Visual biofeedback of postural sway has been shown to optimize postural balance by reducing postural sway during quiet standing. However, it is not yet fully known whether the reduction of postural sway from biofeedback is associated with the increase of postural muscle effort during standing balance.

To investigate the effect of different types of visual biofeedback of postural sway on muscle activity and postural balance during standing balance in young adults.

Twenty-two participants (14 women and 8 men; mean ± standard deviation: 30.44 ± 6.76 years; body mass: 77.56 ± 19.47 kg; height: 1.70 ± 0.11 m; BMI: 26.42 ± 4.94 kg/m2) participated in this cross-sectional study and performed four postural tasks on the force platform for 60 seconds: 1) No biofeedback (control); 2) Centre of pressure (CoP) Biofeedback; 3) Biofeedback by portable laser, controlled by both wrist movement and body movement. The root mean square (RMS) amplitude of the surface electromyogram (EMG) collected from the right medial gastrocnemius and anterior tibialis muscles, and the standard deviation of the CoP displacement in the anteroposterior (AP) and mediolateral (ML) directions were analyzed. . The Friedman test (Shapiro-Wilk, P < 0.05) was applied to assess the main effect of the biofeedback on RMS amplitude and CoP standard deviation, followed by the Wilcoxon test for pairwise comparisons (significance level of 5%).

The RMS amplitude (median; interquartile range) of the tibialis anterior was greater in the wrist laser (46.0; 30.0 µV) and posturography biofeedback (44.0; 25.0 µV) tasks, when compared with the condition without biofeedback (39.0; 13.0 µV) (P < 0.05). For the medial gastrocnemius, no main effect of task was found for the RMS amplitude (P = 0.837). When compared to without biofeedback (7.071; 2.693 mm), the standard deviation of CoP displacement in the AP direction was greater in the body laser (9.585; 6.097 mm) and wrist laser (8.272; 3.307 mm) and, lower in CoP biofeedback (5.858; 2.248 mm). In the ML direction, no differences in the standard deviation of CoP displacement were found between the tasks (P = 0.169).

Different types of biofeedback appear to lead to increased muscular effort at the ankle in the orthostatic position.

Balance rehabilitation and training strategies should consider the specific training objectives and the neuromuscular responsiveness of individuals when choosing the biofeedback to be used.