title: Upper-limb motion and drop jump: effect of expertise.
abstract: OBJECTIVE
  In this study, the role of arm motion in a drop jump was investigated in skilled and unskilled subjects.
  
  
  METHODS
  Nine skilled volleyball players and 8 novice individuals performed a series of jumps from two different heights: 30 cm and 60 cm. Free and restricted arm motion were used to determine the effect of arm motion on the vertical jump. Participants were instructed to land on a force plate and jump as high as possible. The ground reaction force was measured with an AMTI force plate (500 Hz). The kinematics of the jumps was recorded with two digital cameras (50 Hz).
  
  
  RESULTS
  The motion of the arms during the jumps was found to increase the jump height by 15% for the volleyball players and 12% for unskilled jumpers. Volleyball players performed better in the 60 cm than in 30 cm drop height (+8.5%). In the volleyball players, the peak vertical ground reaction force during take-off increased by 7%, the peak power increased by 10.6% while the peak impact force decreased by 6.3%.
  
  
  CONCLUSIONS
  Skilled jumpers were found to have a better use of arm motion than novices in (i) increasing the vertical jump performance, (ii) controlling the balance of the body at take-off (iii) leaving the ground with an optimal body orientation.
authors.affiliation: Cemter for Reaserch Center for Research in Sport Sciences, University Paris Sud 11, Orsay, France. cglaffaye@aol.com
authors.forename: G
authors.initials: G
authors.lastname: Laffaye
authors.forename: B
authors.initials: B
authors.lastname: Bardy
authors.forename: R
authors.initials: R
authors.lastname: Taiar
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D007091:Image Processing, Computer-Assisted; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D009048:Motor Skills / Q000502:physiology; D009068:Movement; D053580:Muscle Strength / Q000502:physiology; D013177:Sports / Q000502:physiology*; D013997:Time Factors; D034941:Upper Extremity / Q000502:physiology*; D014741:Video Recording