TABLE 1.
The definitions.
| Construct | Definition | More lose paraphrases of the definitions |
| Fatigability (1) | If and only if there is the decrement in magnitude or rate of a performance criterion relative to a reference value over a given time of task performance. | Is the decrement in performance between two timepoints. Is the decrement in performance over a consecutive time. |
| X fatigability (2) | If and only if the fatigability of X. | Is the decrement in X performance over a consecutive time. |
| Effort (3) | If an only if there are forces exerted by the individual in order to reach some goal. | |
| Sensation of fatigue (4) | If and only if there is a sensation of (i) feeling the need for rest, or (ii) mismatch between effort expended and actual performance. | Is the feeling of either needing to rest or mismatch between effort expended and actual performance. |
| Sensation of X fatigue (5) | If and only if there is a sensation of (i) feeling the need for X rest, or (ii) mismatch between X effort expended and actual X performance. | Is the feeling of either the need for X rest or mismatch between X effort expended and actual X performance. |
| State fatigue (6) | If and only if there is a momentary sensation of fatigue. | Is the estimation of sensation of fatigue at this moment. |
| Trait fatigue (7) | If and only if there is an overall disposition and intensity of fatigability and sensation of fatigue, during T period of time. | Is the general tendency of fatigability and sensation of fatigue. |
| Prolonged state fatigue (8) | If and only if there is an overall disposition and intensity of fatigability and sensation of fatigue, during the last week. | Is the general tendency of fatigability and sensation of fatigue, after recent events. |
| State X fatigue (9) | If and only if there is a momentary sensation of X fatigue. | Is the estimation of sensation of X fatigue at this moment. |
| Trait X fatigue (10) | If and only if there is an overall disposition and intensity of X fatigability and sensation of X fatigue, during T period of time. | Is the general tendency of X fatigability and sensation of X fatigue. |
| Prolonged state X fatigue (11) | If and only if there is an overall disposition and intensity of X fatigability and sensation of X fatigue, during the last week. | Is the general tendency of X fatigability and sensation of X fatigue, after recent events. |
| Pathological fatigue (12) | If and only if the trait fatigue estimated by the individual or caregiver to interferes with usual and desired activities. | Is when general tendency of fatigability and sensation of fatigue is perceived to interfere with everyday life. |
| Pathological X fatigue (13) | If and only if the pathological fatigue identifiable as caused by, or consequence of, or sequel to a disease/disorder/trauma and if and only if the level of trait fatigue is worse after the disease/disorder/trauma than before. | Is when the general tendency of fatigability and sensation of fatigue is perceived to interfere with everyday life and is caused by, or consequence of, or sequel of X. |