Decreased variability in postural control strategies in young people with non-specific low back pain is associated with altered proprioceptive reweighting

Abstract

Optimal postural control is an essential capacity in daily life and can be highly variable. The purpose of this study was to investigate if young people have the ability to choose the optimal postural control strategy according to the postural condition and to investigate if non-specific low back pain (NSLBP) influences the variability in proprioceptive postural control strategies. Young individuals with NSLBP (n = 106) and healthy controls (n = 50) were tested on a force plate in different postural conditions (i.e., sitting, stable support standing and unstable support standing). The role of proprioception in postural control was directly examined by means of muscle vibration on triceps surae and lumbar multifidus muscles. Root mean square and mean displacements of the center of pressure were recorded during the different trials. To appraise the proprioceptive postural control strategy, the relative proprioceptive weighting (RPW, ratio of ankle muscles proprioceptive inputs vs. back muscles proprioceptive inputs) was calculated. Postural robustness was significantly less in individuals with NSLBP during the more complex postural conditions (p < 0.05). Significantly higher RPW values were observed in the NSLBP group in all postural conditions (p < 0.05), suggesting less ability to rely on back muscle proprioceptive inputs for postural control. Therefore, healthy controls seem to have the ability to choose a more optimal postural control strategy according to the postural condition. In contrast, young people with NSLBP showed a reduced capacity to switch to a more multi-segmental postural control strategy during complex postural conditions, which leads to decreased postural robustness.

Proprioceptive use and sit-to-stand-to-sit after lumbar microdiscectomy: The effect of surgical approach and early physiotherapy

“…Another study, with individuals with comparable moderate-to-high ODI scores after surgery, reported the need for 18 s after lumbar surgery but with vision (Kulig et al, 2009). Additionally, we found a comparable degree of down-weighting of lumbosacral proprioceptive signals and up-weighting of ankle proprioceptive signals in individuals with non-specific LBP without surgical history (Claeys et al, 2011), that affected STSTS performance (Claeys et al, 2012). Therefore, the current study suggests that the reliability of the lumbosacral proprioceptive signals still remains reduced after lumbar microdiscectomy.…”

“…1): transmuscular surgery + physiotherapy (n = 6), transmuscular surgery + usual care (n = 6), paramedian surgery + physiotherapy (n = 6), and paramedian surgery + usual care (n = 7). These groups were clustered by a mixed group design because power analysis (Brumagne et al, 2008;Claeys et al, 2011Claeys et al, , 2012Claeys et al, , 2015Janssens et al, 2015) revealed a sample size of 11 participants to provide adequate power (0.80 with a two-tailed alpha level of 0.05) to detect a clinically relevant difference in center of pressure displacement on unstable support surface (our primary outcome measure with smallest effect size). First, they were randomly allocated (blinded by computer algorithm) for surgical approach into a transmuscular group (n = 12; 7 women/5 men) and paramedian group (n = 13; 7 women/6 men).…”

“…The amount of this center of pressure displacement represents the extent to which an individual makes use of the proprioceptive signals of the vibrated muscles to maintain the upright posture. Muscle vibrators (Maxon motors, Switzerland) were applied bilaterally over the triceps surae ('ankle') muscles and lumbar paraspinal ('back') muscles, as studied previously (Brumagne et al, 2008;Claeys et al, 2011Claeys et al, , 2012Claeys et al, , 2015Janssens et al, 2015). Participants were instructed to stand barefoot on the force plate, with their arms relaxed along the body and occluded vision.…”

“…'Abs ankle' is the absolute value of the mean center of pressure displacement during ankle muscle vibration and 'Abs back' during back muscle vibration. An RPW score equal to 1 corresponds to 100% reliance on ankle muscle proprioception, whereas a score equal to 0 corresponds to 100% reliance on back muscle proprioception (Brumagne et al, 2008;Claeys et al, 2011Claeys et al, , 2012Claeys et al, , 2015Janssens et al, 2015).…”

“…A possible mechanism for this is reduced lumbosacral proprioception. When lumbosacral proprioceptive signals lose reliability due to LBP, individuals are likely to rely dominantly on ankle proprioceptive signals, irrespective of the postural demands (Brumagne et al, 2008;Claeys et al, 2011Claeys et al, , 2015. Consensus on the effect of lumbar surgery on postural control is lacking.…”