title: Fatigue in healthy and diseased individuals.
abstract: OBJECTIVE
  Although fatigue is experienced by everyone, its definition and classification remains under debate.
  
  
  METHODS
  A review of the previously published data on fatigue.
  
  
  RESULTS
  Fatigue is influenced by age, gender, physical condition, type of food, latency to last meal, mental status, psychological conditions, personality type, life experience, and the health status of an individual. Fatigue may not only be a symptom but also a measurable and quantifiable dimension, also known as fatigability. Additionally, it may be classified as a condition occurring at rest or under exercise or stress, as physiologic reaction or pathologic condition, as spontaneous phenomenon or triggerable state, as resistant or irresistant to preconditioning, training, or attitude, as prominent or collateral experience, and as accessible or inaccessible to any type of treatment or intervention. Fatigue may be the sole symptom of a disease or one among others. It may be also classified as acute or chronic. Quantification of fatigability is achievable by fatigue scores, force measurement, electromyography, or other means. Fatigue and fatigability need to be delineated from conditions such as sleepiness, apathy, exhaustion, exercise intolerance, lack of vigor, weakness, inertia, or tiredness. Among neurological disorders, the prevalence of fatigue is particularly increased in multiple sclerosis, amyotrophic lateral sclerosis, Parkinson disease, traumatic brain injury, stroke, and bleeding and also in neuromuscular disorders. Fatigue may be influenced by training, mental preconditioning, or drugs.
  
  
  CONCLUSIONS
  Fatigue needs to be recognized as an important condition that is not only a symptom but may also be quantified and can be modified by various measures depending on the underlying cause.
authors.affiliation: Krankenanstalt Rudolfstiftung, Vienna, Austria fifigs1@yahoo.de.
authors.forename: Josef
authors.initials: J
authors.lastname: Finsterer
authors.affiliation: Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine Monastir, Monastir, Tunisie.
authors.forename: Sinda Zarrouk
authors.initials: SZ
authors.lastname: Mahjoub
mesh_terms: D000208:Acute Disease; D000367:Age Factors; D015415:Biomarkers; D002908:Chronic Disease; D000529:Complementary Therapies; D019937:Diagnostic Techniques and Procedures; D004032:Diet; D015444:Exercise; D005221:Fatigue / Q000145:classification* / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008603:Mental Health; D009468:Neuromuscular Diseases / Q000150:complications*; D015995:Prevalence; D012737:Sex Factors
chemical_list: D015415:Biomarkers
keywords: fatigability; fatigue; muscle performance; review; tiredness