Pereira, Mark A.

OBJECTIVE To test the effect of physical activity on the gut microbiome and circulating short-chain fatty acids (SCFAs) among sedentary adults with prediabetes and overweight or obesity. RESEARCH DESIGN AND METHODS In a pilot and feasibility trial, we randomized 77 adults with prediabetes and a sedentary lifestyle into one of two groups: 1) intervention: invited to engage in home-based moderate-intensity walking 3×/week for 30 min/session in weeks 1–4 and for 45 min/session during weeks 5–8 of the 8-week intervention; or 2) control: maintained habitual physical activity levels. We performed metagenomic sequencing from stool collected at baseline, week 4, and week 8, with SCFAs measured from serum collected at baseline and week 8. Taxonomic and functional profiling was performed on the metagenomic reads; α-diversity metrics were subsequently derived. Linear regression assessed the difference in change between the intervention and control groups for α-diversity and SCFA levels. RESULTS We screened 1,533 participants for eligibility and consented 132. Of these, 87 entered the run-in phase, and 77 were randomized. Participants were mean (SD) 51.4 (8.9) years old, 87.7% female, and 74% non-Hispanic White. Mean fasting glucose was 103.3 (13.2) mg/dL, while mean BMI was 34.4 (5.7) kg/m2. Compared with the control group, the intervention group experienced decreased α-diversity as characterized by Shannon, Richness, and Faith diversity indices by intervention week 8 (P < 0.05). Changes in SCFA levels were not statistically significant different in intervention versus control. CONCLUSIONS Randomization to a walking intervention resulted in modest gut microbiome changes among adults with overweight or obesity and prediabetes.

Abstract Background Non‐alcoholic fatty liver disease (NAFLD) is recognized as a prevalent determinant of cardiometabolic diseases. The association between NAFLD and obesity warrants further research on how NAFLD modifies associations between body mass index (BMI) and Waist circumference (WC) with cardiometabolic risk (CMR). Objective This study assessed whether NAFLD modifies associations between BMI and WC with 5‐year changes in CMR in 2366 CARDIA study participants. Methods Non‐contrast CT was used to quantify liver attenuation, with ≤51 Hounsfield Units (HU) used to define NAFLD in the absence of secondary causes of excess liver fat. The dependent variable was the average Z score of fasting glucose, insulin, triglycerides [log], (−) high‐density lipoprotein cholesterol (HDL‐C), and systolic blood pressure(SBP). Multivariable linear regression was used to estimate the associations between BMI and WC with CMR. Effect modification by NAFLD was assessed by an interaction term between NAFLD and BMI or WC. Results The final sample had 539 (23%) NAFLD cases. NAFLD modified the association of BMI and WC with CMR (interaction p < 0.0001 for both). BMI and WC were associated with CMR in participants without NAFLD ( p < 0.001), but not among those with NAFLD. Participants with NAFLD and normal BMI and WC had CMR estimates that were higher than those without NAFLD in the obese categories. Among those without NAFLD the 5 years CMR change estimate was 0.09 (95% CI: 0.062, 0.125) for BMI ≥30 kg/m 2 compared to −0.06 (−0.092, −0.018) for BMI < 25 kg/m 2 , and among those with NAFLD, these estimates were 0.15 (0.108, 0.193) and 0.16 (−0.035, 0.363). Conclusions NAFLD modifies associations of BMI and WC with CMR. Compared with BMI and WC, NAFLD was more strongly associated with CMR. In the presence of NAFLD, BMI and WC were not associated with CMR. These findings have implications for clinical screening guidelines.

