LBNP + Isometric Exercise for Orthostatic Intolerance

(Unload heart Trial)

Overseen By Tracy Baynard, PhD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Tracy Baynard

Must not be taking: Beta-blockers

Disqualifiers: Cardiovascular, Diabetes, Dementia, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 5

64 Participants Needed

Trial Summary

What is the purpose of this trial?

As people get older, especially women, they often feel dizzy or even faint when they go from sitting or lying down to standing up. This happens because their blood pressure (BP) drops, which can lead to falls, heart problems, and even death in older adults. When BP changes, it affects how well the heart works and how it talks with blood vessels. However, little research has been done on how the heart and blood vessels talk during times of low BP. The crosstalk between the heart and blood vessels is important, as it allows enough blood and oxygen to reach the brain and other vital organs. Some research shows that as we get older, the crosstalk does not work as well. This can make it harder for blood to flow properly or put extra pressure on the heart and arteries. That's why we want to study how the heart and blood vessels talk during a laboratory-simulated situation of low BP in young and older men and women. In our study, participants will lie down with their lower body in a chamber that creates a vacuum around their legs. This safely mimics what happens when you stand up quickly. We can then measure heart function, the stress on arteries, and BP while your legs are in that vacuum. We'll use an ultrasound to check the heart and a finger cuff to measure BP. We'll also see if gripping something firmly can help protect from sudden drops in blood pressure. This study will help us understand more about a condition called orthostatic hypotension and might even suggest that handgrip exercise could prevent it. The main questions the current study aims to address are: * Does the cross-talk between the heart and vessels become more impaired with aging during laboratory-simulated conditions of low BP? * Do women have worse crosstalk between the heart and blood vessels during laboratory-simulated conditions of BP? * Does hand gripping protect against drops in BP during conditions of low BP? All participants will be asked to * Complete two laboratory conditions on two separate days with a randomized order (like flipping a coin): * Exposure to a lower body negative pressure (LBNP) chamber to safely simulate low BP (control) * Exposure to a lower body negative pressure (LBNP) while conducting hand-squeezingexercise (experimental). The investigators will examine how heart and blood vessel interactions, as well as blood pressure (BP) responses, differ in young and older adults of both sexes when exposed to a laboratory-simulated low BP condition (LBNP), both with and without hand squeezing exercise.

Will I have to stop taking my current medications?

The trial does not specify if you need to stop taking your current medications, but people prescribed with beta-blockers cannot participate.

What data supports the effectiveness of the treatment Isometric handgrip exercise, LBNP for orthostatic intolerance?

Research shows that Lower Body Negative Pressure (LBNP) can help prevent orthostatic intolerance (difficulty standing up without feeling faint) by stimulating blood flow in the legs. Studies have demonstrated that people who used LBNP did not experience the same level of dizziness or fainting as those who did not use it. ^{1 2 3 4 5}

Is the combination of LBNP and isometric exercise safe for humans?

Lower Body Negative Pressure (LBNP) has been used safely in various studies to counteract orthostatic intolerance (difficulty standing up without feeling faint) in humans, including astronauts. It has shown beneficial effects without significant safety concerns, although individual responses can vary. ^{1 2 5 6 7}

How does the treatment LBNP differ from other treatments for orthostatic intolerance?

Lower Body Negative Pressure (LBNP) is unique because it uses a vacuum-like device to create negative pressure around the lower body, which helps improve blood flow and counteracts the effects of gravity on blood circulation. This method is different from other treatments as it directly targets the venous system in the lower limbs, potentially restoring cardiovascular function without the use of medication. ^{1 2 6 8 9}

Eligibility Criteria

This trial is for young and older adults who experience dizziness or fainting when standing up due to blood pressure drops. It aims to understand heart and vessel communication during low BP, especially in aging individuals and women.

Inclusion Criteria

Seated systolic and/or diastolic BP <140/90 mmHg

Body mass index <35 kg/m2

I am healthy and do not experience symptoms like nausea or dizziness when standing up.

Exclusion Criteria

Tobacco users

I am currently taking beta-blockers.

Pregnant females

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Baseline Assessment

Baseline measurements of blood pressure and heart function are taken before exposure to LBNP

1 week

1 visit (in-person)

LBNP Exposure

Participants undergo lower body negative pressure (LBNP) to simulate low blood pressure conditions

2 days

2 visits (in-person)

LBNP with Isometric Exercise

Participants perform hand-squeezing exercises during LBNP to assess the impact on blood pressure and heart function

2 days

2 visits (in-person)

Follow-up

Participants are monitored for safety and effectiveness after the experimental conditions

4 weeks

Treatment Details

Interventions

• Isometric handgrip exercise
• LBNP

Trial Overview The study tests how the heart and vessels interact under simulated low BP conditions using a lower body negative pressure (LBNP) chamber, with and without the addition of handgrip exercise.

Participant Groups

Group I: Young male adults Active Control 2 Interventions

All young males will complete both conditions under study: 1) LBNP and LBNP + isometric handgrip exercise

Group II: Young females Active Control 2 Interventions

All young females will complete both conditions under study: 1) LBNP and LBNP + isometric handgrip exercise

Group III: Older male adults Active Control 2 Interventions

All older males will complete both conditions under study: 1) LBNP and LBNP + isometric handgrip exercise

Group IV: Older female adults Active Control 2 Interventions

All older females will complete both conditions under study: 1) LBNP and LBNP + isometric handgrip exercise

Who Is Running the Clinical Trial?

Tracy Baynard

Lead Sponsor

References

1. England pubmed.ncbi.nlm.nih.gov

Cardiovascular deconditioning during weightlessness simulation and the use of lower body negative pressure as a countermeasure to orthostatic intolerance. [2019]

2. England pubmed.ncbi.nlm.nih.gov

Development of lower body negative pressure as a countermeasure for orthostatic intolerance. [2019]

3. United States pubmed.ncbi.nlm.nih.gov

Counteracting effect of supine leg resistance exercise on systolic orthostatic hypotension in older adults. [2013]

4. United States pubmed.ncbi.nlm.nih.gov

Cardiovascular adaptation during simulated microgravity: lower body negative pressure to counter orthostatic hypotension. [2008]

5. United States pubmed.ncbi.nlm.nih.gov

Effect of lower body negative pressure against orthostatic intolerance induced by 21 days head-down tilt bed rest. [2013]

6. United States pubmed.ncbi.nlm.nih.gov

Comparison of 70 degrees tilt, LBNP, and passive standing as measrues of orthostatic tolerance. [2006]

7. United States pubmed.ncbi.nlm.nih.gov

Endurance exercise training: conditions of enhanced hemodynamic responses and tolerance to LBNP. [2022]

8. Germany pubmed.ncbi.nlm.nih.gov

WISE-2005: effect of aerobic and resistive exercises on orthostatic tolerance during 60 days bed rest in women. [2021]

9. United States pubmed.ncbi.nlm.nih.gov

Lower body negative pressure exercise plus brief postexercise lower body negative pressure improve post-bed rest orthostatic tolerance. [2013]