La tensiomiografía como herramienta para evaluar las propiedades mecánicas musculares ante diferentes entornos de rendimiento físico y deportivo

Programa de Doctorado en Ciencias de la Actividad Física y del DeporteLínea de Investigación: Ciencias de la Actividad Física, del Deporte y la SaludClave Programa: DAFCódigo Línea: 113ESTUDIO I: Influencia del tamaño del electrodo y la duración del pulso de estimulación sobre las propiedades contráctiles del músculo medidas con tensiomiografía. Resumen Este estudio tuvo como objetivo determinar los efectos de la duración del pulso y el tamaño del electrodo en las propiedades contráctiles del músculo. En el estudio participaron 36 hombres jóvenes y sanos (edad 24.8 ± 5.8 años; altura 1.78 ± 0.06 m; masa corporal 71.8 ± 7.3 kg; realizando ejercicio físico 3.5 ± 1.2 h¿semana-1). Se utilizó la tensiomografía (TMG) para evaluar las propiedades mecánicas de los músculos recto femoral (RF) y vasto medial (VM) de la pierna dominante. Además, se tuvo en cuenta el tamaño de los electrodos (3.2-5 cm) y la longitud del estímulo (0.2, 0.5 y 1 ms) en las mediciones. Los parámetros incluidos fueron: desplazamiento radial máximo (Dm), tiempo de contracción (Tc), tiempo de retardo (Td), tiempo sostenido (Ts) y tiempo de relajación media (Tr). Se cuantificó la fiabilidad relativa y absoluta. Para analizar los efectos del electrodo y la longitud del estímulo, se utilizó un análisis de varianza de medidas repetidas. Los parámetros Dm y Tc mostraron para ambos músculos una excelente fiabilidad relativa (0.95-0.99) y absoluta (1.6-4.2%). Sin embargo, Ts y Tr mostraron valores bajos de fiabilidad absoluta (4.4-40.9%). En relación al Td, la fiabilidad relativa es (0.85-0.88) y la absoluta (1.6-2.7%). La longitud del estímulo aplicado y el tamaño de los electrodos influyeron significativamente en las propiedades contráctiles del músculo (p < 0.05; ¿2p = 0.09-0.60). La Dm aumentó significativamente tanto con el incremento de la duración del estímulo como con el tamaño del electrodo en ambos músculos. Sin embargo, la Tc y la Td se vieron menos afectadas por ambas condiciones. En conclusión, tanto la duración del estímulo como la dimensión del electrodo influyen en la respuesta muscular obtenida. Además, los parámetros Dm y Tc mostraron una alta fiabilidad, mientras que lo contrario se observó para Ts y Tr. Como aplicación práctica, se sugiere que es necesaria una duración del pulso del estímulo de 1 ms junto con un electrodo de 5 × 5 cm para alcanzar una evaluación fiable y reproducible de las propiedades contráctiles de los músculos RF y VM. ¿ ESTUDIO II: Respuestas mecánicas, neuromusculares y metabólicas agudas ante diferentes configuraciones de la serie en el entrenamiento de fuerza. Resumen El objetivo de este estudio fue investigar el efecto de la configuración de la serie durante el entrenamiento de fuerza sobre la actividad neuromuscular, la respuesta metabólica y las propiedades contráctiles del músculo. Dieciséis hombres entrenados en fuerza realizaron 2 sesiones de entrenamiento en el ejercicio de sentadilla que consistieron en: (a) 3 series de 8 repeticiones con 5 minutos de descanso entre series (3 × 8) y (b) 6 series de 4 repeticiones con 2 minutos de descanso entre series (6 × 4). La intensidad del entrenamiento (75% de una repetición máxima [1RM]), el volumen total (24 repeticiones), el descanso total (10 minutos) y la densidad de entrenamiento se igualaron entre los protocolos. Se realizó una batería de pruebas antes y después de cada protocolo: (a) TMG, (b) concentración de lactato y amonio en sangre, (c) salto con contramovimiento (CMJ), y (d) contracción isométrica voluntaria máxima (MVIC) en el ejercicio de sentadilla. Se registraron los valores de fuerza, velocidad y potencia, junto con los datos electromiográficos, para cada repetición a lo largo de cada protocolo. El protocolo 6 × 4 resultó en mayor rendimiento mecánico (es decir, mayor fuerza, velocidad y potencia) y en marcadores neuromusculares de fatiga más bajos (es decir, menor actividad electromiográfica y mayor frecuencia mediana) durante el ejercicio en comparación con el protocolo 3 × 8, especialmente en las últimas repeticiones de cada serie. El protocolo 3 × 8 indujo mayores concentraciones de lactato y amonio, mayores reducciones en la altura del salto, así como mayores deterioros en la velocidad de deformación derivada de la TMG después del ejercicio que el 6 × 4. Por lo tanto, la implementación de series de menos repeticiones con intervalos de descanso más cortos y frecuentes entre series atenúa los deterioros en el rendimiento mecánico, especialmente en las últimas repeticiones de cada serie. Estos efectos pueden estar mediados por menores alteraciones neuromusculares, menor estrés metabólico y mejor mantenimiento de las propiedades contráctiles del músculo. ¿ ESTUDIO III: Evolución de las propiedades contráctiles de los músculos de las extremidades inferiores a lo largo de una temporada en jugadores de fútbol sala de élite. Resumen Este estudio tuvo como objetivo analizar los cambios producidos durante la temporada, así como determinar el potencial efecto acumulativo de un programa de entrenamiento de fuerza en jugadores de fútbol sala sobre las propiedades contráctiles de la musculatura de las piernas. Catorce jugadores de fútbol sala de élite (2 porteros, 4 defensas, 4 extremos y 3 pivotes) fueron evaluados mediante TMG en las semanas 11 (Pre-), 18 (Mid-) y 28 (Post-) de la temporada. Se evaluó el Dm, Tc, Td y la velocidad de desplazamiento radial (90%) Dm (VrD90). Después de la segunda medición, se incluyó un programa de entrenamiento de fuerza basado en la musculatura del tren inferior. Se llevó a cabo una vez por semana durante 9 semanas. Para el estudio, se utilizó un análisis de varianza de medidas repetidas para detectar los cambios a lo largo de la temporada. Se incluyeron dos factores: el tiempo, que se utilizó como factor intra-sujeto y la posición específica, que se utilizó como factor entre-sujetos. De esta manera, se observó un incremento respecto a los niveles basales para Tc, Td y Dm durante la temporada. Sin embargo, las adaptaciones de las propiedades contráctiles fueron específicas de cada músculo. Además, un programa de fuerza durante la temporada de 9 semanas de duración con una sesión por semana no tuvo efectos significativos sobre las propiedades contráctiles de los jugadores de fútbol sala. Por último, no se observaron diferencias al comparar las distintas posiciones. En vista de los resultados, durante la temporada, se produce un deterioro de las propiedades mecánicas musculares de las piernas en jugadores profesionales de fútbol sala. Además, un entrenamiento de fuerza, realizado una vez por semana en la fase final de la temporada, no fue suficiente para revertir estos deterioros, pero al menos permitió que no se deterioraran más dichas propiedades musculares.Universidad Pablo de Olavide de Sevilla. Departamento de Deporte e Informátic

