motion and has active, as well as passive, components to its stabilization. Many injuries occur every year due to overexertion and strain on the shoulder. Musculoskeletal models can be used as a proactive ergonomics tool for shoulder specific job task design, and to help prevent these injuries before they occur. The purpose of this thesis was to critically evaluate the performance of four optimization criteria (sum of squared activation, sum of cubed activation, sum of quartic activation, and entropy assisted) using the open source modeling platform OpenSIM. Experimental torque, kinematic, and EMG data were collected using ten participants for a variety of dynamic arm movements, and static arm postures, in different planes of action. The kinematic and torque data were processed and used as inputs to OpenSIM to calculate predicted muscle activations and joint reaction forces. Experimental EMG was cross correlated with the predicted muscle activity of 8 muscles, and RMSD was calculated between experimental and predicted muscle activity for evaluation. A co-contraction index was also used to assess the model’s ability to predict co-activation between muscle pairs. Overall, the sum of cubed activation and sum of quartic activation model predictions explained significantly more variance (38 ±2.5%, p<0.01) than the sum of squares and entropy models, when compared with experimental EMG. In conclusion, the type of optimization criterion chosen had an effect on the accuracy of the model predictions. Future research, in the development of optimization criterions for the shoulder, will create better model predictions of muscle forces and joint reaction forces, enabling musculoskeletal models to be more useful as a tool to the clinical and ergonomic populations. / Thesis / Master of Science (MSc) / The shoulder is one of the most complex joints in the body. It has a large range of motion and has muscles and ligaments to support the stability of the complex. Many injuries occur every year due to overexertion and strain on the shoulder. Proactively modelling can help reduce these injuries by evaluating a job's likelihood to injure a worker before the worker does the job. The purpose of this thesis was to evaluate the performance of several different shoulder models. Experimental torque, kinematic, and EMG data were collected using ten participants for a variety of dynamic arm movements, and static arm postures, in different planes of action. The kinematic and torque data were used by the model to predict muscle activations and joint reaction forces. Experimental EMG was cross correlated with the predicted muscle activity of 8 muscles, and RMSD was calculated between experimental and predicted muscle activity for evaluation. A co-contraction index was also used to assess the model’s ability to predict co-activation between muscle pairs. Overall, the sum of cubed activation and sum of quartic activation model predictions explained significantly more variance (38 ±2.5%, p<0.01) than the sum of squares and entropy models, when compared with experimental EMG. In conclusion, the type of model chosen had an effect on the accuracy of the model predictions. Future research, in the development of optimization criterions for shoulder models, will create better model predictions of muscle forces and joint reaction forces, enabling musculoskeletal models to be more useful as a tool to the clinical and ergonomic populations.

Title: Electromyographic Analysis of the Different Handlebars Grips Effect on the Shoulder Blade Fixators Aims: The main objective of this thesis is to carry out a methodological study on the impact of different handlebars grips on the shoulder blades fixators. Result of the grip change is not only reduction of the upper fixators activity and the increase in the lower fixators activity but also co-contraction index increase and muscle fatigue reduction. Based on the hypothesis we assumed that the highest activity rate of the lower blades fixators and the lowest activity rate of the upper blades fixators will be during the handlebars brakes grip. The highest co- contraction index will occur during the handlebar brakes grip and the maximum muscular fatigue will occur during the grip at the top of the handlebars. The first part of the thesis is focused on the literature search and facts retrieval pertaining to the studied issue. In the second special part of the thesis we conducted a research during which the muscle activity of the upper and lower blade fixators was recorded. Three different handlebars grips were considered during the measurement using the cycle ergometer. Methods: Muscle activity was scanned and recorded using surface EMG. Maximal voluntary contraction of selected muscles based on...

Mastering the physical aspect of piano technique has long been a topic of great interest and importance to pianists. This is borne out in the numerous pedagogical approaches on the topic of piano technique. Despite the many contributions from pedagogues and scholars in developing an understanding of piano technique, many conflicting approaches often cause more confusion than clarity. After reviewing the literature on pedagogical approaches to piano technique, this study determined that problematic language might lie at the root of the confusion. Core concepts identified in the review of literature as recurring areas of misunderstanding were tension, relaxation, co-contraction, arm weight, and hand and finger shape. The purpose of this study is to seek where issues of language exist in contemporary piano pedagogical approaches and to show how these problems may contribute to the systemic confusion in piano technique. To do this, the language that is used to describe and define the core concepts identified in the review of literature is analyzed in five modern pedagogical approaches. Five authors who have developed approaches that reflect current trends in piano technique have been selected for this study: Barbara Lister-Sink; Dorothy Taubman; Thomas Mark; Fred Karpoff; and Alan Fraser. The first step of this study entails collecting data from each of the five pedagogical approaches. The data is then analyzed for consistency and accuracy. Problems in language that contribute to the inconsistencies and inaccuracies are examined and illustrated with material from the data collection. This study concludes by identifying the main sources of confusion in the use of language: inconsistent and inaccurate use of terms; wavering between scientific, common, and invented language; challenges in describing opposing qualities that come from tension and relaxation; and failing to discern between the individual subjective experience and the mechanics of movement. By recognizing where the problems in language exist, this study represents an important first step for the pedagogical community to reach a common understanding of the language used to describe the physical aspect of piano technique.

