The effect of lifting and lowering an external load on repositioning error of trunk flexion-extension in subjects with and without low back pain

Objective: To determine whether the repositioning error of trunk flexion-extension in individuals with low back pain is different from that in those not experiencing low back pain when lifting and lowering external loads. Design: A case-control study. Setting: Physical therapy department of a medical centre. Subjects: T wenty subjects with subacute low back pain and 20 control subjects without low back pain. Interventions: Tasks with and without lifting and lowering an external load. Main outcome measures: The trunk repositioning errors were measured with Measurand Shape Tape. Results: In subjects with low back pain, trunk repositioning errors were significantly reduced when lifting and lowering an external load in the direction of flexion (3.77 ± 1.26 degrees in a loaded condition versus 4.82 ± 2.97 degrees in an unloaded condition; P<0.05) and extension (3.17 ± 2.15 degrees in a loaded condition versus 5.03 ± 3.74 degrees in an unloaded condition; P<0.05). In control subjects, trunk repositioning errors were not significantly changed when lifting and lowering an external load in the direction of flexion (2.80 ± 1.39 degrees in a loaded condition versus 2.63 ± 1.24 degrees in an unloaded condition; P > 0.05) and extension (2.87 ± 1.40 degrees in a loaded condition versus 3.15 ± 1.50 degrees in an unloaded condition; P > 0.05). The direction of motion (trunk flexion or extension) was not shown to be significant in this study. Conclusion: Performing the task whilst lifting or lowering a submaximal load showed a reduced trunk repositioning error in subjects with subacute low back pain. Lifting and lowering a submaximal load might be considered as one of the rehabilitative strategies to hasten a return to work.