Whether you're an athletic trainer, coach, nutritionist, physician, academician or athlete, you've likely heard somebody talking about oxygenated water for the athletic occasion.

What's the reason for adding oxygen to water and does the extra oxygen do anything for sports performance? We decided to dig deeper into the science behind these claims.

Sampling the Samples

According to manufacturers, oxygenated water delivers extra oxygen to the body to enhance metabolism and improve endurance.

One step in identifying whether a claim is authentic is giving further scrutiny to the composition of the products. If you take a look at the chart below, you'll notice that:

• Several commercially available beverages claim to contain oxygen in varied amounts, well above that contained in non-oxygenated water

• Most, if not all, oxygenated water products are packaged and sold in plastic. However, molecular oxygen (O₂) easily diffuses through plastic as plastic is permeable, or porous when it comes to retaining oxygen gas. Molecular oxygen eventually permeates through the bottle and is lost to the air. (Carbon dioxide in carbonated beverages stays in bottles because of its larger size.)

• The amount of oxygen measured is seldom higher than the amount you?d find in regular water, according to lab analyses.

*Reported by the American Exercise Council. Beverage temperature at the timing of testing was not reported but will have an effect on amount of gas dissolved in water.

Limits of Nature

Can oxygenated water add oxygen to the blood? It's doubtful. Blood carries the majority of oxygen in a form that is bound to hemoglobin and only a small portion of oxygen travels as gas dissolved in the blood. Since 98 percent of arterial hemoglobin is saturated, any oxygen the gut adds after drinking (according to manufacturers' claims) must travel dissolved in the blood.

However, the small amount of oxygen already present in the blood makes it very difficult for more oxygen to force its way in. Unless exposure to a hyperbaric chamber, for example, increases atmospheric pressure, blood cannot carry more oxygen.

This is further reinforced by the results of an unpublished study conducted by Texas Women's University in Denton, Texas. There, researchers did not see a change in oxygen saturation using pulse oximetry. If the waters truly delivered on their claims and added more oxygen to the system researchers would have seen an increase of oxygen in the blood.

This leads us to believe:

• There?s very little oxygen in the water.
• The intestinal tract does not absorb the oxygen.
• It?s difficult to detect the small amount, if any, of the oxygen that is absorbed by the gut.

Confirmation: No Benefit

Researchers from the University of Wisconsin at LaCrosse recently did a comparison study of super-oxygenated water and unoxygenated bottled water. They shared their findings at the American College of Sports Medicine meetings in June, 2002.

In the study, subjects drank 500 mL (17 oz) of either fluid. Fifteen minutes later, researchers measured subjects?:

• Maximum heart rates
• Maximal oxygen consumption ("max VO₂")
• Duration of time to max VO₂

The max tests were repeated shortly thereafter on the same day to see if either beverage enhanced recovery. Their findings? That there's no difference between beverages for performance, maximum heart rates, markers of recovery (blood lactic acid and ratings of perceived exertion) or performance after recovery.

Summary

The bottom line is that oxygenated manufacturers' claims have lots of theory and very little substance. Human physiology and science show us that oxygenated water won't elevate oxygen levels in the blood or muscle. While claims are enticing, they don't hold up when it comes to improving muscle metabolism and performance.

References

Ganong, W.F. Review of Medical Physiology, 8th edition, 1977, pp 494-500.

Porcari, J.P et al. Effects of superoxyenated water on exercise performance and recovery. Med Sci Sports Exerc 34:S295, 2002.

Anders, M. Drinkable oxygen? ACE FitnessMatters, Sept/Oct., pp 12-13, 2001.