Rate of force development to evaluate the neuromuscular fatigue and recovery after an intermittent isometric handgrip task with different blood flow restriction conditions

Aim: To investigate the neuromuscular fatigue and recovery after an intermittent isometric handgrip exercise (IIHE) executed until failure with different blood flow restriction (BFR) conditions (free flow, partial and total vascular restriction). Methods: Thirteen healthy men carried out an IIHE at 45% of maximum voluntary isometric force (MVIF) until failure with total restriction (TR), partial restriction (PR) or free flow (FF). The rate of force development (RFD) was extracted from the MIVF over the time intervals of 0-30, 0-50, 0-100, and 0-200ms and normalized by MVIF [relative RFD (RFDr)]. Results: The RFDr decreased significantly (p<0.01) after the IIHE in all BFR conditions and time intervals studied, remaining lower for five minutes. The medians of the RFDr in FF condition were significantly lower (p=0.01) at 30ms (1.56 %MVIF·s-1) and 50ms (1.70 %MVIF·s-1) when compared to TR at 30ms (2.34 %MVIF·s-1) and 50ms (2.63 %MVIF·s-1) in minute 1 post failure. Conclusions: These results show that, regardless of the blood flow restriction level, there is no RFD recovery five minutes after an exhaustive IIHE. When the task was executed with FF, the reduction of the RFD was greater when compared with the TR condition.(AU)

Treino moderado de corrida causa alterações nas propriedades biomecânicas do tendão do calcâneo? / Do moderate running training changes the biomechanical properties of the achilles tendon? / ¿Entrenamiento físico moderado causan cambios en las propiedades biomecánicas del tendón de aquiles?

O efeito do treinamento aeróbio ainda apresenta resultados conflitantes com relação às respostas biomecânicas apresentadas pelo tendão após um período de treinamento aeróbio moderado, como a corrida. Este estudo tem como objetivo avaliar o efeito de um protocolo de corrida de intensidade moderada em esteira sobre as propriedades mecânicas dos tendões do calcâneo de ratos. Para o ensaio mecânico os tendões foram tracionados até o ponto de fracasso do espécime. O treinamento aeróbiode intensidade moderada em ratos não causa alterações nas propriedades biomecânicas do tendão de calcâneo, desta forma, parece não representar risco podendo ser eficaz por não levar o tendão do Calcâneo ao estresse e a fadiga mecânica.

The effect of aerobic training has presented conflicting results regarding the biomechanical responses submitted by the tendon after a period of moderate aerobic training such as running. This study aims to evaluate the effect of a protocol running on a treadmill at moderate intensity on the mechanical properties of the Achilles tendons of rats. For mechanical test the tendons were pulled to the point of failure of the specimen. The moderate-intensity aerobic training in rats does not changes in the biomechanical properties of the Achilles tendon, thus, does not seem to pose a risk can be effective for not taking the Achilles tendon to mechanical stress and fatigue.

El efecto de entrenamiento aerobio ha presentado resultados contradictorios respecto a las respuestas biomecánicas presentado por el tendón después de un período de entrenamiento aerobio moderado, como correr. Este estudio pretende evaluar el efecto de un protocolo de correr en una cinta a una intensidad moderada en las propiedades mecánicas de los tendones de Aquiles de las ratas. Para pruebas mecánicas de los tendones se retiraron hasta el punto de fracaso de la muestra. El entrenamiento aerobio de intensidad moderada en las ratas no provoca cambios en las propiedades biomecánicas del tendón de Aquiles, por lo tanto, no parece representar un riesgo puede ser eficaz para no tomar el tendón de Aquiles a la tensión mecánica y la fatiga.