title: Standing economy: does the heterogeneity in the energy cost of posture maintenance reside in differential patterns of spontaneous weight-shifting?
abstract: OBJECTIVE
  Due to sedentarity-associated disease risks, there is much interest in methods to increase low-intensity physical activity. In this context, it is widely assumed that altering posture allocation can modify energy expenditure (EE) to impact body-weight regulation and health. However, we have recently shown the existence of two distinct phenotypes pertaining to the energy cost of standing-with most individuals having no sustained increase in EE during steady-state standing relative to sitting comfortably. Here, we investigated whether these distinct phenotypes are related to the presence/absence of spontaneous "weight-shifting", i.e. the redistribution of body-weight from one foot to the other.
  
  
  METHODS
  Using indirect calorimetry to measure EE in young adults during sitting and 10 min of steady-state standing, we examined: (i) heterogeneity in EE during standing (n = 36); (ii) EE and spontaneous weight-shifting patterns (n = 18); (iii) EE during spontaneous weight-shifting versus experimentally induced weight-shifting (n = 7), and; (iv) EE during spontaneous weight-shifting versus intermittent leg/body displacement (n = 6).
  
  
  RESULTS
  Despite heterogeneity in EE response to steady-state standing, no differences were found in the amount or pattern of spontaneous weight-shifting between the two phenotypes. Whilst experimentally induced weight-shifting resulted in a mean EE increase of only 11% (range: 0-25%), intermittent leg/body displacement increased EE to >1.5 METs in all participants.
  
  
  CONCLUSIONS
  Although the variability in spontaneous weight-shifting signatures between individuals does not appear to underlie heterogeneity in the energy cost of standing posture maintenance, these studies underscore the fact that leg/body displacement, rather than standing posture alone, is needed to increase EE above the currently defined sedentary threshold.
authors.affiliation: Department of Medicine/Physiology, University of Fribourg, Chemin du Musée 5, 1700, Fribourg, Switzerland. jenniferlynn.miles@unifr.ch.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Miles-Chan
authors.affiliation: Department of Medicine/Physiology, University of Fribourg, Chemin du Musée 5, 1700, Fribourg, Switzerland.
authors.forename: Elie-Jacques
authors.initials: EJ
authors.lastname: Fares
authors.affiliation: Department of Informatics, University of Fribourg, Fribourg, Switzerland.
authors.forename: Redina
authors.initials: R
authors.lastname: Berkachy
authors.affiliation: Department of Medicine/Physiology, University of Fribourg, Chemin du Musée 5, 1700, Fribourg, Switzerland.|Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland.
authors.forename: Philippe
authors.initials: P
authors.lastname: Jacquet
authors.affiliation: EA3920 and EPSI Platform, Bourgogne Franche-Comté University, 25000, Besançon, France.
authors.forename: Laurie
authors.initials: L
authors.lastname: Isacco
authors.affiliation: Department of Medicine/Physiology, University of Fribourg, Chemin du Musée 5, 1700, Fribourg, Switzerland.
authors.forename: Yves
authors.initials: Y
authors.lastname: Schutz
authors.affiliation: Department of Medicine/Physiology, University of Fribourg, Chemin du Musée 5, 1700, Fribourg, Switzerland.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Montani
authors.affiliation: Department of Medicine/Physiology, University of Fribourg, Chemin du Musée 5, 1700, Fribourg, Switzerland.
authors.forename: Abdul G
authors.initials: AG
authors.lastname: Dulloo
mesh_terms: D000328:Adult; D001835:Body Weight; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D010641:Phenotype; D004856:Postural Balance / Q000502:physiology; D011187:Posture; D057185:Sedentary Behavior
keywords: Energy expenditure; Posture; Sedentary behaviour; Standing; Weight-shifting