Background: The prevalence of non-alcoholic fatty liver disease (NAFLD) in U.S. adults is over 30%, yet the role of lifestyle factors in the etiology of NAFLD remains understudied. We examined the associations of physical activity, by intensity and type, and television viewing with prevalent NAFLD. Methods: Cross-sectional analysis of a population-based sample of 2726 Black (49%) and White (51%) adults (Mean (SD) age, 50 (3.6) years; 57.3% female) from the CARDIA study. Exposures were aerobic activity by intensity (moderate, vigorous; hours/week); activity type (aerobic, muscle-strengthening; hours/week); and television viewing (hours/week), examined concurrently in all models and assessed by validated questionnaires. Our outcome was NAFLD (liver attenuation < 51 Hounsfield Units), measured by non-contrast computed tomography, after exclusions for other causes of liver fat. Covariates were sex, age, race, study center, education, diet quality, smoking status, alcohol consumption, and body mass index or waist circumference. Results: 648 participants had NAFLD. In the fully adjusted modified Poisson regression model, the risk ratios per interquartile range of each exposure were moderate-intensity aerobic activity, 1.10 (95% CI, 0.97–1.26); vigorous-intensity aerobic activity, 0.72 (0.63–0.82); muscle-strengthening activity, 0.89 (0.80–1.01); and television viewing, 1.20 (1.10–1.32). Relative to less active participants with higher levels of television viewing, those who participated in ≥2 h/week of both vigorous-intensity aerobic and muscle-strengthening activity and <7 h/week of television viewing had 65% lower risk of NAFLD (risk ratio = 0.35, 95% CI = 0.23–0.51). Conclusion: Adults who follow public health recommendations for vigorous-aerobic and muscle-strengthening activity, as well as minimize television viewing, are considerably less likely to have NAFLD than those who do not follow the recommendations and who have relatively high levels of television viewing.

ABSTRACT Objective This study aimed to examine the effect on continuously monitored blood glucose (BG) among participants with impaired fasting glucose (IFG) who used a height-adjustable desk while working. Methods The study was a repeated-measures pilot study in overweight or obese women who had IFG (BG >100 mg·dL −1 ) and a sedentary job. BG was monitored with continuous glucose monitoring devices during two 1-wk periods at work: 1 wk in the seated position and 1 wk using alternate bouts of sitting and standing (by adjusting their desks) throughout the workday. Results Ten women completed the study. Sedentary time significantly predicted BG independently of diet and overall physical activity ( P = 0.02). Dietary carbohydrates, protein, and fat were significant predictors of BG ( P < 0.001). Conclusions Sedentary time is a strong predictor of increased BG in women with IFG and a sedentary job.

Background Sedentary time has been shown to have deleterious effects on health. Today's workforce spends most of the day sitting. The objective of this study was to evaluate the effect of workplace interventions to decrease sedentary time on cardiometabolic risk factors. Methods Sedentary office workers (n=127; ages 22‐64; BMI=28.5±6.1 kg/m 2 ) were recruited from three Minnesota employers and randomized to one of four intervention groups for 6 months: 1) Control, 2) Move (蠅30 min of light activity during the workday), 3) Stand (standing 蠅50% of the workday using a sit‐stand workstation), or 4) Stand+Move (combined Stand and Move). A 'metabolic risk score' (MRS) was calculated at baseline and 6 months using the following cardiometabolic risk factors: blood pressure, fasting blood glucose, log of fasting triglycerides, and HDL‐cholesterol. A z‐score was computed for each risk factor for each subject [(subject value – sample mean)/sample SD]. The MRS was derived by summing the z‐scores (HDL‐z subtracted). Results There was a significant intervention effect on MRS (p<.01). A seasonal time trend was observed, with MRS increasing significantly in Control and Move groups (p<.001), but not for the Stand and Stand+Move. Results (mean±se) are shown in Figure 1. Conclusions Sit‐stand workstations combined with an intervention to increase light physical activity at work may be an effective tool to improve cardiometabolic risk. image

Objective: This study was conducted to determine whether installation of sit-stand desks (SSDs) could lead to decreased sitting time during the workday among sedentary office workers. Methods: A randomized cross-over trial was conducted from January to April, 2012 at a business in Minneapolis. 28 (nine men, 26 full-time) sedentary office workers took part in a 4 week intervention period which included the use of SSDs to gradually replace 50% of sitting time with standing during the workday. Physical activity was the primary outcome. Mood, energy level, fatigue, appetite, dietary intake, and productivity were explored as secondary outcomes. Results: The intervention reduced sitting time at work by 21% (95% CI 18%–25%) and sedentary time by 4.8 min/work-hr (95% CI 4.1–5.4 min/work-hr). For a 40 h work-week, this translates into replacement of 8 h of sitting time with standing and sedentary time being reduced by 3.2 h. Activity level during non-work hours did not change. The intervention also increased overall sense of well-being, energy, decreased fatigue, had no impact on productivity, and reduced appetite and dietary intake. The workstations were popular with the participants. Conclusion: The SSD intervention was successful in increasing work-time activity level, without changing activity level during non-work hours.