Swimming at zero degrees centigrade is probably best left to the ducks – who seem not to mind the low temperature at all. It seems like nobody has told this one here that it’s time to migrate.
Cold exposure – when only affecting the skin and not allowed to induce hypothermia – has a powerful effect on the hormonal systems within the body. Perhaps the most interesting is the production of the hormone “irisin” which converts white fat into brown fat. Brown fat has the special quality of producing heat from mitochondria without any mechanical action – but there is another hidden value. Brown fat acts as a mitochondrial safety valve – burning off excess ATP (energy molecule) and preventing excessive build up of free radicals associated with genetic mutations and aging. Rats for example don’t have this mitochondrial mechanism and they live for about four years. Pigeons, which have a similar metabolic energy need have a strong mitochondrial safety valve and can live for about 36 years.
The hypothalamus in the brain is effectively rewired through cold exposure and this alters the metabolic system considerably as it controls body temperature and the thyroid. So in addition to a ketogenic (high fat) diet cold exposure is a bit like therapy for the thyroid – though a daily drop of 15% Lugol’s solution does wonders too (15% iodine and 30% potassium iodide). Another thing that adaption to the cold brings through the nervous system is a huge reduction in pain sensitivity. All of this of course is very useful as humanity has spent most of its existence in ice. Even today we are in an Ice Age and most people don’t realise it due to political propaganda. Our current Ice Age has been on the go for 2.8 million years.
Perhaps my main interest in cold exposure however is the vagus nerve. This nerve controls a large chunk of the autonomic nervous system – that is organs over which there is no conscious control. The vagus nerve is strongly toned by the cold exposure and the surge of hormones including adrenaline – corresponding to the cold shock received. Adaptation is progressive but rapid over about 10 exposures and the effect of the vagus nerve on the heart can be measured with a simple heart rate monitor and a cardiac variability app on a phone. Nothing improves (increases) heart rate variability faster than cold exposure.
Two winters ago when just starting the ketogenic diet I noticed my maximum heart rate slowly modifying. Most of us are used to seeing it very slowly declining with age and that’s what I saw too – until then. From two months after adopting a high fat diet the max heart rate began to creep upwards. This is so ironic because for most of my life I’d heard the nonsense that fat causes cardiovascular congestion. Up it continued – from 172 to 174, to 176 and 182 to 186 and finally to 191. This was all when running sprint intervals up a steep hill . Meanwhile along with the cold exposure, ketogenic diet and exercise I added vitamin B3 (nicotinic acid) which cleans out the arteries – and vitamin k2 at a one tenth ratio to vitamin D. Today I went back to the sprint intervals for the first time in two years and gradually warmed up with the first interval at 2.1k, the second at 5.6k and the third at 9.1k. The final sprint saw a smooth peak in heart rate at 202 bpm. Well the last time I saw that was in my late 20s so that’s interesting! It wasn’t an equipment artifact – that’s very easy to spot. I know that cardiac emergency patients – with a real problem, can reach over 400 bpm and survive so the 202 is still very normal. Author Sally Edwards – the lady who effectively wrote the book on this subject for Polar states now that you have a max heart rate for life and it only reduces if you are sedentary. I’d like to offer another explanation – it only reduces if you eat inappropriately no matter how much you exercise.