Oscar Valencia

University of the Andes (Chile) | UANDES · Escuela de Kinesiología

Abstract. This study aimed to describe the percentage of intrinsic foot muscles (IFM) activation during maximal toe grip in amateur runners. In this descriptive study, ten amateur runners (age = 22.5 ± 2.8 years; height = 1.67 ± 0,08 m; weight = 67.6 ± 12.0 kg; sex= five female, five male) were evaluated. All volunteers provided prior informed cons...

El objetivo de este estudio es comparar las adaptaciones biomecánicas en la marcha de jóvenes con y sin dolor lumbar crónico (DLC). Se reclutaron 30 participantes (15 personas por grupo, con DLC y grupo control). Las variables biomecánicas analizadas incluyeron inclinación pélvica, oblicuidad y rotación, complementadas con un índice de simetría de...

Current methods for monitoring laryngeal muscle function include techniques such as intramuscular electromyography, external laryngeal palpation, and laryngeal endoscopy. Although these methods have provided much information about muscle activation and function during voice production, they are invasive, uncomfortable, and subjective. The objective...

The muscle coactivation phenomenon (mCoA) has been used to describe motor tasks such as human gait, reflecting the levels of joint stability of the lower limbs in healthy people versus patients with musculoskeletal problems. Nonetheless, scarce literature has described the mCoA evolution in patients with Achilles tendon reconstruction surgery. The...

Wheelchair rugby was created as part of the rehabilitation for patients with spinal cord injury. The biomechanical analysis of wheelchair propulsion (WP) in these athletes seems to be a key element to understand the reasons behind musculoskeletal injuries. This case reports study aimed to describe the electromyographic activity and kinematic parame...

The instantaneous spatial representation of electrical propagation produced by muscle contraction may introduce bias in surface electromyographical (sEMG) activation maps. Here, we described the effect of instantaneous spatial representation (sEMG segmentation) on embedded fuzzy topological polyhedrons and image features extracted from sEMG activat...

The anatomical territory where the neuromuscular junctions are grouped corresponds to the innervation zone (IZ). This can be located in-vivo using high-density electromyography and voluntary muscle contractions. However, in patients with motor impairment, the use of contractions imposed by electrical stimulation (ES) could be an alternative. The pr...

Category Sports; Ankle; Basic Sciences/Biologics Introduction/Purpose Kinematic, muscular architecture and myoelectric activity are altered during the healing process after Achilles tendon surgery. Currently, there are minimally invasive surgical techniques (PARS-Dresden) which have accelerated rehabilitation processes. However, evidence that comp...

Objectives Parkinson's disease (PD) generates a high incidence of falls, however, there is little evidence of instabilities in the initial stages. This investigation sought to compare the muscle activation times in patients with initial PD against a postural disturbance vs. a control group. Materials and methods The electromyographic activity (EMG...

Resumen Objetivos La enfermedad de Parkinson (EP) genera alta incidencia de caídas, sin embargo, existe poca evidencia de inestabilidades en etapas iniciales. Esta investigación buscó comparar los tiempos de activación muscular en pacientes con EP inicial frente a una alteración postural vs. un grupo control. Materiales y métodos Se evaluó la act...

Introduction. Neurophysiological phenomena, such as muscle coactivation, have been used to identify motor tasks requiring greater joint stability in healthy people or with movement disorders. Nonetheless, there are many ways to calculate the coactivation index (CI). This article aimed to create a processing pipeline to calculate the muscular CI by...

Forefoot (FF) and rearfoot (RF) running techniques can induce different lower-limb muscle activation patterns. However, few studies have evaluated temporal changes in the electromyographic activity (EMG) of lower limb muscles during running. The aim of this study was to compare temporal changes in EMG amplitude between RF and FF running techniques....

Resumen: Actualmente, el uso clínico-teórico de la electromiografía (EMG), basado en el comportamiento de los potenciales de acción registrados en el sistema musculoesquelético durante tareas funcionales, ha generado diversas áreas de conocimiento. Desde una perspectiva de investigación, los flujos de procesamientos vinculados a señales biomédicas...

The Short-Time Fourier transform (STFT) is a helpful tool to identify muscle fatigue with clinical and sports applications. However, the choice of STFT parameters may affect the estimation of myoelectrical manifestations of fatigue. Here we determine the effect of window length and overlap selections on the frequency slope and the coefficient of va...

Introduction: According to the literature, eccentric exercise has been considered a precursor of neuromuscular changes generated by post-exercise damage, mainly causing an alteration in the muscle cell membrane. Muscle fiber conduction velocity (MFCV) has been one of the physiological variables that have allowed to quantify this alteration. Some in...

