Isolated planar trunk strengths measurement in normals .3. Results and database

Using the Flexion Extension Lateral Flexion Tester (FELT) and the Axial Rotation Tester (AROT), isolated planar trunk strengths were measured. The use of these specially constructed devices minimized the contaminating and confounding factors of pelvic girdle contribution in flexion extension and movement constraints of the torso in axial rotation. A three-dimensional functional profile of 102 normal subjects (59 males with mean age 31.8 years and 43 females with mean age 30.4 years) was developed. The isolated planar trunk strength capabilities were significantly affected by gender (p < 0.001), mode of activity (isometric vs. isokinetic - p < 0.001), and activity (extension, flexion, lateral flexion, and axial rotation - p < 0.001). The average strength values ranged between 70% to 80% of the peak strength values. The strength ratios between extension and flexion, extension and lateral flexion, and extension and axial rotation were repeatable and significant (p < 0.001). All multiple regression equations to predict strength from anthropometric values and minimal strength variables were significant (p < 0.001). In isometric strength 73-87% variability; and, in isokinetic strength 22-56% variability were accounted for by the anthropometric characteristics and isometric strength in neutral posture. Relevance to industry An understanding of isolated planar strength capability, and an ability to measure and analyze these will allow a strategy for enhancing safety in industry by incorporating the information in job design. Such measurements will provide a means for quantitative assessment of function among injured workers, and appropriate job accommodation for workers returning to work following rehabilitation. A comparison with the database reported here for a normal sample will provide a quantitative assessment of functional decrement allowing appropriate accommodation.