Physical activity, sedentary time and gain in overall and central body fat: 7-year follow-up of the ProActive trial cohort

© 2015 Macmillan Publisher Limited. This work is licensed under a Creative Commons Attribution 3.0 Unported License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/ by/3.0/Objective: The objective of this study is to examine the independent associations of time spent in moderate-to-vigorous physical activity (MVPA) and sedentary (SED-time), with total and abdominal body fat (BF), and the bidirectionality of these associations in adults at high risk of type 2 diabetes. Design and subjects: We measured MVPA (min per day) and SED-time (h per day) by accelerometry, and indices of total (body weight, fat mass (FM), BF% and FM index) and abdominal BF (waist circumference (WC)) using standard procedures in 231 adults (41.3±6.4 years) with parental history of type 2 diabetes (ProActive UK) at baseline, 1-year and 7-year follow-up. Mixed effects models were used to quantify the independent associations (expressed as standardised β-coefficients (95% confidence interval (CI))) of MVPA and SED-time with fat indices, using data from all three time points. All models were adjusted for age, sex, intervention arm, monitor wear time, follow-up time, smoking status, socioeconomic status and MVPA/SED-time. Results: MVPA was inversely and independently associated with all indices of total BF (for example, 1 s.d. higher MVPA was associated with a reduction in FM, β=−0.09 (95% CI: −0.14, −0.04) s.d.) and abdominal BF (for example, WC: β=−0.07 (−0.12, −0.02)). Similarly, higher fat indices were independently associated with a reduction in MVPA (for example, WC: β=−0.25 (−0.36, −0.15); FM: β=−0.27 (−0.36, −0.18)). SED-time was positively and independently associated with most fat indices (for example, WC: β=0.03 (−0.04, 0.09); FM: β=0.10 (0.03, 0.17)). Higher values of all fat indices independently predicted longer SED-time (for example, WC: β=0.10 (0.02, 0.18), FM: β=0.15 (0.07, 0.22)). Conclusions: The associations of MVPA and SED-time with total and abdominal BF are bidirectional and independent among individuals at high risk for type 2 diabetes. The association between BF and MVPA is stronger than the reciprocal association, highlighting the importance of considering BF as a determinant of decreasing activity and a potential consequence. Promoting more MVPA and less SED-time may reduce total and abdominal BF.Seksjon for idretssmedisinske fag / Department of Sports Medicin