title: Intra- and inter-tester reliability and reference values for isometric neck strength.
abstract: OBJECTIVE
  Age- and sex-specific reference values for neck strength based on reliable measurements in the upright position are lacking. The aim of the present study was to determine intra- and inter-tester reliability and age- and sex-specific reference values for isometric neck strength in extension, flexion and lateral flexion in sitting position measured with the David Back Clinic 140 (DBC 140) equipment.
  
  
  METHODS
  The reliability of the DBC 140 equipment was investigated in 30 healthy volunteers and reference values were obtained from 101 healthy men and women.
  
  
  RESULTS
  The reliability study showed that neck strength measured with the DBC 140 equipment has almost perfect intra- and inter-tester reliability (ICC values between 0.85 and 0.97). The mean value of the first in a series of three measurements was the highest for all three test leaders and for almost all directions. Results from the reference value study showed that gender is a much more important determinant of neck strength than age, body weight or body mass index (BMI). Neck strength in women was, on average, 55% of that in men, and when adjusted for body weight or BMI, the percentages were 70% and 59%, respectively. In all directions observed, neck strength decreased by approximately 20% from age 25 to 64 years.
  
  
  CONCLUSIONS
  Measurements of neck strength taken in upright position with the DBC 140 equipment have almost perfect intra- and inter-tester reliability and justify the use of this test procedure. The use of the first measurement in a test series can be recommended for use in clinical practice since it was shown to be the maximal test value and thus, had a very low intra-tester difference. The use of reference values for neck strength when evaluating patients with neck disorders needs to take gender into account.
authors.affiliation: Faculty of Health Sciences, Linköping University, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Peolsson
authors.forename: B
authors.initials: B
authors.lastname: Oberg
authors.forename: R
authors.initials: R
authors.lastname: Hedlund
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D008875:Middle Aged; D009334:Neck Muscles / Q000502:physiology*; D015588:Observer Variation; D011187:Posture / Q000502:physiology; D012016:Reference Values; D012727:Sex Characteristics