Gender variability in electromyographic activity, in vivo behaviour of the human gastrocnemius and mechanical capacity during the take-off phase of a countermovement jump.

PURPOSE: The purpose of this study was to analyse gender differences in neuromuscular behaviour of the gastrocnemius and vastus lateralis during the take-off phase of a countermovement jump (CMJ), using direct measures (ground reaction forces, muscle activity and dynamic ultrasound). METHODS: Sixty-four young adults (aged 18-25 years) participated voluntarily in this study, 35 men and 29 women. The firing of the trigger allowed obtainment of data collection vertical ground reaction forces (GRF), surface electromyography activity (sEMG) and dynamic ultrasound gastrocnemius of both legs. RESULTS: Statistically significant gender differences were observed in the jump performance, which appear to be based on differences in muscle architecture and the electrical activation of the gastrocnemius muscles and vastus lateralis. So while men developed greater peak power, velocity take-offs and jump heights, jump kinetics compared to women, women also required a higher electrical activity to develop lower power values. Additionally, the men had higher values pennation angles and muscle thickness than women. CONCLUSION: Men show higher performance of the jump test than women, due to significant statistical differences in the values of muscle architecture (pennation angle and thickness muscle), lower Neural Efficiency Index and a higher amount of sEMG activity per second during the take-off phase of a CMJ.

Effects of 6-week whole body vibration training on the reflex response of the ankle muscles: a randomized controlled trial.

BACKGROUND: The ligament sprain of the lateral ankle is the most frequent injury that occurs when participating in sports. Whole body vibration (WBV) is a training method that has been recently introduced as a rehabilitative tool for treatment of athletes. It has been hypothesized that the transmission of mechanical oscillations from the vibrating platform may lead to physiological changes in muscle spindles, joint mechanoreceptors, as well as improve balance. PURPOSE: [corrected] The aim of this study was to assess the effects of a 6-week WBV training program on the reflex response mechanism of the peroneus longus (PL), peroneus brevis (PB) and anterior tibialis (AT) muscles in ankle inversion at 30º from horizontal, in a static position. METHODS: This study was a single-blinded and randomized controlled trial. Forty-four healthy, physically active participants were randomly split into two groups: the experimental group (n = 26) (the WBV training) and control group (n = 18). Reaction time (RT), maximum electromyographic (EMG) peak (peak EMG), time to the maximum peak EMG (peak EMG time) and reflex electrical activity of all the muscles were assessed before and after the WBV training through surface EMG. RESULTS: After 6-weeks WBV training, there were no significant changes in the variables analysed for all the muscles involved. CONCLUSION: A 6-week WBV training does not improve the reflex response mechanism of the lateral stabilizing muscles of the ankle. LEVEL OF EVIDENCE: 1b.

Experimental muscle injury: correlation between ultrasound and histological findings.

INTRODUCTION: In this study we correlated ultrasound findings with histological changes taking place during experimentally induced degeneration-regeneration in rat skeletal muscle. METHODS: Gastrocnemius muscles were injected with mepivacaine, and the progress of the muscle injury was monitored by ultrasound from day 1 to day 20. Muscles were extracted on the same days for histological examination. RESULTS: The degenerative phase was characterized by increased echogenicity in the injured area; thereafter, echogenicity gradually diminished during the regenerative phase, attaining normal levels by 20 days postinjection. By this stage, histological examination revealed that regeneration was complete. The heteroechoic texture observed from day 4 to day 10 appeared to reflect the coexistence of degenerative and regenerative processes. CONCLUSIONS: The results suggest that the degenerative and regenerative phases of muscle injury may be distinguished sonographically through differences in echogenicity and echotexture and, using Doppler ultrasound, differences in the degree of vascularization.

Método de diagnóstico y prevención del esguince crónico de tobillo / Diagnosis and prevention method of chronic ankle sprain

Introducción: El esguince del complejo ligamentoso lateral de la articulación del tobillo es la lesión que se produce con más frecuencia durante la práctica deportiva. Se considera fundamental el papel que juega la musculatura que envuelve la articulación en la protección dinámica de la misma. El propósito de este estudio ha sido comparar el tiempo de reacción de los músculos peroneo largo, peroneo corto y tibial anterior en tobillos funcionalmente inestables y en tobillos sanos. Material y método: Muestra: Formaron parte del estudio un total de 33 participantes distribuidos en dos grupos, GI (n =17) con inestabilidad funcional en uno de sus tobillos, y GC (n = 16) con tobillos sanos. Variables: las variables estudiadas fueron el tiempo de reacción de los tres músculos, el pico electromiográfico máximo durante la inversión, el tiempo hasta la consecución de este valor, la activación muscular media enel momento de la inversión y el tiempo que dura la inversión. También se estudiaron las variables antropométricas (talla, peso, masa musculoesquelética, masa grasa, masa musculoesquelética de la pierna estudiada) de los participantes. Protocolo: primero se realizó el test de composición corporal, para posteriormente realizar los test de contracción voluntaria máxima de los tres músculos y finalizar con el test de inversión de tobillo. Resultados: los participantes que pertenecían al GI tuvieron un tiempo de reacción significativamente mayor en los músculos peroneo largo y peroneo corto (57 ms y 57,2 ms respectivamente) que el GC (46,3 ms y 47,6 ms). No se obtuvieron diferencias significativas en el músculo tibial anterior. Conclusiones: la inestabilidad funcional del tobillo provoca un aumento en los tiempos de reacción de la musculatura estabilizadora de esta articulación, aumentando el riesgo de padecer una nueva lesión (AU)

