Heat acclimation enhances the cold-induced vasodilation response

Area of Science:

• Environmental Physiology
• Human Adaptation
• Sports Science

Background:

• Cold-induced vasodilation (CIVD) is crucial for maintaining hand temperature in cold environments.
• Previous research indicates CIVD can be enhanced through local cold or exercise training.
• The potential for environmental stressors like heat and hypoxia to improve CIVD remains underexplored.

Purpose of the Study:

• To investigate if repeated exposure to heat and/or hypoxia improves the cold-induced vasodilation (CIVD) response.
• To determine if environmental stressors known to enhance aerobic performance can also benefit local cold tolerance.

Main Methods:

• Forty males underwent 10-day acclimation protocols: heat acclimation (HeA), heat/hypoxia acclimation (HeA/HypA), and normoxic exercise (NorEx).
• Daily hand immersion in warm water was performed during HeA/HypA and NorEx.
• Finger temperatures were measured before and after 30-min cold water immersions (8°C) and subsequent recovery periods.

Main Results:

• Heat acclimation (HeA) significantly increased finger temperature during cold immersion (13.9°C to 15.5°C) and recovery (22.2°C to 25.9°C).
• HeA also enhanced the rewarming rate of the hand post-immersion.
• Neither HeA/HypA nor NorEx protocols, with or without local warm water immersion, showed significant improvements in the CIVD response.

Conclusions:

• Whole-body heat acclimation enhances the finger vasodilatory response during cold exposure.
• Heat acclimation improves the rewarming rate, potentially increasing local cold tolerance.
• Daily warm water hand immersion did not contribute to improvements in CIVD response.