Mechanomyographic measures of muscle contractile properties are influenced by electrode size and stimulation pulse duration

The aim was to determine the effects of changing pulse duration and electrode size on muscle contractile properties. Thirty-six healthy young male participated in the study (age 24.8 ± 5.8 years; height 178.2 ± 0.6 cm; body mass 71.8 ± 7.3 kg; self-reported weekly moderate intensity activity 3.5 ± 1.2 h·week−1). Tensiomyography was used to assess rectus femoris (RF) and vastus medialis (VM) muscles neuromuscular properties of the dominant leg according to the electrode size (3.2–5 cm) and the stimulus length (0.2, 0.5, and 1 ms). Maximal radial displacement (Dm); Contraction time (Tc); Delay time (Td); Sustained time (Ts) and Half relaxation time (Tr) were measured. Relative and absolute reliability was quantified. To analyze the effects of the electrode and the stimulus length, a repeated-measures analysis of variance was used. Dm and Tc parameters showed for both muscles an excellent relative (0.95–0.99) and absolute reliability (1.6–4.2%). However, Ts and Tr showed low values of absolute reliability (4.4–40.9%). The duration of the stimulus length applied to the RF and VM and electrode size significantly influences muscle’s contractile properties (p < 0.05; η2p = 0.09–0.60). The Dm increases substantially as the duration of the stimulus increases and with the use of the larger electrode in both muscles. However, Tc and Td are less affected by both conditions and not entirely clear. Practically, our study suggests that a stimulus pulse duration of 1 ms together with a 5 × 5 cm electrode is necessary to reach a reliable and reproducible assessment of both RF and VM muscles contractile properti

Mechanomyographic Measures of Muscle Contractile Properties are Infuenced by Electrode Size and Stimulation Pulse Duration

