title: Muscle activity during lifting: examining the effect of core conditioning of multifidus and transversus abdominis.
abstract: BACKGROUND
  It is well accepted that both multifidus and transversus abdominis muscles have a vital role in maintaining spinal stability.
  
  
  OBJECTIVE
  To determine if multifidus and transversus abdominis could be strengthened by a six-week conditioning program and to establish if the amount of electromyographic (EMG) activity in external oblique differed in a lifting and holding task after the conditioning program.
  
  
  METHODS
  EMG activity of external oblique during a lifting and holding task was obtained. Multifidus cross-sectional area and transversus abdominis width were measured using real time ultrasound in six males and five females, with no back pain (mean age of 26.3 (± 5.4) years). The participants then performed a six-week muscle-conditioning program for multifidus and transversus abdominis, after which the EMG activity of external oblique and dimensions of multifidus and transversus abdominis were re-measured.
  
  
  RESULTS
  Both multifidus and transversus abdominis significantly increased in size. There was significantly less activity in external oblique during a lifting task after the conditioning program, with no change in external oblique activity during a holding task.
  
  
  CONCLUSIONS
  this study may indicate a link between the dimensional increase of multifidus and transversus abdominis, and the decrease in EMG activity in external oblique during lifting.
authors.affiliation: School of Health Sciences, University of South Australia, Adelaide, Australia.
authors.forename: J F
authors.initials: JF
authors.lastname: MacKenzie
authors.affiliation: School of Mechanical Engineering, The University of Adelaide, Adelaide, Australia.
authors.forename: P N
authors.initials: PN
authors.lastname: Grimshaw
authors.affiliation: School of Medical Sciences, The University of Adelaide, Adelaide, Australia.
authors.forename: C D S
authors.initials: CD
authors.lastname: Jones
authors.affiliation: International Centre for Allied Health Evidence, Division of Health Sciences, University of South Australia, Adelaide, Australia.
authors.forename: K
authors.initials: K
authors.lastname: Thoirs
authors.affiliation: Centre for Regional Engagement, University of South Australia, Adelaide, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Petkov
mesh_terms: D000009:Abdominal Muscles / Q000033:anatomy & histology / Q000502:physiology*; D000328:Adult; D005260:Female; D006801:Humans; D017770:Lifting; D008297:Male; D009119:Muscle Contraction; D053580:Muscle Strength; D064170:Paraspinal Muscles / Q000033:anatomy & histology / Q000502:physiology*; D064797:Physical Conditioning, Human / Q000502:physiology*; D055815:Young Adult
keywords: EMG; Lifting; muscle conditioning and strengthening; real time ultrasound; spinal stability