Reply to the Discussion of “Letter to the Editor: Standardized use of the terms sedentary and sedentary behaviours” — Sitting and reclining are different states

I thank Dr. Viir and Dr. Veraksits for their interest in sedentary behaviours and for their letter. The Sedentary Behaviour Research Network (SBRN) is an emerging international network of individual members who are interested in research, leadership, education, and advocacy related to the consequences and possible benefits of sedentary behaviour. The mission of SBRN is to advance our understanding of the implications of sedentary behaviours through research, education, and advocacy. One of the greatest barriers to progress toward this mission is the inconsistent definition of “sedentary behaviour” as discussed in our earlier letter (Sedentary Behaviour Research Network 2012). I appreciate the concerns expressed by Drs. Viir and Veraksits. They raise an important point regarding the effects of gravity on physiological functions while in different postures. Furthermore, nuances on how to define “reclining” are raised. The proposal by SBRN that sedentary behaviour be defined as any waking behaviour characterized by an energy expenditure 1.5 METs while in a sitting or reclining posture does not disregard the potential importance of gravity or other mechanical (e.g., pressure on tissues of contact points from sitting or type of clothing being worn) or environmental (e.g., indoor vs. outdoor) factors that may provoke, mediate, or moderate physiological or even cognitive functions. Nor does the definition preclude the study of sedentary behaviours such that perhaps a whole “family” of sedentary behaviour subcategories may emerge based on their physiological influence. The fact that this discussion is occurring is evidence that our earlier letter is achieving its objective and that the mission of SBRN is being successfully pursued. Thanks and please keep the discussion going!