Abstract
The purpose of this study was to investigate the differences in test-retest reliability between maximal and “simulated back injury” efforts in an isometric lumbar extension task and to test the hypothesis that voluntary attempts to “simulate” a back injury would yield less consistent torque production than maximal efforts. Twenty subjects were asked to undergo lumbar extensor testing at seven different positions in a lumbar extension machine. Each subject was tested twice in a maximal effort condition and twice with instructions to “simulate” a back injury. The order of the conditions was counterbalanced across subjects so that half of the subjects performed the maximal effort tests first and half performed the “simulated” effort first. Results indicated high test-retest correlations at all angles in both conditions. There were no differences in test-retest reliability between effort conditions. Therapist ratings of consistency did not differ between conditions and therapists could not discriminate between conditions on the basis of effort consistency. In the “simulated” condition subjects produced reliable, submaximal torque plots consistent with previous data indicating similar reliability at submaximal levels. It was concluded that use of test-retest torque consistency as a measure of sincerity of effort is premature and may be misleading.
Similar content being viewed by others
References
Kishino N, Mayer T, Gatchel R, Parrish M, Anderson C, Gustin L, Mooney V Quantification of lumbar function. Part 4: Isometric and isokinetic lifting simulation in normal subjects and low-back dysfunction patients.Spine 1985, 10: 921–927.
Kroll W. Reliability of a selected measure of human strength.Res. Quart. 1962; 33: 410–417.
Mayer TG, Gatchel RJ, Kishino N., Keeley J, Capra P, Mayer H, Barnett J, Mooney V. Objective assessment of spine function following industrial injury: A prospective study with comparison group and one-year follow-up.Spine 1985; 10: 482.
McIntyre DR, Glover LH, Conino MC, Seeds RH, Levene JA. A comparison of the characteristics of preferred low-back motion of normal subjects and low-back pain patients.J. Spinal Dis, 1991; 4: 90–95.
McIntyre DR, Glover LH, Seeds RH, Levene JA. The characteristics of preferred low-back motion.J Spinal Dis, 1990; 3: 147–155.
Hazard R, Reid S, Fenwick JY, Reeves V. Isokinetic trunk and lifting strength measurements: Variability as an indicator of effort.Spine 1988, 13: 54–57.
Robinson ME, MacMillan M, O'Connor P, Fuller AK, Cassisi JE. Reproducibility of maximal versus submaximal efforts in an isometric lumbar extension task. J Spinal Dis 1991; 4: 444–448.
Hirsch G, Beach G, Cooke C, Menard M, Locke S. Relationship between performance on lumbar dynamometry and waddell score in a population with low-back pain.Spine 1991; 16: 1039–1043.
Niehbur B, Marion R. Voluntary control of submaximal grip strength. Am J Phys Med Rehab 1990; 69: 96–101.
Robinson ME, Greene AF, O'Connor PD, Graves JE, MacMillan M. Reliability of lumbar isometric strength in chronic low back pain patients. Phys Ther 1992; 72: 186–190.
Batti'e M, Bigos SJ, Fisher LD, Hansson TH, Jones ME, Wortley MD. Isometric lifting strength as a predictor of industrial back pain reports.Spine 1989, 14.
Graves JE, Pollock ML, Carpenter DM, Leggett SH, Jones A, MacMillan M, Fulton M. Quantitative assessment of full range-of-motion isometric lumbar extension strength.Spine 1990, 15.
Mayer TG, Barnes D, Kishino ND, Nichols G, Gatchel RJ, Mayer H, Mooney V. Progressive isoinertial lifting evaluation in a standardized protocol and normative database.Spine 1988; 13: 993–997.
Mayer TG, Smith SS, Keley PT, Mooney V. Quantification of lumbar function: Part 2. Sagittal plane trunk strength in chronic low-back patients.Spine 1985; 10: 765–772.
Parnianpour M, Nordin M, Kahanovitz N, Frankel V. The triaxial coupling of torque generation of trunk muscles during isometric exertions and the effect of fatiguing isoinertial movements on the motor output and movement patterns.Spine 1988; 13: 982–992.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Robinson, M.E., O'Connor, P., MacMillan, M. et al. Effect of instructions to simulate a back injury on torque reproducibility in an isometric lumbar extension task. J Occup Rehab 2, 191–199 (1992). https://doi.org/10.1007/BF01078997
Issue Date:
DOI: https://doi.org/10.1007/BF01078997