title: Relationship between landing strategy and patellar tendinopathy in volleyball.
abstract: OBJECTIVE
  The aetiology of patellar tendinopathy (jumper's knee) remains unclear. To see whether landing strategy might be a risk factor for the development of this injury, this study examined whether landing dynamics from drop jumps differed among healthy volleyball players (CON) and volleyball players with a jumper's knee. The patients with jumper's knee were divided into an asymptomatic group with a previous jumper's knee (PJK) and a symptomatic group with a recent jumper's knee (RJK).
  
  
  METHODS
  Inverse dynamics analyses were used to estimate lower extremity joint dynamics from 30, 50 and 70 cm drop jumps in the three groups (CON, n = 8; PJK, n = 7; RJK, n = 9). A univariate repeated measures analysis of variance was used to compare the different landing techniques.
  
  
  RESULTS
  Data analysis of the landing dynamics revealed that PJK showed higher knee angular velocities (p<0.01), and higher ankle plantar flexion moment loading rate (p<0.01). Furthermore, strong tendencies of higher loading rate of vertical ground reaction force (p = 0.05) and higher knee extensor moment loading rate (p = 0.08) were found compared with CON. Higher values for peak knee moment, peak knee power and knee work (all p<0.01) were found for CON compared with RJK. The comparison of the two jumper's knee groups yielded higher knee angular velocities (p<0.01), together with higher ankle plantar flexion and knee extensor moment loading rate (p<0.01 and p<0.05, respectively).
  
  
  CONCLUSIONS
  Where RJK used a landing technique to avoid high patellar tendon loading, PJK used a stiffer landing strategy, which may be a risk factor in the development of patellar tendinopathy.
authors.affiliation: Center for Human Movement Sciences, University Center for Sport, Movement and Health, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. r.w.bisseling@rug.nl
authors.forename: Rob W
authors.initials: RW
authors.lastname: Bisseling
authors.forename: At L
authors.initials: AL
authors.lastname: Hof
authors.forename: Steef W
authors.initials: SW
authors.lastname: Bredeweg
authors.forename: Johannes
authors.initials: J
authors.lastname: Zwerver
authors.forename: Theo
authors.initials: T
authors.lastname: Mulder
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000517:prevention & control*; D016022:Case-Control Studies; D006801:Humans; D015601:Injury Severity Score; D007700:Kinetics; D008297:Male; D017847:Patellar Ligament / Q000293:injuries*; D010806:Physical Education and Training / Q000379:methods*; D016059:Range of Motion, Articular; D012307:Risk Factors; D013177:Sports; D052256:Tendinopathy / Q000209:etiology* / Q000517:prevention & control