title: Change in EMG with skin friction at different frequencies during elbow flexion.
abstract: Modulation of muscle activation in superficial and deeper regions may be induced by tactile stimulation. The purpose of this study was to examine changes in muscle activation with skin friction. Subjects performed an isometric elbow flexion at 30% maximal voluntary cotraction (MVC) with skin friction at different frequencies (0.5-2.7 Hz). Surface electromyography (S-EMG) and intramuscular EMG were obtained from the elbow flexor muscles (BBS: short head of biceps brachii, BBL: long head of biceps brachii, BRA: brachialis). S-EMG activity decreased at a higher frequency of 2.7 Hz and increased linearly with an increase in skin friction frequency (0.5-2.7 Hz) in BBS. A decrease in high-threshold motor unit (HT-MU) firing rate in superficial regions and an increase in low-threshold motor unit (LT-MU) firing rate in deeper regions were observed with skin friction (2.7 Hz) in BBS. The actions of inhibitory interneurons may be influenced by cutaneous afferent input with skin friction. Muscle activation of BBS depended on the intensity of the stimulus. Skin friction over BBS results in an inhibitory response in superficial regions of BBS, most likely due to the increase in firing rate of low-threshold cutaneous mechanoreceptors.
authors: Department of Physiology, Graduate School of Medicine, Toho University, Ohta-ku, Tokyo, Japan. sugawarahi@hs.teu.ac.jp
authors: Hitoshi
authors: H
authors: Sugawara
authors: Ryota
authors: R
authors: Shimose
authors: Chigaya
authors: C
authors: Tadano
authors: Nobuyuki
authors: N
authors: Ushigome
authors: Masuo
authors: M
authors: Muro
mesh_terms: D000328:Adult; D004551:Elbow Joint / Q000502:physiology*; D004576:Electromyography; D017276:Friction; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology*; D010812:Physical Stimulation; D012867:Skin / Q000294:innervation*; D055815:Young Adult