The Effects of Cold Adaptation on Skin Blood Flow, Hand Function, and Comfort in Healthy Adults

NCT05464758 | Completed

• 2 other identifiers: 21-04HMO210025
• Study Type: interventional
• Target: 16
• Locations: 1 country
• Sites: 1

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.

Conditions

Cold Exposure

Outcome Measures

Primary Outcomes (6)

• Skin blood flow

  Skin blood flow will be measured using non-invasive laser-Doppler flowmetry probes before and during cold exposure. Output (red blood cell flux) will be divided by mean arterial blood pressure to give an index of cutaneous vascular conductance \[CVC, flux/mmHg\].

  8 days

• Skin temperature

  Skin temperatures \[in °C\] at up to 10 sites on the body will be measured using skin thermistors before and during cold exposure. Hand and foot skin temperatures will also be measured with a thermography imaging camera.

  8 days

• Manual dexterity - Pegboard

  Pegboard scores will be obtained before and during cold exposure. Scores are the number of pegs placed into the boards.

  3 days

• Manual dexterity - Minnesota Rate of Manipulation

  Minnesota Rate of Manipulation dexterity scores will be obtained before and during cold exposure. Scores are the time \[in seconds\] required to move small blocks various distances.

  3 days

• Hand and finger strength

  Pinch and hand strength \[in kg\] will be measured using a pinch meter and grip strength device (dynamometer). Participants will complete three pinch strength tests and one grip strength test before and during cold exposure.

  3 days

• Cold perception

  Ratings of thermal comfort, thermal sensation, and pain perception \[in arbitrary units\] will be assessed using visual analogue scales before and during cold exposure.

  5 days

Secondary Outcomes (5)

• Metabolic heat production

  5 days

• Body core temperature

  5 days

• Blood pressure

  12 days

• Plasma norepinephrine

  3 days

• Heart rate

  12 days

Study Arms (1)

Cold habituation

EXPERIMENTAL

8-day cold habituation

Other: Repeated cold exposure

Interventions

Repeated cold exposure OTHER

8 consecutive days of exposure to 8°C air for 120 minutes each day

Cold habituation

Eligibility Criteria

• Age: 18 Years - 39 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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

You may not qualify if:

• 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)

Sponsors & Collaborators

• United States Army Research Institute of Environmental Medicine: lead

Study Sites (1)

U.S. Army Research Institute of Environmental Medicine

Natick, Massachusetts, 01760, United States

Location

Study Officials

• Billie K Alba, Ph.D.

  United States Army Research Institute of Environmental Medicine

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: FED
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 6, 2022
• First Posted: July 19, 2022
• Study Start: August 1, 2022
• Primary Completion: September 13, 2024
• Study Completion: September 13, 2024
• Last Updated: December 26, 2025

Record last verified: 2025-12

Locations

US (1)