Article

Prolonged standing has been associated with development and aggravation of low
back pain (LBP). However, the underlying mechanisms are not well known. The aim
of the present study was to investigate postural control and muscle activation
during and as a result of prolonged standing in chronic LBP (cLBP) patients
compared to healthy controls (HCs). Body weight shifts and trunk and hip muscle
activity was measured during 15 min standing. Prior and after the standing trial,
strength, postural sway, reposition error (RE), flexion relaxation ratio (FRR),
and pain were assessed and after the prolonged standing, ratings of perceived
exertion. During prolonged standing, the cLBP patients performed significantly
more body weight shifts (p<.01) with more activated back and abdominal muscles
(p=.01) and similar temporal variability in muscle activation compared to HCs,
while the cLBP patients reported more pain and perceived exertion at the end of
prolonged standing. Moreover, both groups had a similar change in strength,
postural sway, RE and FRR from before to after prolonged standing, where changes
in HC were towards pre-standing values of cLBP patients. Thus, despite a more
variable postural strategy, the cLBP patients did not have higher muscle
activation variability, but a general increased muscle activation level. This may
indicate a reduced ability to individually deactivate trunk muscles. Plausibly,
due to the increased variable postural strategy, the cLBP patients could
compensate for the relatively high muscle activation level, resulting in normal
variation in muscle activation and normal reduction in strength, RE and FRR after
prolonged standing.
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Langue : ANGLAIS