In a rare medical case, a woman in her 70s was hospitalized with heat stroke after stretching in a sauna for 45 minutes.

A woman in her 70s experienced severe heat stroke after a 45-minute sauna session, causing her body temperature to dangerously rise to 107.6°F. She was hospitalized with multiple complications including seizures and kidney injury but eventually made a full recovery.

Most cases of heat stroke occur on hot days, due to overexertion, researchers say. However, “sauna use is a rare but potentially important cause of classical heat stroke,” Dr. William Jack McIver with Birmingham Heartlands Hospital in the UK wrote in a study published Jan. 7 in the journal BMJ Case Reports.

"Sauna use is a rare but potentially important cause of classical heat stroke," the doctors of a new case report warn.

Heat stroke is defined as a sharp increase in core body temperature above 40C that is associated with acutely impaired brain function.