Search

La biomecánica, disciplina de la ciencia que combina los principios de la mecánica con los fenómenos biológicos para analizar los movimientos del cuerpo humano y su interacción con el entorno, representa una rama de la ciencia que ha evolucionado a lo largo de la historia para comprender y optimizar el rendimiento humano proporcionando una visión profunda y cuantitativa de la mecánica del movimiento. El presente estudio se adentra en la biomecánica con un enfoque específico para obtener la orientación de dispositivos inerciales con el objetivo de calcular ángulos de rotación en las articulaciones del cuerpo humano. El estudio de estos movimientos permite llevar a cabo un análisis detallado de la dinámica corporal y desempeña un papel esencial en la mejora del rendimiento, la rehabilitación y la prevención de lesiones. Las unidades de medición inercial se han convertido en herramientas fundamentales en biomecánica debido a su capacidad para registrar datos de aceleración y velocidad angular con alta precisión. Estos datos son de vital importancia para comprender la mecánica de los movimientos corporales y diseñar intervenciones terapéuticas y programas de entrenamiento más efectivos. Por ejemplo, en el ámbito deportivo, estos dispositivos son esenciales en el análisis y optimización del rendimiento en atletas. Los datos capturados permiten evaluar con precisión la técnica de un corredor, un ciclista, un nadador o un jugador de fútbol, lo que lleva a ajustes específicos en su entrenamiento. Para abordar este desafío, este trabajo se enfoca en la utilización de sistemas microelectromecánicos, dispositivos que combinan sensores inerciales como los acelerómetros y los giroscopios, entre otros. Estos dispositivos han revolucionado la forma en que se capturan y analizan los datos biomecánicos, al proporcionar mediciones en tiempo real de la orientación y el movimiento del cuerpo en condiciones no invasivas. Para lograr este objetivo, se abordan los siguientes temas de mane, Biomechanics, the scientific discipline that combines the principles of mechanics and biological phenomena to analyse the movements of the human body and its interaction with the environment, is a branch of science that has evolved throughout history to understand and optimise human performance by providing a deep and quantitative insight into the mechanics of movement. The present study deals with biomechanics with a specific approach to calculate the angles of rotation in the joints of the human body from the alignment of inertial devices. The study of these movements enables a detailed analysis of body dynamics and plays an essential role in performance improvement, rehabilitation and injury prevention. Inertial measurement units have become fundamental tools in biomechanics due to their ability to record acceleration and angular velocity data accurately. These data is crucial for understanding the mechanics of body movements and developing more effective therapeutic interventions and training programmes. In the field of sports, for example, these devices are essential for analysing and optimising the performance of athletes. The data collected enables a precise assessment of the technique of a runner, a cyclist, a swimmer or a football player and leads to specific adjustments to training. To address this challenge, this work focuses on the use of microelectromechanical systems, which combine inertial sensors such as accelerometers and gyroscopes, among others. These devices have revolutionised the way biomechanical data is captured and analysed by providing real-time measurements of body orientation and motion under noninvasive conditions. In order to achieve this goal, the following topics are covered in detail. Firstly, microelectromechanical systems are introduced, which form the technological basis for the operation of very small inertial sensors. These devices, which integrate mechanical and electronic components on a microscopic level, are responsible for

