Leg-ligament-thigh-trunk Dynamic Model to Describe Posture Recovery after Double-leg Landing Task.

One of the most common injuries in athletes is that of the Anterior Cruciate Ligament (ACL). This type of injury is commonly analyzed by observing the dynamics of the body in the sagittal plane. ACL injury can be indicated by a the small knee flexion angle and a small angular position of the trunk at start of leg-landing task. In this article a 4 Degrees of Freedom (DOF) dynamic model of the human body restricted to the sagittal plane is presented. The model represents the movement of the legs, an equivalent ligament between the tibia and femur, thighs and trunk. It is used to represent the recovery of vertical posture during a double leg landing task. Initial conditions in velocity are calculated as those resulting from a free fall from a height H. The results obtained from the simulation were satisfactory since the recovery of the vertical posture is achieved and it is possible to approximate the deformation suffered by the equivalent ligament. In conclusion, this model can be very useful in determining the behavior of the ligament and eventually, the possibility of injury after a double-leg landing task.

Integración de Un Sistema Robótico de Terapia Ocupacional para Extremidades Superiores con Estimulación Visual/Táctil de Los Pacientes / Integration of an Occupational-Therapy Robotic System for Upper Limbs with Visual/tactile Stimulation of Patients

Resumen: Los ejercicios tradicionales de rehabilitación de extremidades superiores tienen como objetivo principal recuperar la fuerza o rango de movimiento del área lesionada de los pacientes. Una opción alternativa que se ha presentado en los últimos años es el uso de interfaces hápticas, las cuales han mostrado ser herramientas potenciales en el apoyo de las terapias de rehabilitación. En este artículo se presenta un sistema de rehabilitación háptico de movimientos finos en extremidades superiores, cuya característica principal es que los usuarios del sistema pueden interactuar de forma visual y táctil con objetos virtuales mezclados con escenarios reales logrando con ello un ambiente de realidad aumentada. El sistema fue probado en dos etapas, ambas con sujetos que presentaban un grado de discapacidad en extremidades superiores. Los datos recopilados fueron trayectorias seguidas, errores de seguimiento y la actividad muscular obtenida por medio de electromiografía; esta información recolectada permitió analizar de forma cuantitativa el grado de avance de los pacientes. Además, se consideraron las valoraciones hechas por fisioterapeutas, concluyendo que el sistema propuesto puede ser utilizado como una herramienta viable que complementa a las terapias de rehabilitación convencionales.

Abstract: Traditional upper limb rehabilitation exercises are primarily aimed at regaining the strength or range of motion of the patients' injured area. An alternative option that has been presented in the last years is the use of haptic interfaces, which have shown their potential as tools that support rehabilitation therapies. This article presents a haptic system of rehabilitation for fine upper limb movements, whose main characteristic is that users of the system can interact in a visual and tactile fashion with virtual objects mixed with real scenarios, thereby achieving an augmented reality environment. The system was tested in two stages, both with subjects who had a degree of disability in upper limbs. The data collected were followed trajectories, follow-up errors and the muscular activity obtained by means of electromyography; the collected information enabled the analysis, in a quantitative way, of the degree of progress of the patients. In addition, the assessments made by physiotherapists were considered, concluding that the proposed system can be used as a viable complementary tool for conventional rehabilitation therapies.

Relation between heart beat fluctuations and cyclic alternating pattern during sleep in insomnia patients.

Insomnia is a condition that affects the nervous and muscular system. Thirty percent of the population between 18 and 60 years suffers from insomnia. The effects of this disorder involve problems such as poor school or job performance and traffic accidents. In addition, patients with insomnia present changes in the cardiac function during sleep. Furthermore, the structure of electroencephalographic A-phases, which builds up the Cyclic Alternating Pattern during sleep, is related to the insomnia events. Therefore, the relationship between these brain activations (A-phases) and the autonomic nervous system would be of interest, revealing the interplay of central and autonomic activity during insomnia. With this goal, a study of the relationship between A-phases and heart rate fluctuations is presented. Polysomnography recording of five healthy subjects, five sleep misperception patients and five patients with psychophysiological insomnia were used in the study. Detrended Fluctuation Analysis (DFA) was used in order to evaluate the heart rate dynamics and this was correlated with the number of A-phases. The results suggest that pathological patients present changes in the dynamics of the heart rate. This is reflected in the modification of A-phases dynamics, which seems to modify of heart rate dynamics.