Postural control involves the maintenance of orientation and postural balance, which are crucial aspects to allow the activities of daily living. The biofeedback technique has been of potential interest to postural control rehabilitation, since it seems to confine postural sway within the stability limits, ensuring postural balance during standing. However, whether the performance of postural balance is associated with other factors, such as anxiety and balance confidence, is an open issue we addressed here.

This study aimed to investigate the effect of different biofeedback techniques on anxiety and balance confidence during standing.

Twenty-sixty participants were recruited in this study and tested in three tasks while standing on the force platform: 1) standing with eyes open (EO); (2) posturography biofeedback (BFcp), consisting of keeping the center of pressure (CP) position as close as possible to a target located in front of the individual; (3) biofeedback of laser (BFlaser), consisting of pointing a laser as close as possible to the same target used before from the right wrist. The CP position was measured using the force platform for 60 seconds and the CP sway area was computed using the whole trial data in each experimental task. Scales for the assessment of balance confidence and anxiety, consisting of visual scales ranging from 0 to 100, were applied at the end of each task. On the confidence scale, “0”, “50” and “100” mean “no confidence”, “moderate confidence” and “complete confidence”, respectively. On the anxiety scale, “0”, “50” and “100” denote “no anxiety”, “moderate anxiety”, and “complete anxiety”. A one-way analysis of variance (ANOVA) for repeated measures was used to compare the emotional scores and CP sway area among postural tasks, and post hoc comparisons were made with the Tukey HSD test (significance level of 5%).

ANOVA (F=6.19, p<0.01) revealed a smaller balance confidence in BFcp (média±desvio padrão; 72.88±22.41) than EO (86.15±22.05), while no differences were observed between BFlaser (81.34±19.82) and the other tasks. For anxiety, ANOVA did not show differences among EO (20.76±33.21), BFcp (27.88±25.42), and BFlaser (24.23±29.78). Moreover, the CP sway area (F=33.11, p<0.01) was significantly smaller in the BFcp (2.27±1,27 cm2) than EO (3.54±2.08 cm2) and BFlaser (5.51±2.87 cm2), and in the EO compared to BFlaser (p<0.01 in all cases).

Balance confidence alterations were identified with BFcp in relation to the other postural tasks. These findings seem to suggest that psychological factors could contribute to explain, even if partially, alterations in the postural stability during the biofeedback; a smaller CP sway area was found in BFcp than EO.

These aspects seem to be little exploited in the clinical environment, in which the knowledge of factors associated with postural stability during biofeedback could assist in improving the evaluation and rehabilitation protocols of postural control.