title: The effect of a passive stretch training protocol on performance during a drop jump in humans.
abstract: OBJECTIVE
  Our study's aim is to show how a five-week stretch training protocol, based on passive stretching, can change muscle performance during a drop jump (stretch shortening cycle).
  
  
  METHODS
  This study observes in 8 healthy subjects (four males and four females), the effect of a 5-week passive stretch training protocol on the stretch shortening cycle (SSC) during the performance of a drop jump, and identify the architectural changes in the muscle. Subjects underwent measurements of their drop jump performance 3 times before, and 3 times after, the stretch training protocol. For the muscle tendon unit (MTU), changes were measured using the Hawkins and Hull's model. In order to calculate the length changes in the MTU, we measured the ankle and knee angles. For changes in the fascicle, the pennation angle and the thickness of the gastrocnemius medialis (GM) muscle were measured.
  
  
  RESULTS
  After the 5-week stretch training protocol, a significant increase in flexibility was observed in the fascicle during the first phase of the jump (a shortening of 10% after training vs. 20% before). No significant change was observed in the tendon, while the MTU showed a highly significant improvement (P<0.01) in muscle compliance during the landing phase. The average performance during the drop jump also showed a highly significant change (P<0.01).
  
  
  CONCLUSIONS
  The results show a higher degree of flexibility in the MTU, enabled the latter to store more energy which was then converted to kinetic energy during the push-off phase of the drop jump.
authors.affiliation: Anatomy, Morphology and Biomechanics Department Haute Ecole Paul Henri Spaak, Brussels, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Lévénez
authors.forename: S
authors.initials: S
authors.lastname: Theunissen
authors.forename: A
authors.initials: A
authors.lastname: Bottero
authors.forename: T
authors.initials: T
authors.lastname: Snoeck
authors.forename: A
authors.initials: A
authors.lastname: Bruyère
authors.forename: A
authors.initials: A
authors.lastname: Tinlot
authors.forename: C
authors.initials: C
authors.lastname: Balestra
authors.forename: S
authors.initials: S
authors.lastname: Provyn
mesh_terms: D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D009068:Movement / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D052580:Muscle Stretching Exercises; D016059:Range of Motion, Articular / Q000502:physiology; D055815:Young Adult