The main objective of this thesis was to solve the 3D inverse dynamic problem during cycling. For this purpose, the procedures used for motion capture using videogrammetry were adapted to the practice of cycling. In addition, modifications were made to a commercial bicycle in order to measure the forces applied to it. In order to achieve the objective, the first of the studies carried out in this thesis was the 3D lower body movement analysis during pedalling. The complexity of accurately measuring movements outside the sagittal plane (plane parallel to the bicycle frame), caused the number of studies focusing on 3D kinematic analysis of cycling to be limited. The studies that opt to analyse kinematics outside the sagittal plane tended to use marker protocols from gait analysis, which did not take into account the cycling particularities. Due to the lack of a specific marker protocol for cycling, one of the aims of this thesis was to develop and evaluate a new marker protocol with which to carry out a 3D kinematic analysis in cycling at the level of position, velocity and acceleration in a simple way and without affecting the comfort of the participant. Because there is no gold-standard of 3D pedalling kinematics accepted by the scientific community, the results obtained have been evaluated by physiological and comparative analysis with previous works. The results obtained were similar to those in the literature, with low intra-subject variability in the sagittal and transverse planes and a high repeatability of the order of that reported by other protocols for gait analysis. Velocity and acceleration results outside the sagittal plane suggested their importance when considering them in the resolution of the inverse dynamic problem. To solve the inverse dynamic problem in the lower body, in addition to the movement of this, the 3D force applied to the pedals had to be known. To obtain this force, the most commonly used equipment tended to focus only on the component, El principal objetivo de esta tesis fue resolver el problema dinámico inverso 3D en el ciclismo. Para ello, los procedimientos empleados para la captura de movimiento mediante videogrametría fueron adaptados a la práctica del ciclismo. Además, se realizaron modificaciones en una bicicleta comercial con el fin de medir las fuerzas aplicadas sobre ella. Para lograr el objetivo de esta tesis, el primero de los estudios realizados fue el análisis 3D del movimiento del tren inferior durante el pedaleo. La complejidad de medir con precisión los movimientos fuera del plano sagital (plano paralelo al cuadro de la bicicleta), hizo que el número de estudios centrados en el análisis cinemático 3D del ciclismo fuera limitado. Los estudios que optaban por analizar la cinemática fuera del plano sagital solían utilizar protocolos de marcadores procedentes del análisis de la marcha, que no tenían en cuenta las particularidades del ciclismo. Debido a la falta de un protocolo de marcadores específico para ciclismo, uno de los estudios llevados a cabo en esta tesis fue desarrollar y validar un nuevo protocolo de marcadores con el que realizar un análisis cinemático 3D en ciclismo a nivel de posición, velocidad y aceleración de forma sencilla y sin afectar a la comodidad del participante. Debido a que no existe un gold-standard de cinemática de pedaleo 3D aceptado por la comunidad científica, los resultados obtenidos han sido evaluados mediante análisis fisiológicos y comparativos con trabajos anteriores. Los resultados obtenidos eran similares a los de la literatura, con una baja variabilidad intra-sujeto en los planos sagital y transversal y una alta repetibilidad del orden de la reportada por otros protocolos de análisis de la marcha. Los resultados de velocidad y aceleración fuera del plano sagital sugerían su importancia a la hora de considerarlos en la resolución del problema de dinámica inversa. Para resolver el problema dinámico inverso en el tren inferior, además del movimient

Postprint (published version)

El ciclismo se trata de una actividad muy extendida hoy en día. Muchas son las personas que usan una bicicleta para desplazarse o para ocio. Por ello, resulta de gran interés realizar estudios en busca del confort y del rendimiento del ciclista a la hora de pedalear. Analizar qué fuerzas ejerce un ciclista durante una sesión de pedaleo, qué posturas son las más eficientes o qué dimensiones de los elementos de una bicicleta son los más adecuados según el ciclista, resulta muy importante para mejorar la ergonomía, el confort, la eficiencia e incluso a la hora de prevenir lesiones. El conocimiento de estos factores es importante también para labores de rehabilitación mediante sesiones de ciclismo, en las que se deben elegir dimensiones muy concretas de la bicicleta dependiendo del participante que vaya a realizar la sesión. Resultan de interés los trabajos que se centran en la estimación de las fuerzas ejercidas por el ciclista en distintos puntos de la bicicleta. La cuantificación de estas fuerzas tiene diversas aplicaciones, tales como la determinación de qué técnicas de pedaleo son mejores para incrementar la eficacia mecánica o para prevención de lesiones y rehabilitación. (Extraído de la Introducción)

