Rapid Evaluation of Individual's Ability to Control Hand Strength

Abstract

We present a rapid and simple evaluation of an individual's ability to control exertions in quasi-isometric conditions. This evaluation is based on a closed loop that consists mainly of a single-axis force measurement system and a computer screen. This provides simultaneously a visual input command and visual feedback to monitor the output exertions. Specific parameters (stability, period duration, deviation, and velocity) were defined and measured to describe the dexterity, accuracy, precision, and endurance associated with the concept of fine control. Tests undertaken by subjects revealed that it is easier to maintain exertion at 30 and 35% of MVC rather than 15 or 20% of MVC. Subjects who exercised provided the best performances. Fatigue seems to affect exertions at 45% of the MVC. The rhythmic activity of the muscle was also evaluated by showing specific frequencies associated with a subject's exertion, which range from 20 Hz up to 25 Hz. When documented, the obtained information is expected to be of interest in clinical practice.