title: Sex differences in neuromuscular recruitment are not related to patellar tendon load.
abstract: OBJECTIVE
  Although male volleyball players report a greater prevalence of patellar tendinopathy than female players, it remains unknown whether higher patellar tendon loading generated during landing by male players is related to sex-specific neuromuscular recruitment patterns. This study aimed to investigate the relationship between neuromuscular recruitment patterns and patellar tendon loading during landing and to determine whether there were any significant differences in lower limb neuromuscular recruitment patterns displayed by male and female volleyball players during landing.
  
  
  METHODS
  The neuromuscular recruitment patterns and patellar tendon loading of 20 male and 20 female volleyball players performing a lateral stop-jump block movement were recorded and calculated. Pearson product-moment correlations were conducted to determine whether neuromuscular recruitment patterns were related to the peak patellar tendon force or patellar tendon force loading rate generated at landing. Independent t-tests were applied to a subset of data for 13 males and 13 females matched for jump height to identify any between-sex differences in neuromuscular recruitment patterns.
  
  
  RESULTS
  Later onset of rectus femoris (r = 0.312), vastus medialis (r = 0.455), and biceps femoris (r = 0.330) were significantly correlated with a higher patellar tendon force loading rate, although these correlation values were weak. Male volleyball players displayed significantly earlier biceps femoris and semitendinosus onset, and significantly earlier peak semitendinosus activity compared with their female counterparts.
  
  
  CONCLUSIONS
  Although male and female volleyball players displayed significantly different muscle onset times, these patterns were not strongly related to patellar tendon loading at landing. It is likely that a multitude of factors, including the frequency of patellar tendon loading, more strongly contributes to developing patellar tendinopathy than neuromuscular recruitment patterns in isolation.
authors.affiliation: 1Biomechanics Research Laboratory, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW, AUSTRALIA; and 2AIS Movement Science, Australian Institute of Sport, Canberra, ACT, AUSTRALIA.
authors.forename: Ina
authors.initials: I
authors.lastname: Janssen
authors.forename: Julie R
authors.initials: JR
authors.lastname: Steele
authors.forename: Bridget J
authors.initials: BJ
authors.lastname: Munro
authors.forename: Nicholas A T
authors.initials: NA
authors.lastname: Brown
mesh_terms: D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D017847:Patellar Ligament / Q000502:physiology*; D059385:Plyometric Exercise; D011999:Recruitment, Neurophysiological / Q000502:physiology*; D012737:Sex Factors; D052256:Tendinopathy / Q000503:physiopathology; D054798:Volleyball / Q000502:physiology; D016474:Weight-Bearing