title: Measurement of impact acceleration: mouthpiece accelerometer versus helmet accelerometer.
abstract: BACKGROUND
  Instrumented helmets have been used to estimate impact acceleration imparted to the head during helmet impacts. These instrumented helmets may not accurately measure the actual amount of acceleration experienced by the head due to factors such as helmet-to-head fit.
  
  
  OBJECTIVE
  To determine if an accelerometer attached to a mouthpiece (MP) provides a more accurate representation of headform center of gravity (HFCOG) acceleration during impact than does an accelerometer attached to a helmet fitted on the headform.
  
  
  METHODS
  Single-factor research design in which the independent variable was accelerometer position (HFCOG, helmet, MP) and the dependent variables were g and Severity Index (SI).
  
  
  METHODS
  Independent impact research laboratory.
  
  
  METHODS
  The helmeted headform was dropped (n = 168) using a National Operating Committee on Standards for Athletic Equipment (NOCSAE) drop system from the standard heights and impact sites according to NOCSAE test standards. Peak g and SI were measured for each accelerometer position during impact.
  
  
  METHODS
  Upon impact, the peak g and SI were recorded for each accelerometer location.
  
  
  RESULTS
  Strong relationships were noted for HFCOG and MP measures, and significant differences were seen between HFCOG and helmet g measures and HFCOG and helmet SI measures. No statistically significant differences were noted between HFCOG and MP g and SI measures. Regression analyses showed a significant relationship between HFCOG and MP measures but not between HFCOG and helmet measures.
  
  
  CONCLUSIONS
  Upon impact, MP acceleration (g) and SI measurements were closely related to and more accurate in measuring HFCOG g and SI than helmet measurements. The MP accelerometer is a valid method for measuring head acceleration.
authors.affiliation: Towson University, Towson, MD 21252, USA. mhiggins@towson.edu
authors.forename: Michael
authors.initials: M
authors.lastname: Higgins
authors.forename: P David
authors.initials: PD
authors.lastname: Halstead
authors.forename: Lynn
authors.initials: L
authors.lastname: Snyder-Mackler
authors.forename: David
authors.initials: D
authors.lastname: Barlow
mesh_terms: D000054:Acceleration / Q000009:adverse effects*; D001265:Athletic Injuries / Q000517:prevention & control; D001696:Biomechanical Phenomena; D006259:Craniocerebral Trauma / Q000517:prevention & control; D004867:Equipment Design; D004869:Equipment Safety; D005069:Evaluation Studies as Topic; D006260:Head Protective Devices / Q000592:standards*; D006801:Humans; D016014:Linear Models; D009064:Mouth Protectors / Q000592:standards*; D011336:Probability; D011482:Protective Devices / Q000592:standards; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical