Comparison of skeletal muscle motor unit discharge characteristics in young and aged humans.
Nelson-RM; Soderberg-GL; Urbscheit-NL
Arch Gerontol Geriatr 1983 Nov; 2(3):255-264
The discharge characteristics of motor unit action potentials were compared in young and aged human volunteers. The young volunteers were 20 to 35 years old and the aged subjects were divided into three decade groups, from 60 to 90 years old. Fine wire electrodes were inserted into the abductor muscle of the little finger of each volunteer and the force resulting from isometric contraction of the muscle was obtained by a transducer and recorded. Single motor unit discharge behavior was described by examining three statistics of the recorded inter spike interval: the distribution, the variability and the relationship of successive inter spike intervals. The 70 to 79 age group was different from the 60 to 69 age group, but not from the 80 to 89 age group. The floating standard deviation values were more variable with age. The 70 to 79 age group had a slow motor unit discharge rate, an increased variability of discharge and a negative serial correlation coefficient. The authors conclude that these factors describing motor unit discharge behavior suggest possible substitution of larger motor units for small motor units active at low tensions for the 70 to 79 age group.
Musculoskeletal-system; Neuromuscular-system; Neurophysiology; Nerve-fiber-excitation; Muscle-contraction; Electrophysiology; Physiological-measurements; Physiological-response; Age-factors;
Author Keywords: motor units; aging
Archives of Gerontology and Geriatrics