Background: Reflecting the rapidly aging population, community-based interventions in the form of
physical exercise have been introduced to promote the health of elderly persons and prevent falls. Postural
response is the critical neural response for preventing falls. The objective of this study was to assess
the effect of long-term daily exercise on neural adjustment in postural response elucidated by sudden
postural perturbation.
Methods: Twenty-six community-based elderly persons (13 men and women; 69.8 ± 0.5 years old) participated
in this study. Daily exercise was composed of walking for longer than 30 min, stretching, muscle
strengthening and balance exercise, and was continued for 3 months. Postural responses were induced by
fore or aft horizontal displacement of a platform with a force plate. Center of pressure on the force plate
and electromyography of the rectus femoris, tibia anterior, biceps femoris and gastrocnemius were measured
in postural response.
Findings: Following the 3 months of physical intervention, the amplitude and timing of the center of
pressure excursion did not change, whereas the amplitude of muscular activities of the lower leg muscles
required for the response significantly decreased. Furthermore, the onset of muscular activation of the
lower leg muscles was significantly shortened following the intervention.
Interpretation: In conclusion, we showed that a program composed of 3 months of comprehensive exercise
modulated the output of the postural response through a neural adjustment in the timing and amplitude
of the muscular activation.