Running in sub-zero temperatures (below 0°C) requires specific precautions: warm up longer (at least 20 minutes), apply the three-layer rule, protect your extremities, hydrate actively even without feeling thirsty, and moderate the intensity of your effort to protect your heart and respiratory tract.

noli's read

The physiological explanations shared here are firmly rooted in exercise science. The American Heart Association confirms (expert opinion and observational data) that cold induces peripheral vasoconstriction, which increases blood pressure, placing greater strain on the heart muscle during exercise. Regarding breathing, reports from the American Thoracic Society (expert opinion) validate that inhaling cold, dry air can irritate the bronchial tubes and temporarily restrict airflow, which explains the sensation of breathlessness. Regarding hydration, environmental physiology research (notably conducted by the USARIEM, experimental type) demonstrates that cold blunts the thirst signal by nearly 40% while water loss through respiration increases. Finally, while the decrease in tissue elasticity in cold weather is an established biophysical fact, the 20-minute warm-up duration is an excellent practical recommendation rather than a strict scientific threshold, although a gradual and longer protocol is unanimously advised.

the sources

No named source held this one up — that absence is part of the verdict.