title: Changes in Passive Properties of the Gastrocnemius Muscle-Tendon Unit During a 4-Week Routine Static-Stretching Program.
abstract: BACKGROUND
  Static stretching (SS) is commonly performed in a warm-up routine to increase joint range of motion (ROM) and to decrease muscle stiffness. However, the time course of changes in ankle-dorsiflexion (DF) ROM and muscle stiffness during a routine SS program is unclear.
  
  
  OBJECTIVE
  To investigate changes in ankle-DF ROM, passive torque at DF ROM, and muscle stiffness during a routine SS program performed 3 times weekly for 4 wk.
  
  
  METHODS
  A quasi-randomized controlled-trial design.
  
  
  METHODS
  The subjects comprised 24 male volunteers (age 23.8 ± 2.3 y, height 172.0 ± 4.3 cm, body mass 63.1 ± 4.5 kg) randomly assigned to either a group performing a 4-wk stretching program (SS group) or a control group.
  
  
  METHODS
  DF ROM, passive torque, and muscle stiffness were measured during passive ankle dorsiflexion in both groups using a dynamometer and ultrasonography once weekly during the 4-wk intervention period.
  
  
  RESULTS
  In the SS group, DF ROM and passive torque at DF ROM significantly increased after 2, 3, and 4 wk compared with the initial measurements. Muscle stiffness also decreased significantly after 3 and 4 wk in the SS group. However, there were no significant changes in the control group.
  
  
  CONCLUSIONS
  Based on these results, the SS program effectively increased DF ROM and decreased muscle stiffness. Furthermore, an SS program of more than 2 wk duration effectively increased DF ROM and changed the stretch tolerance, and an SS program more than 3 wk in duration effectively decreased muscle stiffness.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nakamura
authors.forename: Tome
authors.initials: T
authors.lastname: Ikezoe
authors.forename: Hiroki
authors.initials: H
authors.lastname: Umegaki
authors.forename: Takuya
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Satoru
authors.initials: S
authors.lastname: Nishishita
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ichihashi
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D052580:Muscle Stretching Exercises / Q000379:methods*; D018482:Muscle, Skeletal / Q000502:physiology*; D016059:Range of Motion, Articular; D013710:Tendons / Q000502:physiology*; D013997:Time Factors; D019415:Torque; D055815:Young Adult
keywords: muscle stiffness; stretch tolerance; time course; ultrasound