A potential explanation is that pressurized cabins may reduce the physiological problems that stem from low pressure and high altitude, the authors write. Even if oxygen saturation dips slightly, it may not be enough to lead to worse health outcomes.

In addition, healthy, fit people such as trained athletes and military cadets may be more likely to acclimate to the physiological changes that occur during flight.

A limitation of the study is that the symptom evaluations didn’t occur immediately after flights, so the research team can’t say whether flying affects short-term concussion symptoms. In addition, only a small number of athletes flew within six hours of injury, took long flights or crossed multiple time zones.

Future research could indicate whether flying immediately after a concussion, cross-country flights or international flights are more likely to affect concussion recovery.

“Oxygen saturation declines significantly in athletes during long-haul commercial flights, in response to reduced cabin pressure,” said Dr. Celeste Geertsema, a sports medicine specialist who has worked with numerous national and international teams in New Zealand. Dr. Geertsema, who wasn’t involved with this study, has previously researched the effect of commercial airline travel on oxygen saturation in athletes.

“The concern is that altitude exposure may exacerbate hypoxemia,” which can affect blood flow in the brain, said Dr. Geertsema, who is now with Aspetar Qatar Sports and Orthopaedic Hospital in Doha. “Several studies have documented the immediate and delayed physiological effects of altitude exposure, but longer-term changes still remain unclear.”