Effects of prolonged vibration to vastus intermedius muscle on force steadiness of knee extensor muscles during isometric force-matching task.
Afferent inputs from Ia fibers in muscle spindles are essential for the control of force and prolonged vibration has been applied to muscle-tendon units to manipulate the synaptic input from Ia afferents onto α-motor neurons. The vastus intermedius (VI) reportedly provides the highest contribution to the low-level knee extension torque among the individual synergists of quadriceps femoris (QF). The purpose of the present study was to examine the effect of prolonged vibration to the VI on force steadiness of the QF. Nine healthy men (25.1±4.3years) performed submaximal force-matching task of isometric knee extension for 15s before and after mechanical vibration to the superficial region of VI for 30min. Target forces were 2.5%, 10%, and 30% of maximal voluntary contraction (MVC), and force steadiness was determined by the coefficient of variation (CV) of force. After the prolonged VI vibration, the CV of force at 2.5%MVC was significantly increased, but CVs at 10% and 30%MVCs were not significantly changed. The present study concluded that application of prolonged vibration to the VI increased force fluctuations of the QF during a very low-level force-matching task.
Faculty of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama, Japan. Electronic address: a-saito@aoni.waseda.jp.
Akira
A
Saito
Graduate School of Education and Human Development, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan; Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, Japan.
Ryosuke
R
Ando
Graduate School of Education and Human Development, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan; Research Center of Health, Physical Fitness & Sports, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan.
Hiroshi
H
Akima
D000328:Adult; D006801:Humans; D007537:Isometric Contraction; D007717:Knee / Q000502:physiology*; D007719:Knee Joint / Q000502:physiology; D008297:Male; D009046:Motor Neurons / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D019415:Torque; D014732:Vibration
Fluctuation; Ia afferent; Quadriceps femoris; Steady contraction; Surface electromyogram; Synergistic muscles