balance improvement due to a specific training in elderly

Introduction

Aging is a complex process involving many variables that interact with one another. Mobility decline (due to the muscle and nerve decline) is associated with increased risk for falls. With advancing age, human skeletal muscle strength is gradually reduced due to the reduction of motor units (Lexell et al. 1988). This reduction seems to be associated with falls. The purpose of the present study was to determine the effect of Tibialis Anterior (TA) ElectroStimulation (ES) training, a principal dorsiflexor involved in standing, on postural tasks of increasing difficulty in the elderly.

Methods

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 (4weeks, 4s/week, 40min/session) superimposed (electrically evoked and voluntary activation, Myo 4, CEFAR, Sweden) isometric dorsiflexions while seated. Before and after training, participants performed 3 static balance tasks (Normal Quiet Stance, NQS, Sharpened Romberg, SR, and One-Legged Stance, OLS) during which postural sway was quantified using maximum range and standard deviation of Centre of Pressure (CoP) displacement (Kistler 9281C, 1000Hz). Bipolar surface electrodes were used to record the Electromyographic activity (EMG) of TA, Medial Gastrocnemius, Rectus Femoris and Semi-Tendineous. Isometric dorsiflexion moment/angular position relationship was also established using a Cybex 6000 dynamometer.

Results

Maximum range and standard deviation of the CoP in Anterior/Posterior and MedioLateral axis, significantly decreased for the TG during SR and OLS, as a result of ES training . We also observed that EMG activity of the ankle, but not hip muscles, recorded during SR and OLS tasks significantly increased for the experimental group. In addition, dorsiflexion moment significantly increased at all ankle angles.

Discussion / Conclusions

Electrostimulation training could reduce postural sway and improve functional performance in the elderly. The manner in which the CNS modulates muscle responses during postural control could be modified by ES and the use of ankle muscles, which is more characteristic of young adults, could appear in the elderly as well.

References

Lexell et al(1988). J Neurol Sci 84: 275-294.