Age Group and Individual Differences in Controlled Force Exertion by a Computing Sinusoidal and Quasi-Random Target-Pursuit System

Abstract

　The study aimed to examine age group and individual differences of the controlled force exertion by the sinusoidal and quasi-random waveforms. A total of 180 male adults who were right-handed and aged 20 to 86 years (Age 45.8±18.6 yrs) matched their submaximal grip strength to changing demand values, displayed as either a sinusoidal or a quasi-random waveform appearing on the display of a personal computer. The quasi-random waveform was changed by π radian with amplitude and in π/2 radian with frequency (peak and mean frequency were 0.1 Hz in both waveforms). The subjects performed both the controlled force exertion test for 3 trials with 1-min intervals (one trial was 40 sec), after one practice trial using the dominant hand. The measurement order was randomly assigned. A total of the differences between the demand value and the grip exertion value for 25 sec was used as an evaluation parameter. The measurements showed a constant tendency to increase with age group in both waveforms. Significant linear regressions were identified (r2SW=0.83, r2RW=0.89), but there was no significant difference in the rate of increase of both waveforms. The result of the analysis of variance showed insignificant differences among means of both waveforms, except for those after 70 years of age, and the differences between means in ages greater than 50 years and 20 years enlarged in both waveforms. Individual differences were almost the same in both waveforms (CVSW=24.1〜42.1, CVRW=22.9〜41.8). The performance of the controlled force exertion test tended to decrease with age in both the sinusoidal and quasi-random waveforms, and their rates of decrease are remarkable after 50 years of age. The change of individual differences with age is almost the same in both waveforms.