Differences between the Postural Reactions of Young Adults and Aged People after Perturbations from the Upper Back

Abstract

[Purpose] To investigate age-related differences in postural reaction after perturbations from the upper back. [Participants and Methods] A weight load that induced backward stepping was added to the upper back of young adults and aged people. Muscle activities of the trunk and lower limbs were recorded using surface electromyography. The start time and the peak time of each muscle activity from the time of weight load were measured. [Results] Compared to the young adults, the peak time of muscle activities after applying the weight load was significantly delayed in the aged people. No obvious rules were found in the order of muscle activities in both the young and the aged groups. [Conclusion] In aged people, delay of the peak muscle activities after perturbations from the upper back may easily cause falls which frequently occur in the elderly.