Acute and Chronic Metabolic Flexibility in Individuals Living With Obesity: The i-FLEX Study

Study Overview
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Brief Summary
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Regular exercise is a cornerstone in the prevention and the management of cardio-metabolic risk factors. Some of the beneficial effect of exercise training occurs through metabolic flexibility' enhancement. Metabolic flexibility is the ability to respond or adapt to conditional changes in metabolic demand, and previous literature has shown that individuals living with obesity have an impaired metabolic flexibility compared to lean individuals. However, there is a lack of empirical evidence on the impact of sprint interval training on metabolic flexibility and whether this translates into clinically meaningful outcomes. This study will evaluate the impact of 4-week sprint interval training in normal weight individuals as well as individuals living with obesity on acute and chronic metabolic flexibility, irisin secretion and insulin sensitivity.

Official Title
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Sprint Interval Training: Insulin Sensitivity and Acute-Chronic Metabolic Flexibility in Individuals Living With Obesity: The i-FLEX Study

Conditions
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Obesity, Obesity; Endocrine, Insulin Sensitivity, Exercise

Intervention / Treatment
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* Behavioral: Sprint Interval Training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults (Ages 19-60) Physically inactive for individuals living with obesity (not meeting Canadian Physical Activity Guidelines) Normal Weight (BMI ≥ 18.5 < 25.0 km/m2) Obesity (BMI ≥ 30.0 km/m2) Exclusion Criteria: Individuals with Type 2 Diabetes. Individuals with impaired glucose tolerance. Individuals living with obesity that partake in regular exercise training / meet the Canadian Physical Activity Guidelines. Individuals with a condition or injury that may impact the ability to perform exercise or may be worsened by exercise. Individuals currently being treated with corticosteroids or atypical antipsychotics, as these agents significantly influence carbohydrate metabolism. have experienced >10% weight loss or enrolled in weight loss program within six months of enrolment. require use of medication(s) known to affect insulin sensitivity or secretion within the last 30 days. Medication(s) known to cause weight gain. weight loss medication(s).

Ages Eligible for Study
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Minimum Age: 19 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Individuals living with obesity (BMI ≥ 30 km/m2; n=15) as well as normal weight (BMI ≥ 18.5 < 25.0 km/m2; n=15) adults (aged between 19 to 60 years) will be recruited to participate in the study. All participants will be asked to come in for a total of two visits and participate in a 4-week intervention.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Normal Weight<br>BMI ≥ 18.5 < 25.0 km/m2 Sprint Interval Training | Behavioral: Sprint Interval Training<br>* The 4-week sprint interval intervention will consist of a work-rest ratio of four 30-s intervals of exercise at maximal capacity and 4-min of passive recovery at 50% of maximal capacity between intervals. There will be three sessions per week.<br>|
| Experimental: Individuals living with Obesity<br>BMI ≥ 30.0 km/m2 Sprint Interval Training | Behavioral: Sprint Interval Training<br>* The 4-week sprint interval intervention will consist of a work-rest ratio of four 30-s intervals of exercise at maximal capacity and 4-min of passive recovery at 50% of maximal capacity between intervals. There will be three sessions per week.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Metabolic Flexibility | Chronic and acute metabolic flexibility will be quantified from the respiratory quotient (RQ) at rest and from the respiratory exchange ratio (RER) during a 4-6 minutes steady rate exercise bout. | Baseline and post-intervention (4 weeks) | 
| Change in Insulin Sensitivity | Insulin sensitivity will be measure with the Matsuda Index | Baseline and post-intervention (4 weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Irisin | This hormone will be quantified in the plasma during one acute session of exercise. | Baseline and post-intervention (4 weeks) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Metabolic flexibility, Insulin sensitivity, Sprint interval training, Obesity, Exercise intensity