Dynamic balance testing with electrically evoked perturbation: a test of reliability.

OBJECTIVE

To investigate the reliability of a newly developed perturbation protocol for assessing dynamic balance.

DESIGN

Each subject was tested in two experimental balance conditions, static and dynamic. The dependent variables for the static condition were sway area (SA), sway path length (SPL), sagittal sway standard deviation (SSD), and lateral sway standard deviation (LaSD). During the dynamic condition trials a stimulus was delivered to the tibial nerves of both legs to perturb the subjects. The subjects were instructed to return to the pre-perturbation level of steadiness as soon as possible after the stimulation. The dependent variables for the dynamic condition were dynamic phase duration (DPD), sway path mean (SPM), linear sway standard deviation (LiSD), and sagittal sway standard deviation (SSD).

SETTING

The motor control laboratory of a university department of kinesiology.

PATIENTS

Ten subjects from a population-based sample of healthy adults.

MAIN OUTCOME MEASURE

An intraclass reliability estimate for all dependent measures in the static and dynamic conditions.

RESULTS

In the static condition, the variables SA, SPL, SSD, and LaSD had reliabilities of .94, .98, .86, and .92, respectively, and in the dynamic condition the reliability estimates for DPD. SPM, LiSD, and SSD were .90, .71, .80, and .92, respectively.

CONCLUSIONS

The results indicate the current technique provides a means of objectively measuring a subject's ability to regain static postural stability following electrically induced perturbation.