Abstract
Abstract Objective: To evaluate the effect of vestibular manipulation on the postural sway and muscle activation of younger and older adults. Methods: The study analyzed the effects of three intensity levels of galvanic vestibular stimulation (GVS) (0.3; 0.6 and 1m) on the pattern of muscle activity and center of pressure (CP) displacements of 12 older adults (EG) and 12 young adults (CG) while maintaining their balance on a stable surface, with no vision. Results: The EG showed a positive correlation between CP displacement and muscle activity and GVS intensity. On the other hand, the magnitude of postural response in the EG was not modulated in accordance with GVS intensities. Additionally, during the highest GVS intensity level (1 mA) greater muscle activity was used to increase stiffness, decrease the amplitude of oscillation and ensure stability. This unusual response characterizes a pattern of co-activation and is perhaps a safety mechanism to ensure stability. Conclusion: The EG individuals were not able to select the appropriate motor strategy to efficiently compensate the effects of GVS. This unusual strategy reflects deficits in the vestibular system of older adults, a fact which negatively interferes with their ability to reevaluate sensory information.
Highlights
Postural control is performed by motor and sensory mechanisms ranging from relatively simple peripheral responses to complex events involving high levels of cognitive function and sensorimotor integration
The primary findings for the Control Group (CG) were that (1) there was a significant increase with galvanic vestibular stimulation (GVS) in the gastrocnemius medialis (GM) and biceps femoris (BF) muscle activity, and (2) there was a positive correlation between postural response and GVS intensity
In terms of gerontological care, the results suggest that multiprofessional health teams should be aware of the presence of sensory processing disorders and their impacts on postural control in older adults
Summary
Postural control is performed by motor and sensory mechanisms ranging from relatively simple peripheral responses to complex events involving high levels of cognitive function and sensorimotor integration. There is a decline in motor and sensory functions, impairing postural stability and increasing the number of falls. According to the World Health Organization, between 28-35% of people aged 65 and over fall each year and this number rises to 32-42% from the age of 701.The resulting injuries can lead to reduced levels of independence, poor quality of life, and high levels of anxiety[1]. It is vital that any risk factors associated with instability and falling are identified early. Detection of these factors can guide preventive programs, making them more efficient and less costly. Several risk factors contribute to postural instability, and these can impair the detection of specific causes of a decline in instability
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