A number of possible mechanisms for<unk>  have been proposed. One stipulates that microtrauma to the muscles are created faster than the body can heal them. Another proposes that amino acids are used up faster than they are supplied in the diet, a condition sometimes referred to as "protein deficiency". Finally, systemic inflammation has been considered as a mechanism in which the release of cytokines activates an excessive immune response.
Overtraining
Deconditioning
Preconditioning 
Allostatic load
Stress shielding
Homeostasis
Neuraxial blockade
Meditation