Introduction: Ankle sprains are very common during sports and occur most commonly those affecting the lateral ligament complex. Once produced this injury, there is a high probability that symptoms during over time, thus becoming a chronic type injury. It is believed that the stabilizing musculature of the joint must be strong enough to counteract the mechanism of this injury. The aim of this study was to compare the reaction time of the peroneus longus, peroneus brevis and tibialis anterior in unstable and healthy functionally ankles. Methods: Subjects: participated in the study a total of 33subjects divided into two groups: GI (n = 17) with instability functional in one of theirs ankles, and GC (n = 16) with healthy ankles. Variables: The variables studied were the reaction time of the three muscles, the maximum peak of EMG during inversion time, the average muscle activation of inversion time and the inversion duration. It examined the anthropometric variables (height, weight, skeletal muscle mass, fat mass, leg skeletal muscle mass under study) of the subjects. Protocol: first we made the body composition test, later to perform the of maximum voluntary contraction of the three muscles test and finally the inversion ankle test.Results: GI had a significantly longer reaction time in the peroneus longus and brevis (57 ms and 57.2 ms respectively)than the CG (46.3 ms and 47.6 ms). There were no significant differences in tibialis anterior. Conclusions: functional ankle instability causes an increase in reaction times of the muscle stabilized ankle, increasing the risk of reinjury (AU)

Aplicaciones avanzadas de la ecografía en las lesiones musculoesqueléticas / Advanced applications of ultrasound in musculoskeletal injuries

Durante los últimos años se ha producido un notable desarrollo de la ecografía en el estudio de las lesiones del aparato locomotor, especialmente a nivel de los tejidos blandos, lugar donde habitualmente asientan aquellas patologías por sobrecarga. Las ventajas de la ecografía en el manejo de la lesión de partes blandas han provocado una enorme expansión de esta técnica en varias especialidades médicas, como la medicina primaria, laboral, deportiva y últimamente se han extendido a nuevas especialidades clínicas como la reumatología, la medicina de emergencias y la anestesiología. Se describe por ello en este artículo, las aplicaciones avanzadas del estudio ecográfico en el diagnóstico y tratamiento de las lesiones músculo-esqueléticas que afectan al deportista. La ecografía músculo-esquelética intervencionista es la aplicación terapéutica de esta técnica de imagen cuyas indicaciones son múltiples, aunque las más frecuentes permiten guiar la colocación de una aguja para la infiltración de un fármaco o para la aspiración de una colección líquida. En otras ocasiones puede facilitar algunos procedimientos invasivos como el drenaje de hematomas o abscesos, la toma de muestras de biopsia y las técnicas de reparación quirúrgica menor. Por otra parte la aplicación dinámica de la ecografía permite observar las características de la arquitectura muscular en las diferentes fases de un gesto deportivo, para determinar los momentos de alto riesgo que dependiendo de las exigencias técnicas de cada modalidad deportiva pueden provocar una lesión. En resumen, esta técnica en una herramienta básica en el diagnóstico de la lesión, y en el tratamiento a través de cirugía mínimamente invasiva de pequeñas lesiones músculo-esqueléticas del deportista. En este trabajo se formulan nuevas aplicaciones para la prevención de lesiones musculares (AU)

Over the past years there has been a remarkable development of ultrasound in the study of injuries of the muscle skeletal system, especially at the level of the soft tissues, where they usually settle those overload pathologies. The advantages of ultrasound in the management of soft tissue injury has caused an enormous expansion of this technique in several medical specialties, including primary, labour and sports medicine and have recently been extended to new clinical specialties such as rheumatology, emergency medicine and anesthesiology. This is described in this article, the advanced applications of ultrasound in the diagnosis and treatment of musculoskeletal injuries affecting the athlete. Interventional musculoskeletal ultrasound is the therapeutic applications of this technique has many indications, but the most common means of guiding the placement of a needle for drug injection or aspiration of fluid collection. At other times may give some invasive procedures such as drainage of hematomas or abscesses, biopsy sampling and minor surgical repair techniques. Moreover, the dynamic application of ultrasound allows us to observe the features of muscle architecture in the different phases of a sports movement to identify hight-risk times depending on the technical requirements of each sport can cause injury. In summary, this technique in a basic tool in the diagnosis of injuries, and treatment throught minimally invasive surgery of small musculoskeletal injuries of the atlete. In this paper, new applications are formulated to prevent muscle injuries (AU)