Effects of XXXX in quadriceps femoris during force-matching task.

@entity1 @entity1162 @entity2472
UNASSIGNED: The quadriceps femoris (QF) muscle group plays an essential role in @entity1 movement, such as standing, walking and running. The ability to maintain a steady force during physical activity of the @entity1 lower limb is important for mobility, postural control and balance. Although prolonged mechanical vibration of the muscle-tendon unit can moderate the efficacy of synaptic input from Ia afferent onto the a-motor neuron pathway, the effect of prolonged tendon vibration on fluctuations of knee extensor force has received little attention. The purpose of the present study was to examine the effects of @entity1162 on the force steadiness of the QF muscle. Nine healthy @entity1 performed a submaximal force-matching task involving isometric knee extension before and after patellar tendon vibration or quiet seated rest (n  =  7, control condition) for 30  min. The target force was 2.5, 10 and 30  % of maximal @entity2472 (MVC). Surface electromyography (EMG) of the four QF synergists was recorded and normalized to EMG amplitude during the MVC. The knee extension force and the EMG amplitude of vastus medialis during the MVC were significantly reduced after the vibration, but did not significantly decrease in the control condition. Fluctuations of force and normalized EMG of individual QF muscles at each submaximal force level did not significantly change after the vibration. We conclude that @entity1162 does not influence the force steadiness of the QF muscle during an isometric force-matching task.
