NEUROMUSCULAR CONTROL OF LIFTING IN THE ELDERLY

The aim of this investigation was to determine, utilising an electromy ographic (EMG) technique, the influence of the ageing process on the n euromotor control of the stoop-lift. Seven elderly (60-75 years) and s even young (18-25 years) subjects completed a series of ten unresisted (no weight) stoop-lifts. EMG potentials were recorded with 4-mm bipol ar surface electrodes from the erector spinae and medial hamstring mus cle groups. The temporal features of the stoop-lift itself were record ed with an electrogoniometer. The results of this investigation showed that the elderly subjects had a significantly (p < 0.05) earlier onse t of the erector spinae muscle during the up-phase of the stoop-lift c ompared to the younger subjects. In addition, reactivation of the erec tor spinae muscle in the up-phase occurred at hand positions significa ntly (p < 0.05) closer to the floor in the elderly group indicating mo re stooped postures. Thus the EMG profiles of the erector spinae withi n the elderly subjects performing unresisted stoop-lifts approximated those previously reported in younger subjects performing resisted (wit h a weight) lifting. The earlier onset of the erector spinae in the up -phase of the stoop-lift was partially explained by a significant (p < 0.05) reduction in flexibility (sit and reach test) associated with t he elderly subjects. The results further stress the potential for inju ry associated with the utilisation of the stoop-lift, particularly by elderly populations.