Introducción: La electromiografía de superficie ha sido una técnica usada para describir la actividad muscular durante la carrera. Sin embargo, hay poca literatura que analice el comportamiento de la coactivación muscular en corredores, descri-biendo el efecto entre dos técnicas asociadas al contacto inial, tal como el uso de retropié y antepié. Ma...

Introducción. La articulación de la rodilla es una de las más propensas a sufrir lesiones en el ambiente deportivo, siendo la ruptura del ligamento cruzado anterior (LCA) una de las más importantes asociadas a la práctica del fútbol. Se ha descrito que, en mujeres, la incidencia de esta lesión es dos veces mayor que en hombres, lo que ha sido atrib...

Compartmentalization of animal and human skeletal muscle by multiple motor nerve branches known as the neuromuscular compartment (NMC) has been observed primarily in muscles that participate in a plane of motion. In this context, the peroneus longus muscle contributes to eversion and plantarflexion of the ankle and the presence of NMCs has been rep...

Introducción: Desafortunadamente, posterior a una tenorrafia del tendón de Aquiles existe abandono de la práctica deportiva. Frente ello, son desconocidas las causas y si la capacidad de tolerancia a la fatiga muscular podría ser un factor en disfunción. Objetivo: Comparar la pendiente y tiempo de la fatiga isométrica de la musculatura plantiflexor...

SUMMARY: Anatomical studies describe the vastus medialis (VM) as being subdivided into two morphologically distinct components, the vastus medialis obliquus (VMO) and the vastus medialis longus (VML). However, there are discrepancies regarding the functional differentiation of these components. The aim of this study was to compare the levels of act...

El tronco y la pelvis se afectan como consecuencia de un ictus, lo que predispone a caídas y dependencia. El objetivo de esta revisión fue describir la cinemática lineal y angular de tronco y pelvis durante la marcha en pacientes con secuela de accidente cerebrovascular. Se incluyeron estudios publicados hasta junio de 2018 que hubieran utilizado u...

The purpose of the present investigation was twofold 1) To compare the hip and thigh muscular activity of professional soccer players when performing the isometric squat with and without controlled hip contraction; 2) To determine the muscular relationships that take place during these methods of execution of the exercise. Methods: 11 healthy male...

To determine the effect of Length and Sliding windowing on Fuzzy Topographical Structure of maps obtained through high-density Electromyography technique.

Pedestrian injuries related to the use of cell phone have increased in relation to the total number of pedestrian accidents. The aim of this study was to compare kinematic and electromyographic variables in both lower limbs at facing an obstacle, with (WC) and without (WoC) the use of a cell phone. Ten young women were evaluated while walking and f...

Regional changes in muscle activation occur at different contraction intensities. These changes can be observed with activity maps created with high-density electromyography (HDEMG). When quantifying these changes, statistical parametric mapping (SPM) is a neuroimaging technique that may be used to perform statistical analyses with high sensitivity...

The purpose of this study was to compare the kinetic effect, with (WT) and without (WoT) the use of ankle taping, during a change of direction in basketball players. Twenty-two players were evaluated (11 men, 11 women; age = 21.50 ± 1.74 years, mass = 72.80 ± 13.14 kg, height = 1.71 ± 0.11 m). The functional task of "change of direction in 60°" was...

Resumen. Un importante porcentaje de las lesiones de miembros inferiores ha sido vinculado a la técnica de carrera, en particular, al contacto inicial con retropié (RP) o antepié (AP). Sin embargo, existe limitada evidencia de la actividad electromiográfica (EMG) para ambas condiciones. El objetivo de este estudio fue comparar la amplitud EMG en mi...

Category Ankle Introduction/Purpose Different techniques have been described for Achilles Tendon Rupture repair, but no biomechanical evaluation have been performed separately for proximal and distal suturing techniques.The purpose of this study was to biomechanically analyze 3 proximal and 2 distal suture configurations during a simulated cyclic...

Background Different techniques have been described for percutaneous Achilles tendon rupture repair, but no biomechanical evaluation has been performed separately for proximal and distal suturing techniques. The purpose of this study was to biomechanically analyze proximal versus distal percutaneous Achilles suture configurations during cyclic load...

Introduction: Entropy and location of center (LoC) are used to understand the muscles function from activation patterns obtained by High-density electromyography. However, the size and sliding of the windowing could influence the generation of topographic map, where entropy as the location of center are extracted as the most important feature of ch...

