We examined the correlation between jump distance and the maximum flexion angle of the knee joint during jumping to evaluate whether healthy men adjust to jump distance by changing the angle of the knee joint. Fourteen subjects jumped 3 times with their eyes closed to each of what they thought was 25%, 50%, and 75% of their maximum jump distance, a total of 9 jumps for both the vertical and standing broad jump. We measured the knee joint flexion angle at the time of the motion and examined the correlation between jump distance and knee joint flexion angle. The results show a relationship between jump distance and knee joint flexion angle for both the vertical and standing broad jump. We determined that jump distance is controlled by knee joint flexion angle in healthy men. Thus, a factor of jump control was clarified in this study.
Abstract.We investigated the effect of motor learning of a grip force-retaining task with the dominant hand on the transfer of that learning to the non-dominant hand. Seventy right-handed healthy volunteers were enrolled in this study. These subjects were randomly divided into seven groups classified by frequency of knowledge of results. In motor learning, all subjects performed a grip force adjusting task consisting of 30 trials. The task was to press a grip force measurer with a force that the subject estimated to be 20% of the maximum force. To test the effectiveness, an initial test and retention tests of 5 mins, 1 day, and 1 week after an acquisition phase were performed with 5 trials each on the dominant and nondominant hands. The efficiency of motor learning was determined by the error value of the retention test. The effect of the retention test was determined by comparing the initial test with each of the 3 phases of the retention tests. The effect of intermanual transfer was determined by correlation coefficients between the dominant and non-dominant hands. Our results revealed that there was a strong relationship between the groups with highly efficient motor learning and correlation coefficients of error of the grip force between the dominant and non-dominant hands. We need to develop a program for more efficient motor learning using the dominant hand.
During the developmental period of the cortex, neurocyte cells are produced, differentiated in each area, then move in radial and tangential directions and form a layer structure. We immunohistochemically studied the expression of PGP9.5 (Ubiquitin-carboxyl terminus-enzyme) which was discovered as a unique protein substance in the neurocyte cells of the human cortex during the developmental period. The expression of PGP9.5 during development in humans increased in Cajal-Retzius cells in the external molecular layer at 13 weeks of gestation, then in the fifth layer pyramidal cells, the second and fourth layers granular cells, the third layer pyramidal cells and neurophils in that order, and decreased with advancing age. In cerebral white matter, PGP9.5 was increased in the deep layer around the same time as the molecular layer, then decreased with advancing age. The expression of cells positive for PGP9.5 increases with the healthy development of the human cortex, and it is thought that it reflects the growth and development of neurites and dendrites. Furthermore, from the fact that nerve stem cells develop after damage and show development of neurites and dendrites, they are thought to be an index of regeneration of neurites and dendrites as protein after damage.
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