World Health Organization Ageing and Health Programme Growing Older - Staying Well Ageing and physical activity in everyday life

1. AGEING Ageing is an integral, natural part of life. The way in which we grow old and experience this process, our health and functional ability all depend not only on our genetic makeup, but also (and importantly) on what we have done during our lives; on what sort of things we have encountered in the course of our lifetime; on how and where we have lived our lives. Lifespan is defined as the maximum survival potential for a particular species. In human beings, the lifespan is thought to be about 110 to 115 years (Matteson 1988). Life expectancy, then, is defined as the average observed years of life from birth or any stated age. Despite recent developments, the basic biological mechanisms involved in the ageing process remain largely unknown. What we do know is that: 1) ageing is common to all members of any given species; 2) ageing is progressive; and 3) ageing involves deleterious mechanisms that affect our capacity to perform a number of functions. Ageing is a highly complex and variable phenomenon. Not only do organisms of the same species age at different rates, but the rate of ageing varies within the single organism of any given species. The reasons for this are not fully known. Some theorists argue that individuals are born with a particular amount of vitality-the ability to sustain life-which continually diminishes with advancing age. Environmental factors also mediate the length of life and time of death (Dychtwald 1986). With the process of ageing, most organs undergo a decline in functional capacity and in their ability to maintain homeostasis. Ageing is a slow but dynamic process which involves many internal and external influences, including genetic programming and physical and social environments (Matteson 1988). Ageing is a lifelong process. It is multidimensional and multidirectional in the sense that there is variability in the rate and direction of change (gains and losses) in different characteristics for each individual and between individuals. Each period of life is important. Thus it follows that ageing should be viewed from a life course perspective. With the continuing growth of elderly populations in modern societies, it has become a matter of increasing urgency to look for ways to maintain and improve the functional abilities of ageing people, to help them cope independently in the community and ultimately, to raise the quality of their lives. The incidence of many chronic illnesses and …