Tag Archives: studies

Weight Loss

Some basic reasoning tells us that cold showers can assist in weight loss. Consider the acute effects of a cold shower. The water hits the skin and almost immediately the body jump starts; blood flow increases, muscles harden, and heart rate increases. All of these things require energy.

It may help to think of the body as a heat engine. A typical heat engine utilizes a hot reservoir and a cold reservoir to run a motor, as in the diagram below. Only, instead of a motor, the body runs various metabolic processes.

Why Your Body is Warmer Than the Environment

Why Your Body is Warmer Than the Environment

Like a heat engine, the body must transfer heat to the environment. Even on a blistering hot day, we transfer latent heat to the air by sweating. Internal body temperature is the “hot reservoir” of the heat engine, while the “cold reservoir” is the air (or water) that surrounds the body. Without this transfer of heat, the energy of all our metabolic processes would have nowhere to go.

The key is that the metabolic output (W), equals the amount of heat flowing from the hot to cold reservoir. Taking a cold shower or bath forces you to burn more energy. And by estimating water temperature, you could calculate approximately how much.

In a 2.5 year experiment, rats of equal age were gradually accustomed to standing in cool water (at 23° C, 73° F) until they were standing in it 4 hours per day, 5 days per week. Even though the rats ingested 44% more food than the control group, their body weight was significantly lower. Incidentally, their lifespan was also slightly longer (by approximately 5%), and they had significantly fewer tumor formations [1].

This also trains your physiology to deal with colder temperatures, raising your resting metabolism. This is similar to the effect of physical exercise. The only difference is that while working out raises it through a direct stimulus to metabolism (through will power), showering in cold water is more of an indirect stimulus.

[1] http://www.ncbi.nlm.nih.gov/pubmed/3781978

Athletic Recovery


Cold water can help alleviate inflammation and muscle soreness from intense exercise. The concept dates back to the tale of semi-legendary hydrotherapist Vincenz Priesnittz, who, seeing a deer hold a wounded limb in a stream, became inspired to heal the masses with his cold water treatment. Jockeys have known for years that cold water wraps and compresses can speed up recovery and help prevent injury in horses. There are a significant amount of studies, sponsored by the sports industry, showing that cold water immersion bestows some athletic advantages.

Muscle Soreness and Dysfunction

In an experiment at Loughborough University in the UK, researchers ran 20 young males through an intense drill of intermittent shuttle runs, a 90 minute session “previously shown to result in marked muscle damage and soreness”. Half the group was assigned to partake in cold water immersion immediately afterwards in 10 ° C water (50 ° F) for 10 minutes. The control group received no treatment. At regular intervals for 7 days, they measured:

  • Perceived muscle soreness
  • Muscular function
  • Efflux of intracellular proteins

The group that received cryotherapy (cold water immersion) reported less muscle soreness than the control group, and tested superiorly for certain signs of muscle damage. The researchers concluded: “The results suggest that cold-water immersion immediately after prolonged intermittent shuttle running reduces some indices of exercise-induced muscle damage. [1]”

Faster Recovery

Some studies have looked at how cold water therapy affects physical performance when used in between consecutive days of exercise. These include experimentation with treatment methods for players during a basketball tournament, and likewise between climbing sessions for experienced rock climbers.

The basketball tournament consisted of 29 males, mean age 19.1, playing for 3 days. The researchers aimed to see how different treatments affected performance in fitness tests such as vertical jump, sprints, and sit-and-reach flexibility. Out of three different treatments, they concluded: “Cold water immersion appears to promote better restoration of physical performance measures than carbohydrate + stretching routines and compression garments” [2].

The rock climbing experiment tested the performance of 13 females (mean age 27.1) who climbed an overhanging wall, twice, separated by 20 minutes of recovery. The recovery methods tested were:

Active Recovery – Riding a stationary bicycle.

Passive Recovery – Doing “nothing”, I presume.

Cold Water Immersion – The forearms and arms  were submerged (three periods of 5 min at 15 +/- 1 degrees C).

Electromyostimulation – The forearm muscles received a bisymmetric TENS current (a battery powered current commonly used to reduce perception of pain).

