Does swimming in cold water make you live longer?

The data from animals clearly shows that exposure to cold temperatures increases longevity. 

As I mention in a previous post, longevity is increased quite a bit by living in cold water. A species of the freshwater pearl mussel is found at different latitudes. Those bivalve mollusks that live in the arctic Russian rivers exhibit five times longer lifespans compared to the same species that live in the warmer river waters in Spain (1).

Cold temperatures produce a positive effect on lifespan in cold-blooded species (2) as well as experimentally (flies (3) and mice (4)). For example, flies raised at  18 °C lived 148 days versus flies raised at 12 °C lived 247 days, 66% longer lifespan (3).

Furthermore, animals that use torpor (like reptiles) or hibernation (like bats) to reduce their metabolic rate and survive harsh winters depress their body temperature. Needless to say, animals that exhibit significant reductions in core body temperatures during hibernation enjoy longer lives (5).

Cold water swimming clearly has benefits (6, 7, 8). However, acute exposure to very cold water in persons unaccustomed to cold water swimming is detrimental and can be deadly, as it causes sudden changes in the cardiorespiratory system (increase blood pressure, heart rates, and a cold shock respiratory response) and predisposes to significant hypothermia (8). 

The key to getting the benefit of cold water swimming is adaptation such that the body develops compensatory mechanisms over weeks of graded exposure. Swimmers that have adapted to repeated cold water immersion have the ability to maintain core body temperatures (by lowering heat loss from the skin). They also avoid shivering (by using internal means of heat production), and have decreased "fight/flight" hormone activation.

In fact, habituated winter swimmers act as if it is business as usual, even at very cold water temperatures. Their body does not need to generate as much internal heat as individuals that are not cold-habituated.

What is fascinating about swimming in cold water is the plethora of positive effects that are induced. The following metabolic effects have been noted (6, 7):

• Decrease in oxidative stress markers, cortisol, homocysteine, and insulin
• Increase in anti-oxidant enzyme concentrations
• Increase in multiple immune system elements
• Shift from glucose to fat metabolism
• Increase blood flow to brown adipose tissue and the use of free fatty acids for heat generation
• Higher levels of adiponectin. This protein is produced by fat cells. Higher levels have been linked to lower age-related disease. Centenarians have elevated plasma adiponectin levels
• improved cardiovascular risk factor markers

Of note, these positive effects are more pronounced in open water swimming. Unfortunately, swimming in pools has the disadvantage of being exposed to chlorine and organic matter byproducts (8). 

When you have adapted to the cold water, your body does not have to go into "fight or flight" mode. This condition revs up negative metabolic energy.

In many ways, adapting to cold water through regular exposure brings about the same positive metabolic changes that are found in bats (5) and whales (9).

And who wouldn't want to emulate the longevity that is seen in bats and whales.