Effect of Grip Strength on Controlled Force Exertion in Different Strength Exertion Phases in Young Men

It is important to develop a method for the accurate measurement of controlled force exertion (CFE). The CFE test requires subjects to exert force while coordinating submaximal grip strength; therefore, grip strength may affect the CFE value. This study examined the differences in measured values in low and high phases of demand value in the CFE test and the relationship between the measured values and grip strength using 54 healthy young males aged 19-23 years. On the basis of standard values of grip strength related to age (455.7 ± 67.6 N), participants were divided into the following three groups: G1, with low grip strength (n = 13, mean age, 19.9 years, standard deviation (SD) = 0.8 years); G2, with medium grip strength (n = 33, mean age, 20.6 years, SD = 1.3 years); and G3, with high grip strength (n = 8, mean age, 21.6 years, SD = 0.7 years). The participants adjusted the submaximal grip strength of their dominant hands according to changes in the demand values, which were displayed as a sinusoidal waveform with a frequency of 0.1 Hz on a computer screen. The test, which lasted for 40 s, was performed three times, with one-minute intervals, after one practice trial. The sum of the differences between the demand value and the measured grip exertion value in the low demand value phase [5%-15% maximum voluntary contraction (MVC)] and high demand value phase [15%-25% MVC] for 30 s was used as the evaluation parameter. Significant differences were found in the measured CFE values of the three groups only in the low demand value phase (F = 3.43, p < 0.05), and the values for G3 were lower than those for G1 and G2, but the effect size (η2) was low (η2 = 0.12). The CFE values showed significant low correlation with grip strength only in the high demand value phase (r= −0.32, p < 0.05). We inferred that the difference in maximum grip strength has a negligible effect on the measured value in both low and high demand value phases of the CFE test in young males.