Fig. 1.

Constant isometric force task with the FDI muscle. Each subject was instructed to exert a force with abduction of the index finger against a force transducer and match the horizontal target line for 20 s. The subjects were asked to match the target accurately and consistently for the last 10 s of each trial marked by the vertical black line in the center of the screen at 10 s. a Representative trial from one subject when exerting a constant isometric force at 10% MVC with a visual feedback gain of 2 pixels/N (left column) and 64 pixels/N (right column). b The force and EMG analysis was based on the selected segment of each trial. The top row represents the force trace for the trials represented in a and the bottom row is the corresponding FDI EMG activity. The analysis was performed from 11 to 19 s on each trial