33 Archives of Physical Health and Sports Medicine V3 . I2 . 2020 Introduction According to the World Health Organization, population older than 60 years would duplicate by 2050, with an increase from 900 million in 2015 to 2 billion elders worldwide(1). Aging is a natural and complex process with decline in physiological and cognitive functions, the velocity of establishment depends on intrinsic (genetics) and extrinsic (environment and lifestyles) factors. It also depends largely by the burden of chronic diseases throughout life (2, 3). The benefits of physical activity and exercise include pulmonary, cardiovascular, hematopoietic, neurophysiologic, metabolic, and musculoskeletal adaptations. Which protect against chronic diseases and along with a healthy diet and mental well-being, contribute to successful aging (2, 4, 5). Physical activity is associated with reduction in all-cause mortality and mortality of cardiovascular causes by 33% and 35% respectively, extending lifespan by one to two years (6-8) Detraining refers to total or partial loss of exercise induced adaptations in response to a lack or reduction in training stimulus (9, 10). Its efects depend to an important extent on age, clinical conditions, type and intensity of previous training (9-11). The loss of adaptations also depends on timeof detraining(9-13). In the past decades there has been a demographic shift with inversion of the population pyramid, this has expanded the number of adults over 65 years, among whom physical inactivity is frequent. With increasing age, a vicious circle is generated between deconditioning, perception of loss of functionality, physical inactivity, and sedentary lifestyle. Thus, in older adults where the burden of chronic diseases is higher, knowledge of detraining becomes as Archives of Physical Health and Sports Medicine ISSN: 2639-1805 Volume 3, Issue 2, 2020, PP: 33-43 Physiology of Detraining in Older Population: Pandemic Time Considerations Ana María Anaya 1 *, Diego Serna 1 , Paula Torres 1 , Néstor Bustamante 1 , Paola Callejas 1 Jorge García 1 , Claudia Escobar 1 , Hugo Pabón 1 , Mauricio Garzón 2 * 1 Sports Medicine Resident, Faculty of Medicine, Universidad El Bosque, Bogotá, Colombia. 2 Faculty of Medicine. School of Kinesiology and Physical Activity Sciences. University of Montreal, Montreal, Canada. *Corresponding Author: Ana María Anaya, Sports Medicine Resident, Faculty of Medicine, Universidad El Bosque, Bogotá, Colombia, Calle 116 # 22 72 AP 603, Bogotá, Colombia. Abstract With population aging, physical activity is among the factors that determine quality of life. A considerable numberof elders do not meet the minimum requirements for physical activity or are sedentary. Moreover, adults who were physically active can decrease their activity due to diseases or even the confinement generated by the SARS-CoV-2 pandemic. Therefore, it is important to describe the characteristics of detraining in the elderly populationto determine how detraining impacts the biological systems of human body, and the deleterious effects that converge with aging per se, making it difficult to determine the influence of each in the physical health of individuals. It is remarkable how quickly the deleterious effects of detraining occur, which shows the importance of maintaining a physically active life at the appropriate intensity throughout life. The aim of this review is to describe the effects of training cessation on the cardiovascular, pulmonary, metabolic, and musculoskeletal systems. Key words: Exercise, aging, longevity, physical fitness.