The aim was to determine the efects of changing pulse duration and electrode size on muscle contractile properties. Thirty-six healthy young male participated in the study (age 24.8±5.8 years; height 178.2±0.6cm; body mass 71.8±7.3kg; self-reported weekly moderate intensity activity 3.5±1.2h·week−1). Tensiomyography was used to assess rectus femoris (RF) and vastus medialis (VM) muscles neuromuscular properties of the dominant leg according to the electrode size (3.2–5cm) and the stimulus length (0.2, 0.5, and 1ms). Maximal radial displacement (Dm); Contraction time (Tc); Delay time (Td); Sustained time (Ts) and Half relaxation time (Tr) were measured. Relative and absolute reliability was quantifed. To analyze the efects of the electrode and the stimulus length, a repeated-measures analysis of variance was used. Dm and Tc parameters showed for both muscles an excellent relative (0.95–0.99) and absolute reliability (1.6–4.2%). However, Ts and Tr showed low values of absolute reliability (4.4–40.9%). The duration of the stimulus length applied to the RF and VM and electrode size signifcantly infuences muscle’s contractile properties (p<0.05; η2 p=0.09–0.60). The Dm increases substantially as the duration of the stimulus increases and with the use of the larger electrode in both muscles. However, Tc and Td are less afected by both conditions and not entirely clear. Practically, our study suggests that a stimulus pulse duration of 1ms together with a 5 × 5cm electrode is necessary to reach a reliable and reproducible assessment of both RF and VM muscles contractile properties.Ciencias de la Actividad Física y del Deport

Electromyographic Activity Evolution of Local Twitch Responses During Dry Needling of Latent Trigger Points in the Gastrocnemius Muscle: A Cross-Sectional Study

Trigger points (TrPs) are hypersensitive spots within taut bands of skeletal muscles that elicit referred pain and motor changes. Among the variety of techniques used for treating TrPs, dry needling is one of the most commonly applied interventions. The question of eliciting local twitch responses (LTRs) during TrP dry needling is unclear. Our main aim was to investigate the evolution of the electromyographic (EMG) peak activity of each LTR elicited during dry needling into latent TrPs of the gastrocnemius medialis muscle. Methods. Twenty asymptomatic subjects with latent TrPs in the gastrocnemius medialis muscle participated in this cross-sectional study. Changes in EMG signal amplitude (root mean square [RMS]) with superficial EMG were assessed five minutes before, during, and five minutes after dry needling. The peak RMS score of each LTR was calculated (every 0.5 sec). Results. Analysis of variance revealed a significant effect (F ¼ 29.069, P <0.001) showing a significant decrease of RMS peak amplitude after each subsequent LTR. Differences were significant (P <0.001) during the first three LTRs, and stable until the end of the procedure. No changes (P ¼0.958) were found for mean RMS data at rest before (mean ¼ 65.2 mv, 95% confidence interval [CI] ¼ 47.3–83.1) and after (61.0 mv, 95% CI ¼ 42.3–79.7) dry needling. Conclusions. We found that, in a series of LTRs elicited during the application of dry needling over latent TrPs in the medial gastrocnemius muscle, the RMS peak amplitude of each subsequent LTR decreased as compared with the initial RMS peak amplitude of previous LTRs. No changes in superficial EMG activity at rest were observed after dry needling of latent TrPs of the gastrocnemius medialis muscle.Ciencias de la Actividad Física y del Deport

Effects of different inertial load settings on power output using a flywheel leg curl exercise and its inter-session reliability

This study aimed to analyze the influence of the inertial load on both concentric and eccentric power output production during the flywheel leg curl exercise, and to assess the reliability of power output variables. Sixteen participants (8 males, 8 females) attended 4 testing sessions. During testing, participants performed one set of eight repetitions using a specific inertial load (0.083, 0.132, 0.182, 0.266 and 0.350 kg·m2) with a flywheel leg curl exercise. Concentric (CON) power, eccentric (ECC) power and the ECC/CON ratio were analyzed. The reliability analysis between sessions was performed. A significant interaction of inertia load x gender was found in CON power (p < 0.001) and in ECC power (p = 0.004), but not in the ECC/CON ratio (p = 0.731). A significant with-in (inertia loads) effect was found in CON power (p < 0.001) and in ECC power (p < 0.001), but not in the ECC/CON ratio (p = 0.096). CON power showed very high reliability scores, ECC power showed high to very high reliability scores, while the ECC/CON ratio ranged from poor to moderate. A significant between gender effect was found in CON power (p < 0.001) and in ECC power (p < 0.001), but not in the ECC/CON ratio (p = 0.752). This study is the first to report that power output in the flywheel leg curl exercise is altered by the inertia load used, as well as power output is different according to gender. CON and ECC power output presents high to very high reliability scores, and the ECC/CON ratio should not be used instead. These results can have important practical implications for testing and training prescription in sports

Localization of Muscle Edema and Changes on Muscle Contractility After Dry Needling of Latent Trigger Points in the Gastrocnemius Muscle

