Neuromuscular control of lifting in the elderly

The aim of this investigation was to determine, utilising an electromyographic (EMG) technique, the influence of the ageing process on the neuromotor control of the stoop-lift. Seven elderly (60-75 years) and seven young (18-25 years) subjects completed a series of ten unresisted (no weight) stoop-lifts. EMG potentials were recorded with 4-mm bipolar surface electrodes from the erector spinae and medial hamstring muscle groups. The temporal features of the stoop-lift itself were recorded with an electrogoniometer. The results of this investigation showed that the elderly subjects had a significantly (p < 0.05) earlier onset of the erector spinae muscle during the up-phase of the stoop-lift compared to the younger subjects. In addition, reactivation of the erector spinae muscle in the up-phase occurred at hand positions significantly (p < 0.05) closer to the floor in the elderly group indicating more stooped postures. Thus the EMG profiles of the erector spinae within the elderly subjects performing unresisted stoop-lifts approximated those previously reported in younger subjects performing resisted (with 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 the elderly subjects. The results further stress the potential for injury associated with the utilisation of the stoop-lift, particularly by elderly populations.