The term "saropenia" was coined by Irwin Rosenberg in 1989 to refer to age-related loss of skeletal muscle mass. The purpose of this current opinion is to provide an evolutionary overview of sarcopenia research since 1989. This includes the creation of an operational definition of sarcopenia; consideration of the impacts of sarcopenia on physical function, chronic disease, and mortality risk; the distinction between the process of sarcopenia and the process of age-related loss of muscle strength, a phenomenon that has recently been termed dynapenia; a comparison of the independent effects of sarcopenia and dynapenia on physical function, chronic disease, and mortality risk; and consideration of the combined influence of sarcopenia and dynapenia with obesity (i.e., sarcopenic-obesity and dynapenic-obesity) on physical function, chronic disease, and mortality risk.