The asymmetries study between both legs of the forces applied to the pedals in cycling is important because they may affect the performance of the cyclist or prevent the occurrence of injuries. Studies focused on analysing asymmetries in forces tend to consider only the effective force, disregarding the three-dimensional nature of the force. Furthermore, these studies do not analyse the possible physical or neurological causes that may have led to the appearance of the asymmetries. This paper presents a methodology to carry out three-dimensional analysis of the asymmetries of the forces applied in both pedals and discriminate the possible sources of these asymmetries. Seven participants, amateurs and without pathologies, were analysed. Two commercial pedals were instrumented to measure the three components of the force applied to each pedal. The Normalized Symmetry Index (NSI) and the Cross Correlation Coefficient (CCC) were used for the asymmetries analysis. Results showed that both indexes need to be used in conjunction to analyse the causes of asymmetry in the pedal forces from a 3D perspective along the pedal cycle. The NSI is an index that makes it possible to evaluate asymmetry by considering only the value of the force applied by each leg at each instant. The CCC makes it possible to evaluate whether the temporal evolutions of the forces applied by each leg are similar. Preliminary results suggest that the proposed methodology is effective for analysing asymmetries in the forces in a pedalling cycle from a three-dimensional point of view. Forces in the sagittal plane showed a high level of symmetry. The lateral-medial force presented the highest level of asymmetry due to the difference in the magnitudes of the applied forces by both legs and the existing time shift between the two force patterns. The results of this work will allow for more complete and accurate three-dimensional dynamic analyses of the lower body during pedalling.

Knowledge of the forces applied to the pedals during cycling is of great importance both from the point of view of improving sporting performance and medical analysis of injuries. The most common equipment for measuring pedal forces is usually limited to the study of forces in the sagittal plane. Equipment that measures three-dimensional forces tends to be bulky and to be incorporated into bicycles that are modified to accommodate it, which can cause the measurements taken to differ from those obtained in real pedalling conditions. This work presents a device for measuring the 3D forces applied to the pedal, attachable to a conventional bicycle and pedals, which does not alter the natural pedalling of cyclists. The equipment consists of four gauges located on the pedal axis and two on the crank, controlled by a microcontroller. Pedal forces measurements were made for six cyclists, with results similar to those shown in the literature. The correct estimation of the lateral-medial direction force is of great interest when evaluating a possible overload at the joints; it will also allow a comparison of the effectiveness index during pedalling, showing the role of this component in this index from a mechanical standpoint.

Inverse dynamics problems are usually solved in the analysis of human gait to obtain reaction forces and moments at the joints. However, these actions are not the actual forces and moments supported by the joint structure, because they do not consider the forces of the muscles acting across the joint. Therefore, to analyse bone-on bone forces it is necessary to estimate those muscle forces. Usually, this problem is addressed by means of optimization algorithms. One of the parameters required to solve this problem is the musculotendon geometry. These data are usually taken from cadavers or MRI data from several subjects, different from the analysed subject. Then, the model is scaled to the subject morphology. This procedure constitutes a source of error. The goals of this work were two. First, to perform a sensitivity analysis of the influence of muscle insertion locations on the muscle forces acting on the hip joint and on the hip joint bone-on-bone forces. Second, to compare the hip joint bone-on-bone forces during gait cycle obtained through muscle insertion locations taken from a musculoskeletal model template and a scaling procedure to those obtained from a subject-specific model using an MRI of the subject. The problem was solved using OpenSim. Results showed that anatomical variability should be analysed from two perspectives. One the one hand, throughout the gait cycle, in a global way. On the other hand, at a characteristic instant of the gait cycle. Variations of ±1 cm in the position of the attachment points of certain muscles caused variations of up to 14.21% in averaged deviation of the muscle forces and 58.96% in the peak force in the modified muscle and variations up to 57.23% in the averaged deviation of the muscle force and up to 117.23% in the peak force in the rest of muscles. Then, the influence of that variability on muscle activity patterns and hip bone-on-bone forces could be described more precisely. A biomechanical analysis of a subject-speci