A number of trials over the course of several weeks showed that cold water immersion had a positive effect. The official conclusion was: “Active recovery and cold water immersion are two means of preserving performance when repeating acute exhausting climbing trails in female climbers. These positive effects are accompanied by a greater lactate removal and a decrease in subcutaneous tissues temperatures, respectively” [3].

Other Studies

Fitness Assessment (Soccer)

“In this study, we investigated the effect of water immersion on physical test performance and perception of fatigue/recovery during a 4-day simulated soccer tournament…. These results suggest that immediate post-match cold-water immersion does not affect physical test performance or indices of muscle damage and inflammation but does reduce the perception of general fatigue and leg soreness between matches in tournaments”.

Pre-Marathon Whole-Body Cold Shower

“To examine the effects of a prerace whole-body cold shower on muscle soreness (MS) and on serum creatine kinase (CK) and creatine kinase MB (CK-MB) isoenzyme activities, 16 experienced distance runners were randomly assigned to one of two treatment categories prior to running a marathon…. The results showed a marked (P < .05) difference between the cold shower group and the group without cold showers for CK-MB/CK ratio, and no difference for CK, CK-MB, and MS”.

Strengthen Immune System

immunesystemCold showers are sometimes touted as a preventative tonic for colds, flu, and infections. However, are these reported benefits just a placebo effect – the power of suggestion, or do cold showers have a direct and measurable effect on our immunity?

Once again, studies show at least some support for the popular wisdom. An experiment in Prague studied the effect of cold water immersions on athletic young men. They immersed them in water at 14 °C (57 °F), three times a week for six weeks. They concluded that the immersions activated the immune system “to a slight extent”.

Among many changes, they saw increased levels of two types of white blood cells: monocytes and lymphocytes. While certain lymphocytes are instrumental in eliminating bacteria, viruses, and toxins, monocytes are indirectly responsible for the engulfing and consuming of pathogens and foreign materials [2,3].

Considering these effects, it’s no surprise that mice exposed to 8 days of brief cold water stress survived significantly longer when exposed to the intracellular parasite, Toxoplasma gondii [4].

So, cold showers can help keep away the sniffles, but who knows what other nasty virus or pathogen you might also happen to ward off?

[1] Immune system of cold-exposed and cold-adapted humans.
[2] http://en.wikipedia.org/wiki/Lymphocyte
[3] http://en.wikipedia.org/wiki/Monocyte
[4] Cold stress-induced modulation of cell immunity during acute Toxoplasma Gondii infection in mice.

Activate Brown Fat



Babies typically have a constitution of 5% brown fat. It is one of their main mechanisms for staying warm.

Many people report that they feel warmer throughout the day after taking a cold shower or bath. This could partly be due to enhanced circulation, but the stimulation of brown fat also seems a likely cofactor.

Brown fat is one of two types of fat in the body – the other being white fat, or what we normally just refer to as “body fat”. While white fat should be kept to a minimum, brown fat is beneficial because it helps burn calories and generate body heat. A study at the University of Maastricht in the Netherlands revealed that obese people have less brown fat than lean people [1].

A cold shower could be a good way to stimulate the body’s supply of brown fat. A branch of the aforementioned university found that in men, exposure to chilly temperatures increased the metabolic rate of brown fat 15-fold. Sustaining this rate alone could help a person shed 9 pounds a year. Women typically have twice as much brown fat as men [1].

In a Chinese experiment involving voles exposed to a 5° C environment, they found that the “thermogenic capacity” of brown fat increased; the cold-exposed voles had a higher content of uncoupling protein 1 in their brown fat, increasing their ability to convert stored calories into heat [2].

However, in one small study of six men, the researchers did not find that their adaption to cold was facilitated by brown fat [3]. Hopefully future studies will find the most favorable conditions for activating brown fat and the precise benefits we can expect.

[1] Brown Fat: Don’t Try To Burn It
[2] Cold exposure does not decrease serum leptin concentration, but increases energy intake and thermogenic capacity in pregnant Brandt’s voles (Lasiopodomys brandtii).
[3] Effects of acclimitazation to cold baths on men’s responses to whole-body cooling in air.