The interaction among these health characteristics will ultimately determine the intrinsic capacity of the individual – that is, the composite
of all the physical and mental capacities that
an individual can draw on.
However, whether older people can achieve
the things that they have reason to value will be
determined not just by this capacity but also by
further interactions with the environments they
inhabit at a particular point in time. For example,
older people with limitations in their physical
capacity may still have the mobility they need
if they use an assistive device and live close to
public transport that provides access for people
with disabilities. Another person with the same
physical limitation but who lives in less enabling
environments may find it much more difficult.
This final combination of the individual and
their environments, and the interaction between
them, is the individual’s functional ability.