title: Effect of soccer heading ball speed on S100B, sideline concussion assessments and head impact kinematics.
abstract: OBJECTIVE
  To examine the effect of soccer heading ball speed on S-100B serum concentration, concussion sideline assessments and linear head impact acceleration.
  
  
  METHODS
  Sixteen division I soccer players participated in this pre-test post-test design study. Athletes performed five standing headers over a 10 minute period at 30 (n = 5), 40 (n = 5) or 50 (n = 6) miles per hour (mph) (randomized). S-100B serum concentration (ng mL-1) and sideline concussion assessments were measured prior to and post-heading. Peak resultant linear head acceleration (gravitational units; g) was measured during soccer heading.
  
  
  RESULTS
  No statistically significant interaction effects were identified between ball velocity groups over time on S100B (effect sizes ranged from 0.03-0.23) or concussion assessments tests. There was a non-significant increase (p = 0.06) in head impact acceleration from the 30 (30.6; SD = 6.2 g) to 50 mph (50.7; SD = 7.7 g) ball speed.
  
  
  CONCLUSIONS
  In this controlled setting, an acute bout of soccer heading across various ball velocities did not affect S100B or concussion assessment test scores. These findings are preliminary, as the small sample size in each group may have played a role in the lack of significant findings.
authors.affiliation: a Department of Kinesiology , Temple University , Philadelphia , PA , USA and.
authors.forename: Millie
authors.initials: M
authors.lastname: Dorminy
authors.affiliation: a Department of Kinesiology , Temple University , Philadelphia , PA , USA and.
authors.forename: Ashley
authors.initials: A
authors.lastname: Hoogeveen
authors.affiliation: a Department of Kinesiology , Temple University , Philadelphia , PA , USA and.
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Tierney
authors.affiliation: b Department of Kinesiology , Towson University , Towson , MD , USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Higgins
authors.affiliation: a Department of Kinesiology , Temple University , Philadelphia , PA , USA and.
authors.forename: Jane K
authors.initials: JK
authors.lastname: McDevitt
authors.affiliation: a Department of Kinesiology , Temple University , Philadelphia , PA , USA and.
authors.forename: Jan
authors.initials: J
authors.lastname: Kretzschmar
keywords: Brain injury; brain injury biomarker; head impact acceleration; sub-concussive head impacts; subconcussion