Background. Myofascial trigger points (TrPs) are hyperirritable spots within taut bands of skeletal muscles that elicit local and referred pain when stimulated. Among the variety of techniques used for treating TrPs, dry needling (DN) is the most commonly applied intervention. The physiological mechanisms underlying the effects of DN remain to be elucidated. Objective. To examine changes in skeletal muscle after DN in the area where the TrP is located. Methods. We measured in vivo changes that occur in human skeletal muscle one hour after DN over a TrP with magnetic resonance imaging (MRI) and tensiomyography. The study included 18 asymptomatic subjects with a latent TrP in one medial gastrocnemius muscle, and the contralateral leg was used as control. Results. The results showed that MRI signal intensity significantly increased one hour after the DN intervention, suggesting the presence of intramuscular edema. Tensiomyographic parameters showed higher muscle stiffness with an improvement in contraction time after DN. Conclusions. This is the first study showing intramuscular edema after TrP DN in human skeletal muscle. Future research should focus on using DN therapy in patients with active TrPs and on monitoring changes occurring at longer follow-up with imaging techniques.Fisioterapi

Effects of moderate vs. high iso-inertial loads on power, velocity, work and hamstring contractile function after flywheel resistance exercise

Flywheel iso-inertial training has been shown to positively affect muscular strength and sports performance (e.g. agility). However, implementing such eccentrically-biased training during a microcycle needs to be carefully planned due to its purported effects on the neuromuscular system that can last for hours/days post-exercise. This study aimed at using tensiomyography to verify the effects of different inertias during the hip extension exercise on the contractile function of biceps femoris and semitendinosus muscles of the dominant leg for up to 72 hours post-exercise. Thirty participants (24.4 ± 3.4 years) were divided into 0.075 or 0.1 kgm2 inertia groups and a control group. Magnitude-based analysis was used for the comparisons. Several tensiomyography parameters were changed after both intensities of flywheel exercise (in most cases indicating a decrement in muscle stiffness), whereas most between-group differences suggested that in the semitendinosus muscle, the higher inertia (0.1 kgm2) influenced the muscle stiffness parameters more (e.g. Dm = maximal radial displacement) while in the biceps femoris, the greater effect was caused by the lower inertia (0.075 kgm2) (e.g. Tc = contraction time). Most changes in contractile properties of the investigated muscles occur within 24 hours post-exercise, but can persist for up to 72 hours. However, higher inertia (0.1 kgm2) influenced the stiffness of the semitendinosus muscle more, while in the biceps femoris, the greater effect was caused by the lower inertia (0.075 kgm2). These findings should be considered by practitioners when prescribing flywheel iso-inertial training

T2 Hamstring Muscle Activation during the Single-Leg Roman Chair: Impact of Prior Injury

Previous studies have shown inhibition of previously injured hamstrings during eccentric exercises, but it is unknown whether this effect is also present during an isometric position-control exercise such as the single-leg Roman chair hold (SLRCH). Methods: This cross-sectional study investigated muscle activation during the SLRCH in individuals with prior hamstring injuries.Medicin

Effects of moderate vs. high iso-inertial loads on power, velocity, work and hamstring contractile function after flywheel resistance exercise.

Flywheel iso-inertial training has been shown to positively affect muscular strength and sports performance (e.g. agility). However, implementing such eccentrically-biased training during a microcycle needs to be carefully planned due to its purported effects on the neuromuscular system that can last for hours/days post-exercise. This study aimed at using tensiomyography to verify the effects of different inertias during the hip extension exercise on the contractile function of biceps femoris and semitendinosus muscles of the dominant leg for up to 72 hours post-exercise. Thirty participants (24.4 ± 3.4 years) were divided into 0.075 or 0.1 kg·m2 inertia groups and a control group. Magnitude-based analysis was used for the comparisons. Several tensiomyography parameters were changed after both intensities of flywheel exercise (in most cases indicating a decrement in muscle stiffness), whereas most between-group differences suggested that in the semitendinosus muscle, the higher inertia (0.1 kg·m2) influenced the muscle stiffness parameters more (e.g. Dm = maximal radial displacement) while in the biceps femoris, the greater effect was caused by the lower inertia (0.075 kg·m2) (e.g. Tc = contraction time). Most changes in contractile properties of the investigated muscles occur within 24 hours post-exercise, but can persist for up to 72 hours. However, higher inertia (0.1 kg·m2) influenced the stiffness of the semitendinosus muscle more, while in the biceps femoris, the greater effect was caused by the lower inertia (0.075 kg·m2). These findings should be considered by practitioners when prescribing flywheel iso-inertial training