ISPGR International Conference edition:19 location:Bologna date:21-25 June 2009
Introduction: Persons with non-specific low back pain (NSLBP) have been observed to have an altered postural control strategy during static postural conditions (e.g. quiet standing), due to decreased reliance on lumbosacral proprioceptive inputs . It remains unclear whether persons with NSLBP show an altered proprioceptive control strategy during more dynamic postural tasks. Therefore, the aim of the present study was to examine the performance of a sit-to-stand-to-sit task (STSTS) on a stable support surface in persons with NSLBP and healthy controls.
Methods: The total duration of five consecutive STSTS movements as well as the duration of each stance, sitting and movement phase of 47 young subjects with NSLBP and 9 young pain-free subjects was recorded. Postural sway characteristics were evaluated with a six-channel force plate during the five consecutive STSTS movements. In addition, muscle vibration on triceps surae muscles and lumbar multifidus muscles was used to appraise the relative proprioceptive weighting (RPW) . A score equal to 1 corresponds to 100% reliance on afferent input from triceps surae muscles for postural control, a score equal to 0 corresponds to 100% reliance on back muscle afferent input.
Results: Persons with NSLBP need significantly more time to perform five consecutive STSTS movements compared to pain-free subjects (p<0.005). This longer performance is mainly caused by longer stance phases (p<0.05), while the durations of the sit-to-stand, the stand-to-sit movements and the sitting phases are not significantly different between the people with NSLBP and the healthy controls (p>0.05). Furthermore, the postural sways during the stance phases are significantly larger in persons with NSLBP compared to the healthy controls (p<0.05). In addition, persons with NSLBP have significantly higher RPW values in comparison with the healthy persons (NSLBP: 0.71Â±0.17; Healthy: 0.51Â±0.15; p<0.05).
Conclusion: The adopted proprioceptive postural control strategy (i.e. more ankle-steered vs. multi-segmental control observed in healthy persons) in people with NSLBP seemed to have a negative effect on the performance of a dynamic postural task such as STSTS. A task of associated movements or anticipatory postural adjustments is to maintain postural stability during movements with high acceleration or mass displacement . Therefore, the observations of the longer duration of the stance phases and the concomitant larger sways suggest mainly impairments in anticipatory postural adjustments and not in the focal motor program in persons with NSLBP. Moreover, the control of pelvic movement in the process of mass redistribution during trunk movement is normally highly efficient, however, this proprioceptive control of the pelvis may be impaired in these subjects with NSLBP [2,3]. Further study with direct measurement of pelvis kinematics is needed to underscore this hypothesis.
1. Brumagne S et al. Eur. Spine J. 17:1177-84, 2008.
2. Cordo PJ, Gurfinkel VS. Prog. Brain Res. 143:29-38, 2004.
3. Brumagne S et al. Spine 25:989-994, 2000.