| Fatigue |
A subjective lack of physical and/or mental energy that is perceived by the individual or caregiver to interfere with usual and desired activities. Perceptions of fatigue refer to subjective sensations of weariness, exhaustion, increasing sense of effort, or a mismatch between effort expended and actual performance |
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| Cognitive fatigue (mental fatigue) |
A transient increase in mental exhaustion resulting from prolonged periods of cognitive activity. Cognitive fatigue can be described as feelings of mild to extreme mental exhaustion which can last anywhere from several hours to days and is often felt as a rebound effect after mental exertion |
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| Physical fatigue (physiological fatigue) |
The transient inability to maintain optimal physical performance following physical exercise. The contractile properties of muscles are reduced, and continued exertion is difficult until the muscle is allowed to rest. Includes both a central and peripheral component |
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| Central fatigue |
A form of fatigue that is associated with changes in the synaptic concentration of neurotransmitters within the CNS, including the brain and spinal cord, which affects exercise performance and muscle function and cannot be explained by factors that affect muscle function. It is linked to neurotransmitter systems in the brain, primarily involving serotonin, noradrenaline and dopamine, which are linked to arousal, sleepiness and mood. When central fatigue develops, the CNS is unable to sufficiently enervate the muscles to maintain optimal muscle activation, resulting in reduced muscle force as well as generalized feelings of tiredness, loss of drive and sleepiness. Central fatigue tends to be of a lower intensity and duration than peripheral fatigue |
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| Peripheral fatigue |
A form of fatigue resulting from internal changes in the skeletal muscles and the neuromuscular junction during exercise such that the muscles are unable to continue producing the same level of force. Peripheral fatigue is caused by a decrease in the availability of energy resources within the muscle, and with an increase of lactic acid and other metabolites within the muscle (causing a burning sensation) |
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| Emotional fatigue |
A form of fatigue encountered when dealing with life events that cause intense emotional reactions such as problems in a relationship, the illness or death of a loved one or problems with a child. These emotional situations engender feelings of fear, dread, confusion, grief or anger that are perceived as overwhelming and that cause generalized stress to the body. This state of constant tension can drain energy and leave one feeling drained of emotional and physical resources |
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| Stress fatigue |
A form of fatigue occurring as a result of chronic stress that can be related to jobs, managing family obligations or dealing with unexpected setbacks. If this stress is not managed, it can result in fatigue, to damage to the heart and blood vessels and a number of other serious diseases. Stress fatigue can be related to emotional fatigue, but it can occur independently. Exercise, meditation, biofeedback training or engaging in absorbing hobbies can all help to relieve stress and increase emotional wellbeing |
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| Fatigability |
An objective change in performance. Fatigability is defined as the magnitude or rate of change in a performance criterion relative to a reference value over a given time of task performance or measure of mechanical output |
