Running in temperatures below 0 °C puts significant stress on the body and requires rigorous adjustments (a three-layer clothing system, active hydration, reduced intensity) and a 20-minute warm-up to protect the heart, bronchial tubes, and joints.

noli's read

Sports physiology confirms that training in extreme cold significantly increases cardiovascular strain. A 2023 meta-analysis of epidemiological studies demonstrates that falling temperatures increase overall cardiovascular risk, while physiology reviews (Castellani & Young, 2016) estimate that cold increases cardiac workload by 10 to 30% due to the reflex contraction of peripheral blood vessels. This cardiac compensation phenomenon justifies the caution recommended for sedentary individuals or those over 40. Regarding respiration, inhaling cold, dry air causes a loss of mucosal hydration and temporary narrowing of the bronchial tubes, an irritation mechanism validated by field studies conducted on winter athletes (University of Alberta). Finally, the expert consensus from the American College of Sports Medicine (ACSM, 2021) confirms that cold reduces the elasticity of muscle and tendon tissues, which scientifically validates the utility of a prolonged, progressive warm-up to prevent injury.

the sources

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