Age dependency of neuromuscular function and dynamic balance control

The purpose of the present study was to examine whether static and dynamic balance control are related to neuromuscular function and ageing. For this purpose, we constructed a new dynamic balance measurement system that simulates natural falling. Ten young (age 21-31 years) and 20 elderly (age 60-70 years) men participated in the experiment. Maximal isometric torque (MVC) and activation level were measured from the quadriceps and plantar flexor muscles. The H-reflex, V-wave, and maximal M-wave were measured from the soleus muscle. In dynamic balance control, anterior-posterior centre-of-pressure swaying was 74 +/- 8.1 mm in the young men and 91.5 +/- 19.4 mm in the elderly men (P0.05), whereas in the static condition there were no significant differences between the two groups. Knee extension MVC (young: 181 +/- 42 N center dot m; elderly: 135 +/- 39 N center dot m; P0.01), torque after 500 ms (young: 147 +/- 36 N center dot m; elderly: 108 +/- 39 N center dot m; P0.05), and activation level (young: 96.2 +/- 0.8%; elderly: 93.8 +/- 2.1%; P0.01) were higher in the young than the elderly men; no differences were observed in plantar flexion. The amount of re-stabilization after a sudden disturbance seems to be an age-related phenomenon, which is seen as a connection between balance control and rapid force production.