Sub-Zero

 HORMESIS

Hormesis is the term used to describe a process in which exposure to a low dose of a chemical agent or environmental factor that is damaging at higher doses induces an adaptive beneficial effect.

The zone in which the biological response to a stressor is favourable is known as the hormetic zone. There are a number of examples of stressors with which we have a hormetic relationship like physical exercise, fasting, sunlight and even oxygen.

Like all of the other things in the list, cold exposure is hormetic, with profound benefits at the right dose but also the cause of some harmful conditions like hypothermia or frostbite when not in a controlled environment.

Cold exposure is a physiological challenge to the body and its systems in order maintain temperature in the brain and organs of the core by regulating heat production and loss mechanisms.

RECOVERY

A meta-analysis (a study of studies) found that cold water immersion (CWI) improved muscle soreness to a greater extent compared to passive recovery. The studies looked at CWI within an hour of exercise (running, cycling and jumping) for anywhere between 5 and 20 minutes.

Looking at the results of each study the analysis concluded that CWI was superior for muscle recovery.

Individual studies published in 2011 and 2016 showed that when athletes were immersed in cold water following exercise, they reported significantly less muscle soreness.

There is a caveat however - cold exposure has shown to limit some gains in hypertrophy and strength training. As a result of its inflammation busting benefits, it has been found to blunt muscle mass and strength adaptations if done too soon after exercise.

Experts suggest to wait at least 4 hours, if not 6-8 hours after (strength) training to utilise cold exposure UNLESS your goal is simply to recover without the specific adaptation.

ENERGY & FOCUS

When exposed to cold stimulus the body experiences two different autonomic responses called the cold shock and diving response.

The cold shock response is a reflex triggered when your skin feels sudden cold. These reactions include a rapid heartbeat, gasping for breath, rapid and uncontrollable breathing, narrowing of blood vessels in the limbs, and increase in blood pressure.

The diving response is activated when your face is submerged in cold water. Its the reason, if you’ve ever tried CWI, that your body triggers a separate response as soon as you dip your head under water. The diving response has a bit of a push-pull with cold shock as it results in a slowing of the heartbeat, inhibition of respiratory neurons (to avoid breathing), redirects blood to vital organs and releases extra blood cells.

These reflexive triggers are the cause of significant adrenaline and noradrenaline release in the brain and body. Both neurotransmitters cause an influx of chain reactions responsible for increasing heart rate, activating heat production, constricting blood vessels, modulating immune function and more.

A long term study compared women who underwent CWI at 4.4°C for 20 seconds vs those who received whole-body cryotherapy for 2 minutes at -110°C. In both groups, norepinephrine concentrations in the blood increased by 200-300 percent. 

Cold exposure causes levels of adrenaline and noradrenaline to stay elevated for some time and their ongoing impact on your physiology aids to increase your energy and focus that can be translated to other activities you may go about during your day.

METABOLISM

In the near term, cold exposure increases metabolism as the body burns calories to increase core body temperature and deal with the cold stimulus. In the grand scheme of things, the calories burned whilst in a cold plunge are not significant so when mentioning its metabolic benefits, we refer to the adaptations created as a result of cold exposure.

Mammals tend to store two adipose (fatty) tissue types - white and brown. White fat is the type of fat we are all familiar with, it is a store of energy. Brown fat however is very metabolically active as it is used to maintain your body temperature when you get too cold.

Cold exposure has been seen to convert white fat into brown fat which not only enables people to feel more comfortable in cold temperatures but results in a more sustained increase in metabolism in the long term.

A study exposed half of their participants to cold (17°C) for two hours a day, whilst the other half maintained their lifestyles without the stimulus. Among those exposed to the cold, thermogenesis (the body’s production of heat and therefore energy expenditure) increased 58% compared with baseline resulting in a loss of around 1.5 pounds of fat mass.

In addition, activating brown fat when exposed to a cold stimulus may improve glucose and insulin sensitivity as well as increase fat utilisation and protect against diet-induced obesity.

MOOD AND COGNITION

We spoke already about how noradrenaline aids focus and energy - in fact noradrenaline is a key player in the mechanism behind cold exposure enhancing mood and cognition as its a neurotransmitter involved in vigilance, focus, attention and mood. The lack of noradrenaline is associated with inattention, decreased focus and cognitive ability, low energy and poor mood.

Besides the aforementioned neurotransmitters, cold exposure causes the prolonged release of dopamine - associated with elevated mood, focus, attention and goal-oriented behaviour.

A study in healthy young men found CWI at colder temperatures (14°C) noradrenaline increased by 530%, dopamine by 250% and energy expenditure by 350% compared with pre-immersion levels. Such affect was not observed in those immersing in warmer temperatures (20 and 32 degrees).

A study enrolled 92 participants with depression to undertake 10 cyrotherapy sessions. The results show a marked reduction in depressive symptoms and improved quality of life and mood. Findings from a separate case report indicate that a cold shower for 2 to 3 minutes can relieve depressive symptoms when performed once or twice daily.

A particularly interesting case study found a 24 year-old woman who had experienced anxiety and depression since age 17, trial a program of weekly open water cold swimming.

Over time her symptoms decreased so significantly share was able to stop taking medication to treat them. A year later, doctors returned to find that cold water swimming kept her symptoms at bay - this is likely a result of the compounded effect of cold exposure and cardiovascular exercise.

PROTOCOL

Method:

• Research has shown that many different types of cold stimuli work from CWI and cryotherapy to cold showers and even simply being outside

• Do what works best for you, start with cold showers if you are a beginner and then perhaps look into getting a cold plunge (you can get one for less than £100) if you have the space

Timing:

• Aim for a minimum of 11 minutes total per week of cold exposure

• That can be divided across the week however convenient, for example you can do 2 minutes a day, every day for 14 minutes total or perhaps 5 minutes, 3 times a week for 15 minutes works better for you - make it work around you

• Aim to do this earlier in the day as deliberate cold has energy and focus benefits, in addition to increasing core body temperature that can interfere with your sleep if done too close to bed time

• Avoid cold exposure for at least 4 hours after hypertrophy or strength training to avoid inhibiting some of the adaptations generated from the training session

Temperature:

• If you have a thermometer, evidence shows that less than 15 degrees Celsius is where the maximum benefit is to be gained

• Without a thermometer, you should aim to get the temperature cold enough where it is uncomfortable to stay in, but safe enough to do so for several minutes

• A useful gauge is also whether or not your body triggers the reflexive shock response - if not, its probably too warm

Useful Tips:

• Stay Safe: If you have never undergone cold exposure, start at higher temperatures and for shorter durations whilst your body adapts to the stressor. If you are taking a cold shower or plunge, start by immersing your feet and legs to get a feel for the temperature before putting the rest of the body in

• Remain moving regardless of the method used as our bodies create a thermal layer to insulate ourselves from the cold. By moving we can break up the thermal layer which makes the water feel colder - increasing the stimulus without needing to lower the tempature of the water

• If you have the time, the best way to maximise the benefit from the stimulus is to allow your body to reheat naturally. Avoiding ending in a warm shower or towel drying when you can, helps to really bolster the benefits