Muscle force assessment in the presence of indeterminate deficiency

Indeterminate deficiency is encountered when a subject puts an artificial limit on his/her muscle abilities, in which case his/her true muscle force cannot be assessed in a straight forward manner. Self-restriction of muscle performance during testing may be unintentional due to lack of motivation, lack of self-confidence or due to fear of pain. It can, however, be intentional resulting from unwillingness to cooperate. The aim of this study was to develop an objective system aimed at directing subjects into generating more intense muscle forces than they aimed, thus leading to their true force potential. The methodology used combines mind distraction techniques and Computer Adaptive Testing (CAT) theory. The first element is aimed at distracting the examinees from restricting their muscle force, or shifting the interval of convenience of their performance. The examined subject is thus directed into generating higher muscle forces than he/she has intended to, thus reaching the highest possible force. Practically, the tested subject is asked to perform tasks of varying intensities, visually presented in subject-unanticipated real-time converted-scale display biofeedback. For the second element of our methodology we made use of the Item Response Theory custom-tailored itemized test, for people with various ability levels. A developed iterative CAT algorithm provided, individually for each subject, rapid convergence to the highest force level possible. The results of this study bear potential significance in two major areas: Rehabilitation Medicine, by indicating training procedures for unconfident patients and in Occupational Medicine, for the functional evaluation of subjects who exhibit lack of motivation or cooperation.