title: The effects of acute and prolonged muscle vibration on the function of the muscle spindle's reflex arc.
abstract: OBJECTIVE
  Localized mechanical vibration, applied directly to a muscle, is known to have powerful, duration-dependent effects on the muscle spindle's reflex arc. Here, the conditioning of the function of the spindle reflex arc via vibration was examined with considerations for use as a non-invasive, sensorimotor research tool.
  
  
  METHODS
  Muscle spindle function was examined with patellar tendon taps prior to and following exposure to muscle vibration applied to the quadriceps femoris for acute (<5 s) and prolonged (20 min) durations. Surface electromyography (sEMG), torque, and accelerometry signals were obtained during the taps to quantify various measures of reflex magnitude and latency.
  
  
  RESULTS
  Our findings suggest that acute vibration had no effect on normalized reflex torque or sEMG amplitude (p > 0.05), but increased total reflex latency (p = 0.022). Alternatively, prolonged vibration reduced normalized reflex torque and sEMG amplitude (p < 0.001), and increased reflex latency (p < 0.001).
  
  
  CONCLUSIONS
  Our findings support the use of prolonged vibration as a practical means to decrease the function of the muscle spindle's reflex arc. Overall, this suppressive effect was evident in the majority of subjects, but the extent was variable. This approach could potentially be used to help delineate the muscle spindle's role in various sensory or motor tasks in which more direct measures are not feasible. Acute vibration, however, did not potentiate muscle spindle function as hypothesized. Rather, our results suggest that acute vibration increased total reflex latency. Accordingly, potential mechanical and neurophysiological mechanisms are discussed.
authors.affiliation: a Applied Musculoskeletal and Human Physiology Laboratory, Oklahoma State University , Stillwater , OK , USA.
authors.forename: Zachary K
authors.initials: ZK
authors.lastname: Pope
authors.affiliation: a Applied Musculoskeletal and Human Physiology Laboratory, Oklahoma State University , Stillwater , OK , USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: DeFreitas
mesh_terms: D061725:Accelerometry; D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D009470:Muscle Spindles / Q000294:innervation / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012026:Reflex, Stretch / Q000502:physiology*; D013997:Time Factors; D014732:Vibration; D055815:Young Adult
keywords: Stretch reflex; myotatic reflex; patellar tendon reflex; proprioception; thixotropy