title: Analysis of Jumping-Landing Manoeuvers after Different Speed Performances in Soccer Players.
abstract: OBJECTIVE
  Running at high speed and sudden change in direction or activity stresses the knee. Surprisingly, not many studies have investigated the effects of sprinting on knee's kinetics and kinematics of soccer players. Hence, this study is aimed to investigate indices of injury risk factors of jumping-landing maneuvers performed immediately after sprinting in male soccer players.
  
  
  METHODS
  Twenty-three collegiate male soccer players (22.1±1.7 years) were tested in four conditions; vertical jump (VJ), vertical jump immediately after slow running (VJSR), vertical jump immediately after sprinting (VJFR) and double horizontal jump immediately after sprinting (HJFR). The kinematics and kinetics data were measured using Vicon motion analyzer (100Hz) and two Kistler force platforms (1000Hz), respectively.
  
  
  RESULTS
  For knee flexion joint angle, (p = 0.014, η = 0.15) and knee valgus moment (p = 0.001, η = 0.71) differences between condition in the landing phase were found. For knee valgus joint angle, a main effect between legs in the jumping phase was found (p = 0.006, η = 0.31), which suggests bilateral deficit existed between the right and left lower limbs.
  
  
  CONCLUSIONS
  In brief, the important findings were greater knee valgus moment and less knee flexion joint angle proceeding sprint (HJFR & VJFR) rather than no sprint condition (VJ) present an increased risk for knee injuries. These results seem to suggest that running and sudden subsequent jumping-landing activity experienced during playing soccer may negatively change the knee valgus moment. Thus, sprinting preceding a jump task may increase knee risk factors such as moment and knee flexion joint angle.
authors.affiliation: Department of Sports Injuries and Corrective Exercises, Faculty of Physical Education and Sport Science, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Abdolhamid
authors.initials: A
authors.lastname: Daneshjoo
authors.affiliation: Department of Biomedical Engineering, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Noor Azuan
authors.initials: NA
authors.lastname: Abu Osman
authors.affiliation: Department of Sports Injuries and Corrective Exercises, Faculty of Physical Education and Sport Science, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Mansour
authors.initials: M
authors.lastname: Sahebozamani
authors.affiliation: Sports Centre, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Ashril
authors.initials: A
authors.lastname: Yusof
mesh_terms: D000328:Adult; D054874:Athletic Performance; D001696:Biomechanical Phenomena; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D012916:Soccer; D055815:Young Adult