Mastering the physical aspect of piano technique has long been a topic of great interest and importance to pianists. This is borne out in the numerous pedagogical approaches on the topic of piano technique. Despite the many contributions from pedagogues and scholars in developing an understanding of piano technique, many conflicting approaches often cause more confusion than clarity. After reviewing the literature on pedagogical approaches to piano technique, this study determined that problematic language might lie at the root of the confusion. Core concepts identified in the review of literature as recurring areas of misunderstanding were tension, relaxation, co-contraction, arm weight, and hand and finger shape. The purpose of this study is to seek where issues of language exist in contemporary piano pedagogical approaches and to show how these problems may contribute to the systemic confusion in piano technique. To do this, the language that is used to describe and define the core concepts identified in the review of literature is analyzed in five modern pedagogical approaches. Five authors who have developed approaches that reflect current trends in piano technique have been selected for this study: Barbara Lister-Sink; Dorothy Taubman; Thomas Mark; Fred Karpoff; and Alan Fraser. The first step of this study entails collecting data from each of the five pedagogical approaches. The data is then analyzed for consistency and accuracy. Problems in language that contribute to the inconsistencies and inaccuracies are examined and illustrated with material from the data collection. This study concludes by identifying the main sources of confusion in the use of language: inconsistent and inaccurate use of terms; wavering between scientific, common, and invented language; challenges in describing opposing qualities that come from tension and relaxation; and failing to discern between the individual subjective experience and the mechanics of movement. By recognizing where the problems in language exist, this study represents an important first step for the pedagogical community to reach a common understanding of the language used to describe the physical aspect of piano technique.

Mastering the physical aspect of piano technique has long been a topic of great interest and importance to pianists. This is borne out in the numerous pedagogical approaches on the topic of piano technique. Despite the many contributions from pedagogues and scholars in developing an understanding of piano technique, many conflicting approaches often cause more confusion than clarity. After reviewing the literature on pedagogical approaches to piano technique, this study determined that problematic language might lie at the root of the confusion. Core concepts identified in the review of literature as recurring areas of misunderstanding were tension, relaxation, co-contraction, arm weight, and hand and finger shape. The purpose of this study is to seek where issues of language exist in contemporary piano pedagogical approaches and to show how these problems may contribute to the systemic confusion in piano technique. To do this, the language that is used to describe and define the core concepts identified in the review of literature is analyzed in five modern pedagogical approaches. Five authors who have developed approaches that reflect current trends in piano technique have been selected for this study: Barbara Lister-Sink; Dorothy Taubman; Thomas Mark; Fred Karpoff; and Alan Fraser. The first step of this study entails collecting data from each of the five pedagogical approaches. The data is then analyzed for consistency and accuracy. Problems in language that contribute to the inconsistencies and inaccuracies are examined and illustrated with material from the data collection. This study concludes by identifying the main sources of confusion in the use of language: inconsistent and inaccurate use of terms; wavering between scientific, common, and invented language; challenges in describing opposing qualities that come from tension and relaxation; and failing to discern between the individual subjective experience and the mechanics of movement. By recognizing where the problems in language exist, this study represents an important first step for the pedagogical community to reach a common understanding of the language used to describe the physical aspect of piano technique.

Mastering the physical aspect of piano technique has long been a topic of great interest and importance to pianists. This is borne out in the numerous pedagogical approaches on the topic of piano technique. Despite the many contributions from pedagogues and scholars in developing an understanding of piano technique, many conflicting approaches often cause more confusion than clarity. After reviewing the literature on pedagogical approaches to piano technique, this study determined that problematic language might lie at the root of the confusion. Core concepts identified in the review of literature as recurring areas of misunderstanding were tension, relaxation, co-contraction, arm weight, and hand and finger shape. The purpose of this study is to seek where issues of language exist in contemporary piano pedagogical approaches and to show how these problems may contribute to the systemic confusion in piano technique. To do this, the language that is used to describe and define the core concepts identified in the review of literature is analyzed in five modern pedagogical approaches. Five authors who have developed approaches that reflect current trends in piano technique have been selected for this study: Barbara Lister-Sink; Dorothy Taubman; Thomas Mark; Fred Karpoff; and Alan Fraser. The first step of this study entails collecting data from each of the five pedagogical approaches. The data is then analyzed for consistency and accuracy. Problems in language that contribute to the inconsistencies and inaccuracies are examined and illustrated with material from the data collection. This study concludes by identifying the main sources of confusion in the use of language: inconsistent and inaccurate use of terms; wavering between scientific, common, and invented language; challenges in describing opposing qualities that come from tension and relaxation; and failing to discern between the individual subjective experience and the mechanics of movement. By recognizing where the problems in language exist, this study represents an important first step for the pedagogical community to reach a common understanding of the language used to describe the physical aspect of piano technique.

No description available.