Anticipatory and compensatory postural adjustments during catching a ball in condition of postural instability and stability

Abstract

Young individuals preselect their postural adjustment strategies before an external perturbation, based on the characteristics of the task. However, it is not well documented how the central nervous system deals with anticipatory and compensatory postural adjustments during some balance training programs, which are commonly used in Physical Therapy settings. Thirteen young individuals were submitted to 20 external postural perturbations of catching a ball thrown by an experimenter in conditions of postural stability and instability (standing on a foam). The electromyographic activities of triceps brachii (focal muscle), rectus abdominis, and lumbar paraspinal muscles were investigated in the time windows typical for anticipatory and compensatory postural adjustments, as well as the center of body pressure peak displacement after the perturbation. The magnitude of the triceps brachii integral electromyographic activity was significantly smaller in conditions of postural instability, there was no statistical difference between the stable and unstable conditions for the integral electromyographic activity of the rectus abdominis, and lumbar paraspinal muscles. The peak of the center of body pressure anterior posterior displacement was similar between the two conditions. Balance training associated with external perturbation standing on a foam might not be more effective or efficient than when standing on a stable surface, when it seeks to modify the activity of the postural trunk muscles. In addition, this balance training may contribute to decrease the electromyographic activity (anticipatory postural adjustments) of the focal muscle.