Isometric back extension endurance tests: A review of the literature

Objective: To review the literature that describes and evaluates the use of isometric back extension endurance tests. Data Collection: Relevant articles in English were retrieved through a sear ch of MEDLINE and the Index to Chiropractic Literature. Key search terms we re back muscle endurance, isometric back endurance, trunk extensors, back m uscle performance, and Sorensen test. Data Synthesis: The principal criterion for inclusion was as follows: any s tudy 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 devic es. Much of the research on this topic has centered on a procedure known as the Sorensen test. Normative databases have been established for the Soren sen test and 2 other test types. Validity and reliability have been assesse d 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 factor s warrant further research. On the basis of the literature reviewed, we det ermined that the Sorensen is probably the most clinically useful of these t ests; it is easy to perform, requires no special equipment, and enjoys the most support from the literature.