Motor control learning at the lumbar spine using sensor-based postural feedback: preliminary results of a randomized controlled trial

Abstract

Introduction Extrinsic feedback can be provided in different ways during motor control exercises for patients with low back pain (LBP). However, little is known about the most effective form of feedback. Aims (1) To evaluate whether sensor-based postural feedback is more effective than conventional feedback to learn a motor control task for the lumbar spine. (2) To assess whether there is a carry-over effect from an analytical to a functional task. Materials and methods Thirty healthy adults who experienced no LBP and performed no lumbar stabilization exercises in the past year were recruited. At baseline assessment, participants were asked to perform a forward bending movement in the hip joints (waiter’s bow, analytical task) and to lift a box (functional task), while keeping the physiological lordosis in the lumbar spine. Each task was repeated five times, and both conditions were standardized to the subject’s height. Lumbopelvic kinematics (deviation from the starting position in the lumbar spine and hip) were measured with inertial sensors (Valedo®Motion, version 1.0) placed at L1, S1 and the femur. After the baseline evaluation, participants were randomized into three groups: the sensor-group (SG) received sensor-based postural feedback on a computer screen, the mirror-group (MG) received mirror-based feedback and the control-group (CG) received no feedback. After randomization, subjects practiced the waiter’s bow (3 x 6 repetitions), during which they received their assigned form of feedback. Lumbopelvic kinematics of both tasks were re-assessed immediately after the learning phase. Results Regarding the waiter’s bow, the mean maximal deviation in the lumbar spine decreased in the SG (23.4° to 12.8°, p< 0.01), while there was no significant difference in the MG (18.4° to 20.4°) and the CG (20.5° to 19.7°). Post-hoc analysis showed that there was a between group difference in favor of the SG, which improved more than the MG and CG (p< 0.05). No significant within and between group differences were present for the lifting task, although there was a trend towards a within group improvement in the SG (p= 0.09). Results for the hip angles are currently being analyzed. Conclusions Sensor-based postural feedback appears to be more effective than conventional feedback and no feedback for improving task-specific motor control training. There was no carry-over effect to the functional task, suggesting that motor control training should be task-specific or that the duration of the learning period was not sufficient. These results should be confirmed in a low back pain population.