Henwood, Timothy R. (2012). Detraining. In James M. Rippe (Ed.), Encyclopedia of lifestyle medicine and health (pp. 307-309) Thousand Oaks, CA, United States: Sage Publications. doi:10.4135/9781412994149.n100
Periods of activity cessation, or detraining, following structured exercise regimes can be experienced at all training levels. For professional athletes, training regimes are often varied depending on the competition calendar, while individuals undertaking social exercise take holidays or experience training interruptions due to personal, family, or work commitments. Moreover, no matter what level of activity an individual adheres to, injury or morbidity-related enforced inactivity is a further consideration in training interruption. As opposed to the positive gains associated with regular progressive physical training, periods of detraining are characterized by the reversal of physiological or performance adaptations. In short, the principle of detraining is the principle of reversibility. To date, a number of studies have followed athletes and nonathletes through varied periods of detraining, and while data are somewhat mixed, it appears that the level of loss of experience is accentuated by increasing age and is associated with the extent and level of training prior to detraining and the detraining duration. Some of these losses, and the mechanisms at work, are outlined as follows.