Exposure to cold and hypoxia, two conditions frequently encountered in mountain environments, endurance sports, and operational settings, creates an ideal scenario to observe how our peripheral physiology behaves. The hand, highly sensitive to changes in perfusion and vasomotor activity, becomes a key region for studying the effects of thermal stress.

In this article, we review a scientific study that analyzed how hand temperature changes during and after cold-water immersion under two conditions: normoxia and normobaric hypoxia. Temperature was continuously monitored using thermocouples and infrared thermography, allowing for a detailed thermal map of the hand’s response.

Does the cold affect us more under hypoxia? Not exactly

During the 30-minute immersion of the hand in 8 °C water, the researchers found that:

• The drop in temperature was virtually identical in both conditions. Hypoxia did not worsen the initial cooling or the minimum temperature reached by the fingers. This suggests that cold induces such a strong vasoconstrictor effect that it overshadows any vasomotor influence caused by acute hypoxia.
• The CIVD response (cold-induced vasodilation), the characteristic thermal “waves” that appear during prolonged exposure to cold, was not significantly altered either. Although Tmax was slightly lower under hypoxia, the difference was not substantial enough to change the overall CIVD pattern.

This finding is particularly relevant because earlier literature suggested that hypoxia exaggerates cold-induced vasoconstriction. However, this study shows that under acute and controlled exposures, hypoxia does not significantly modify the cooling response.

Hypoxia slows down rewarming

Clear differences emerged during the recovery phase. Across the 15 minutes of spontaneous rewarming, thermography revealed that:

• The hand rewarms significantly more slowly under hypoxia.
• All regions, distal and proximal phalanges, palm, and dorsum, showed lower temperatures compared with normoxia.
• The vasodilation required to restore skin temperature occurred more slowly and less efficiently.

This impaired rewarming appears to be driven by:

• Increased sympathetic activation
• Hypocapnia resulting from hypoxia-induced hyperventilation
• A delayed vascular response in distal tissues

Taken together, the study suggests that peripheral thermal recovery is the main vulnerability under acute hypoxia.

Why does this matter? Implications for performance and health

These results have relevant practical applications in high-altitude, sports science, and clinical contexts.

1. Increased risk of cold injury at altitude

A hand that recovers temperature more slowly is more susceptible to cold-related tissue damage, especially during prolonged exposure.

2. Key insights for mountain and endurance athletes

Alpinists, skiers, trail runners, military personnel, and other individuals exposed to hypoxic conditions may benefit from thermal monitoring strategies.

3. Thermography as an early detection tool

Slower rewarming may serve as an early marker of hypoxia-induced vascular dysfunction, even when the cooling phase appears unaffected.

4. Understanding peripheral perfusion under environmental stress

Thermography provides an objective, non-invasive, and detailed way to assess how the body redistributes blood flow in extreme environments.

Conclusions

The study demonstrates that:

• Hypoxia does not worsen the initial temperature drop during cold exposure.
• But it markedly slows and reduces the efficiency of peripheral rewarming.

These findings help explain why cold injuries are more frequent at altitude, where hypoxia adds an extra layer of physiological stress.

Infrared thermography emerges as a powerful tool to monitor these responses, enabling precise, fast, and non-invasive assessment of peripheral vascular behavior.

Reference

Keramidas, M. E., Kölegård, R., Mekjavic, I. B., & Eiken, O. (2014). Acute effects of normobaric hypoxia on hand-temperature responses during and after local cold stress. High Altitude Medicine & Biology, 15(2), 183-191.