Effect of regular winter swimming on the activity of the sympathoadrenal system before and after a single cold water immersion.
Level 4 - case-series / case-control
Prospective repeated-measures before-and-after study without an unexposed control group
What was done
Hormonal responses to acute cold water immersion (mean duration 36 seconds) were evaluated in regular winter swimmers across a season: at baseline in autumn (river water temperature 10 degrees C), and following one and three months of regular swimming (river water temperature 4 degrees C). Plasma noradrenaline, plasma adrenaline, and serum cortisol were measured immediately before and after test immersions.
What was found
The abstract does not provide absolute numerical concentrations, reporting only directions and p-values. Pre-immersion resting plasma noradrenaline (p < 0.001) and adrenaline (p < 0.01) significantly decreased after one month of regular swimming. Acute immersion significantly raised noradrenaline (p < 0.001), with 4 degrees C immersion at one month producing a noradrenaline level similar to 10 degrees C immersion at baseline. Post-immersion plasma adrenaline and serum cortisol levels varied (reported as increased or decreased). Following three months of regular winter swimming, post-immersion catecholamine levels were significantly attenuated (p < 0.01).
Why it matters
The findings demonstrate that habitual cold water exposure leads to physiological sympathoadrenal habituation, lowering the catecholamine surge triggered by acute cold stress.
Limits
The abstract omits sample size, participant characteristics, and exact hormone concentrations. The study lacked an unexposed control group, and water temperature differed between baseline (10 degrees C) and follow-up (4 degrees C) tests.
Cited by
- context Deliberate cold plunge immersion immediately and reliably causes the release of adrenaline.