Kinematic and Electromyography Responses to Increasing Proprioception Demand and a Lack of Visual Feedback in Healthy, Middle-Aged Women Tested on an Unstable Platform.

The purpose of the study was to investigate which changes in kinematics and muscle activity in healthy, middle-aged women are introduced to maintain balance on an unstable platform. Biodex Balance System tests were used in stable and unstable modes (sudden with eyes open/closed and gradual with eyes open). Simultaneously, lower-extremity kinematics and surface electromyography of back and legs muscles were captured. The dependence between balance scores, movement ranges, and root mean square of electromyography was assessed with multiple regression to evaluate the strategy used. The results showed multisegmental movements in sudden instability, and activity of at least one of the following muscles: gluteus maximus, erector spinae, and soleus in all conditions. Best balance scores were achieved when movements appeared in pelvis in transverse, and hip in frontal planes, worst when in pelvis in frontal, hip, and ankle in sagittal planes, and when mentioned muscles were activated. Further research is needed to identify the determinants of strategy choice.