Healthspan. Healthspan is the period of life without functional limitations, chronic diseases. and disability but with a beginning loss of functional capacity symbolized by a change from green to orange colour (a). This period may be prolonged by curative medicine (b), but longer disability may also occur. Optimal healthspan can potentially be achieved by preserving or improving the functional abilities of the organism and therefore lead to a shorter period of functional limitations, chronic diseases, and disability at the end of life (c). Good physical fitness is thought to contribute essentially to optimal healthspan. Adapted from Seals et al.