Influence of age on postural control during dual task: a centre of pressure motion and electromyographic analysis

Abstract Background Dual task infuences postural control. A cognitive task seems to reduce muscle excitation during a postural balance, especially in older adults (OA). Aim The aim of this study is to evaluate the efect of three cognitive tasks on muscle excitation and static postural control in OA and young adults (YA) in an upright posture maintenance task. Methods 31 YA and 30 OA were evaluated while performing a modifed Romberg Test in fve diferent conditions over a force plate: open eyes, closed eyes, spatial-memory brooks’ test, counting backwards aloud test and mental arithmetic task. The surface electromyographic signals of Tibialis anterior (TA), Lateral Gastrocnemius (GL), Peroneus Longus (PL), and Erector Spinae (ES) was acquired with an 8-channel surface electromyographic system. The following variables were computed for both the electromyographic analysis and the posturographic assessment: Root mean square (RMS), centre of pressure (CoP) excursion (Path) and velocity, sway area, RMS of the CoP Path and 50%, 95% of the power frequency. Mixed ANOVA was used to detect diferences with group membership as factor between and type of task as within. The analysis was performed on the diferences between each condition from OE. Results An interaction efect was found for Log (logarithmic) Sway Area. A main efect for task emerged on all posturographic variables except Log 95% frequencies and for Log PL and ES RMS. A main efect for group was never detected. Discussion and conclusion This study indicates a facilitating efect of mental secondary task on posturographic variables. Non-silent secondary task causes increase in ES and TA muscle activation and a worsening in static postural control performance