Effects of Overnight Low Oxygen Exposure on Energy Balance

NCT ID: NCT04151927

Last Updated: 2021-11-29

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 20 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2019-12-11
• Study Completion Date: 2021-10-02

Brief Summary

This research study will evaluate changes in resting metabolic rate, appetite, and heart rate variability following overnight exposure (8 h/night) to normobaric hypoxia (NH) or normobaric normoxic (NN). In randomized order, participants will sleep one night in NH conditions (~15% oxygen; achieved with nitrogen dilution, equivalent to ~8500 feet elevation) and another night in NN (control) conditions (~20% oxygen; achieved with nitrogen dilution, equivalent to ~1000 feet elevation).

Detailed Description

Weight loss is a common factor reported in lowlanders traveling to high altitudes. Although the exact cause is unknown, studies have shown that weight loss at high altitude is associated with the amount of time and severity of the altitude exposure. Upon arrival to high altitude (≥ 5000 feet), numerous physiological adaptations occur that may promote weight loss, such as increased energy expenditure and reduced appetite. The breadth of current altitude research is limited by the logistical and monetary constraints of traveling to remote locations or access to an altitude chamber. A more logistically feasible alternative is the simulation of low oxygen conditions at sea level, using a commercially available tent and generator system to reduce ambient oxygen concentrations. The current research study will evaluate changes in resting metabolic rate, appetite, and heart rate variability following overnight exposure (8 h/night) to normobaric hypoxia (NH) or normobaric normoxic (NN). In randomized order, participants will sleep one night in NH conditions (~15% oxygen; achieved with nitrogen dilution, equivalent to ~8500 feet elevation) and another night in NN (control) conditions (~20% oxygen; achieved with nitrogen dilution, equivalent to ~1000 feet elevation). In the morning, following NH or NN exposure, resting metabolic rate will be measured using indirect calorimetry, appetite using an ad libitum buffet meal protocol, and heart rate variability by electrocardiogram. It is hypothesized that exposure to overnight NH will result in increased resting metabolic rate, decreased appetite, and decreased heart rate variability.

Conditions

Resting Metabolic Rate; Appetite; Heart Rate Variability

Keywords

High altitude; Metabolic adaptations; Energy balance

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: SINGLE

Study Groups

Normobaric Hypoxia (NH)

Overnight exposure (8 hours) to NH conditions (\~15% oxygen; achieved with nitrogen dilution, equivalent to \~8500 feet elevation) using a commercially available tent and generator system (Hypoxico, Inc., New York, NY).

Group Type: EXPERIMENTAL

Normobaric Hypoxia

Intervention Type: DEVICE

Low oxygen exposure to mimic \~8500 feet elevation.

Normobaric Normoxia

Intervention Type: DEVICE

Normal oxygen exposure to mimic \~1000 feet elevation (sham comparator).

Normobaric Normoxia (NN)

Overnight exposure (8 hours) to NN conditions (\~20% oxygen; achieved with nitrogen dilution, equivalent to \~1000 feet elevation) using a commercially available tent and generator system (Hypoxico, Inc., New York, NY).

Group Type: SHAM_COMPARATOR

Normobaric Hypoxia

Intervention Type: DEVICE

Low oxygen exposure to mimic \~8500 feet elevation.

Normobaric Normoxia

Intervention Type: DEVICE

Normal oxygen exposure to mimic \~1000 feet elevation (sham comparator).

Interventions

Normobaric Hypoxia

Low oxygen exposure to mimic \~8500 feet elevation.

Intervention Type: DEVICE

Normobaric Normoxia

Normal oxygen exposure to mimic \~1000 feet elevation (sham comparator).

Intervention Type: DEVICE

Eligibility Criteria

Inclusion Criteria

• Men and women aged 20 - 45 years
• Body mass index between 18.5 - 24.5 kg/m2
• Born at altitudes less than 2,100 meters (~7,000 feet)
• Currently residing in Tallahassee, Florida or the surrounding area
• Not taking any medication(s) that interfere with metabolism or oxygen delivery/transport for four weeks before and throughout the entire study (e.g., includes sedatives, sleeping aids, tranquilizers, and/or any medication that depresses ventilation, diuretics, alpha, and beta-blockers).
• Willing to refrain from smoking, vaping, chewing tobacco, and dietary supplement use throughout the entire study
• Willing to spend two overnight visits on the Florida State University campus.

Exclusion Criteria

• Living in areas that are more than 1,200 m (~4,000 feet), or have traveled to areas that are more than 1,200 m for five days or more within the last two months
• Metabolic or cardiovascular abnormalities, gastrointestinal disorders, or any condition that interferes with metabolism or oxygen delivery/transport (e.g., kidney disease, diabetes, cardiovascular disease, etc.)
• Prior diagnosis of apnea or other sleeping disorders
• Prior diagnosis of high-altitude pulmonary edema or high-altitude cerebral edema
• Prior diagnosis of anemia or sickle cell anemia/trait
• Present condition of alcoholism, anabolic steroid, or other substance abuse issues
• Women who are pregnant, lactating, planning to become pregnant, or who have had an irregular menstrual cycle in the past six months.
• Allergies or intolerance to foods included in the standardized or ad libitum meal (e.g., lactose intolerance/milk allergy)

• Minimum Eligible Age: 20 Years
• Maximum Eligible Age: 45 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Florida State University

OTHER

Sponsor Role: lead

Responsible Party

Claire E. Berryman

Assistant Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Claire E Berryman, Ph.D.

Role: PRINCIPAL_INVESTIGATOR

Department of Nutrition, Food, and Exercise Science at Florida State University.

Locations

Florida State University

Tallahassee, Florida, United States

Countries

United States

Other Identifiers

STUDY00000184

Identifier Type: -

Identifier Source: org_study_id