Adipose Tissue Responses to Breaking Sitting in Men and Women with Central Adiposity

Purpose Breaking prolonged sitting reduces postprandial glucose and insulin concentrations and influences skeletal muscle molecular signalling pathways but it is unknown whether breaking sitting also affects adipose tissue. Methods Eleven central overweight participants (7 men and 4 post-menopausal women) aged 50 ± 5 years (means ± SD) completed two mixed-meal feeding trials (PROLONGED SITTING versus BREAKING SITTING) in a randomised, counterbalanced design. The BREAKING SITTING intervention comprised walking for 2 min every 20 min over 5.5 h. Blood samples were taken at regular intervals to examine metabolic biomarkers and adipokine concentrations. Adipose tissue samples were taken at baseline and at 5.5 h to examine changes in mRNA expression and secretion of selected adipokines ex-vivo. Results Postprandial glycaemia and insulinaemia were attenuated by approximately 50% and 40% in BREAKING SITTING compared to PROLONGED SITTING (iAUC: 359 ± 117 versus 697 ± 218 mmol·330 min·L-1, p = 0.001 and 202 ± 71 versus 346 ± 150 nmol·330 min·L-1, p = 0.001, respectively). Despite these pronounced and sustained differences in postprandial glucose and insulin concentrations, adipose tissue mRNA expression for various genes (IL-6, leptin, adiponectin, PDK4, IRS1/2, PI3K and Akt1, etc.) and ex-vivo adipose tissue secretion of IL-6, leptin and adiponectin were not different between trials. Conclusions: This study demonstrates that breaking sitting with short bouts of physical activity has very pronounced effects on systemic postprandial glucose and insulin concentrations but this does not translate into corresponding effects within adipose tissue. Corresponding author: Professor Dylan Thompson, Department for Health, University of Bath, Bath, BA2 7AY, United Kingdom, Email: d.thompson@bath.ac.uk This project was funded by Ministry of Education (Taiwan) and the University of Bath. The authors declare no competing interests. The results of the present study do not constitute endorsement by the American College of Sports Medicine. The results of this study are presented clearly, honestly, and without fabrications, falsification, or inappropriate data manipulation. Accepted for Publication: 5 April 2018 © 2018 American College of Sports Medicine

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