title: Repeatability of electromyography normalization of the neck and shoulder muscles in symptomatic office workers.
abstract: OBJECTIVE
  The purpose of the study was to examine the repeatability of electromyography (EMG) normalization in office workers with neck and shoulder symptoms.
  
  
  METHODS
  Fifteen female office workers with neck/shoulder symptoms were recruited to participate in two separate days of testing. Maximum voluntary isometric contraction (MVIC) was used for the normalization of EMG data on the following muscles: cervical erector spinae, upper trapezius, lower trapezius and anterior deltoid. Repeatability was calculated using the intra-class correlation (ICC), relative standard error of measurement (%SEM) and relative coefficient of variation (%CV).
  
  
  RESULTS
  Peak root mean square (rms) and median frequency (MF) showed good to high repeatability in the UT, AD and CES (ICC = 0.87-0.95, %SEM= 2.65-9.48, %CV= 0.2-5.9). The repeatability of peak rms was good (ICC = 0.87, %SEM = 12.56, %CV = 3.3) and the MF of the LT was fair (ICC = 0.76, %SEM = 5.71, %CV = 2.9).
  
  
  CONCLUSIONS
  Peak rms and MF from the MVIC normalization method can be measured with sufficient repeatability in symptomatic office workers.
authors.affiliation: a Faculty of Allied Health Sciences , Chulalongkorn University , Thailand.
authors.forename: Montakarn
authors.initials: M
authors.lastname: Chaikumarn
authors.affiliation: b Faculty of Physical Therapy , Rangsit University , Thailand.
authors.forename: Nuttika
authors.initials: N
authors.lastname: Nakphet
authors.affiliation: a Faculty of Allied Health Sciences , Chulalongkorn University , Thailand.
authors.forename: Prawit
authors.initials: P
authors.lastname: Janwantanakul
mesh_terms: D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D009334:Neck Muscles / Q000502:physiology*; D009784:Occupational Diseases / Q000503:physiopathology; D012782:Shoulder / Q000502:physiology*
keywords: UMIN-CTR = UMIN000008385; electromyography; normalization; repeatability; symptomatic office workers