The word fatigue is used in everyday living to describe a range of afflictions, varying from a general state of lethargy to a specific work induced burning sensation within muscle. Physiologically, ‘fatigue’ describes the inability to continue functioning at a prescribed work rate (Gandevia et al., 1995; Hagberg, 1981; Hawley et al., 1997) in the presence of an increased perception of effort (Enoka & Stuart 1992). Fatigue is ubiquitous in everyday life, but becomes particularly marked during heavy exercise. Bold textItalic text // Headline text REDIRECT Insert text --70. ... In medicine, a sign is a feature of disease as detected by the doctor during physical examination of a patient. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... // R00-R99 - Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R09) Symptoms and signs involving the circulatory and respiratory systems (R00) Abnormalities of heart beat (R000) Tachycardia, unspecified (R001) Bradycardia, unspecified (R002) Palpitations (R008) Other and unspecified abnormalities of heart beat (R01) Cardiac murmurs and other... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Diseases Database is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... PSYCHOLOGY In psychology and the cognitive sciences, perception is the process of acquiring, interpreting, selecting, and organizing sensory information. ... (for options, see option exercise) U.S. marine emerges from the water upon completing the swimming portion of the triathlon. ...

The development of fatigue is characterised by an initial, disproportionate increase in the perception of effort required to maintain or increase the work output before the inability to exert the required force is experienced (Cafarelli, 1988; Garner et al., 1990; Jones et al., 1983; Matthews, 1982). The seemingly dichotomous nature of fatigue has lead scientists to describe the aetiology of fatigue in terms of peripheral and central components (Gandevia, 1992; Kent-Braun, 1999).

Enoka and Stuart (Enoka & Stuart 1992) propose that the origin of fatigue depends on the mode of work that is being undertaken; a concept that they called task dependency. St Clair Gibson et al (St Clair Gibson et al., 2001) used the task dependency model to examine neural control mechanisms during different types of activities. They concluded that the force output appears to be regulated through inhibitory efferent commands in order to maintain a reserve capacity within the muscle and other organs so that there is always reserve capacity during volitional exercise. The nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and processes input from the senses, and initiates actions. ... Efferent nerve fibers carry information away from the brain. ... A top-down view of skeletal muscle Muscle is the contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. ... Volition is the study of will, choice, and decision. ... (for options, see option exercise) U.S. marine emerges from the water upon completing the swimming portion of the triathlon. ...

Fatigue can be dangerous when performing tasks that require constant concentration, such as driving a vehicle. When someone is sufficiently fatigued, they may experience microsleeps that can cause them to lose concentration; however, objective cognitive testing should be done to differentiate the neurocognitive deficits of brain disease from those attributable to tiredness. To meet Wikipedias quality standards, this article or section may require cleanup. ... A microsleep is a period of sleep lasting no more than a few seconds up to a minute. ...

The sense of fatigue is believed to originate in the reticular activating system of the lower brain. However, the brain did not evolve merely to register representations of the world; rather it evolved for adaptive action and behaviour. Musculoskeletal structures co-evolved with appropriate brain structures so that the complete unit functions together in an adaptive fashion (Edelman, 1989). The entire systems of muscles, joints, and proprioceptive and kinaesthetic functions plus parts of the brain evolve and function together in a unitary way (Kelso, 1995). The reticular activating system is the name given to part of the brain (the Reticular Formation and its connections) believed to be the centre of arousal and motivation in animals (including humans). ... The human musculoskeletal system is the musculoskeletal system that gives us the ability to move. ...

Types

There are seen to be two main types of fatigue; Central and Peripheral.

• Central Fatigue The central component to fatigue is generally described in terms of a reduction in the neural drive or motor command to working muscles that results in a decline in the force output (Gandevia, 2001; Kay et al., 2001; Kent-Braun, 1999; Vandewalle et al., 1991). It has been suggested that the reduced central drive during exercise may be a protective mechanism to prevent organ failure if the work was continued at the same intensity (Bigland-Ritchie & Woods, 1984; Noakes, 2000). The exact mechanisms of central fatigue are unknown although there has been a great deal of interest in the role of serotonergic pathways (Davis, 1995; Newsholme et al., 1987; Newsholme et al., 1995).

