The Effects of Dietary Salt on Post-exercise Hypotension

University of Delaware

Status: Completed

Conditions: Post-Exercise Hypotension; Blood Pressure

Treatments: Other: High dietary salt; Other: Placebo

Study type: Interventional

Funder types: Other

Identifiers

NCT03565653

1085139

Details and patient eligibility

About

The new American Heart Association (AHA) blood pressure guidelines are expected to raise the prevalence of high blood pressure to ~46% in the United States. One recommendation for lowering blood pressure is aerobic exercise, which produces a period of lowered blood pressure (post-exercise hypotension; PEH) that lasts up to 24 hours. It is believed that PEH may be responsible for the observations of lowered blood pressure following initiation of exercise. However, most Americans eat too much salt, which expands plasma volume and may prevent PEH, rending aerobic exercise ineffective in improving blood pressure status.

Full description

Recently released blood pressure guidelines from the American Heart Association and American College of Cardiology are expected to raise the prevalence of hypertension in America from ~33% to ~46%. A single bout of aerobic exercise produces a prolonged period (up to 24 hours) of lowered blood pressure (post-exercise hypotension; PEH). Repeated bouts of aerobic exercise results in maintenance of lowered blood pressure, leading to recommendations of aerobic exercise for improvement of blood pressure status. However, more than 90% of Americans consume more sodium in their diets than is recommended. This is alarming, as excess dietary sodium intake expands plasma fluid volume, which may in turn attenuate the reduction in BP following exercise. Therefore, the objective of this project is to determine the effects of high dietary sodium intake on PEH. The investigators hypothesize that, compared to a recommended sodium diet, a high salt diet will attenuate post-exercise hypotension.

Enrollment: 20 patients

Sex: All

Ages: 18 to 40 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Recreationally active

Exclusion criteria

• high blood pressure (>140/90 mmHg)
• history of cardiovascular disease
• history of cancer
• history of diabetes
• history of kidney disease
• obesity (BMI > 30 kg/m2)
• smoking or tobacco use
• current pregnancy
• nursing mothers
• communication barriers

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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20 participants in 2 patient groups

High dietary salt

Experimental group

Description:

For 10 days each, participants will be asked to eat a recommended sodium diets (2300 mg Na+/d) while taking unmarked pills containing uniodized table salt. On the 10th day, participants will report to the lab to complete 60 minutes of cycling exercise. Following exercise, participants will rest for 60 minutes while undergoing serial blood pressure measurements. Participants will then be outfitted with ambulatory blood pressure cuffs for assessment of blood pressure over the following 24 hours.

Treatment:

Other: High dietary salt

Placebo

Experimental group

Description:

For 10 days each, participants will be asked to eat a recommended sodium diets (2300 mg Na+/d) while taking unmarked pills containing a placebo (dextrose). Participants will complete both interventions in random order. On the 10th day, participants will report to the lab to complete 60 minutes of cycling exercise. Following exercise, participants will rest for 60 minutes while undergoing serial blood pressure measurements. Participants will then be outfitted with ambulatory blood pressure cuffs for assessment of blood pressure over the following 24 hours.

Treatment:

Other: Placebo