Accuracy of Force Exertion in Each Demanded Value Based on Subjective Information and Laterality

This study aimed to examine the direction of errors between demand values and exerted forces using submaximal grip strength based on laterality. Subjects were 100 healthy young males (age: 22.4 ± 2.8 years). After maximum grip strength (MGS) was measured, each subject exerted handgrip for each demanded value (20%, 40%, 60%, and 80%), twice with a 2-min rest between each trial. The means of all subjects were used for statistical analysis. Evaluation parameters were errors between exertion and demand values, which are relative values based on MGS. The Shapiro-Wilk test was performed to confirm the normality of the frequency distribution. It was confirmed that errors in demand values, except for 80% in the dominant hand, show a normal distribution. The result of two-way repeated measures analysis of variance (ANOVA; demanded values × dominant/non-dominant) and multiple comparisons showed that significant differences were found among demand values, except between 60% and 80% in the dominant hand, and the error was greater as follows: 20% > 40% > 60% and 80%. The error in the non-dominant hand was greater in the order of 20%, 40%, 60%, and 80%. A significant difference was found between errors of the dominant and non-dominant hands in demand values of 20%–60%, and the error was smaller in the dominant hand. Test of independence for the frequency difference of exertion direction showed significant difference in all demand values except for 80%; 20% and 40% did more in the positive direction (overexertion) in both hands, and 60% did more in the negative direction (underexertion) in the dominant hand and in the plus direction in the non-dominant hand. In conclusion, in the dominant hand, the error of grip force exertion toward demand values is greater in demand values under 60% and small grip vales are exerted. In contrast, in the non-dominant hand，the error of grip force exertion toward demand values is greater in demand values under 80% and grip values are exerted largely in demand values under 60%. Accuracy of force exertion differs among demand values, and laterality is found in low demand values of 20%–60%.