• Peripheral Fatigue Fatigue during physical work is usually modelled from the peripheral context of an inadequate capacity to supply metabolic substrate to the contracting muscles to meet the increased energy demand. This causes contractile dysfunction that is manifest in the inability to maintain or increase work output.

The fundamental difference between the peripheral and central theories of fatigue is that the peripheral model of fatigue assumes failure at one or more sites in the chain that initiates muscle contraction. Peripheral regulation is therefore dependent on the localised accumulation or depletion of substrates within the active muscle. Whereas the central model of fatigue is an intregrated mechanism that works to preserve the integrity of the system by initiating fatigue through muscle derecruitment, based on collective feedback from the periphery, before cellular or organ failure occurs. Therefore the feedback that is assimilated by the central regulator could include chemical and mechanical as well as cognitive cues. The significance of each of these factors is dependent on the nature of the work that is being performed. The nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and processes input from the senses, and initiates actions. ...

Causes

It is typically the result of working, mental stress, jet lag or active recreation, but also from boredom or disease or simply lack of sleep. It may also have chemical causes, such as poisoning or mineral or vitamin deficiencies. In classical economics and all micro-economics labour is a measure of the work done by human beings and is one of three factors of production, the others being land and capital. ... The factual accuracy of this article is disputed. ... Jet lag (or jet-lag) is a physical condition caused by crossing multiple time zones during flight. ... Tigers playing in the water. ... Boredom is a reactive state of emotion that interprets the condition of ones environment as wearingly dull due to repetitive, non-existent or tedious stimuli. ... A disease is an abnormal condition of the body or mind that causes discomfort, dysfunction, or distress to the person afflicted or those in contact with the person. ... It has been suggested that Primary insomnia be merged into this article or section. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Minerals are natural compounds formed through geological processes. ... A vitamin is an organic molecule required by a living organism in minute amounts for proper health. ...

When chronic (meaning of six months or more duration) it is a symptom of nearly 30 different diseases. Post exertional fatigue, also known as exercise intolerance, is however far more rare, and is primarily found in organic brain diseases, mitochondrial disease, and neuromuscular disease. Exercise Intolerance is a medical term used to describe a condition where the patient who is unable to do physical exercise at the level that would be expected of someone in his or her general physical condition, or who experiences unusually severe post-exercise pain, fatigue, or other negative effects. ... Mitochondrial diseases are a group of disorders relating to the mitochondria, the organelles that are the powerhouses of the eukaryotic cells that comprise higher-order lifeforms (including humans). ... Neuromuscular disease is a very broad term that encompass many diseases and ailments of muscle. ...

PostPrandial Repercussional Fatigue (PPRF)

PostPrandial Repercussional Fatigue, as postulated by King's College London scholars Swaneet Singh and Derek Uittenbroëk, refers to the fatigue and drowsiness that one experiences after eating a large meal. The biological justification for this is that the blood in the body is diverting to the digestive system in order to break down the meal and transport it through the body. A lower amount of blood, therefore, feeds through the brain and one may perceive themselves to be physically exhausted or drained. Meals rich in carbohydrates and starch (such as potatoes or pasta) may increase the intensity of the fatigue that the individual experiences. "PostPrandial Repercussional Fatigue" as mentioned above, is also influenced by a condition referred to as "Acute Vegitative State" recognised by other King's College London scholars Jonathan Coshever and Robert Toscano. This condition concerns the stimulation of the bodies 'parasympathetic branch of its autonomic nervous system'. The ingestion of food results in the release of many substances including 'Acetylcholine' (One of the bodies neurotransmitters) that stimulates the parasympathetic neurones innervating the Gastro-Intestinal-Tract (GIT), this results in the dilation of the blood vessels carrying oxygenated blood to the GIT and the constriction of the blood vessels supplying the extra GIT systems of the body - all of this contributing to the redirecting of blood flow as mentioned in the above theory of "PostPrandial Repercussional Fatigue".

