Motor control enhancements by sub-threshold mechanical noise applied to foot soles during quiet standing.
Jeshaiah Zhen Syuen Khor, Boon Leong Lan, Alpha Agape Gopalai
PMID 40646582WHAT IT FOUND
Sub-threshold noise in shoe insoles reduced sway and calf muscle effort during standing, especially on a soft foam surface that mimics balance impairment.
The noise helped muscles work more efficiently, but this was a small lab study in ten healthy young adults.
Key findings
01Mechanical noise significantly reduced postural sway on a compliant surface, decreasing side-to-side range, side-to-side speed, and swept area.
02Noise significantly reduced muscle activity (RMS) in all three calf muscle groups on both firm and compliant surfaces, without changing motor unit type recruitment.
03The lateral gastrocnemius contributed more to forward-backward balance control when noise was applied, indicated by a significant increase in correlation on the firm surface and marginal increase on the compliant surface.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only ten healthy young adults, so the results cannot be directly generalized to elderly patients or those with balance impairments. The compliant surface was used to simulate impairment, but it does not replicate the specific pathologies of stroke, diabetes, or aging. Multiple comparisons were not corrected for due to the small sample size, increasing the risk of false-positive findings. Surface EMG can have crosstalk from nearby muscles, although the authors state this was minimized by the participants' low body fat.
Declared interests
The authors declared no competing interests.
The easy way to misread this
Do not conclude that noise insoles improve balance in patients with clinical balance impairments. The study was conducted on healthy young adults, and the 'balance impairment' was simulated using a foam pad, which does not replicate the sensory or motor deficits of conditions like stroke or diabetic neuropathy.