Conclusion
Dramatic global population ageing has brought new demands to improve older people's health by adding "quality" to their extended lives. The review was undertaken against the background of the WHO recommendations on PA for adults aged 65 years and older. Despite these recommendations physical inactivity is an increasing global health burden with PA surveillance emerging as one of the priorities of global public health for the development of effective non-communicable disease prevention programmes. International efforts to increase PA have been reported within the adult or youth populations. However, PA levels of older adults have attracted less interest so there are limited data regarding the prevalence of various types of PA in older adults and the proportion of older people whose PA meets PA guidelines. This review is the first of its kind and revealed many methodological challenges to data analysis across the selected studies. Robust studies which recruit representative random samples and consistently employ validated measurement instruments are needed to enable comparisons in PA levels to be drawn over time and between countries. More evidence of PA levels amongst older people is needed to inform public health strategies which could extend the health and quality of life of people into old age.