The effects of cutaneous vibration on dynamic balance control

Vibratory noise applied to cutaneous receptors has been shown to improve static balance control in a wide range of populations, including healthy young adults, older adults, and individuals with diabetic neuropathy. However, comparatively little research has investigated whether similar sensory augmentation can improve reactive balance control during dynamic perturbations. This gap is important because falls are a leading cause of injury among older adults in Canada and often occur under dynamic conditions when individuals fail to recover from unexpected balance disturbances. Therefore, the primary purpose of this thesis was to determine whether vibratory noise applied to cutaneous regions of the ankles and hips influences reactive balance control during unexpected transient and continuous support-surface translations. A secondary purpose was to determine whether the same stimulation improves conscious detection of small anterior-posterior translations using a psychophysical detection paradigm. Twenty healthy young adults underwent three stimulation conditions presented in randomized order: no stimulation, stimulation at 90% of perceptual threshold, and stimulation at 110% of perceptual threshold. Vibratory noise was delivered simultaneously to bilateral ankle and hip sites. Subjects completed a psychophysical translation-detection task, unexpected transient backward translations, and continuous pseudorandom anterior-posterior translations, while reactive balance was assessed using electromyographic (EMG) onset latencies and amplitudes from six postural muscles, as well as whole-body dynamic stability quantified by the margin of stability. Results showed that subthreshold vibration improved perceptual performance, as translation detection thresholds were significantly lower with 90% stimulation than with no stimulation. In contrast, stimulation did not significantly affect EMG onset latencies, EMG amplitudes, or the margin of stability during either transient or continuous perturbations. Suprathreshold vibration also did not differ from no stimulation on any outcome. These findings indicate that cutaneous vibratory noise can enhance near-threshold sensory detection without altering automatic balance-correcting responses or dynamic stability in healthy young adults. Together, the results suggest that stochastic resonance may be more effective for improving simple balance tasks rather than reactive dynamic balance in unimpaired populations. Future studies should examine whether this approach is more beneficial in increasingly vulnerable groups, such as older adults or clinical populations with reduced somatosensory function.