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.