Galileo Galilei’s quote ‘measure what is measurable, and make measurable what is not so’
has particular relevance to health behaviours, such as physical
activity (PA), sitting and sleep, whose measurement during free living
is notoriously difficult. To date, much of what we know about how these
behaviours affect our health is based on self-report by questionnaires
which have limited validity, are prone to bias and inquire about
selective aspects of these behaviours. Although self-reported evidence
has made great contributions to shaping public health and exercise
medicine policy and guidelines until now,1
the ongoing advancements of accelerometry-based measurement and
evidence synthesis methods are set to change the landscape. The aim of
this editorial is to outline new directions in PA and sleep-related
epidemiology that open new horizons for guideline development and
improvement; and to describe a new research collaboration platform: the
Prospective Physical Activity, Sitting, and Sleep consortium (ProPASS).