In grip strength a subject being ordered to show one-third, one-second and twothird of his own maximum value after checking his maximum, the value he shows is not always the same as the ordered value. The Discrepancy Index was determined by the grade of the difference between the ordered value mentioned above and the value showed actually.
For 2117 subjects composed of both sexes our experiment was performed.
1) The possibility of training effect for one-third and two-third of their own maximum value existed but little for one-second.
2) Up to 16 years of age the training effect increased with their physical development, but after 17 years remarkable change of their grading ability was not found.
3) There existed no relation between the experimental results of one-third value and two-third, between the left hands and the right, and between the Discrepancy Index of pre-training and post-training.
4) The larger maximum value of grip strength became, the smaller the Discrepancy Index was. Sometimes in the individuals who have larger maximum value, the more training effect was recognized.
5) The champions of weight-lifting, Kendo and volleyball showed better results than those of the control groups.