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/m(2)) 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.