title: Kinematic and dynamic biomechanical values in relation to muscle activity during contact head impact.
abstract: OBJECTIVE
  For the evaluation of neck injury the relative distance was observed between a marker placed on the forehead and a marker placed on the shoulder and also by change of the angle. To compare the severity of head injury a value of maximum head acceleration was used, HIC and a 3 ms criterion. All criteria were related to the activity of musculus sternocleidomastoideus and musculus trapezius in a situation of expected or unexpected contact impact.
  
  
  METHODS
  The situation was recorded using a Qualisys system, head acceleration of probands in three axes was recorded using the accelerometer, activity of neck muscles was monitored by a mobile EMG.
  
  
  RESULTS
  Maximum head acceleration was 5.61 g for non-visual and 5.03 g for visual. HIC36 was 6.65 non visual and 5.97 for visual. 3-ms criterion was 5.37 g for non-visual and 4.89 g for visual and max. force was 291 N for non-visual and 314 N for visual. The average time of muscle activation of the observed group without visual perception is 0.355 s after hitting an obstacle, with visual perception 0.085 s before the crash.
  
  
  CONCLUSIONS
  Kinematic values indicate more favourable parameters for neck injuries for visual. Head injury criteria show an average decrease of about 10% for visual. We can conclude that the visual perception means a significant increase in pre-activation of the observed muscle group of almost 745% and lower activation in following phase of approximately 90%.
authors.affiliation: Department of Anatomy and Biomechanics, Faculty of Physical Education and Sport, Laboratory of Biomechanics of Extreme Loading, Charles University, Czech Republic.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Fanta
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, Charles University in Prague, First Faculty of Medicine, University Hospital Motol, Prague, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Boucek
authors.affiliation: Department of Anatomy and Biomechanics, Faculty of Physical Education and Sport, Laboratory of Biomechanics of Extreme Loading, Charles University, Czech Republic.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hadraba
authors.affiliation: Department of Anatomy and Biomechanics, Faculty of Physical Education and Sport, Laboratory of Biomechanics of Extreme Loading, Charles University, Czech Republic.
authors.forename: Richard
authors.initials: R
authors.lastname: Billich
authors.affiliation: Department of Anatomy and Biomechanics, Faculty of Physical Education and Sport, Laboratory of Biomechanics of Extreme Loading, Charles University, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Kubovy
authors.affiliation: Department of Anatomy and Biomechanics, Faculty of Physical Education and Sport, Laboratory of Biomechanics of Extreme Loading, Charles University, Czech Republic.
authors.forename: Karel
authors.initials: K
authors.lastname: Jelen
mesh_terms: D000054:Acceleration / Q000009:adverse effects; D000328:Adult; D001696:Biomechanical Phenomena; D006259:Craniocerebral Trauma / Q000503:physiopathology*; D004576:Electromyography / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory; D009334:Neck Muscles / Q000502:physiology* / Q000503:physiopathology; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult