Postural control during prolonged standing in persons with chronic low back pain
From: Gait Posture. 2008 Dec 10; [Epub ahead of print]
Prolonged standing has been associated with the onset of low back pain symptoms in working populations. So far, it is unknown how individuals with chronic low back pain behave during prolonged unconstrained standing. The aim of the present study was to analyze the control of posture by subjects with chronic low back pain during prolonged unconstrained standing in comparison to matched healthy adults. The center of pressure position of 12 chronic low back pain subjects and 12 matched healthy controls was recorded in prolonged standing (30min) and quiet stance tasks (60s) on a force plate. The number and amplitude of center of pressure patterns, the root mean square, speed, and frequency of center of pressure sway were analyzed. Statistical analyses showed that chronic low back pain subjects produced less postural changes in the antero-posterior direction with decreased postural sway during the prolonged standing task in comparison to the healthy group. Only chronic low back pain subjects were influenced by the prolonged standing task, as demonstrated by their increased center of pressure root mean square, center of pressure speed and center of pressure frequency in the quiet standing trial after the prolonged standing task in comparison to the pre-prolonged unconstrained standing trial. The present study provides additional evidence that individuals with chronic low back pain might have altered sensory-motor function. Their inability to generate responses similar to those of healthy subjects during prolonged standing may contribute to chronic low back pain persistence or an increase risk of recurrent back pain episodes. Moreover, quantification of postural changes during prolonged standing could be useful to identify chronic low back pain subjects prone to postural control deficits.
