Objective: To examine and compare trunk stability by examining acceleration of the trunk while performing the Timed Up and Go (TUG) test in Thai elderly and young women.

Material and Method: Fifty female volunteers resided in Chiang Mai province were divided into the elderly group (aged 60-74 year; n=25) and the young group (aged 18-25 years; n=25). Each participant performed the TUG test while wearing a tri-axial accelerometer placed over the lower trunk. Independent t-test was used to compare trunk acceleration values between groups.

Results: The elderly and the young group had a mean time of the TUG of 11.94±1.03 second and 8.82±0.56 second (mean±S.D.), respectively. In the anteroposterior direction, compared to the young group, the elderly group had significantly lower normalized trunk acceleration in the sit-to-walk, walk1 (walking away from the chair), and stand-to-sit subtasks (p<0.05). In the vertical direction, the elderly group had significantly lower normalized trunk acceleration in the walk1, and stand-to-sit subtasks (p<0.005). In the mediolateral direction, on the other hand, the elderly group had significantly greater normalized trunk acceleration in the walk2 (walking toward the chair) and stand-to-sit subtasks (p<0.05).

Conclusion: Trunk accelerometry can be used to examine the quality of movement during the TUG test. Acceleration in the anteroposterior and vertical directions indicated the agility in the direction of body progression while the mediolateral acceleration indicated the ability to control balance during changing of body position. There is a possibility to use the trunk acceleration coupled with the TUG test for evaluating the risk of fall in the elderly.