The effect of unstable footwear on trunk muscle EMG and postural sway in healthy adults
OA Musculoskeletal Medicine
Introduction Preliminary evidence suggests that unstable footwear is beneficial for back pain. It has been proposed that the effect may be mediated by challenging balance, causing an increase in core stabilising muscle activity. However, no studies have investigated the effects of unstable footwear on core muscle activity. The primary aim of this study was to investigate if trunk muscle activation during quiet two-legged stance was affected by unstable footwear in comparison to usual footwear
... to usual footwear or on barefoot conditions. Materials and methods In this randomised repeated measures design, healthy participants (n = 21) stood on a Kistler™ force platform for 30 seconds three times under three conditions: (1) barefoot, (2) usual footwear and (3) unstable footwear. Under each condition, postural sway and the average intensity of electromyographic activity was collected for three different muscles bilaterally: transversus abdominus (TrA), external obliques (EO) and rectus abdominis (RA). Results A repeated measures ANOVA found increased postural sway (centre of pressure velocity) in the unstable footwear condition compared to both the barefoot (4.2 (1.7 -6.7) mm.s -1 ) (mean difference, 95 CI) and usual footwear conditions (4.9 (3.2 -6.7) mm.s -1 ). However, there was no statistically significant difference in trunk muscle activity between these conditions. Conclusion This study found no evidence that unstable footwear can increase/alter trunk muscle activity suggesting that any positive effects of unstable footwear on back pain may be mediated via different mechanisms other than core muscle training effects. However, further investigation with a clinical population over longer time periods, using different functional tasks may be warranted.