Objetivo general: Comparar la distribución topográfica del umbral del dolor en el músculo Gastrocnemio medial (GM) luego de sesiones repetidas de ejercicio excéntrico. Discusión y conclusiones: La distribución topográfica del dolor cambia antes sesiones repetidas de ejercicio excéntrico en el músculo GM, generando variaciones medi0laterales solo de...

Purpose: To assess the presence of control impairment (CI) of the lumbopelvic region in the axial plane in men without low back pain (LBP) with CI in the sagittal plane. Methods: Twenty-four males, between 18 and 23 of age, BMI = normal, who did not report episodes of LBP in the 12 months prior to the study, were studied. Assessment of the sagit...

Introducción: En la actualidad, varios estudios reportan cambios estructurales del pie en corredores amateur. Sin embargo, existe poca evidencia de los posibles cambios cinemáticos en miembro inferior, considerando adicionalmente la gran incidencia de lesiones en corredores con un retropié mayor a 10° (pronadores). Objetivo: Comparar la cinemática...

Introducción: En Chile, uno de los deportes más practicados es el "running". Generando cada año 37-56% de lesiones, siendo un factor de incidencia el tipo de técnica utilizada: antepié (AP) o retropié (RP). Sin embargo, existe poca evidencia del comportamiento electromiográfico asociado. Objetivo: Comparar niveles de coactivación para: Tibial anter...

Temporo-spatial parameters (TSP) are commonly used to characterize human gait. These help to differentiate population groups in different conditions of gait, but can be influenced by lower limb anthropometry. Different strategies are assumed to normalize TSP and permit comparison among people. However, it is not clear how dimensions of the differen...

Category Basic Sciences/Biologics, Midfoot/Forefoot Introduction/Purpose Metatarsal osteotomies for Hallux Rigidus (HR) is a treatment option when neither a cheilectomy nor an arthrodesis are indicated. Different osteotomies exist that elevate, shorten or depress the metatarsal head. No biomechanical information exists that evaluates the effect of...

Introducción: Una de las articulaciones más afectadas en la práctica deportiva, es la rodilla. Siendo el aterrizaje, uno de los mecanismos frecuentes de lesión, con mayor incidencia en mujeres. En el vóleibol, el bloqueo paso atrás se relaciona directamente con el estrés mecánico que recibe esta articulación durante el aterrizaje. Sin embargo, exis...

Introducción: El ballet clásico es un tipo de danza donde se realizan movimientos en un espacio y tiempo determinado, al ser de alta exigencia puede llevar a incidencia de lesiones musculoesqueléticas, siendo la articulación del tobillo la más afectada. Sin embargo, existen pocos estudios que describan el comportamiento cinemático de esta articulac...

El rol del vasto medial de los cuádriceps, como estabilizador rotuliano medial, ha sido vinculado a la pato mecánica de la disfunción patelofemoral, que es una patología de alta prevalencia, especialmente en mujeres. Desde el punto de vista anatómico, se ha descrito que este músculo tiene dos grandes grupos de fibras que están alineadas de manera d...

La rodilla es la articulación con mayor incidencia de lesiones en los corredores. Una de las causas ha sido relacionada con el estrés rotacional durante la carrera. En la práctica clínica es común el uso de vendaje funcional, como: Kinesiotape y Taping, herramientas que han sido transformado en método de prevención y rehabilitación de lesiones. Hay...

Introduction: Cervico-uterine cancer is the fourth most common type of cancer in women worldwide, with an estimated incidence of 528,000 new cases annually (2012). Around 1,000 new cases were registered in Chile during 2008. The mortality rate for 2008 was 7.5 per 100,000 women. Objective: To report on the overall survival of patients with a diagno...

El uso de zapatos de tacón alto en mujeres jóvenes se hace cada vez más frecuente y precoz, generando diversas patologías musculoesqueléticas. El objetivo de este estudio fue determinar el efecto agudo del uso de zapatos de tacón alto sobre las FRA del tobillo durante la marcha en mujeres jóvenes no adaptadas. Mediante un ensayo clínico no aleatori...

Introducción. Producto de una lesión de miembro inferior (MI), el bastón canadiense (BC) es ampliamente indicado para producir una descarga del MI. Sin embargo , existen escasos antecedentes de la magnitud de la fuerza articular compresiva (FAC) durante la marcha, frente al uso del bastón al lado ipsi o contralateral en relación al MI afectado. Obj...

La lesión del ligamento cruzado anterior (LCA) tiene un alta prevalencia en jugadores de fútbol. En esta disciplina, las carreras con cambios de dirección son frecuentes y pueden ser un factor de riesgo para el desarrollo de lesiones del LCA sin contacto.