Walking downstairs and running are common actions in daily life; however, older adults with functional decline are prone to falls or injuries. To cope with various situations and avoid falls, the first neuroprotective motor mechanism activated by the body is the regulation of lower-extremity stiffness. Hence, this study retrieved and collected relevant research results from databases such as China Knowledge, Wanfang, Google Scholar, and Web of Science, using keywords such as elderly and lower-extremity stiffness, and summarized the similarities and differences in changes in lower-extremity stiffness in different action tasks. The findings show that interventions on controllable factors can improve changes in lower-limb stiffness to prevent falls in older adults. However, owing to the small number of related studies, it is necessary to further investigate the effects of action interventions on lower-limb stiffness in older adults to obtain reliable regularity features and references.