Static balance improvement in elderly after dorsiflexors electrostimulation training

Abstract

The purpose of the present study was to determine the effect of dorsiflexors' ElectroStimulation (ES) training, on postural tasks of increasing difficulty in the elderly. Twenty-one elderly adults were randomly assigned into one of two groups: a Training (TG) and a Control Group (CG). The TG (n = 10) performed (4 weeks, 4 s/week, 40 min/session) superimposed (electrically evoked and voluntary activation) isometric dorsiflexions (ankle 100 degrees ) while seated. Biphasic, rectangular symmetrical pulses (300 ms, 70 Hz, 20-60 mA) were used to provoke maximal muscle activation. Participants performed three static balance tasks (Normal Quiet Stance, Sharpened Romberg, and One-Legged Stance) during which postural sway was quantified using maximum range and standard deviation of Centre of Pressure displacement (Kistler 9281C, 1,000 Hz). Bipolar surface electrodes were used to record the Electromyographic activity (EMG) of Tibialis Anterior, Medial Gastrocnemius, Rectus Femoris and Semi-Tendineous. Two-dimensional kinematic data were collected (60 Hz) and analyzed using the APAS Motion Analysis software. The body was modeled as a five-segment rigid link system. Isometric dorsiflexion moment/angular position relationship was also established using a Cybex dynamometer. ES training resulted in decreased postural sway (P < 0.05), greater ankle muscles EMG activity (P < 0.001), greater stability of the ankle joint (P < 0.05) and significant changes in mean position of all three joints of the lower limb. In addition, dorsiflexion moment significantly (P < 0.001) increased as a result of ES training. It is concluded that dorsiflexors' ES training, could reduce postural sway and the use of ankle muscles, more characteristic of young adults, might appear in the elderly as well.