The Cold Hard Facts | Part 1
The first installment exploring the science behind cold water immersion therapy
At Sunday Swim, our mission is to empower our community in the pursuit of a happier, healthier, and more vital lifestyle. Since the start of the New Year, we’ve been utilizing cold exposure to do just that. We view cold water immersion therapy (also known as cryotherapy) as one of our founding principles and one of our most powerful tools for positively affecting others' lives at scale.
Thus to kick off our newsletter, we will begin with the first installment of a three-part series exploring the “methods behind the madness”. That is, the cold hard facts about deliberate cold exposure.
The use of cold water immersion has a long and rich history. From the Edwin Smith Papyrus (3500 BC), to Ancient Greece (350BC) and Golden Age Rome (100AD), ancients physicians and medical practitioners have long understood the therapeutic effects of cold exposure. It was only until recently, however, that modern science has begun to gradually uncover the underlying physiological processes behind the power of the cold.
Today we will explore what happens to your body when you get in the cold water, as it specifically relates to Mental State (neural circuits/pathways) and Metabolism (core metabolic processes/body composition). We will then set the stage for the effect on Immune health, which will be discussed in depth in part 2.
Mental State: Energy, Focus, Mood, and Discipline
One of the most notable benefits of cold exposure is increased energy and focus. Deliberate cold exposure triggers a release of epinephrine (adrenaline) and norepinephrine (noradrenaline) into the bloodstream. These hormones are responsible for the fight-or-flight response, and can make us feel alert and/or agitated. This is why many people report feeling more energized after a cold shower or a cold swim.
The immediate spike in epinephrine and norepinephrine not only leads to feelings of increased energy and alertness, but actually improves visual attentional control (aka cognitive performance) for a period following this spike. A study published in 2018 showed that participants in this heightened state outperformed the placebo group in a series of mental tasks by a significant margin, displaying increase mental energy and sustained focus. So whether you have an exam, an important call with a client, or simply need to perform at your best, starting the day with cold immersion will likely benefit you throughout the day.
Cold exposure has also been linked to improvements in mood. A 2000 study published in the European Journal of Applied Physiology found that cold exposure increased the production of dopamine, responsible for the "runner's high," and serotonin, responsible for feelings of happiness and well-being. Increased dopamine release can last for as long as eight hours after cold exposure, and increased serotonin release can last for as long as 24 hours after cold exposure.
Finally, Cold Water Immersion therapy contributes to mental resilience, conditioning the participant to maintain composure under stress. It is no coincidence that cold immersion is heavily utilized within training protocols of the most mentally resilient organizations, such as the Navy SEALS notorious BUDS Camp. The ability to maintain mental clarity, calmness, and determinism under the intense stress/discomfort of cold water immersion directly translates to other situations wherein you are forced to perform under intense pressure/stress.
Metabolism: Core Metabolic Rate and Body Composition
Cold exposure has been shown to increase energy expenditure in two ways. Firstly, is the immediate energy output required to maintain body temperature in the cold environment. Although notable, this spike is not significant in relation to one’s daily metabolic output, and will not be enough alone to help someone lose weight, for example.
The second form of energy expenditure, however, is more significant and long-lasting. A 2014 study published in the journal CellPress found that cold exposure increased energy expenditure by activating brown adipose tissue (BAT), a type of fat tissue that is responsible for thermogenesis or the production of heat.
White fat cells have a low metabolic output, as they simply store energy for future expenditure (this is the fat you want to “burn”). Brown fat cells host tons of mitochondria, increase core metabolic rate, and burn white fat for energy output when you are in a caloric deficit.
Cold exposure effectively increases long-term metabolism and BAT activation, as norepinephrine binds to white fat cells and converts them to active brown fat cells. Thus, if one of your goals is to lose excess fat or improve body composition, routine deliberate cold exposure is a healthy and sustainable method for increasing energy expenditure.
Immune Health: Disease Prevention, and the Power of the Breath
Alongside the shock felt upon stepping into the cold, you may also discover changes to your breath. You experience a quick switched from calm steady breaths to deep and intense inhalations. This subconscious response optimizes the throughput of your respiratory system, alkalizing your blood with increased oxygen content.
As we will discover in next week’s article, the breath and the cold work in tandem. The power of breathing techniques have recently been found to go beyond what modern science previously thought possible, including an ability to directly affect the sympathetic nervous system, white blood cell count, and immune function.
Hope you enjoyed this article. Feel free to ask us questions on Twitter and Instagram and stay tuned for part 2.