Dynamic adaptation of the peripheral circulation to cold exposure

Area of Science:

• Physiology
• Environmental Medicine
• Human Adaptation

Background:

• Individuals in cold climates often show enhanced cold-induced vasodilation (CIVD) compared to those in warmer regions.
• This suggests that thermal responses to cold exposure may improve through acclimatization or acclimation.
• However, the role of genetics versus environmental adaptation in this enhanced response is unclear.

Purpose of the Study:

• To systematically review the existing literature on the trainability of cold-induced vasodilation (CIVD).
• To determine if repeated local cold exposure leads to adaptive changes in peripheral circulatory dynamics.
• To assess the risk of cold injuries in humans after extended exposure to cold environments.

Main Methods:

• Systematic review of longitudinal and laboratory studies on repeated extremity cold exposure.
• Analysis of studies investigating changes in peripheral blood flow and CIVD response.
• Consideration of confounding factors such as genetic predisposition and self-selection.

Main Results:

• Longitudinal studies show ambiguous adaptive responses to repeated cold exposure.
• General cold acclimation may increase sympathetic activity, potentially reducing finger blood flow.
• Laboratory studies often show no consistent changes in peripheral blood flow even after weeks of exposure.
• Limited subject numbers and high variability in CIVD responses complicate findings.

Conclusions:

• Repeated local cold exposure does not appear to significantly alter circulatory dynamics in the extremities.
• The trainability of CIVD is limited, and adaptive responses are not consistently observed.
• Humans remain at risk of cold-related injuries even after prolonged periods in cold environments.