Examination of force-production properties during static explosive grip based on force-time curve parameters

The present study attempts to clarify the properties of force-time curves in the force-development phase during static explosive grip exertion and to determine force-time parameters in relation to static explosive strength. 80 healthy young males (age 17.8 +/- 2.5 yr.) exerted maximal isometric force as fast and forcefully as possible. In total, 21 variables, e.g., time to fixed level, integrated area, average force, integrated area to fixed time, force at the maximal rate of force development, and maximal rate of force development, were selected as force-time parameters. Good reliability was obtained for average force in force levels above 90% of maximal strength (.64-.93), integrated area to a fixed time of 1.0-2.0 sec. (.86-.93), force at the maximal rate of force development (.67), and maximal rate of force development (.73). In addition, these values correlated closely with maximal grip strength (r= .65-.93). Further, significant differences in maximal grip strength, average force in force levels above 90% of maximal strength, integrated area to fixed time, and force at the maximal rate of force development were found among three groups categorized by average force in force levels of maximal strength. These results suggested that individual differences were present in the force-time curve patterns during the force-development phase of static explosive grip exertion and that the average force in force levels of maximal strength might be a valuable tool for evaluating static explosive strength.