Individuals who operate in cold weather are at risk of developing cold injuries, for example, frostbite. They also often experience a loss of hand function and joint mobility due to a decrease in skin temperature and blood flow. In addition, the risk of getting a cold injury is higher in the Black population compared to other racial and ethnic groups. Increases in oxidant compounds can cause the blood vessels in the skin to narrow and decrease skin temperature in the cold. However, it is unknown whether the higher risk of cold injury in Black individuals is because of a greater amount of oxidant compounds in the blood vessels. The purpose of this research is to see if an antioxidant supplement called MitoQ can help to improve skin temperature and blood flow in the cold and if the improvement is greater in Black individuals.
In a randomized, double-blinded, crossover design, healthy volunteers (18-40 yrs) will undergo a set of cold exposures following acute ingestion of a high-dose MitoQ supplement and placebo. The cold exposures will consist of a hand immersion in 54°F water and a 90-min exposure to 41°F air during which skin blood flow and temperatures will be measured. The hypothesis is that the declines in skin blood flow and temperature will be greater during cold exposure in Black individuals and that MitoQ supplementation will improve skin blood flow and temperature to a greater extent in Black individuals.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
30
Four 20 mg MitoQ capsules (80 mg total) are ingested orally.
Four placebo (microcrystalline cellulose) capsules are ingested orally.
Volunteers place one hand in cold (54°F) water for 30 minutes.
Volunteers sit in cold (41°F) air for 90 minutes.
U.S. Army Research Institute of Environmental Medicine
Natick, Massachusetts, United States
Skin blood flow
Skin blood flow is measured on the arm, hand, and finger using non-invasive laser probes. Output (red blood cell flux) will be divided by mean arterial blood pressure to give an index of cutaneous vascular conductance \[CVC, flux/mmHg\].
Time frame: Up to 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Body skin temperature
Skin temperatures (°C) at 12 sites on the body will be measured using temperature sensors.
Time frame: Within 1 hour before and up to 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Manual dexterity
Manual dexterity is assessed by placing pegs into a pegboard, moving small blocks on a table, and placing bullets into magazines. Scores are the number of pegs placed into the board in 1 minute, the time (seconds) required to move small blocks various distances on the table, and the number of bullets placed into magazines in 2 minutes.
Time frame: Within 1 hour before and approximately 2 hours after supplement dose on each cold air exposure study day
Finger strength
Finger strength (kilograms) is measured using a pinch meter. Participants will complete three pinch strength tests on each hand.
Time frame: Within 1 hour before and approximately 2 hours after supplement dose on each cold air exposure study day
Hand strength
Hand strength (kilograms) is measured on each hand using a grip strength meter.
Time frame: Within 1 hour before and approximately 2 hours after supplement dose on each cold air exposure study day
Body core temperature
Body core temperature (°C) is measured using a telemetry pill self-inserted as a suppository or ingested orally.
Time frame: Up to 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Metabolic heat production
Oxygen consumption (liters/minute) and carbon dioxide production (liters/minute) are measured by breathing into a mouthpiece connected to a metabolic cart for \~5 minutes. Oxygen consumption and carbon dioxide production will be combined to report metabolic heat production in Watts per meter squared.
Time frame: Up to 2.5 hours after supplement dose on each cold air exposure study day
Blood pressure
Brachial artery blood pressure (mmHg) is measured using an automated cuff.
Time frame: Up to 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Heart rate
Heart rate (beats per minute) is measured using an automated cuff.
Time frame: Up to 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Plasma MitoQ
Circulating concentrations of MitoQ (pmol/milliliter) is assessed in blood collected by venipuncture.
Time frame: Within 30 minutes before, 1 hour after, and 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Plasma malondialdehyde
Circulating concentrations of malondialdehyde (umol/liter) is assessed in blood collected by venipuncture.
Time frame: Within 30 minutes before, 1 hour after, and 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Plasma total antioxidant status
Total antioxidant status (mmol/liter) is assessed in blood collected by venipuncture.
Time frame: Within 30 minutes before, 1 hour after, and 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Thermal comfort
Thermal comfort is assessed using a 1-7 scale (higher number is more discomfort).
Time frame: Up to 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Thermal sensation
Ratings of thermal sensation is assessed using a -50 to 50 scale (50 is extremely hot and -50 is extremely cold).
Time frame: Up to 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
Pain perception
Pain is assessed using a 0-10 scale (higher number is more pain).
Time frame: Up to 2.5 hours after supplement dose on each cold air exposure and cold water hand immersion study day
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