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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
20
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)
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)
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
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.
University of Guelph - Human Cardiovascular Physiology Laboratory
Guelph, Ontario, Canada
Forearm blood flow
Doppler ultrasound - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 3 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: Immediately after active and control interventions (IPC only)
Heart rate
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ECG - tested at rest and during rhythmic handgrip exercise with and without lower body negative pressure
Time frame: 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
Time frame: 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
Time frame: 3 hours after active and control interventions (Diet intervention only)