Response Variability to Exercise

Study Overview
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Brief Summary
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In this proposal, the investigators challenge the assumption that following the physical activity guidelines implies benefit for ALL adults, and that if benefit is not achieved in response to first line therapy, it will be by simply exercising more. Thus, for improving cardiorespiratory fitness and cardiometabolic risk factors, unanswered questions include: 1) To what extent, regardless of increasing exercise intensity or amount, is exercise not associated with benefit? Demonstration of a resistance to benefit through exercise in a substantial number of adults would be a novel and important finding, would counter the assumptions of many if not most health care practitioners, and could have immediate and direct application in all health care settings. 2) To what extent will non-responders to first line therapy (150 min/wk) be required to increase exercise intensity or amount to achieve benefit? 3) To what extent will failure to improve CRF segregate (be associate with) with cardiometabolic risk factors? The investigators propose that adults who remain exercise resistant for improvement in CRF and cardiometabolic risk despite increasing amount or intensity are at high risk of metabolic disease and consequently, are candidates for alternative treatment strategies.

Detailed Description
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The trial has two objectives: Primary objective: After 16 weeks of first line therapy (150 min/wk of MPA), does increasing exercise intensity or amount for 16 weeks improve cardiorespiratory fitness (CRF, VO2peak) deferentially depending on the CRF response at 16 weeks. Secondary objective: Determine whether common cardiometabolic risk factors segregate/cluster with respect to variation in CRF to first line therapy in adults, and, whether clinically meaningful improvements in cardiometabolic risk factors segregate with improvement in CRF.

Official Title
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Response Variability to Exercise in Adults

Conditions
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Exercise, Cardiorespiratory Fitness

Intervention / Treatment
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* Behavioral: Low amount, low intensity exercise
* Behavioral: Low amount, high intensity exercise
* Behavioral: High amount, high intensity exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Sedentary lifestyle (planned physical activity for one day per week or less). Weight stable (± 2 kg) for 6 months prior to the beginning of the study. BMI between 20 and 40 kg/m2. Exclusion Criteria: Physical impairment which would make the intervention very difficult or unsafe according to doctor's advice. Diabetes, current smokers. Plan to move from the area in next 8 months.

Ages Eligible for Study
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Minimum Age: 25 Years
Maximum Age: 65 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: randomized trial
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Low amount, low intensity exercise<br>exercise dose (amount and intensity) will be controlled. | Behavioral: Low amount, low intensity exercise<br>* Participants will exercise under supervision. Exercise dose will vary by amount and intensity<br>|
| Experimental: Low amount, high intensity exercise<br>exercise dose (amount and intensity) will be controlled. | Behavioral: Low amount, high intensity exercise<br>* Participants will exercise under supervision. Exercise dose will vary by amount and intensity<br>|
| No Intervention: Control<br>no exercise intervention | |
| Experimental: High amount, high intensity exercise<br>exercise dose (amount and intensity) will be controlled. | Behavioral: High amount, high intensity exercise<br>* Participants will exercise under supervision. Exercise dose will vary by amount and intensity<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cardiorespiratory Fitness | Cardiorespiratory fitness will be determined using direct (open circuit spirometry) measures of oxygen consumption (expressed in L/min) obtained during a maximal treadmill test. | Measured at baseline and every 4 weeks for 32 weeks. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in glucose | Fasting glucose (mmol/L) | Measured at baseline, 16 and 32 weeks. | 
| Change in blood lipids | Fasting LDL- and HDL-cholesterol (mmol/L) | Measured at baseline, 16 and 32 weeks.] | 
| Change in insulin | fasting insulin (pmol/L) | Measured at baseline, 16 and 32 weeks.] | 
| Change in triglycerides | fasting triglycerides (mmol/L) | Measured at baseline, 16 and 32 weeks. | 
| Change in body fat | Total adiposity | Measured at baseline, 16 and 32 weeks | 
| Change in abdominal fat | Visceral adiposity | Measured at baseline, 16 and 32 weeks. | 
| Change in lean body mass | Lean mass | Measured at baseline 16 and 32 weeks. | 
| Change in subcutaneous fat | Subcutaneous adiposity | Measured at baseline, 16 and 32 weeks. | 
| Change in obesity phenotype | waist circumference | Measured at baseline 16 and 32 weeks. | 
| Change on body weight | Body weight | Measured at baseline, 16 and 32 weeks. |