Last spring, as the cool Mediterranean Sea was gradually warming up under the sun, I noted this observation: I was more chilled in 23 C (74 F)water than in 22 C (72 F).
I had started swimming in March when the water was 19 C (67 F) and used my quickjohn sleeveless wetsuit for about two weeks then felt ready (desperate actually) to go without.
In April the sea was 21-22 and I could swim an hour briskly and stay fairly comfortable until the end when my hands and feet would get numb and I’d lose a little bit of fine motor ability. Then one day I went to a different place on the coast and went for a swim to explore. I recall feeling cooler than usual, even from the beginning and felt sure that I must be swimming in a pocket of slightly cooler-than-normal water.
So I took my thermometer and measured it after the swim. It read 1 degree C warmer than what I was used to swimming in! ????
How could I be relatively ‘comfortable’ in 22 C water and then suddenly feel chilled in 23-24 C?
This was the experience for a couple weeks until the water warmed up a bit more.
Here is my theory- and it is by all means open to discussion:
At my level of adaptation, the 21-22 C water was cold enough to trigger certain survival reactions inside my body. The blood flow to my extremities was restricted and pooled in my brain and my core. So I enjoyed that ‘furnace’ feeling in the essential places of my body for the duration of my swim.
But what I am guessing could have happened is that 23 C was just before the threshold of that survival trigger, and so when I plunged in the body did not go into ‘survival mode’ as usual but let more blood flow to the extremities which allowed a much quicker rate of cooler for the entire body. All that blood flowing freely to the limbs was like hot water being cooled by the wind against the car engine’s radiator. Hence, within 5 minutes I was chilled and urged to swim harder than normal to stay warm.
Now I am at the edge of the reverse situation. The sea is gradually cooling down. It is 23 C right now and I am swimming an hour, briskly, and I feel an edge of discomfort I don’t recall experiencing last winter at 22 C. I am very curious now how I will feel at 22 C in a week or so when it must drop down another degree.
There is another factor I am aware of – the sea is COOLING down, colder weather is coming, and my brain knows this – consciously and subconsciously – I can feel a slight underlying touch of stress because of this anticipation. In the spring, I was comforted mentally by the anticipation of warmer weather coming- any discomfort I felt was only going to get less and less (until the heat made me suffer on the other extreme). But now I know it is only going to get cooler and cooler and any discomfort may very well increase.
Calm. Breathe. Adapt, Mat, Adapt.
There is one element of motivation for pursuing cool water swimming I must point out – this has served me powerfully for years – I absolutely love the sensation, the ‘after-glow’ of exercise in cool weather and water. For whatever discomfort I experience in the activity itself (and I don’t train to get good at suffering, but to remove it), my brain is deeply drawn to the pleasure I experience in the relaxation and energy that comes afterward. The intrinsic motivation is far more powerful than any extrinsic motivations (i.e. bragging rights- and 16 C is nothing to brag about among hardy ow swimmers).