The influence of stimulation frequency and ankle joint angle on the moment exerted by human dorsiflexor muscles

Central Activation and Force-Frequency Responses of the Lumbar Extensor Muscles

“…The F 50 values reported here are between those reported for the knee extensors (21.6 Hz) (25) and the dorsiflexors (14 Hz) (18) in studies that used the Hill equation to calculate the F 50 . Other investigators who define the F 50 as simply the frequency at which 50% of the maximum force is produced report lower F 50 values in both the knee extensors (13)(14)(15)(16)(17)(18) Hz) (1,5,30) and the ankle dorsiflexors (12 Hz) (21). If we use this latter definition for our data, we obtain a value of È10 Hz, lower than what has been reported for either muscle group, but certainly closer to the dorsiflexors.…”

“…Few data are available on the Hill coefficients of different muscle groups, but one laboratory has reported a value of È3.5 for the ankle dorsiflexors (18). Analysis of a data set of control participants used in a published manuscript (25) gave a value of È2.1 for the knee extensors (S. Binder-Macleod, personal communication), much closer to the value of 2.2 found here for the lumbar extensors.…”

“…The fitting procedure also provides the Hill coefficient, which indicates the steepness of the linear portion of the relationship. Although several investigators have determined both the F 50 and the slope of the FFR using linear interpolation (1,5,15,30), fitting the FFR data with the Hill Equation provides more objective values for these parameters and has been performed in other muscle groups (18,25). All data are reported as means (SD).…”

Post Activation Potentiation of the Plantarflexors: Implications of Knee Angle Variations

“…Variations in the ankle joint angle were found to affect PT enhancements (i.e. higher PAP at shorter muscle lengths) for the tibialis anterior (Mela et al, 2001; Vandervoort et al, 1983), and PAP levels in the medial gastrocnemius (MG) and soleus (SOL) muscles, measured independently via mechanomyographic amplitude, were also found to be ankle joint dependent (Miyamoto et al, 2010). …”

Análisis de los efectos de un protocolo de electroestimulación y ejercicios excéntricos, isométricos y concéntricos sobre el dolor y la funcionalidad en el tratamiento y readaptación de la tendinopatía rotuliana o rodilla del saltador

“…Es el número de veces que se repite un impulso en un segundo y se mide en hercios (HZ). Cuanto mayor es la frecuencia, hablando siempre de baja frecuencia comprendida entre 0 y 200Hz, mayor será la fuerza generada [246], aunque según estudios recientes, con frecuencias de 80Hz se generaría menor fuerza que con 40 Hz [247], pero se debe tener en cuenta que este último estudio utilizó tiempos de contracción de 10 segundos lo que favorecería la fatiga y ésta también aumenta con la frecuencia [248], lo que indica que con frecuencias altas, los tiempos de contracción deben ser más cortos.…”