In recent years, water that has been treated with additional oxygen has been marketed as both a sports drink and as a general nutritional supplement. These oxygen-enhanced water products are popularly known as oxygenated water or oxygenized water, depending on the particular manufacturer. The substances are marketed commercially under a variety of trade names.
Oxygenated water is a product whose appeal can be traced to the rise of the marathon and the triathlon as mass participation sports in the late 1970s and early 1980s, developments that sparked the formation of the international sports drink industry. By the late 1990s, sports drinks had established a significant niche in the health and nutrition marketplace as a whole, with advertising campaigns that took clear aim at both athletic and non-athletic consumer targets. Sports drinks have been subsequently marketed not simply as a rehydration tool for the active athlete, but also for the inherently healthy formulations that is claimed by their producers.
In a similar fashion, oxygenated water, like mineral water, is claimed to promote better general health among its users. Its proponents also advocate oxygenated water as a supplement that will significantly enhance athletic performance, particularly in endurance sports.
Water, both in its pure laboratory form and in its natural state, is a fluid, a molecule created through the binding of two hydrogen atoms and a single oxygen atom. The chemistry of water is expressed as the formula H2O. Oxygen in its elemental state is a constituent of water, but that oxygen is tightly bound to the hydrogen atoms within the water molecule; this oxygen is not capable of any release from the chemical structure in a sports drink in a fashion that the body can use in the production of energy, in the manner that oxygen inhaled through the lungs is subsequently transported by the erythrocytes (red blood cells) in the bloodstream. The oxygen added to an oxygenated sport drink is injected into the fluid under pressure and bottled.
The theory in support of oxygenated water as a training aid is the more oxygen that a person can consume, through any means, the more oxygen will be directed into the cells of the body. Once it enters the stomach, oxygenated water will be ingested through the small intestine. The cardiovascular system will transport the additional oxygen to the cells that need it, as with any other nutrient. As a result, the oxygenated water will enhance athletic performance, stamina, and overall energy levels, because the cells have more oxygen available to them to metabolize its energy stores.
A number of scientific studies conducted since the late 1990s concerning the benefits of oxygenated water have reached conclusions that counter the claims of the water manufacturers. All of these studies confirm the physiological proposition that oxygen carried into the stomach through the water consumed will not enter the bloodstream, as this oxygen will never pass beyond the membranes of the intestine. None of the studies conducted found any observable difference in the heart rate or overall cardiovascular function in persons using oxygenated water.
The American Council in Exercise was one research group to conclude that the only method by which oxygen could reach an energy-producing cell would be by way of the hemoglobin present in each erythrocyte, or by way of the tiny amounts that might be dissolved in blood plasma. Hemoglobin is the oxygen carrier present in every red blood cell. As the hemoglobin is at all times saturated with oxygen (as much 95% capacity) through the normal oxygen transport processes centered in the exchange mechanism situated in the alveoli, the tiny air sacs within the lungs, the oxygenated water has no delivery mechanism available to it.
Confirmation of the research critical of the oxygenated water industry claims is also supported, in a more oblique way, through the controversies regarding the illegal use of the hormone erythropoietin (EPO) by endurance athletes. EPO is the natural hormone that spurs the production of greater numbers of red blood cells to increase the body's oxygen-carrying capacity. The considerable body of science concerning EPO confirms that the only method by which oxygen capacity can be increased in an athlete is through increasing the number of erythrocytes available in the bloodstream.
While the athletic performance-enhancing claims made with respect to oxygenated water may be of questionable scientific validity, there is also the placebo effect of such products to be considered. Unlike many other sports supplements, pure water is not inherently harmful, and the consumption of oxygenated water is safe. The cost of these products aside, oxygenated water is a proper method with which to obtain the daily recommended water consumption levels. If the athlete believes that he or she is obtaining a physical advantage through the consumption of oxygenated water, the athlete may have created a personal psychological edge.