764. Objectively Measured Daily Steps and Subsequent Long Term All-Cause Mortality: The Tasped Prospective Cohort Study
Commentary by Adrian Bauman, GlobalPANet Director, The University of Sydney
The paper by Dwyer and colleagues is an interesting example of an epidemiological study that pooled comparable data from three population-based cohorts [total sample around 2500 Australian adults]. It is unusual to pool data across physical activity epidemiological studies, but as their exposure measure [objective physical activity measurement] and outcome measure were identical, this became possible. The researchers used pedometers as an objective measure of physical activity exposure, and examined the relationship to all-cause mortality. The pedometer measure was two days of consecutive pedometer use, which is only a measure of step counts, and is less comprehensive than accelerometer measures. The innovation in this paper is that few studies have examined objective measures of physical activity in relation to health outcomes, and hence this is an important study. They measured people at baseline, re-measured most of them five years later, and assessed all-cause mortality within a 10 year follow-up period. The sample was made up of adults with an average age of around 58 years at baseline.
They classified people into quintiles of step counts; interestingly the highest two quintiles (40% of the population) achieved these 10,000 steps a day and showed between a 38 and 62% reduction in risk of all-cause mortality. The relationship across quintiles of step counts was reasonably linear, with each increment in step counts associated with a lower mortality. They also show that changing step counts is beneficial, examining people at baseline and five years later, and each additional increase of 1000 steps/day was associated with a subsequent 6% decreased risk of mortality. These data show the substantial benefits of physical activity, and particularly noteworthy as few cohorts have measured physical activity objectively. This provides greater strength to the self-report physical activity and health outcomes evidence, as this study corroborates self-report relationships by objective assessment. It also provides some objective rationale for the 10,000 steps per day cutpoint or threshold, which has been widely used but seldom evidenced.
Source: PLoS ONE, 10: e0141274. Access to this article may depend on your institutional rights. The link to the full article can be found here.