In recent years there has been a burgeoning popularity in the use of cold exposure (whether it be air or water as the medium) due its much proclaimed health benefits. However, despite the noise surrounding it, the scientific literature regarding these health benefits is somewhat lacking.
A systemic review published on the 22nd of September has put this literature under the microscope.
104 studies were included in the review after a filtering process that disregarded studies due to certain factors such as water temp >20 degrees Celsius.
After trawling through these studies the researchers found that some of the claims made by the proponents of cold exposure have foundations within the research.
Cold-water immersion appears to reduce body adipose tissue, though the mechanism that this occurs through has not yet been fully identified (it seems to be a combination of the activation of brown adipose tissue and the shivering response to cold, both of which produce heat). The effect of cold-water immersion may also increase insulin sensitivity and decrease insulin resistance. This is thought to be due to an increase in the levels of plasma adiponectin, which is a peptide that is involved in the regulation of insulin and lipid oxidation.
The flow on effects of reduced body adipose tissue, increased insulin sensitivity, and reduced insulin resistance are profound, and indicated in a reduction in the risk of many diseases such as cardiovascular disease and diabetes. However, these downstream benefits may not only be related to cold-water immersion, as this review points out in its discussion.
Most of the 104 studies investigated by the researchers were done on a small sample size, usually of a single gender, with a skew towards people that are classed as ‘winter swimmers’.
Whether the benefits above were from cold-water immersion or were due confounding variables, such as a healthy study population, is unclear and unfortunately no solid conclusions can be drawn from the studies so far done on cold-water therapy.
With that being said, the area is one that is currently undergoing intense research, in no small way thanks to its popularity, and whilst there is still room for debate, it appears that the answers may well arrive sooner, rather than later.