title: Young men utilise limited neuromuscular preparation to regulate post-impact knee mechanics during step landing.
abstract: OBJECTIVE
  The neuromuscular mechanisms determining the mechanical behaviour of the knee during landing impact remain poorly understood. It was hypothesised that neuromuscular preparation is subject-specific and ranges along a continuum from passive to active.
  
  
  METHODS
  A group of healthy men (N=12) stepped-down from a knee-high platform for 60 consecutive trials. Surface EMG of the quadriceps and hamstrings was used to determine pre-impact onset timing, activation amplitude and cocontraction for each trial. Partial least squares regression was used to associate pre-impact preparation with post-impact knee stiffness and coordination.
  
  
  RESULTS
  The group analysis revealed few significant changes in pre-impact preparation across trial blocks. Single-subject analyses revealed changes in muscle activity that varied in size and direction between individuals. Further, the association between pre-impact preparation and post-impact knee mechanics was subject-specific and ranged along a continuum of strategies.
  
  
  CONCLUSIONS
  The findings suggest that neuromuscular preparation during step landing is subject-specific and its association to post-impact knee mechanics occurs along a continuum, ranging from passive to active control strategies. Further work should examine the implications of these strategies on the distribution of knee forces in vivo.
authors: Institute of Health & Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia; Sydney Orthopaedic Research Institute, Chatswood, NSW, Australia. Electronic address: cscholes@sori.com.au.
authors: Corey J
authors: CJ
authors: Scholes
authors: Michael D
authors: MD
authors: McDonald
authors: Anthony W
authors: AW
authors: Parker
mesh_terms: D001696:Biomechanical Phenomena; D004576:Electromyography / Q000379:methods*; D064368:Healthy Volunteers; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D013177:Sports / Q000502:physiology*; D055815:Young Adult
keywords: Coordination; Electromyography; Knee; Pre-impact preparation; Stiffness