Factors That Influence Blood Vessel Regulation During Exercise in Humans

Study Overview
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Brief Summary
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This study will examine two separate interventions: 1) the effects of ischemic preconditioning or 2) a high fat meal on the capacity of the brachial artery to overcome sympathetic activation and dilate during exercise (also known as functional sympatholysis). Participants will be asked to complete rhythmic handgrip exercise with and without the application of -20 mmHg lower body negative pressure to increase sympathetic activation. Doppler ultrasound will be used to continuously measure brachial artery blood flow. Participants will complete the handgrip exercise and lower body negative pressure before and after the applications of each interventions. Participants may elect to only complete one intervention rather than complete both protocols. Intervention one is active or control ischemic preconditioning. Intervention two is high or low fat meals.

Official Title
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Factors That Influence Blood Vessel Regulation During Exercise in Humans

Conditions
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Ischemic Preconditioning, Dietary Exposure

Intervention / Treatment
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* Procedure: Ischemic preconditioning
* Procedure: Ischemic preconditioning control
* Dietary Supplement: Low fat meal
* Dietary Supplement: High fat meal


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18 years or older Healthy Exclusion Criteria: History of smoking (tobacco or cannabis), defined as any smoking within the past 3 months Diagnosed cardiovascular or metabolic disease(s) Recent musculoskeletal injury handgrip exercise Prescription of chronic medications other than oral contraceptives History of hypertension or presence of arrhythmia

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 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: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: Ischemic preconditioning control<br> | Procedure: Ischemic preconditioning control<br>* Four 5-minute cycles of 20 mmHg cuff inflation of the brachial artery, each separated by 5-minutes deflated recovery (i.e. 40 minutes total time)<br>|
| Active Comparator: Ischemic preconditioning<br> | Procedure: Ischemic preconditioning<br>* Four 5-minute cycles of 200 mmHg cuff inflation of the brachial artery, each separated by 5-minutes deflated recovery (i.e. 40 minutes total time)<br>|
| Active Comparator: High fat meal<br> | Dietary Supplement: Low fat meal<br>* Meal containing 1006 calories, 1 g fat, 0.2 g saturated fat, 0 g trans fat, 20 mg cholesterol, 191 g carbohydrates, 60 g protein, 1560 mg sodium<br>|
| Placebo Comparator: Low fat meal<br> | Dietary Supplement: High fat meal<br>* Meal containing 1030 calories, 62 g fat, 23 g saturated fat, 0.5 g trans fat, 445 mg cholesterol, 76 g carbohydrates, 41 g protein, 2080 mg sodium.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Forearm blood flow | Doppler ultrasound - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | Baseline - Immediately before active and control interventions | 
| Forearm blood flow | Doppler ultrasound - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | Immediately after active and control interventions (IPC only) | 
| Forearm blood flow | Doppler ultrasound - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 1 hour after active and control interventions (Diet intervention only) | 
| Forearm blood flow | Doppler ultrasound - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 2 hours after active and control interventions (Diet intervention only) | 
| Forearm blood flow | Doppler ultrasound - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 3 hours after active and control interventions (Diet intervention only) | 
| Forearm vascular conductance | Blood flow divided by blood pressure - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | Baseline - Immediately before active and control interventions | 
| Forearm vascular conductance | Blood flow divided by blood pressure - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | Immediately after active and control interventions (IPC only) | 
| Forearm vascular conductance | Blood flow divided by blood pressure - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 1 hour after active and control interventions (Diet intervention only) | 
| Forearm vascular conductance | Blood flow divided by blood pressure - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 2 hours after active and control interventions (Diet intervention only) | 
| Forearm vascular conductance | Blood flow divided by blood pressure - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 3 hours after active and control interventions (Diet intervention only) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood pressure | Finger plethysmography - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | Baseline - Immediately before active and control interventions | 
| Blood pressure | Finger plethysmography - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | Immediately after active and control interventions (IPC only) | 
| Blood pressure | Finger plethysmography - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 1 hour after active and control interventions (Diet intervention only) | 
| Blood pressure | Finger plethysmography - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 2 hours after active and control interventions (Diet intervention only) | 
| Blood pressure | Finger plethysmography - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 3 hours after active and control interventions (Diet intervention only) | 
| Heart rate | ECG - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | Baseline - Immediately before active and control interventions | 
| Heart rate | ECG - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | Immediately after active and control interventions (IPC only) | 
| Heart rate | ECG - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 1 hour after active and control interventions (Diet intervention only) | 
| Heart rate | ECG - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 2 hours after active and control interventions (Diet intervention only) | 
| Heart rate | ECG - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 3 hours after active and control interventions (Diet intervention only) |