If you're an injured runner, should you breathe in pure oxygen to hasten the healing process? That's what some sports scientists are recommending, as the inhalation of oxygen under high pressure (also called hyperbaric oxygen therapy) becomes an increasingly popular form of treatment for hurting athletes.
Several English football teams used hyperbaric oxygen therapy (HBO3) to treat their players this year, apparently with excellent results. In one case, an athlete with ligament damage reduced recovery time by 33 per cent with hyperbaric oxygen therapy, and a second player receiving hyperbaric oxygen therapy recovered in only four days even though doctors had predicted a three-week lay-off.
Why would hyperbaric oxygen therapy be helpful? First of all, hyperbaric oxygen treatment boosts white blood cell activity in damaged parts of the body, controlling infections. Hyperbaric oxygen therapy also tends to constrict blood vessels and decrease the amount of blood pumped by the heart. Although this sounds like a negative effect, it actually diminishes blood flow to an injured region, helping to reduce pressure and swelling. Even though blood supply is curtailed, the amount of oxygen actually reaching damaged tissues rises with hyperbaric oxygen treatment because of the surplus oxygen inhaled.
Over the past 20 years or so, hyperbaric oxygen therapy has been used fairly successfully to treat a wide variety of medical conditions, including gangrene, carbon-monoxide poisoning, and the decompression sickness sometimes experienced by deep-sea divers. Hyperbaric oxygen treatment has occasionally worked well for patients whose tissues have been damaged by radiation, and there's some indication that hyperbaric oxygen therapy could be a useful treatment for bone infections, cyanide poisoning, smoke inhalation, recurrent infections, bums, and traumatic 'crush injuries' in which body parts are mechanically squashed as a result of a car accident or a hard physical blow to the body.
However, scientific research concerning the effectiveness of hyperbaric oxygen therapy, much of it carried out in the former Soviet Union, has yielded somewhat mixed results. Overall, the studies suggest that after radiation treatments for malignant cancer, hyperbaric oxygen therapy can enhance tendon and ligament repair in damaged parts of the body but has much more limited success with restoring injured nerve cells.
Hyperbaric oxygen therapy has helped to lessen the impact of some spinal cord injuries in experimental animals, especially when the oxygen was given within two hours after a trauma-producing event. Hyperbaric oxygen therapy has also promoted the healing of gunshot wounds and boosted recovery in patients after nerve-tissue surgery. One study found that hyperbaric oxygen treatment initially limited pressure and swelling inside the brain after a traumatic head injury, although the effect was not long-lasting and pressure eventually rebounded to abnormally high levels.
Most relevant to runners in particular is a recent study in which hyperbaric oxygen therapy controlled the tissue damage associated with 'compartment syndrome'. Compartments are simply sections of the leg which are enclosed by tough, connective-tissue wrappers, and compartment syndrome is a condition in which fluid pressure rises to abnormal levels inside one of the compartments, sometimes producing nerve and muscle damage. It's a fairly uncommon affliction, but it does affect some runners. Unfortunately, this study was carried out with dogs, so it's not certain that hyperbaric oxygen treatment can effectively treat compartment syndrome in humans.
Other studies have found that hyperbaric oxygen therapy speeds recovery in rats suffering from injuries to the connective tissue surrounding their teeth, and that (thankfully) hyperbaric oxygen treatment is not toxic to the treated rats' testes.
Overall, hyperbaric oxygen therapy does seem to limit bleeding and swelling following traumatic injury. However. most running injuries don't involve bleeding, and they tend to be the somewhat limited 'wear-and-tear' type rather than the major catastrophes for which hyperbaric oxygen therapy has normally been used. To date, not a single published study has linked hyperbaric oxygen treatment with quicker recovery from injury in runners. There's also a potential downside to hyperbaric oxygen treatment: the increased tissue-oxygen levels may actually increase free-radical damage to muscle-cell membranes throughout the body (free radicals are chemicals which react destructively with the outer wrappers of cells; free-radical concentrations increase as oxygen levels rise). Although hyperbaric oxygen therapy is promising, it's simply too early to say whether hyperbaric oxygen therapy will one day be as popular as aspirin and ice among runners.