• Relaxation
• Lack of sleep
• Chronic fatigue syndrome (CFS)
• Depression
• Diabetes
• Hyperparathyroidism
• Hypothyroidism
• Myasthenia gravis
• Addison's disease
• Pregnancy
• Parkinson's disease
• Anemia
• Multiple sclerosis
• Arthritis
• Mononucleosis
• Mitral valve prolapse/Mitral regurgitation
• Certain medications, e.g. lithium salts, ciprofloxacin

The word relaxation can mean the following: The opposite of stress or tension; the aim of recreation and leisure activities. ... In an ideal situation, sleep should be undisturbed and experienced in the same room every night Sleep is the regular state of natural rest observed in all mammals, birds and fish. ... Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), post-viral fatigue syndrome (PVFS) and various other names, is a syndrome of unknown and possibly multiple etiologies, affecting the central nervous system (CNS), immune, and many other systems and organs. ... Clinical depression is a state of sadness or melancholia that has advanced to the point of being disruptive to an individuals social functioning and/or activities of daily living. ... This article is about the disease that features high blood sugar. ... Hyperparathyroidism is overactivity of the parathyroid glands resulting in excess production of parathyroid hormone (PTH). ... Hypothyroidism is the disease state caused by insufficient production of thyroid hormone by the thyroid gland. ... Myasthenia gravis (MG, Latin: grave muscle weakness) is a neuromuscular disease leading to fluctuating weakness and fatiguability. ... Addisons disease (also known as chronic adrenal insufficiency, or hypocortisolism) is a rare endocrine disorder. ... Pregnancy is the carrying of one or more embryos or fetuses by female mammals, including humans, inside their bodies. ... This article discusses the medical condition. ... Arthritis(from Greek arthro-, joint + -itis, inflammation) is a group of conditions that affect the health of the bone joints in the body. ... Infectious mononucleosis (also known as mono, the kissing disease, Pfeiffers disease, and, in British English, glandular fever) is a disease seen most commonly in adolescents and young adults, characterized by fever, sore throat and fatigue. ... Mitral valve prolapse (MVP) is a heart valve condition marked by the displacement of an abnormally thickened mitral valve leaflet into the left atrium during systole. ... Mitral regurgitation (MR), also known as mitral insufficiency, is the abnormal leaking of blood through the mitral valve, from the left ventricle into the left atrium of the heart. ... Lithium salts are chemical salts of lithium used primarily in the treatment of bipolar disorder as mood stabilizing drugs. ... Ciprofloxacin is the generic international name for the synthetic antibiotic manufactured and sold by Bayer Pharmaceutical under the brand names Cipro® and Ciproxin® (and other brand names in other markets, e. ...

See also

• Combat stress reaction (Battle fatigue)
• Malaise
• Asthenia
• Paresis
• Debility
• Muscle weakness
• Muscle fatigue
• Infectious mononucleosis

// History The history of CSRs has shown a remarkable variation in the interest and knowledge of those whose tasks it has been to deal with them. ... Malaise is a term used to refer to a general state of discomfort, tiredness, or illness. ... Asthenia is a medical term denoting weakness, lack of energy and strength. ... During the nineteenth century general paresis of the insane emerged as a new psychiatric disorder which was extremely common and completely devastating. ... In the field of astrology a debility is referred to when a planet or other celestial body is in the sign of its detriment or fall. ... Muscle weakness (or lack of strength) is a general term used during a diagnosis before the etiology can be identified. ... Muscle fatigue is the decline in ability of a muscle to create force. ...

External links

• NIH/Medline
• National Cancer Institute
• Don't Fall Asleep at the Wheel!

