Fingertip light touch contact increases anteroposterior limits of stability in healthy young and older adults

Abstract

Background: The limit of stability (LoS), an index of stance balance ability, is reduced in older adults. Although contacting an earth-fixed external surface through fingertips' light touch improves older adults' stance balance control, its effects on the LoS in this population are unclear.

Research question: Does light touch increase the LoS and reduce postural sway in the LoS?

Methods: This study included 20 young adults (11 women and 9 men, mean age = 20.6 years) and 15 community-dwelling older adults (8 women and 7 men, mean age = 74.5 years). The position and path length of the center of pressure (CoP) during quiet standing (QS) and the anterior and posterior LoS (A-LoS and P-LoS, respectively) were measured using a force platform under two touch conditions (no-touch condition and light-touch condition). In light-touch condition, participants placed the tip of their dominant index finger on a load cell, which had an applied force of <1 N.

Results: In both touch conditions, the older group had a more limited CoP position in the anteroposterior LoS and a longer CoP path length in the QS and LoS than the younger group. In both participant groups, the light-touch condition showed a wider CoP position in the anteroposterior LoS and a shorter CoP path length in the QS and LoS than the no-touch condition.

Significance: Light touch increases the anteroposterior LoS and decreases postural sway in the LoS. Therefore, contacting an external object by fingertips' light touch may be an effective training protocol to increase the LoS in older adults.

Keywords: Kinetics; Light touch; Postural balance; Stability limit; Standing.