What to know about rhabdomyolysis after death of 24-year-old NYC Marathon runner Rachel Apa

NEW YORK -- A 24-year-old woman has died after participating in the 2026 TCS New York City Marathon on Sunday.

The woman, identified as Rachel Apa, was given lifesaving measures on the race course before being taken by ambulance to a nearby hospital, where she later died, according to the New York Road Runners, which organizes the race.

“We are deeply saddened by Rachel’s passing following running in Sunday’s race," the NYRR said in a statement Tuesday to ABC News. "Our thoughts and sincere sympathies are with her family, friends, and the entire running community.”

Apa's cause of death was not confirmed by the NYRR. Her father told The New York Times in an interview published Monday that his daughter died of rhabdomyolysis, a life-threatening condition that can develop during physical activity.

“It’s unfathomable,” Steve Apa, who could not be reached by ABC News, told the NYT of his daughter's unexpected death. “Perfect health, perfect shape, 24 years old.”

Apa's alma mater, Bucknell University, also confirmed her death, remembering her in a statement to ABC News Tuesday, as a "four-year member and key contributor" to the university's field hockey team.

What is rhabdomyolysis?

Rhabdomyolysis, sometimes shortened to rhabdo, is a serious, life-threatening condition that develops when damaged tissues in muscles release electrolytes and proteins into the bloodstream, leading to nausea, vomiting, organ damage, seizures, heart arrhythmias or death, according to the Centers for Disease Control and Prevention.

The kidneys are particularly susceptible to injury or damage in rhabdo cases. They typically filter the blood and remove waste but when rhabdo develops, they are unable to filter the high amounts of proteins and electrolytes in time, which can lead to acute kidney injury or damage.

Who is at risk for rhabdomyolysis?

The CDC notes that anyone can develop rhabdo, including people who are in "great shape," such as athletes and marathoners.

People who are at higher risk of developing rhabdo include those who are exposed to heat or trauma or have physically demanding jobs, such as first responders and firefighters and servicepeople and outdoor workers, where the muscles can be damaged through overuse, by heat, or through accidents or other causes.

Others who may get rhabdo include people taking medications like amphetamines, statins, individuals with genetic muscle diseases, infections, low blood phosphate levels and low blood potassium levels or people who have undergone lengthy surgeries, according to MedlinePlus, a publication of the National Institutes of Health's National Library of Medicine.

What are the symptoms of rhabdomyolysis?

Rhabdo may look like other heat-related illnesses, including heat cramps and heat exhaustion.

In general, symptoms of the condition include aches, severe pains, like joint pain, muscle cramps, dark-colored urine, fatigue or weakness, and exercise intolerance or an inability to complete a task or finish an exercise one was previously capable of finishing, per the CDC.

How is rhabdomyolysis treated?

Anyone with symptoms of rhabdo should seek medical treatment immediately.

Treatment for rhabdo can vary depending on severity of injuries or organ damage. Milder cases require intake of fluids with bicarbonate, getting out of extreme heat, and rest, according to the CDC.

For more severe cases, treatment may include require kidney dialysis, medications, IV fluids or hospital intervention, to treat secondary conditions like low blood pressure, renal failure, chemical imbalances in the blood, seizures, arrhythmias, compartment syndrome, high potassium and more, according to Medline Plus.