Hyperbaric oxygen therapy (HBOT) has long been associated with the treatment of difficult wounds, decompression illness and radiation injury. More recently, it has gained attention for its effective role in neurological rehabilitation, sports recovery, boosting sports performance, and regenerative medicine.

Interestingly, one of the industries that has embraced HBOT for decades is thoroughbred racing.

In fact, HBOT has become so well established in elite racehorse management that many racing authorities around the world have introduced rules restricting its use immediately before competition.

Why?

The theory behind HBOT in racehorses

A racehorse represents one of the most extraordinary athletic performers on the planet.

During maximal exercise, a thoroughbred can reach speeds exceeding 70 km/h, placing enormous demands on the cardiovascular, respiratory and musculoskeletal systems.

The rationale for using HBOT is similar to that in human sports medicine:

• Increasing oxygen delivery to tissues

• Supporting recovery from intense training

• Reducing inflammation

• Enhancing tissue repair

• Assisting recovery from musculoskeletal injuries

• Shortening the time required between training sessions

While definitive evidence that HBOT directly improves race-day performance is limited, many trainers and veterinarians believe that improving recovery allows horses to tolerate higher-quality training over time.

Why do racing authorities regulate HBOT?

One of the fascinating aspects of HBOT in horse racing is that many international racing jurisdictions do not prohibit its use altogether.

Instead, they prohibit when it may be used.

Several jurisdictions have introduced rules preventing horses from receiving HBOT within a specified period—often 24 to 48 hours—before racing.

The reasoning is precautionary.

If HBOT has the potential to alter physiology, enhance recovery or improve readiness to perform, regulators seek to ensure that all competitors race under comparable conditions.

In other words, the concern is that HBOT may provide an unfair competitive advantage.

A fascinating contrast with human medicine

This creates an interesting paradox.

In elite horse racing, HBOT is considered sufficiently influential that its timing before competition is regulated.

In human sport, HBOT remains an area of active scientific investigation.

Currently, evidence that HBOT consistently increases aerobic performance measures such as VO₂ max, endurance or race-day performance in healthy, well-trained athletes is not established, however there are some promising results from research performed by the Efrati group. (Effects of Hyperbaric Oxygen Therapy on Mitochondrial Respiration and Physical Performance in Middle-Aged Athletes: A Blinded, Randomised Controlled Trial: Efrati et al, 2022).

Training recovery may be the real advantage

Elite performance is not determined by a single workout or a single race. The ability to improve VO2 max and aerobic threshold greatly improves the ability to push harder and recover faster.

If a therapy helps tissues recover more efficiently, and utilise oxygen more effectively, athletes may be able to:

• maintain training consistency,

• reduce time lost to injury,

• and return to peak performance sooner and/or improve peak performance

This is one reason HBOT continues to attract interest across professional sport, despite the limited evidence for direct performance enhancement.

What does this mean for the future?

The regulation of HBOT in horse racing raises an intriguing question.

If racing authorities believe the therapy has sufficient potential to influence performance that they restrict its use immediately before competition, what does this tell us about the biological effects of oxygen?

Perhaps the answer lies not in viewing HBOT as a "performance enhancer" in the traditional sense, but as a recovery optimiser.

Modern sport increasingly recognises that elite performance depends not only on training harder, but on recovering better.

Hyperbaric oxygen therapy may be one of several tools that support that recovery process.

As research continues to evolve, we are likely to gain a clearer understanding of which athletes benefit most, under what circumstances, and with what treatment protocols.

Until then, the racehorse industry offers a fascinating example of how seriously the potential physiological effects of oxygen therapy are regarded—seriously enough that many of the world's racing authorities have chosen to regulate its use before the starting gates open.

- Samantha Winters