The effect of different biofeedback techniques on the level of muscle activation in orthostatism, a non-randomized comparative study

Abstract

Introduction: Visual biofeedback has been shown to be effective for balance training in order to reduce body sway. It is not yet known which strategies the postural control system uses to reduce postural sway in the standing position, either by attenuating or
increasing the activation of postural muscles. Objective: To investigate the effect of different types of visual biofeedback on muscle activity and postural balance in the standing position in young adults. Methods: This is a descriptive cross-sectional study. Twenty-two participants (14 women) participated in the study and performed four postural tasks on the force platform for 60 seconds: 1) No biofeedback (control); 2) Biofeedback by posturography; 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 medial gastrocnemius and tibialis anterior muscles, and the standard deviation of the center of pressure (CoP) displacement in the anteroposterior (AP) and mediolateral (ML) directions were analyzed. Results: The RMS amplitude (median; interquartile range) of the tibialis anterior was greater in the wrist laser (46.0; 30.0 uV) and posturography biofeedback (44.0; 25.0 uV) tasks, when compared with the condition without biofeedback (39.0; 13.0 uV) (P<0.05). No significant differences were found between the tasks without biofeedback and body laser (39.0; 16.0 uV) (P=0.738). For the medial gastrocnemius, no main effect of task was found for the RMS amplitude (P=0.837). 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) tasks than without biofeedback (7.071; 2.693 mm) (P<0.05). A significant difference in AP CoP variability was observed between posturography biofeedback (5.858; 2.248 mm) and the task without biofeedback (7.071; 2.693 mm) (P=0.052). In the ML direction, no differences were found in the standard deviation of CoP displacement between the tasks (P=0.169). Conclusion: Different types of biofeedback appear to lead to increased muscle effort at the ankle in the orthostatic position.