Risk versus effort in the assessment of motor fatigue

The choice of probability leffort (COPE) devices require fatigued subjects to choose between risk and effort. In a first experiment, where fatigue was induced by an intense or by a prolonged motor task and where the required effort was perceptual, the fatigue did not generalize to the test mode. A second experiment used motor fatigue of the arm or leg, and tested with arm muscle effort, showing that subjects fatigued with either limb chose riskier alternatives in order to avoid the effort. The data correlated with self-rated fatigue, and closely paralleled earlier work using perceptual fatigue and perceptual effort.