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Oxygenated Water and Athletic Performance
To the Editor: Bottled waters described as "oxygenated" are sold with claims that they confer health benefits. The waters are advertised to contain 7 to 40 times more oxygen (O2) than ordinary water and to enhance exercise, with statements such as "enhanced sports performance"1 and "improves cardiovascular and muscle endurance"2 commonly used. We measured O2 in oxygenated water and assessed its effect on maximal performance during exercise.
Methods
We first measured the PO2 in 5 brands of bottled water advertised as "oxygenated" and compared the values with those of well-stirred tap water. Samples were obtained by inserting a needle into the bottles through the sidewall or cap and drawing water into a gas-tight syringe. PO2 was measured in triplicate using a blood gas analyzer calibrated into the hyperbaric range (Model 1604, Instrumentation Laboratory, Lexington, Mass). Water O2 content was calculated from PO2 with a standard formula.3
Participants were 11 healthy adults (7 men, 4 women; mean age, 35 [SD, 7] years). Each performed 2 standard maximal cardiopulmonary exercise tests on separate days at least 3 days apart. Five minutes before exercise, the participants drank in random order and double-blind fashion either 355 mL (12-ounce bottle) of oxygenated water (brand 5; Table 1) or a bottle of the same brand that had been deoxygenated by agitation in air. A graded maximal exercise protocol was performed on a cycle ergometer and measurements obtained using a computerized metabolic cart. Differences between exercise after consumption of oxygenated and ordinary water were analyzed by paired t test. Our study was approved by the Duke University institutional review board. All participants provided written informed consent.
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Table 1. Results of Water PO2 Measurements*
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Results
Four of 5 brands of water had PO2 values greater than that of tap water and 1 was similar (Table 1). The water with the highest PO2 (brand 5) was the only one packaged in a glass bottle. There were no significant differences in exercise results after participants drank either oxygenated or tap water for any measured variables (Table 2). Furthermore, the participants were unable to identify oxygenated water by taste.
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Table 2. Summed Data for Maximal Exercise Performance Variables in Participants (N = 11) Following Consumption of Oxygenated or Tap Water
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Comment
Of 5 tested brands of oxygenated water, 4 contained more O2 than tap water, but their O2 content was not great because O2 is relatively insoluble in water. The highest contained 80 mL of O2 in a typical 12-ounce bottle.
However, air is 20.9% O2, and a normal human tidal breath of roughly 500 mL contains 100 mL of O2. Thus, a single breath of air contains more O2 than a bottle of oxygenated water. Given that hemoglobin is already nearly saturated with O2 during air breathing, and that only a small amount of additional O2 can be dissolved in plasma, it is not surprising that oxygenated water did not improve maximal exercise performance. Furthermore, given the small amount of oxygen in bottled water compared with that in air, any benefit would likely be quite brief.
Acknowledgment: The Edward H. Morgan Chair in Pulmonary and Critical Care Medicine, Virginia Mason Medical Center, Seattle, Washington, provided financial support for this study.
Neil B. Hampson, MD
Section of Pulmonary and Critical Care Medicine
Virginia Mason Medical Center
Seattle, Wash
Neal W. Pollock, PhD
Department of Anesthesiology
Duke University Medical Center
Durham, NC
Claude A. Piantadosi, MD
Division of Pulmonary and Critical Care Medicine
Duke University Medical Center
1. hiOsilver Oxygen Water Web site. Available at: http://www.hiosilver.com. Accessed October 14, 2003.
2. BEVsystems International Inc Web site. Available at: http://www.lifeo2.com. Accessed October 14, 2003.
3. Lide DR, Frederikse HPR. Solubility of selected gases in water. In: CRC Handbook of Chemistry and Physics. 77th ed. New York, NY: CRC Press; 1997;6-3 to 6-4.
Letters Section Editor: Stephen J. Lurie, MD, PhD, Senior Editor.
JAMA. 2003;290:2408-2409.
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