Fatigue is defined as “a relative temporary decline in the level of various functional capabilities, physical, mental, psychological, sensory, and emotional when performing work related to those capabilities.” (177:2) It is also known as “the gradual decline in performance efficiency as a result of continued exertion of effort.” (350:7) It is also known as “the consumption of energy sources in the muscles and the increase in waste products resulting from fatigue as a result of a lack of oxygen.” (209:5) It is defined as “a natural physiological life phenomenon, which is a relative decline in the level of various functional capabilities.” (1:10) It is also known as “a physiological, organic, psychological, defensive phenomenon that causes a decline in functional capabilities as a result of exposure to external pressures.” (1:9) It is defined (Dr. Wajih Mahjoub, 1990) as “a physiological process originating from the central nervous system that protects the organs and systems.” From internal damage during work.” (109:11) From all of these definitions, it is clear that fatigue is the relationship of running out of stored energy.
In its forms, which the player implements during the training unit or training program, and this is what was indicated by (Dr. Bastawisi Ahmed 1999, p. 177), and from it the internal physiological growth of the organs occurs through repeated periods of load and rest, which leads to an increase in their ability to work and endure whenever the load is repeated again. And the occurrence of a state of adaptation within it in proportion to the activity carried out, as pointed out by (Dr. Amrullah Ahmed Al-Basati, 1998) “that adaptation occurs as a result of the proper marking between the periods of load performance and the periods of rest, and thus adaptation occurs to the organs and systems of the body through a balance between the processes of demolition and construction.” ( 60:1-61).
During muscular work, the cells that make up the muscles consume energy, which causes the waste resulting from this consumption to be excreted in the form of acids, which is called lactic acid, inside the muscle in large quantities that lead to irritation of the nerves and give instructions to the brain that it must stop muscular work.
