title: Objective vs. Self-Reported Physical Activity and Sedentary Time: Effects of Measurement Method on Relationships with Risk Biomarkers Physical Activity versus Sedentary Behavior: Associations with Lipoprotein Particle Subclass Concentrations in Healthy Adults Diet or diet plus physical activity versus usual care in patients with newly diagnosed type 2 diabetes: the Early ACTID randomised controlled trial Objectively Measured Moderate- and Vigorous-Intensity Physical Activity but Not Sedentary Time Predicts Insulin Resistance in High-Risk Individuals Impact of objectively measured sedentary behaviour on changes in insulin resistance and secretion over 3 years in the RISC study: interaction with weight gain.
abstract: Purpose Imprecise measurement of physical activity variables might attenuate estimates of the beneficial effects of activity on health-related outcomes . We aim ed to compare the cardiometabolic risk factor dose-response relationships for physical activity and sedentary behaviour between accelerometer- and question naire-based activity measures . Methods  Physical activity and sedentary behaviour  were assessed in 317 adults by 7-day accelerometry and International Physical Activity Question naire ( IPAQ ) . Fasting blood was taken to determine insulin , glucose , triglyceride and total , LDL and HDL cholesterol concentrations and homeostasis model-estimated insulin resistance ( HOMAIR ) . Waist circumference , BMI , body fat percentage and blood pressure were also measured . Results For both accelerometer-derived sedentary time ( < 100 counts.min−1 ) and IPAQ-reported sitting time significant positive ( negative for HDL cholesterol ) relationships were observed with all measured risk factors – i.e. increased sedentary behaviour was associated with increased risk ( all p≤0.01 ) . However , for HOMAIR and insulin the regression coefficients were > 50 % lower for the IPAQ-reported compared to the accelerometer-derived measure ( p<0.0001 for both interactions ) . The relationships for moderate-to-vigorous physical activity ( MVPA ) and risk factors were less strong than those observed for sedentary behaviours , but significant negative relationships were observed for both accelerometer and IPAQ MVPA measures with glucose , and insulin and HOMAIR values ( all p<0.05 ) . For accelerometer-derived MVPA only , additional negative relationships were seen with triglyceride , total cholesterol and LDL cholesterol concentrations , BMI , waist circumference and percentage body fat , and a positive relationship was evident with HDL cholesterol ( p = 0.0002 ) . Regression coefficients for HOMAIR , insulin and triglyceride were 43–50 % lower for the IPAQ-reported compared to the accelerometer-derived MVPA measure ( all p≤0.01 ) . Conclusion Using the IPAQ to determine sitting time and MVPA reveals some , but not all , relationships between these activity measures and metabolic and vascular disease risk factors . Using this self-report method to quantify activity can therefore underestimate the strength of some relationships with risk factors Background Physical activity ( PA ) and sedentary behavior ( SED ) may have independent effects on health and disease . This might be due to PA and SED having distinct effects on lipoprotein metabolism . The aim of this study was to determine associations between lipoprotein subclass particle concentrations ( -P ) and accelerometer-measured SED and moderate-to-vigorous PA ( MVPA )  in a sample of healthy adult subjects . Methods Lipoprotein subclass particle concentrations were determined by proton nuclear magnetic resonance spectroscopy , whereas SED and MVPA were measured using Agtigraph GT1 M and GT3X+ accelerometers . We obtained valid data in 73 subjects ( 30 men and 43 women , age 40.5 ± 10.6 years ; body mass index 24.0 ± 2.8 ) . Multiple regression analysis was used to determine associations ( partial correlations ) with lipoproteins . Results Positive associations were detected between SED and small VLDL-P , large LDL-P and TG ( partial r = 0.24 to 0.25 , p < .047 ) . Corresponding associations were non-significant  for MVPA ( partial r = -0.12 to 0.04 , p > .355 ) . On the contrary , MVPA was positively associated with large HDL-P , average HDL size , Apo A1 and HDL-cholesterol ( partial r = 0.28 to 0.50 , p < .027 ) , whereas SED was not ( partial r = -0.06 to 0.07 , p > .607 ) . Conclusion There might be a specific effect of SED versus MVPA on lipoprotein metabolism . However , our results must be interpreted carefully due to possible effect-modification by gender and a low sample size . Thus , our findings should be viewed as preliminary BACKGROUND Lifestyle changes soon after diagnosis might improve outcomes in patients with type 2 diabetes mellitus , but no large trials have compared interventions . We investigated the effects of diet and physical activity on blood pressure and glucose concentrations . METHODS We did a r and omised , controlled trial in southwest Engl and in adults aged 30 - 80 years in whom type 2 diabetes had been diagnosed 5 - 8 months previously . Participants were assigned usual care ( initial dietary consultation and follow-up every 6 months ; control group ) , an intensive diet intervention ( dietary consultation every 3 months with monthly nurse support ) , or the latter plus a pedometer-based activity programme , in a 2:5:5 ratio . The primary endpoint was improvement in glycated haemoglobin A(1c)(HbA(1c ) ) concentration and blood pressure at 6 months . Analysis was done by intention to treat . This study is registered , number IS RCT N92162869 . FINDINGS Of 593 eligible individuals , 99 were assigned usual care , 248 the diet regimen , and 246 