Geek out on Cold Exposure Training

Health, January 14, 2017

This article is backing up cold exposure training. The references are sourced from work completed by Dr. Rhonda Patrick (FoundmyFitness) who promotes strategies to increase health and wellness with a deeper understanding of biology.

I've been playing round with cold exposure for almost 2 years now. Last winter I scheduled in at least one sea swim every week (up to 1.5km) wearing a wetsuit and a neoprene cap. In November 2015 I decided to add cold showers to my daily habits (I will have a warm shower if I have been exercising outside in the rain and come home chilled - a cold shower on top of that risks over exposure and getting sick). This last winter I swam in the sea weekly without a wetsuit, and completed one 500m swim in Blue lake when it was 11.4 degrees.

 

One profound physiological response to cold exposure is a release of noradrenaline into the bloodstream as well as in the locus coeruleus of the brain (noradrenaline is a hormone and a neuro transmitter - involved in vigilance, focus, attention and mood). As a hormone it increases vasoconstriction (decreasing the total surface area of which the blood loses heat to the environment). Research shows that 1 hour exposure at 14 degrees Celsius increased noradrenaline by 530% and dopamine by 250% (Human physiological responses to immersion into water of different temperatures, P.Sramek et al, European Journal of Applied Physiology, Feb 2000, vol 81, Issue 5, p 436-442). 

 

Exposure to cold also triggers heat shock proteins and in addition cold shock proteins. When the body is cooled many genes are shut down except genes involved in lipid metabolism (fat burning), and a group of proteins known as "cold shock proteins (CSP)". One particular CSP RNA binding motif 3 (RBM3) found in the brain, heart, liver, and skeletal muscle increases massively with cold exposure. It's affect on the brain (with experiments in mice) is to prevent the loss of synapses (one of the effects of aging and neurogenerative disease). It is proposed that controlled cold exposure has benefits for neurological disease. 

 

The inflammation process is an important part of how we as humans function. The purpose of inflammation is to do away with the initial cause of cellular injury, clear out dead tissue and cells damaged from the injury and inflammatory process and initiate repair. Unfortunately when this process gets out of hand (with no biological threat) it causes unnecessary problems. A recent study looking at the bio-markers in people aged between 85-110+ and showed that low inflammation was the only bio-marker that predicted cognitive capabilities and longevity across all the age groups. Noradrenaline decreases inflammation inhibiting the inflammation pathway by decreasing tumor necrosis factor TNF-alpha. Excessive cytokine TNF-alpha has been implicated in almost every human disease from Type 2 diabetes, to inflammatory bowel disease to cancer. This pro-inflammatory molecule has been shown to cross the blood-brain barrier activating the brains immune cells (microglia) aging the brain. These inflammatory molecules probably contribute to depression and anxiety by inhibiting release of serotonin.  Noradrenaline also reduces macrophage inflammatory protein - 1g (MIP-1a) - this is produced by immune cells and may play a role in rheumatoid arthritis.

 

Cold exposure is shown in many research papers to increase our stock of immune cells boasting general immunity. This is a good thing as making it to an old age is associated with having a healthier biological stock of immune cells. Long term cold water immersion (3 x wk for 6 weeks) in healthy males increased lymphocyte numbers (Immune system of cold-exposed and cold adapted humans, jansky,L et al, European Journal Applied Physiol Occup Physiol. 1996;72 (5-6):445-50) and habitual winter swimmers have higher numbers of white blood cells compared to non-habitual winter swimmers (Adaption related to cytoknes in man :effects of regular swimming in ince-cold water, Dugue, B et al, Clinical Physiology 2000, March; 20 (2):114-21). Another study showed that cold exposure in a climatic chamber at 5 degrees Celsius increased white blood cell numbers including cytotoxic T lymphocytes (specialised type of immune cells that kill cancer cells) ( Immune changes in humans during cold exposure: effects of prior heating and exercise, I.K.M Brenner et al, Journal of Applied Physiology, Aug 1999 Vol 87, 2; 699-710). An association has been demonstrated in epidemiological studies between winter swimming and a 40% decrease in incidence of respiratory tract infections.

 

Cold exposure has become very popular due to the effects of cold on weight loss. One of the bodies methods of dealing with cold is to increase metabolism (not to produce energy in the form of adenosine triphosphate (ATP)) but to produce heat by burning fat. This process is called "cold thermogenesis". There are two types of thermogenesis, one occurs in the muscle - shivering thermogenesis, the second occurs in adipose tissue - non-shivering thermogenesis. This seond process is partly regulated by noradrenaline.  Cold induced noradrenaline increases the expression of protein UCP1 (uncoupling protein 1). This uncouples the mitochondria (energy producing powerhouses of the cell) producing more mitochondria in adipose tissue. This has a "browning effect" - meaning that under a microscope each fat cell has more mitochondria making the white fat seem brown. In simple terms the more brown adipose tissue your body has the more fat your body will burn and the more efficient you will be as an endurance machine. It was once thought that we mostly had brown fat as children and lost it as we became adults. It's now been shown that brown fat shows an inverse correlation to % body fat in an individual (Cold -activated brown adipose tissue in healthy men, Lichtenbelt WD, et al, New England journal of Medicine, 2009 April 9;360 (15):1500-8). The % of young men with brown fat tissue is high, but it's activity is reduced in men who are overweight or obese.

 

Exercise induced inflammatory response.

Immediately after exercise activity there is a spike in the production of pro-inflammatory cytokines (molecules that activate immune cells involved in tissue repair) This A/I responce to this inflammation peaks at 1 hr post exercise - hormones such as IGF-1 return to pre exercise levels around 1 hr post exercise. These A/I cytokines keep the immune system from going overboard modulating the activity of the immune cells preventing them from causing excessive damage.
Exercise causes different stress upon the body in responce the body activates many genes and pathways that build resilience to that stress - the type of stress determines the characteristics of the adaptation that occurs.
Strength training (mechanical)
Whole body cryotherapy done one hr after plyometric exercise (squats and leg curls) showed improvements 3 days after the treatment. If the cold treatment occurs immediately after resistance training (during the peak pro-inflammatory process it may blunt some of the long term muscle hypertrophy benefits)

 

Endurance

Cold exposure activates a gene PGC-1g which makes more mitochondria in the muscle (mitochondrial biogenesis). This translates to more aerobic capacity. One study of cyclists (elite) engaged in cold water emersion (15 degrees) for 15min 4 x week for 39 days. They experienced 4.4% increase in sprint power, 3% enhancement in repeat cycling performance, and 2.7% increased power over the 39 day training period ( Does hydrotherpay help or hinder adaptation to training in competitive cyclists? halson SL et al, Med Sci Sports Exercise 2014, Aug; 46 (8): 1631-9.)_

If you have any coronary risk factors or other heart related risk factors avoid contrast therapy  *Acute myocardial infarction induced by alternating exposure to heat in a sauna and rapid cooling in cold water, Imai. Y et al, Cardiology, 1998; 90 (4) 299-301.

 

I'm loving my cold training sessions and will continue to push my boundaries swimming in colder water for longer periods. In the winter of 2017 I'm hoping to swim in the Rotorua lakes at less than 10 degrees for over 500m. My daily cold showers will continue for life. The short term discomfort always gives way to an awesome invigorating buzz and I'm staring to relish rather than endure the cold wake up shower. Cold exposure training is one more habit that is now entrenched to allow me to be EVERFIT.

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