Relationship between motor imagery accuracy and gait variability in older adults

The purpose of this study was to examine whether the accuracy of motor imagery is associated with gait variability in older adults and whether the relationship between the accuracy of motor imagery and gait variability varies with the functional level in the older adults.

Participants were 51 community dwelling older adults and 11 older adults using long-term care insurance services (long-term care insurance users). Exclusion criteria were those with a history of cerebrovascular, neuromuscular, or psychiatric diseases, those with pain affecting daily life, those with cognitive decline, and those who could not understand how to measure motor imagery ability. Motor imagery ability was evaluated using mental chronometry (MC). MC was used to examine the error between the imagery time and the execution time of the 10-m walk and calculated using the formula for the ratio of exercise imagery walking time to actual walking time (M/A ratio). During the 10-m walk, a triaxial accelerometer (8-channel compact wireless motion recorder MVP-RF8-HC, Micro Stone) was attached to the upper part of the healthy outer malleolus to measure Stride Time Variability (STV) and walking time. Spearman's correlation analysis was used to examine the relationship between M/A ratio and STV for all participants. We divided our participants into two groups: community dwelling older adults and long-term care insurance users, and performed a Spearman’s correlation analysis. All analyses were performed using IBM SPSS Statistics 26.0. Statistical significance was set at p0.05.

Forty-three older adults were analyzed (35 community dwelling older adults and 8 long-term care insurance users). The results of correlation analysis with all participants in  the analysis showed a significant positive correlation (r=0.44, p0.05). When the participants were examined by dividing them into two groups, a significant positive correlation was found for the community dwelling older adults (r=0.47, p0.05), but no significant relationship was found for the long-term care insurance users (r=0.52, p=0.18).

This study revealed that the greater the value of the M/A ratio, the greater the variation in gait variability, and this relationship was observed in community dwelling older adults. Therefore, in addition to screening for falls, the discrepancy between imagery time and execution time of a walking may assess changes in spatial parameter.

This study suggested that the discrepancy between imagery time and execution time of a walking  be useful as one of the gait assessments for community dwelling older adults in physical therapy because it may identify changes in spatial parameter as well as screening for falls.