New insights on how fatigue impacts performance

Due to its common usage, the word fatigue has so many meanings that it is essentially meaningless. We propose fatigue be considered a symptom that indicates a decline in work capacity due to actual and perceived reductions in performance capabilities. The level of fatigue reported by an individual person indicates the size of the reduction indicates how much their work capacity has been lowered.

The impact of fatigue on performance depends on how long it takes to reach a specific level of fatigue; the longer it takes, the less fatigable the person. Fatigability depends on the rates speed of reduction in performance capabilities and changes in perceptions that challenge the integrity of the performer. As a symptom, fatigue may be thought of as having properties that compare to symptoms of is analogous to pain. Therefore, fatigue and can only be measured by self-report, whereas fatigability can be quantified measured both in terms of performance and perceptions. Much remains to be learned about the functionally relevant mechanisms that underlie fatigue and fatigability.