Clinical trial NCT05464758: The Effects of Cold Adaptation on Skin Blood Flow, Hand Function, and Comfort in Healthy Adults
Official title: The Effects of Cold Habituation on Peripheral Blood Flow, Hand Function, and Thermal Comfort
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Cold Exposure
Lead sponsor: United States Army Research Institute of Environmental Medicine
Sponsor class: FED
First posted: 2022-07-19
Enrollment: 16
Sex: ALL
Minimum age (years): 18
Maximum age (years): 39
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: BASIC_SCIENCE

Brief summary: In cold weather environments, blood flow to the extremities is significantly reduced, which severely impairs hand function and induces thermal discomfort. Prolonged or repeated cold exposure elicits an adaptive habituation response that is characterized by blunted skin vasoconstriction and thus may be an effective strategy to improve peripheral perfusion, reduce thermal discomfort, and maintain hand function during cold weather military operations. Since mission conditions often involve low ambient temperatures, countermeasures that reduce cold-induced decrements in hand function and thermal comfort are important to enhance Warfighter readiness in cold weather battlefield environments. The goals of this study are to 1) evaluate the effectiveness of cold habituation in improving skin blood flow, hand function, and thermal comfort during cold exposure and 2) identify the mechanisms that contribute to improvements in skin blood flow following habituation.

Detailed description: Participants (n=15, 18-39 yrs) will complete a preliminary cold air exposure (baseline testing) followed by 8 days of repeated cold air exposures with minimal clothing. The cold exposures will be 2 hours in duration and will be conducted in 8°C (46°F) conditions. Before and after the repeated cold exposures, participants will undergo hand function tests, assessments of thermal comfort, and skin blood flow testing.

Eligibility criteria: Inclusion Criteria:

* Male or female, age 18-39
* In good health as determined by OMSO (Office of Medical Support and Oversight)
* Willing to refrain from exercise and caffeinated or alcoholic beverages for 12 hours before each testing session
* Willing to refrain from smoking or tobacco use 8 hours before each testing session

Exclusion Criteria:

* History of cold injuries of any severity (e.g., frostbite, trench foot, chilblains).
* Raynaud's syndrome.
* Cold-induced asthma/bronchospasm
* Previous hand/finger injuries that impair dexterity and hand function.
* Metal hardware (plates/screws) in the forearms and hands.
* Current use of medications or dietary supplements that could alter cardiovascular, thermoregulatory, or vascular control (e.g., anti-hypertensives, statins).
* Known allergies to medical adhesives.
* Heart, lung, kidney, muscle, or nerve disorder(s)
* A planned MRI during the study or within 2 days after completing a cold test.
* Women who are pregnant, planning to become pregnant, or breastfeeding.
* Not willing to have small areas of skin on the body shaved (if deemed necessary for attachment of study instrumentation)

Primary outcomes:
measure: Skin blood flow
timeFrame: 8 days
measure: Skin temperature
timeFrame: 8 days
measure: Manual dexterity - Pegboard
timeFrame: 3 days
measure: Manual dexterity - Minnesota Rate of Manipulation
timeFrame: 3 days
measure: Hand and finger strength
timeFrame: 3 days
measure: Cold perception
timeFrame: 5 days
Secondary outcomes:
measure: Metabolic heat production
timeFrame: 5 days
measure: Body core temperature
timeFrame: 5 days
measure: Blood pressure
timeFrame: 12 days
measure: Plasma norepinephrine
timeFrame: 3 days
measure: Heart rate
timeFrame: 12 days
Other outcomes:
Locations:
city: Natick
country: United States
facility: U.S. Army Research Institute of Environmental Medicine
state: Massachusetts
Study officials:
affiliation: United States Army Research Institute of Environmental Medicine
name: Billie K Alba, Ph.D.
role: PRINCIPAL_INVESTIGATOR
References: