Effects of practice on the ability to perform lumbar stabilization exercises

Study Design: Randomized pretest-posttest control group design. Objectives: To determine the intratester and intertester reliability of a modified isometric stability test and to use this test to evaluate the effects of practice following a 1-week stabilization exercise program with weekly reinstruction. Background: Although "stabilization'' exercise programs are commonplace in the clinic, the reliability of a tool capable of measuring changes in the ability to perform increasingly difficult stabilization exercises has not, to our knowledge, been reported. In addition, it is not clear if practice improves the ability to perform stabilization exercises. Methods and Measures: A convenience sample of 44 asymptomatic subjects was pretested using a pressure transducer placed beneath the lumbar spine to detect motion (+/-4 mm Hg). A series of 7 exercises was attempted, which required increasing levels of muscular control of the lumbar spine for stability Subjects received a pass or fail for each exercise level based on the pressure gauge readings and the absence of movement compensations. Subjects were assigned randomly to exercise and nonexercise groups, and posttest measurements were taken after 4 weeks. The control group did not receive additional instruction. Results: The weighted kappa coefficient of 0.61 for intratester and 0.62 for intertester represents good agreement. The median level of exercise attainment increased for the exercise group but not for the nonexercise group. Conclusion: These results suggest that the modified isometric stability test was reliable and that a 4-week lumbar stabilization exercise program, with weekly intervals of reinstruction and testing, improves the ability to perform progressively difficult lumbar stabilization exercises.