Oxygenated water: Full of hot air?

Can oxygenated water improve physical performance? Yes, you did read that correctly—I did say oxygenated water.

What’s oxygenated water?

For the uninitiated, oxygenated water is water that’s been infused with oxygen gas. This involves adding extra oxygen molecules to the water through methods like bubbling oxygen gas through water or using specialised equipment to dissolve the gas into the liquid. Proponents of oxygenated water claim a host of health benefits, from improved athletic performance and increased energy levels to enhanced detoxification and better overall hydration. However, the scientific evidence supporting these claims is limited and often contested.

A study makes a splash

A recent study has brought oxygenated water back into the spotlight. So, let’s take a closer look at how it stacks up against these claims. 

The study used a double-blind, placebo-controlled design among 10 cyclists and reported that consuming oxygenated water improves time trial times by 2.4%, with even larger improvements (7.1%) seen in peak power during Wingate tests. These increases are fairly large—and such substantial effects can sometimes raise red flags.

These finding conflict with most previous literature, which isn’t always a bad thing, but it means we need dig deeper and examine any potential mechanisms accounting for this improved performance. It’s also worth noting the study was funded by Avrox, a company that sells oxygen-containing beverages. This isn’t a reason to dismiss the results outright, but it does invite greater scrutiny.

The 10 cyclists participated in two exercise protocols i) 30 minutes of steady-state cycling at 60% VO2 peak followed by a 16.1-km time trial, and ii) 4 × 30-second Wingate tests with 4-minute recovery intervals in between. During each test, they consumed either 500 mL of oxygenated water (called oxygen nanobubble) or a placebo beverage. 

Drinking your oxygen rather than inhaling it seems downright odd—right?. Obviously, the beverage ends up in the intestine, not the lungs. The primary way our bodies absorb oxygen is through our lungs, not our digestive systems. This fundamental point casts doubt on the supposed benefits of oxygenated water.

So how can this aid performance? The authors suggest oxygenated water might deliver supplemental oxygen—increasing oxygen availability for the exercising muscle. A big problem is that they fail to provide any evidence that the extra oxygen in the drink is actually utilised by the body. There were no between group differences in PO2 (partial pressure of oxygen, a measure of the amount of oxygen gas dissolved in the blood) or oxygen saturation. In fact, there weren’t any treatment effects on physiological outcomes such as blood lactate, pH, PCO2, or [HCO3−] during the time trial or the Wingate test.

An insightful editorial on this paper explained that even if the water was contributing oxygen, it would be small—about 15 mL. To put this in perspective, the mean VO2 peak for this group of cyclists was around 57 mL/kg/min. The athletes would have inspired about 75 L of oxygen during the 30 min of steady-state exercise prior to the time trial and a further 80 L of oxygen during the 16.1 km time trial itself. So even if the extra 15 mL from the drink was somehow used, it would account for a mere 0.01% of the oxygen derived during exercise through pulmonary ventilation (breathing!). So, we're talking about a drop in the bucket compared to what our body needs during exercise.

The Verdict

It’s hard to see how this would make a difference. The study authors do hint at the possibility of a placebo effect. Given the lack of any plausible mechanism or change in observed physiological outcomes, this seems a likely explanation. Or maybe it’s one of those chance findings we sometimes see with science. In the latter case, it’s crucial for researchers to replicate studies and confirm results to distinguish true effects from those that might be due to chance. This is particularly important given the small sample size and the limited details in the paper regarding the sample size calculation.  

Replication is a cornerstone of scientific research. Without it, we can’t be confident in the findings. So, while oxygenated water - packaged up in 'nano-bubbles' - might sound intriguing, the current evidence doesn’t support its claimed benefits. For now, it's best to stay sceptical and look for more robust evidence before making any conclusions about its efficacy, or worse, spending money on it.