title: Combined effects of preceding muscle vibration and contraction on the tonic vibration reflex.
abstract: As a result of intrafusal thixotropy, muscle contraction at a short length followed by passive lengthening enhances the subsequent tonic vibration reflex (TVR). We studied the effects of muscle vibration, contraction, and their combination on the subsequent TVR in the left biceps in 20 healthy men. The preceding vibration (20 or 80 Hz) conditioning at a short or long length was applied to the muscle belly with and without a contraction. After conditioning, distal tendon vibration (80 Hz) was used to elicit the TVR at the test length. The strength of the TVR was measured by surface electromyography. Conditioning with 80-Hz vibration at a short length followed by passive lengthening enhanced the subsequent TVR, which was greater in the presence than in the absence of a conditioning contraction. These results suggest that vibration and contraction work synergistically to develop intrafusal thixotropy.
authors.affiliation: Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakajima
authors.forename: Masahiko
authors.initials: M
authors.lastname: Izumizaki
authors.forename: Chikara
authors.initials: C
authors.lastname: Sekihara
authors.forename: Takashi
authors.initials: T
authors.lastname: Atsumi
authors.forename: Ikuo
authors.initials: I
authors.lastname: Homma
mesh_terms: D000328:Adult; D000344:Afferent Pathways / Q000502:physiology; D004576:Electromyography; D005246:Feedback / Q000502:physiology; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D009470:Muscle Spindles / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D012018:Reflex / Q000502:physiology*; D014732:Vibration; D055815:Young Adult