References

• Bigland-Ritchie, B & Woods, JJ. 1984, 'Changes in muscle contractile properties and neural control during human muscular fatigue'. Muscle Nerve, vol. 7, pp. 691-699.
• Cafarelli, E. 1988, 'Force sensation in fresh and fatigued human skeletal muscle'. Exercise and Sport Science Review, vol. 16, pp. 139-168.
• Davis, JM. 1995, 'Carbohydrates, branched-chain amino acids, and endurance: the central fatigue hypothesis'. International Journal of Sport Nutrition, vol. 5 Suppl, pp. S29-S38.
• Edelman, GM 1989, The remembered present : a biological theory of consciousness. Basic Books, New York.
• Enoka, RM & Stuart, DG. 1992, 'Neurobiology of muscle fatigue'. Journal of Applied Physiology, vol. 72, pp. 1631-1648.
• Gandevia, SC. 1992, 'Some central and peripheral factors affecting human motoneuronal output in neuromuscular fatigue'. Sports Medicine, vol. 13, pp. 93-98.
• Gandevia, SC. 2001, 'Spinal and supraspinal factors in human muscle fatigue'. Physiological Review, vol. 81, pp. 1725-1789.
• Gandevia, S. C., Enoka, R. M., McComas, A. J., Stuart, D. G., & Thomas, C. K. 1995, 'Neurobiology of muscle fatigue - Advances and issues'. Advances in Experimental Medicine and Biology, vol. 384. pp. 515-25.
• Garner, SH, Sutton, JR, Burse, RL, McComas, AJ, Cymerman, A, & Houston, CS. 1990, 'Operation Everest II: neuromuscular performance under conditions of extreme simulated altitude'. Journal of Applied Physiology, vol. 68, pp. 1167-1172.
• Hagberg, M. 1981, 'Muscular endurance and surface electromyogram in isometric and dynamic exercise'. Journal of Applied Physiology, vol. 51, pp. 1-7.
• Hawley, JA & Reilly, T. 1997, 'Fatigue revisited'. Journal of Sport Science, vol. 15, pp. 245-246.
• Jones, LA & Hunter, IW. 1983, 'Effect of fatigue on force sensation'. Experimental Neurology, vol. 81, pp. 640-650.
• Kay, D, Marino, FE, Cannon, J, St Clair Gibson, A, Lambert, MI, & Noakes, TD. 2001, 'Evidence for neuromuscular fatigue during high-intensity cycling in warm, humid conditions'. European Journal of Applied Physiology, vol. 84, pp. 115-121.
• Kelso, JAS 1995, Dynamic patterns : the self-organization of brain and behavior. MIT Press, Cambridge, MA.
• Kent-Braun, JA. 1999, 'Central and peripheral contributions to muscle fatigue in humans during sustained maximal effort'. European Journal of Applied Physiology, vol. 80, pp. 57-63.
• Matthews, PB. 1982, 'Where does Sherrington's "muscular sense" originate? Muscles, joints, corollary discharges?'. Annu.Rev.Neurosci, vol. 5, pp. 189-218.
• Newsholme, E. A., Acworth, I. N., & Blomstrand, E. 1987, 'Amino acids, brain neurotransmitters and a functional link between muscle and brain that is important in sustained exercise', in G Benzi (ed.), Advances in Myochemistry, Libbey Eurotext, London, pp. 127-133.
• Newsholme, E. A. & Blomstrand, E. 1995, 'Tryptophan, 5-hydroxytryptamine and a possible explanation for central fatigue', in SC Gandevia (ed.), Fatigue, Plenum Press, New York, pp. 315-320.
• Noakes, TD. 2000, 'Physiological models to understand exercise fatigue and the adaptations that predict or enhance athletic performance'. Scandinavian Journal of Medicine and Science in Sports, vol. 10, pp. 123-145.
• St Clair Gibson, A, Lambert, MI, & Noakes, TD. 2001, 'Neural control of force output during maximal and submaximal exercise'. Sports Medicine, vol. 31, pp. 637-650.
• Vandewalle, H, Maton, B, Le Bozec, S, & Guerenbourg, G. 1991, 'An electromyographic study of an all-out exercise on a cycle ergometer'. Arch.Int.Physiol.Biochem.Biophys, vol. 99, pp. 89-93.