In this study the investigators will test the hypothesis that acute consumption of inorganic nitrate (supplied in concentrated beetroot juice) reduces artery stiffness and resting blood pressure, and lessens the rise in blood pressure during handgrip exercise in postmenopausal women. Understanding and improving artery function and blood pressure regulation in women is important because they undergo accelerated arterial stiffening after menopause and have much larger increases in blood pressure when they exercise compared with either premenopausal women or men of similar age.
Postmenopausal women have stiff central arteries and exaggerated blood pressure (BP) responses during exercise compared with either premenopausal women or men of similar age. Arterial stiffness and exaggerated BP responses to exercise are prognostic for heart wall thickening, future hypertension, adverse cardiovascular events, and mortality. Previous studies have reported that acute consumption of nitrate-rich beetroot juice can lower resting and exercising BP responses in older adults. However, these studies included both sexes and did not compare the effects of beetroot juice to a nitrate-depleted placebo (a true control). Thus, the potential BP lowering effects of nitrate supplementation per se have not been established in postmenopausal women. The present study examines the acute (single dose) effects of nitrate-rich beetroot juice on resting hemodynamics (peripheral and central BP, arterial wave properties, etc), and physiological responses to handgrip exercise in metabolically healthy post-menopausal women.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
16
This beverage contains 0.3 g of inorganic nitrate per 70 ml container, and is bottled and supplied by James White Drinks (UK).
This beverage is identical in look and taste to the Beet-It organic shot, but has the nitrate removed. It is also bottled and supplied by James White Drinks (UK).
Penn State University
University Park, Pennsylvania, United States
Resting Aortic Blood Pressures
Aortic Blood pressures were measured in the arm (cuff) and estimated in the aorta (radial artery tonometry).
Time frame: Resting systolic blood pressure at 90 minutes after beetroot juice ingestion
Blood Measures of Nitrate Absorption and Conversion
Venous blood will be withdrawn (venipuncture) for determination of plasma nitrate and nitrite.
Time frame: Change from baseline measures of plasma nitrate and nitrite at 90 minutes and at approximately 6 hours
Resting Arterial Stiffness/Wave Properties
Carotid to femoral artery pulse wave velocity will be assessed using arterial tonometry.
Time frame: Change from baseline resting pulse wave velocity at 90 minutes after beet root juice ingestion
Handgrip Exercise Blood Pressure Responses (Relative Change From Baseline)
Beat-to-beat blood pressure (finger cuff) will be assessed at rest and during handgrip exercise to volitional fatigue.
Time frame: Approximately 180 minutes after ingestion of beetroot juice
Peak Rate of Perceived Exertion Scores During Handgrip Exercise
The Borg Rating of Perceived Exertion Scale (RPE) was used to assess exercise intensity during handgrip exercise. The RPE scale ranges from a minimum of 6 (no exertion at all) to a maximum of 20 (maximal exertion) units on a scale.
Time frame: Approximately 90 minutes after ingestion of beetroot juice
Handgrip Exercise Tolerance
Time to fatigue (seconds) was assessed during a progressive blood flow restricted handgrip exercise protocol.
Time frame: Approximately 90 minutes after ingestion of beetroot juice
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