title: Isometric back extension endurance tests: a review of the literature.
abstract: OBJECTIVE
  To review the literature that describes and evaluates the use of isometric back extension endurance tests.
  
  
  METHODS
  Relevant articles in English were retrieved through a search of MEDLINE and the Index to Chiropractic Literature. Key search terms were back muscle endurance, isometric back endurance, trunk extensors, back muscle performance, and Sorensen test.
  
  
  RESULTS
  The principal criterion for inclusion was as follows: any study that discussed or tested an isometric type of back endurance extension test. Studies that were excluded did not use an isometric testing protocol. Thirty-seven of the initial studies are included in this review.
  
  
  RESULTS
  Six different types of isometric back extension endurance testing methods were found. Three of these procedures require special testing devices. Much of the research on this topic has centered on a procedure known as the Sorensen test. Normative databases have been established for the Sorensen test and 2 other test types. Validity and reliability have been assessed for some of the procedures.
  
  
  CONCLUSIONS
  The influence of motivation and effort exerted by the subject are limiting factors in all of the tests reviewed. These psychologic factors warrant further research. On the basis of the literature reviewed, we determined that the Sorensen is probably the most clinically useful of these tests; it is easy to perform, requires no special equipment, and enjoys the most support from the literature.
authors.affiliation: Horrigan Sports Chiropractic Soft Tissue and Athletic Injuries, Los Angeles, Calif 90067, USA. cemoreau@earthlink.net
authors.forename: C E
authors.initials: CE
authors.lastname: Moreau
authors.forename: B N
authors.initials: BN
authors.lastname: Green
authors.forename: C D
authors.initials: CD
authors.lastname: Johnson
authors.forename: S R
authors.initials: SR
authors.lastname: Moreau
mesh_terms: D000328:Adult; D015444:Exercise; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000628:therapy; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture; D015203:Reproducibility of Results; D013997:Time Factors