Physical activity that is below 3.5 METS (light activities) or a
total amount of activity that is below around 4200 kJ/week
(equivalent to more than 3 h of brisk walking per week) is
unlikely to produce health-related changes in adults. However,
in older adults who have mobility limitations, the metabolic cost
of activities that involve walking are higher than the average
adult16 and should be considered when advising people with
mobility limitation about physical activity levels. For people
without a mobility limitation, time spent in sedentary activities
(such as watching TV) and light activities (including light housework)
does not reach activity levels high enough to improve
health outcomes.