Quantification of the loading characteristics of the upper body and back extension strength on a variable angle Roman chair.

The purpose of this study was to quantify the loading characteristics of the upper body during variable angle Roman chair (VARC) exercise and to compare back extension strength outputs obtained from a VARC to a criterion measure (lumbar dynamometer). For twenty-four healthy volunteers (age, 22.7 ± 3.2 years), the load attributed to the upper body and isometric back extension strength were measured twice at six positions over a full range of lumbar flexion on a VARC. In addition, isometric back extension strength was measured at seven positions over a full range of lumbar flexion on a lumbar dynamometer. Test-retest reliability was high for measures of the load attributed to the upper body (r = 0.99) and isometric strength (r = 0.96 to 0.97) on the VARC. The load attributed to the upper body increased from the most flexed to most extended position, while isometric strength increased from the most extended to the most flexed position on the VARC. Average VARC and dynamometer strength values were highly correlated (r = 0.90), but were lower on the VARC than on the dynamometer (888.4 ± 249.8 N vs. 1050.0 ± 438.5 N, respectively; p < 0.05).