Should you quit taking cold showers, using cold water immersion, or icing those sore muscles after a workout?
-Increase in adiponectin
The hormone adiponectin is released from fat tissue in response to cold. The list of benefits from adiponectin read something like a “miracle drug," as it increases metabolism and fat burning, increases insulin sensitivity, induces mitochondrial biogenesis in muscle tissue, decreases systemic inflammation, relaxes epithelial tissue, relaxes cardiac tissue, kills certain types of cancer cells, and is positively correlated with longevity. Whew!
Research has shown that adiponectin triggers the release of free fatty acids from fat tissue and the uptake into muscle tissue to be burned as fuel. It increases metabolism without increasing hunger. As mentioned earlier, it increases the number of mitochondrial in skeletal muscle, and makes mitochondria more efficient in their generation of energy. This results in the production of fewer free radicals and reduces the chance of free radicals altering or mutating DNA.
Adiponectin increases the uptake of glucose into muscles, and allows nutrients to be funneled away from fat formation, and into muscle. It reduces inflammation and relaxes cardiac and epithelia tissue, and kills harmful junk cells and certain types of cancer cells via a natural process called apotosis.
Speaking of apoptosis, or programmed cell death that results in longevity, it been shown that direct exposure of fat to cold temperatures can cause the subcutaneous fat underneath the cold area to undergo cold-induced apoptosis, become inflamed, and be reabsorbed, resulting in a form of spot reduction of stomach fat.
-Increase in growth hormone
Cold exposure can increase levels of “heat shock proteins,” which increase growth hormone levels. Growth hormone is also inversely related to blood glucose levels, so by keeping glucose levels down via cold exposure before bedtime, you may maximize your natural growth hormone release.
-Increased immune system health
Glutathione, T-killer cells, lymphocytes, and a variety of other immune system cells and functions are strengthened and enhanced in response to cold (so no, cold exposure doesn’t make you more sick or susceptible to cold!).
-Increased insulin sensitivity
Cold thermogenesis can significantly enhance insulin sensitivity. Insulin helps nutrients to be transported into various body tissues such as fat and muscle. But insulin resistance is a condition in which your body’s cells do not efficiently respond to insulin, making you “resistant” to it’s function of transporting nutrients (especially glucose) into your cells. This results in chronically high blood glucose levels, obesity, and systemic inflammation. Insulin resistance is also a major contributing factor to development of Type-II diabetes, heart disease, and chronic metabolic diseases that affect nearly 2/3 of all Americans, including Alzheimer’s and cancer.
By increasing insulin sensitivity, cold exposure can cause nutrients to be pulled into muscles more effectively, fat to be burned by brown adipose tissue more effectively, a reduction in systemic inflammation, a reduction in insulin related diseases, and a potential for better nutrient partitioning and better storage of glycogen (storage carbohydrate). Cold stress amplifies insulin sensitivity, directing nutrients away from fat tissue, and instead shuttling them into muscle.
-Improved thyroid health
Your thyroid gland rests on the neck, near the Adam’s apple. It influences many other glands and organs, regulates body temperature, and controls overall metabolism.
Cold exposure has been shown to boost thyroid levels in animal models, and NIH funded experiments are currently underway to confirm cold’s effect on human thyroid levels as well.
Last week, you learned about a free sleep hack that involved putting your barefeet outside of the covers to cool your body and allow for more deep sleep and getting to sleep faster. In the same way, cold showers, cold baths and other forms of cold thermogenesis can enhance sleep, and make it easier to fall asleep and achieve a deeper sleep, especially if you use evening or nighttime cold exposure. Furthermore, in the same way that looking at sunshine in the morning can help send a message to your body to increase cortisol and to wake up, an invigorating morning cold shower may help “reset” circadian rhythms and allow you to more easily fall asleep later that night.
Ultimately, there is indeed evidence to suggest that when you’re doing a mild to moderate amount of resistance training, the frequent use of icing and cold water immersion may indeed blunt the training response, and possibly inhibit muscle and strength building.
But obviously, with the host of benefits that cold can provide, we need to consider far more than simply whether or not cold exposure can make infrequent exercisers strong or not. Do I personally plan on avoiding my morning “fat burning” cold shower, or quitting my habit of using cold baths or a jump into the icy cold river to cool inflammation and body temperature after an extremely difficult multi-hour workout? Not anytime soon, and especially not until I see a study that shows cold to actually inhibit the host of other benefits you’ve learned about in this episode!
If you have questions about whether cold showers and cold baths are really bad for you, then leave your thoughts over at the Facebook.com/GetFitGuy page!