Quantitative Evaluation Method of Timed Up and Go Test for Hospitalized Patients Using Inertial Sensors

This study aimed to assess ambulation in hospitalized patients undergoing rehabilitation and determine the timing of independence using the Timed Up and Go (TUG) test as an evaluation method. The objective of this study was to categorize hospitalized patients based on their TUG completion time and level of walking independence, and to compare their movement patterns as measured by inertial sensors across the groups. The study included hospitalized patients undergoing rehabilitation who were already independent in walking with a walker. The patients performed the TUG test by walking as quickly as possible without assistance or with a cane. Inertial sensors were attached to both lower legs and the lumbar region, and the acceleration and angular velocity of the lumbar region were analyzed. A total of 21 patients were included in the analysis: 9 patients in the Independent Fast (IF) group, who were independent in walking without aids or with a cane and had a TUG time of less than 13.5 seconds; 6 patients in the Independent Slow (IS) group, who were independent in walking but had a TUG time greater than 13.5 seconds; and 6 patients in the Monitored Slow (MS) group, who required monitoring during walking and had a TUG time greater than 13.5 seconds. The IF group demonstrated significantly lower total TUG time and total number of steps compared to the other two groups, and the IS group had significantly lower values than the MS group. For the sit-to-stand phase, the mean pitch angle of the IF group was significantly higher than that of the other two groups. For the second turn phase, the maximum, mean, and range of yaw angle were significantly higher in the IF group compared to the MS group. The autocorrelation coefficient of acceleration for the anterior-posterior axis for the first walk phase was significantly higher in the IF group compared to the other two groups. These results may indicate recovery, as the IS group exhibited slower TUG times but had movement patterns closer to those of the IF group. Consequently, this highlights the potential of inertial sensors as an objective tool for assessing walking independence.