Deconditioning is adaptation of an organism to less demanding environment, or, alternatively, the decrease of physiological adaptation to normal conditions. Decondition may result from decreased physical activity, prescribed bed rest, orthopedic casting, paralysis, aging, etc.  A particular interest in the study of deconditioning is in aerospace medicine, to diagnose, fight, and prevent adverse effects of the conditions of space flight.
Deconditioning due to decreased physical effort results in muscle loss, including heart muscles.
- McGraw-Hill Encyclopedia of Science and Technology
- Lenz, Thomas L. (2007). Lifestyle Modifications in Pharmacotherapy. Baltimore: Lippincott Williams & Wilkins. p. 298. ISBN 978-0-7817-7651-6.
- Woods, Susan L.; Erika Sivarajan Froelicher; Sandra Adams Motzer (2004). Cardiac Nursing. Philadelphia: Lippincott Williams & Wilkins. p. 921. ISBN 0-7817-4718-X. Retrieved 2013-04-07. CS1 maint: discouraged parameter (link)