The Effects of Dietary Salt on Post-exercise Hypotension

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.

Study Overview

• Status: Completed
• Conditions: Blood Pressure; Post-Exercise Hypotension
• Intervention / Treatment: Other: High dietary salt; Other: Placebo

Detailed 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.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Delaware
    • Newark, Delaware, United States, 19713
      • Department of Kinesiology and Applied Physiology, University of Delaware

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 40 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High dietary salt; 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.	Other: High dietary salt; ~4,000 mg Na+/day
Experimental: Placebo; 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.	Other: Placebo; dextrose

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Post-exercise hypotension	Change in mean arterial pressure from pre- to post-exercise	24 hours following exercise

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Blood pressure reactivity	Change in mean, systolic, and diastolic blood pressure from baseline to exercise	10th day of high salt diet

Collaborators and Investigators

• Sponsor: University of Delaware

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2018
• Primary Completion (Actual): June 30, 2019
• Study Completion (Actual): July 1, 2019

Study Registration Dates

• First Submitted: June 11, 2018
• First Submitted That Met QC Criteria: June 11, 2018
• First Posted (Actual): June 21, 2018

Study Record Updates

• Last Update Posted (Actual): October 1, 2019
• Last Update Submitted That Met QC Criteria: September 27, 2019
• Last Verified: September 1, 2019

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Nervous System Diseases; Autonomic Nervous System Diseases; Primary Dysautonomias; Orthostatic Intolerance; Hypotension; Post-Exercise Hypotension
• Other Study ID Numbers: 1085139

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No