The effects of vibrotexture insoles on anticipatory postural adjustments during a bilateral rapid arm raise task in healthy younger and older adults

Sensory-stimulating insoles that deliver a single-sensory stimulus (texture or vibration) can improve standing balance. Vibrotexture insoles combine both stimuli, but their effects on anticipatory postural adjustments (APAs) during internal perturbation tasks remain unclear. The aim was to investigate the effects of vibrotexture insoles on APAs during bilateral rapid arm-raises in healthy younger and older adults. Thirty healthy younger (16 males, 23.6 ± 3.9 years) and thirty healthy older (14 males; 69.8 ± 5.8 years) adults performed rapid, bilateral arm-raises wearing four different insoles (vibrotexture, vibrating, textured, and control). Balance outcomes included time to onset and peak centre of pressure (COP) displacement, and COP displacement and position on the force platform. Surface electromyography of the deltoid, gluteus medius, biceps femoris, and medial gastrocnemius were recorded to determine onset of muscle activity. COP and electromyography outcomes were analysed using a linear mixed model, with Bonferroni adjustment. There were no differences in balance or electromyography outcomes between the vibrotexture and other insole conditions. An isolated difference in onset of biceps femoris activity was observed between vibrating and textured insoles in younger adults (p = 0.001); however, no other COP or muscle activity outcomes differed between insoles. Vibrotexture insoles may not alter APAs during rapid bilateral arm-raises in healthy adults.