The present study is a 100-participant randomized controlled 2-arm parallel trial that employs a metagenomic approach to examine how 8 weeks of supervised moderate-intensity treadmill walking exercise (MWE) for 30-45 min 3 times/week alters the gut microbiome, serum short chain fatty acids, and the cardiometabolic profile, body weight, and body composition of individuals 30-64 years old who have overweight or obesity and have prediabetes.
All eligible and consented participants will complete a 3-week run-in phase during which baseline outcome assessments will be performed. During run-in weeks 1 and 2, participants will wear a Fitbit Inspire 2 smartwatch and complete three unannounced dietary recalls. During the run-in week 3 (see table below), participants will consume their 3-day standardized meal plan on days three through five, obtain a fecal sample, complete a study questionnaire, and complete a study assessment visit. To quantify compliance with the 3-day meal plan, participants will be provided with a paper checklist of all foods to be consumed, and will be asked to indicate which foods were consumed and to document any deviation. The study assessment visit will include a fasting blood draw (at baseline and week eight only), blood pressure in triplicate, weight measure and body fat assessment in duplicate, and a saliva sample.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
77
Three walking sessions/week for a total of 8 weeks (24 total sessions) - Walking sessions will either take place on new commercial treadmills in the Epidemiology Clinical Research Center or remotely at or around a participant's home. Regardless of the walking location, walking sessions will be 30 min in duration during intervention weeks 1 through 4 and a minimum of 45 min each during intervention weeks 5 through 8.
University of Minnesota
Minneapolis, Minnesota, United States
Change in Shannon Index (Unitless)
Changes to the gut microbiome will be assessed via metagenomic sequencing, from pre- to post-intervention. The Shannon Index-a measure of microbial community diversity-will be the primary indicator for changes in gut microbiota composition, and will be assessed at baseline, and following the 4th and 8th weeks. Index values are unitless and range from 0 to 1. Lower values indicate more diversity while higher values indicate less diversity. Outcome will be reported at baseline, 4 weeks, and 8 weeks and as the change from baseline to 4 weeks and baseline to 8 weeks.
Time frame: 8 weeks
Change in Serum Short Chain Fatty Acids (SCFA)
Participants will undergo fasted blood draws to assess serum SCFA levels. This work will be performed using the Metabolon pipeline. Outcome is reported as the sum of the serum concentrations of acetate, propionate, and butyrate in Z-score units. We report the Week 8 means and standard errors from a linear model adjusted for the Week 0 (baseline) values. The original units are reported in ng/mL and the final results are reported as standardized z-scores in which each value subtracts the mean and the difference is divided by the standard deviation. Higher values represent higher levels of SCFA which is considered better. The scale is in standard deviation units. A value of 0 = the population mean.
Time frame: 8 weeks
High-density Lipoprotein Cholesterol (HDL-C)
High-density lipoprotein cholesterol (HDL-C) will be measured using standard laboratory test and report in units of mg/dl. We report the Week 8 means and standard errors from a linear model adjusted for the Week 0 (baseline) values.
Time frame: 8 weeks
Triglycerides
Blood triglycerides will be measured using a standard laboratory test and reported in units of mg/dl. We report the Week 8 means and standard errors from a linear model adjusted for the Week 0 (baseline) values.
Time frame: 8 weeks
Fasting Insulin
Fasting insulin will be measured by laboratory test and reported in units of pm/ml. We report the Week 8 means and standard errors from a linear model adjusted for the Week 0 (baseline) values.
Time frame: 8 weeks
Fasting Glucose
Fasting glucose will be measured by standard laboratory test and reported in units of mg/dl. We report the Week 8 means and standard errors from a linear model adjusted for the Week 0 (baseline) values.
Time frame: 8 weeks
C-reactive Protein (CRP)
C-reactive protein (CRP) will be measured by laboratory test and reported in units of mg/l. We report the Week 8 means and standard errors from a linear model adjusted for the Week 0 (baseline) values.
Time frame: 8 weeks
Resting Systolic Blood Pressure (BP)
Resting systolic blood pressure will be reported in units of mmHg. We report the Week 8 means and standard errors from a linear model adjusted for the Week 0 (baseline) values.
Time frame: 8 weeks
Body Composition
Body composition will be analyzed using bioelectrical impedance. Outcome will be reported as percent body fat. We report the Week 8 means and standard errors from a linear model adjusted for the Week 0 (baseline) values.
Time frame: 8 weeks
Cardiometabolic Risk Score (CMR)
The Cardiometabolic Risk Score (CMR) is the mean Z-score across systolic blood pressure, glucose, insulin, HDL, % body fat, and triglycerides. We report the Week 8 means and standard errors from a linear model adjusted for the Week 0 (baseline) values. The final results are reported as standardized z-scores in which each value subtracts the mean and the difference is divided by the standard deviation. Higher values represent higher levels of cardiometabolic risk which is considered worse. The scale is in standard deviation units. A value of 0 = the population mean.
Time frame: 8 weeks
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