Addressing Individual Variability in Response 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 exercise amount or intensity, 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 amount or intensity 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. 4) To what extent is biological sex and/or phenotype a determinant of response or non-response to exercise?

Detailed Description
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The trial has three objectives: Primary objective: Determine whether alterations in exercise amount and intensity improves the rate of clinically meaningful improvements in aerobic exercise capacity as measured by cardiorespiratory fitness (CRF, VO2peak) among adults. Secondary objective: Determine whether common cardiometabolic risk factors segregate with respect to variation in CRF to first line therapy in adults, and, whether clinically meaningful improvements in cardiometabolic risk factors segregate with associated improvement in CRF. Tertiary objective: Identify whether biological sex and/or phenotype are determinants of variation in CRF and cardiometabolic risk factors in response to first line therapy, and, whether they predict variability in CRF response to alterations in exercise dose.

Official Title
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Addressing Individual Variability in Response to Exercise

Conditions
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Exercise, Cardiorespiratory Fitness

Intervention / Treatment
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* Other: 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: 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Low amount, low intensity<br> | Other: Exercise<br>* Participants will exercise under supervision. Exercise dose will vary by amount and intensity<br>|
| Experimental: Low amount, high intensity<br> | Other: Exercise<br>* Participants will exercise under supervision. Exercise dose will vary by amount and intensity<br>|
| Experimental: High Amount, low intensity<br> | Other: Exercise<br>* Participants will exercise under supervision. Exercise dose will vary by amount and intensity<br>|
| Experimental: High Amount, high intensity<br> | Other: Exercise<br>* Participants will exercise under supervision. Exercise dose will vary by amount and intensity<br>|
| No Intervention: Control<br> | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in 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 cardiometabolic risk factors | Fasting glucose (mmol/L) | Measured at baseline, 16 and 32 weeks. | 
| Change in cardiometabolic risk factors | Fasting LDL- and HDL-cholesterol (mmol/L) | Measured at baseline, 16 and 32 weeks. | 
| Change in cardiometabolic risk factors | fasting insulin (pmol/L) | Measured at baseline, 16 and 32 weeks. | 
| Change in cardiometabolic risk factor | fasting triglycerides (mmol/L) | Measured at baseline, 16 and 32 weeks. |