Oral Nitrite Synthesis and Post-exercise Hypotension

Study Overview
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Brief Summary
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Exercise is probably the most effective approach to reduce blood pressure. In fact, a single bout of exercise induces a physiological response known as Post-Exercise Hypotension (PEH) where a prolonged decrease in resting blood pressure occurs in the minutes and hours after exercise. However, it is not fully understood how this response triggers. Recent evidence suggests that oral bacteria may play a key role in blood pressure control by enhancing nitrite, and then nitric oxide (NO) bioavailability under resting conditions in humans. However, no previous study has investigated whether this is a key mechanism involve in PEH. Thus, the main aim of this study was to investigate if the oral nitrate/nitrite pathway is a key regulator of PEH and vasodilation in healthy humans.

Official Title
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The Impact of Nitrate-reducing Capacity of Oral Bacteria on Post-exercise Hypotension in Healthy Individuals.

Conditions
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Blood Pressure, Sports Physical Therapy

Intervention / Treatment
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* Other: Exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Blood pressure (SBP < 130 mmHg; DBP < 90 mmHg) BMI < 30 kg/m2 Age 18 to 50 years old Exclusion Criteria: Smoker Hypertension Dyslipidaemia Diabetes Gingivitis or periodontitis Using antibacterial mouthwash or tongue scrapes Taking antibiotics 1 month before the start of the study Females without have irregular menstrual periods

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: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Placebo Mouthwash<br> | Other: Exercise<br>* Four sets of 7 minutes at 65% of VO2peak interspersed with 3 min of passive recovery<br>|
| Active Comparator: Antibacterial Mouthwash<br> | Other: Exercise<br>* Four sets of 7 minutes at 65% of VO2peak interspersed with 3 min of passive recovery<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in blood pressure after exercise | Blood pressure was measured before and at 1 hour and 2hours after exercise using an electronic sphygmomanometer (ProBP 3400, Welch Allyn). The second and third readings will be averaged to determine mean blood pressure. | Baseline and 1 hour and 2 hours after exercise | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in reactive hyperaemia | Tissue oxygenation index (TOI) were recorded on the left forearm (extensor digitorum) using a NIRS system (NIRO-200NX, Hamamatsu) before exercise and 2 hours after exercise. After baseline measurements (2 minutes), an automatic pneumatic cuff (Hokanson E-20 AG101) was inflated  5cm above the elbow for 5 minutes to an occlusion pressure of 200 mmHg. Then, inflation of the cuff was rapidly released (< 1 second) and the NIRS measurements were continuously monitored for 5 minutes. | Baseline and 1 hour and 2 hours after exercise |