The Effect of Force Level Condition before Controlling on the Characteristics of Grading

Abstract

We investigated the effect of force level condition before controlling on the characteristics for force generation using graded isometric contractions of the knee extensors. Participants performed the following grading tasks as quickly and accurately as possible. From baseline of 0％ MVC, force was increased to the target force levels of 20％, 40％ and 60％ MVC. From baseline of 10％ MVC, force was increased to the target force levels of 30％, 50％ and 70％ MVC. We compared the conditions （baseline; 0％ and 10％） and magnitudes of force level （magnitudes between the target level and baseline; 20％, 40％ and 60％）. The following parameters of the recorded force were calculated for analysis: point of accuracy （constant error, absolute error）, reproducibility （variable error）, and quickness （reaction time, adjustment time, and rate of force development）. As a results, the errors as accuracy were no difference between two conditions. The reaction time as quickness was shorter for 10％ MVC than 0％ MVC baseline condition in 20％ and 40％ magnitudes. These results suggested that the characteristics of quickness, especially in starting to adjustment, was affected by the force level condition before controlling.