Trunk muscle function and anterior and posterior limits of stability in community-dwelling older adults

Abstract Background Understanding of the influence of trunk muscles on the older adult's limit of stability (LOS) is important for clinical practice. Objective To compare the anterior and posterior LOS and the flexor and extensor trunk muscle function; verify the association of trunk muscles and LOS, and the association of LOS and the previous falls of community-dwelling older adults. Methods Sample characterization data, trunk muscle function (peak torque - PT and torque steadiness - TS), LOS and previous falls (6 months) were collected from 79 older people. Comparisons were made between the variables of the anterior/posterior LOS (Reaction time, Movement velocity, Maximum excursion, Directional control), between trunk extensors/flexors muscle function and between TS at 10% and at 50%. Associations were made between the anterior/posterior LOS and the number of previous falls and between LOS and trunk muscle function. Results The posterior LOS was worse than the anterior LOS, except for the reaction time. The flexor muscles obtained a lower PT, but better performance in TS. The TS at 10% of the trunk extensor was associated with the posterior directional control (p=0.032). There was no association between trunk muscle function and the anterior LOS, or between previous falls and LOS. Conclusions The older adults presented worse performance in the posterior LOS and worse TS in the trunk extensor muscles, although the trunk extensor muscles presented a higher PT. Although no association between LOS and previous falls, the better the TS at 10% of the trunk extensors, better posterior directional control.