The association between objectively measured sitting and standing with body composition: A pilot study using MRI

Objective: To investigate the association between objectively measured sitting and standing, using a postural allocation technique, with MRI-assessed body composition. Design: The present study was a cross-sectional pilot study. Setting: Participants were examined at one centre located in London, UK. Participants: Normal weight Caucasian women (30.9±6.1 years; body mass index (BMI), 22.9±3.4 kg/m²) with desk-bound occupations were recruited to minimise variability in body composition outcomes. A convenience sample of 12 women was recruited in January 2014 from University College London. Outcome measures: For each participant a number of body composition variables were attained from a single whole-body MRI session. Main outcome variables included: total and liver adiposity, visceral/subcutaneous fat ratio and BMI. Main exposure variables included: average sitting time, standing:sitting ratio and step count. Pearson correlations were carried out to examine associations between different activity categories and body composition variables. Results: There were significant correlations between average daily sitting and liver adiposity and visceral/subcutaneous abdominal fat ratio (r=0.66 and 0.64, respectively); standing:sitting ratio was moderately correlated with liver adiposity and visceral/subcutaneous abdominal fat ratio (r=- 0.53 and -0.45); average daily step count was moderately correlated with liver adiposity, total adiposity and visceral/subcutaneous abdominal fat ratio (r=-0.45, -0.46 and -0.51, respectively). Conclusions: This pilot study has provided preliminary evidence of relationships between objectively measured sitting and standing and precise measures of body composition.