Effects of Microbouts of Activity on Metabolic Health

To compare the effects of 4-weeks of microbursts of moderate-intensity activity to a
calorically equivalent single bout of 45 minutes of moderate-intensity exercise training,
both performed 5 days per week for a total of 45 minutes, in free-living sedentary overweight
adults on:

Aim 1: plasma inflammatory and cardiometabolic health biomarkers in association with total
energy expenditure and time spent in sedentary behaviors.

H1: Microbursts of activity will result in higher daily energy expenditure and lower time
spent sedentary, as respectively measured with doubly labeled water and accelerometry, than
traditional exercise training. This will be associated with healthier inflammatory
Interleukin 1 alpha (IL1a), Interleukin 6 (IL6), Interleukin 10 (IL10), Tumour Necrosis
Factor alpha (TNFa) and cardiometabolic (triglycerides, cholesterol, C-Reactive Protein
(CRP), High-density lipoprotein (HDL), and Low-density lipoprotein (LDL) profiles compared to
those obtained with traditional exercise training program.

Aim 2: 24-hr total fat and carbohydrate oxidation, exogenous carbohydrate oxidation, dietary
fat trafficking between oxidation and incorporation into muscle lipid fractions, and
mitochondrial function.

H2: Both one single continuous bout and microbouts of activity will increase 24-hr total
(whole-room calorimetry) and dietary (D9-palmitate) fat oxidation due to greater
mitochondrial lipid oxidation (high resolution respirometry) and lower incorporation of
dietary fatty acid into muscle lipid fractions (D9-palmitate), as compared to baseline
sedentary control condition. Microbouts of activity will further result in greater increases
in 24-hr total (whole-room calorimetry) and exogenous (U-13C6 glucose) carbohydrate oxidation
and in mitochondrial carbohydrate-linked oxidation, than traditional isocaloric exercise
training.

Aim 3: Whole-body insulin sensitivity. H3: Both one single continuous bout and microbouts of
activity will improve whole-body insulin sensitivity Intravenous Glucose Tolerance Test
(IVGTT) compared to the baseline sedentary condition, but the improvement will likely be
higher with the microbouts of activity.

Exploratory aim: Self-perceived appetite, hunger, and levels of mood, fatigue and
vigor/energy.

H3: Microbursts of activity will result in less appetite, hunger and fatigue but in greater
feelings of vigor and overall well-being than traditional isocaloric exercise training. As a
result adherence to microbursts will be better than adherence to single bouts of physical
activity.

Inclusion Criteria:

- Overweight but weight stable (+/- 3kg over previous 6 months) sedentary male and
female adults (n=30) will be recruited.

- Ages between 18-45 years old

- BMI of 25-35 kg/m2

- Sedentary (< 1hr/wk of moderate-to-vigorous activity, less than 6,500 steps per day as
measured for 5 days in free-living conditions with a pedometer). Based on subjects
self-report during the H&P visit

- The use of birth pill control will be accepted

Exclusion criteria:

- Any history of renal (present or past kidney failure, kidney transplant, dialysis or
kidney cysts),

- Uncontrolled hypertension

- Cardiovascular (present or past atherosclerosis, heart attack, ischemic stroke, heart
failure)

- Hepatic diseases (past or present hepatitis B or C, fibrosis, cirrhosis, NAFLD/NASH)

- Type 1 or 2 diabetes

- Cancer

- Smoking

- Consumption of drugs (marijuana included)

- Consumption of alcohol (>40g/d)

- HIV positivity

- Psychiatric disorders

- Any medications known to interfere with lipid or energy metabolism

- Known physical activity contraindications

- Major illness/physical problems (acute or chronic) that may limit their ability to
perform the walking activities

- The blood draw will be used to objectively exclude peri- or postmenopausal women
(FSH>25 mlU/mL in early follicular phase)

- Hypertriglyceridemia (triglycerides > 400mg/dL).