diet plus activity . Outcome data were available for 587 ( 99 % ) and 579 ( 98 % ) participants at 6 and 12 months , respectively . At 6 months , glycaemic control had worsened in the control group ( mean baseline HbA(1c ) percentage 6·72 , SD 1·02 , and at 6 months 6·86 , 1·02 ) but improved in the diet group ( baseline-adjusted difference in percentage of HbA(1c ) -0·28 % , 95 % CI -0·46 to -0·10 ; p=0·005 ) and diet plus activity group ( -0·33 % , -0·51 to -0·14 ; p<0·001 ) . These differences persisted to 12 months , despite less use of diabetes drugs . Improvements were also seen in bodyweight and insulin resistance between the intervention and control groups . Blood pressure was similar in all groups . INTERPRETATION An intensive diet intervention soon after diagnosis can improve glycaemic control . The addition of an activity intervention conferred no additional benefit . FUNDING Diabetes UK and the UK Department of Health OBJECTIVE Low levels of physical activity appear to be associated with insulin resistance . However , the detailed associations of these complex relationships remain elusive . We examined the prospect i ve associations between self-reported TV viewing time , objective ly measured time spent sedentary , at light-intensity activity , and at moderate- and vigorous-intensity physical activity ( MVPA ) with insulin resistance . RESEARCH DESIGN AND METHODS In 192 individuals ( 81 men and 111 women ) with a family history of type 2 diabetes , we measured  physical activity and anthropometric and metabolic variables at baseline and after 1 year of follow-up in the ProActive UK trial . Physical activity  was measured objective ly by accelerometry . Insulin resistance was expressed as fasting insulin and the homeostasis model assessment score ( HOMA-IR ) . RESULTS Baseline MVPA was a significant predictor of fasting insulin at follow-up ( β = −0.004 [ 95 % CI −0.007 to −0.0001 ] , P = 0.022 ) , and the association approached significance for HOMA-IR ( β = −0.003 [ −0.007 to 0.000002 ] , P = 0.052 ) , independent of time spent sedentary , at light-intensity activity , sex , age , smoking status , waist circumference , and self-reported TV viewing . Time spent sedentary and at light-intensity activity were not significantly associated with insulin resistance . The change in MVPA between baseline and follow-up was inversely related to fasting insulin ( β = −0.003 [ −0.007 to −0.0003 ] , P = 0.032 ) and the HOMA-IR score ( β = −0.004 [ −0.008 to −0.001 ] , P = 0.015 ) at follow-up , after adjustment for baseline phenotype in addition to the same confounders as above . CONCLUSIONS These results highlight the importance of promoting moderate-intensity activity such as brisk walking for improving insulin sensitivity and possibly other metabolic risk factors to prevent type 2 diabetes AIMS The importance of reducing sedentary time is increasingly being recognized in the prevention of diabetes and cardiovascular disease . Despite this , the prospect i ve association between sedentary time and physical activity with insulin sensitivity and cardiometabolic risk factors has been little studied . METHODS In an analysis of data from the European RISC study , sedentary time and time spent in activity of moderate or vigorous intensity were assessed by accelerometry at baseline in 313 men and 414 women , aged 30 - 60 years , with insulin sensitivity as measured by euglycaemic-hyperinsulinaemic clamp . Three years later , cardiometabolic risk factors ( anthropometry , glucose , insulin , lipids ) were available for 549 participants . RESULTS In cross-sectional analyses using baseline data , after adjusting for age , gender , recruitment centre and time spent in activity of moderate or vigorous intensity , significant unfavourable associations were observed between higher sedentary time with body weight , HDL cholesterol , triglycerides , clamp-measured insulin sensitivity and insulin secretion ( all P(trend)<0.002 ) .  Sedentary time  remained significantly associated with insulin secretion after adjusting for insulin sensitivity ( P(trend)=0.02 ) . In longitudinal analyses , higher baseline sedentary time  was associated with 3-year increases in fasting glucose , fasting insulin and the HOMA insulin-resistance index score for the 50 % of the study population who increased their BMI by at least 0.3 kg/m(2 ) ( all P(trend)<0.01 ) ; these relationships remained significant after adjusting for time spent in activity of moderate or vigorous intensity . The 3-year increase in insulin secretion was lower in those spending more time doing activity of moderate or vigorous intensity ( P(trend)=0.03 ) . CONCLUSION These prospect i ve data suggest that less sedentary behaviour may partly counteract some of the negative effects of increasing body weight on glucose-insulin homoeostasis
target: There was consistent evidence from cross-sectional data of an unfavourable association between total sedentary time and insulin sensitivity .
  There was also some evidence that total sedentary time was unfavourably associated with fasting insulin , insulin resistance and triglycerides .
  Furthermore , there was some evidence from cross-sectional data of a favourable association between breaks in sedentary time and triglycerides .
  CONCLUSION Total sedentary time was consistently shown to be associated with poorer insulin sensitivity , even after adjusting for time spent in physical activity .
background: OBJECTIVE We conducted a systematic review to investigate the cross-sectional and prospect i ve associations of accelerometer-measured total sedentary time and breaks in sedentary time with individual cardiometabolic biomarkers in adults ≥18years of age .