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I am a reasonably experienced swimmer and I was swimming in the nearby lake almost every day through the summer and autumn. I live in northern Europe, and I was still swimming occasionally in October when the water was around 15 degrees Celsius, and had no problem with it.

Yesterday the weather was nice and sunny, so I thought I would give it a try and dip in the water, which was around 1-2 degrees Celsius (the nearby puddles were frozen). I read a lot about the benefits of cold water, and was curious to try. I am generally fit and healthy and many people do ice dipping around this time of the year, so I thought why not.

I was only able to stay in about a minute as it was very cold, but I felt very good afterwards so I went in for another minute. Then I covered myself if a thermo blanket, drank some hot tea, walked home, and took a warm shower. However, I got very exhausted and slept for the rest of the day, and also through the night (around 12 hours, which is unusual).

Cold water therapy is reported to have an energising effect and a positive impact on fitness:

When compared to a control group on the profile of mood states rating scale, winter swimmers experience less stress and fatigue and more vigor. They report to have a better memory function, better mood and feel more energetic, active and brisk.

I can confirm the positive impact on mood. However, I was definitely experiencing more fatigue and was feeling less energetic afterwards.

Is it normal to feel exhausted after a short dip in extremely cold water?

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For someone cold challenged or actually in hypothermia your body is going to use a ton of energy to rewarm you and you'd likely feel the effect of blood shunting.

It's the difference between "a dip" versus your study (linked in wikipedia) which talked about "swimming", the latter of which generates enough heat in a trained athlete to stave off hypothermia.

The linked NY Times piece above backs that suspicion up:

If the muscles cannot generate enough heat and the fat insulation is insufficient to keep what heat there is from draining away, the body's reaction is to try to preserve the heat it generates. Most body heat is lost through the skin, whose large surface area drains heat away from the blood into the cold air. To prevent this heat loss, the body shunts blood away from the skin, with the result that you feel cold.

On the heat (hyperthermia) side, it can take about two weeks for your body to adjust by doing things like reducing salt sweated out, not as much vasoconstricting, etc. A 2007 study shows that cold acclimatization takes about the same amount of time:

The results suggest that cold adaptation induced by winter swimming attenuates the catecholamine responses to cold water. Adrenaline responses are also affected by its level prior to the immersion.

A 2001 study states pretty clearly that regular exposure and training in cold water changes one's hormonal responses (the catecholamine response noted above), which is how shunting and other physiological changes occur.:

The results suggest that cold adaptation induced by winter swimming attenuates the catecholamine responses to cold water. Adrenaline responses are also affected by its level prior to the immersion.

In short, the study you're referencing is for people who were cold-conditioned prior to the study ("regular winter swimming"), and unlike your experience they were aerobically engaged.

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  • Thanks, makes sense. I think the answer is incomplete though, as 2 minutes is nowhere near enough for hypothermia to occur, so what might be causing the exhaustion is still unclear for me. – BKE Feb 6 '18 at 18:11
  • Hypothermia can absolutely happen that fast, and shunting happens within seconds. Read up on climbers falling into crevaces. If they're not scooped out within minutes survivability drops rapidly. – Eric Feb 7 '18 at 7:00
  • Survival is a different question. Hypothermia means the core body temperature falls below 35 degrees Celsius which does not happen in 1-2 minutes. Shunting happens to prevent it actually. – BKE Feb 7 '18 at 16:46
  • useakayak.org/references/hypothermia_table.html loss of dexterity in 2 minutes, potentially unresponsive in 15 – Eric Feb 8 '18 at 7:42
  • I am not concerned about loss of dexterity. The question I would like to understand is what mechanism might cause exhaustion hours after being immersed to ice cold water for a short time. Is it the hormonal response you mention? – BKE Feb 8 '18 at 15:10

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