Yoshinori Nagasawa^1,, Shinichi Demura²

It is important to develop a method to accurately measure controlled force exertion (CFE) in order to evaluate coordination of neuromuscular function. This study aimed at examining the effect of short-term exercise on controlled force exertion in healthy young and middle-aged adults. Ten young (mean age = 20.7 y) and 10 middle-aged (mean age = 49.8 y) adults were included in the study. All subjects had a healthy central nervous system and had no disability in terms of motor functions. Also, none had engaged in regular exercise in the year prior to the study. Everyone participated in a general muscle strength training and aerobic exercise program twice a week during a 3-week period. They exerted the grip strength of the dominant hand and adjusted the grip strength based on the changing demand values displayed as a bar chart with a frequency of 0.3 Hz on a computer screen. A sum of errors between the demand values and the grip exertion values for 25 s was used as the evaluation parameter. A two-way analysis of variance (group and period) was used to examine significant differences among the means. Significant differences of variance were calculated to examine individual differences between the two groups by period. The middle-aged group had significantly greater errors than the young group. The errors decreased by approximately 20% in the young group and by approximately 10% in the middle-aged group during the second and third weeks. The variation in the errors in the middle-aged group was significantly greater than that in the young group during each period. In conclusion, we report that a combination of a general muscle strength training and aerobic exercise improves CFE in middle-aged and young adults. This effect is, however, less pronounced in middle-aged adults who also displayed a particularly small interindividual difference in CFE.

force output, grip strength, psychomotor performance, tracking paradigm, visuomotor processing