Runner, 24, texted her dad 'Ow ow' miles before collapsing and dying near the New York marathon finish

Rachel Apa, a 24-year-old former Division I field hockey player from Lewisberry, Pennsylvania, collapsed at mile 24 of her debut New York City Marathon on Sunday and later died. She had been running in honour of her grandfather, who died of Parkinson's. Her father Steve confirmed that rhabdomyolysis was the cause of death — an uncommon condition in which muscle tissue breaks down and floods the body with toxins that the kidneys cannot cope with, something that can affect even fit athletes who push too hard.

Doctors caution that rhabdomyolysis announces itself through easily overlooked warning signs — swelling, weakness and dark urine — that athletes often brush aside.

A bystander sustained her with seven minutes of CPR before race medics arrived with a defibrillator; she was transported to Mount Sinai Medical Center, where she was pronounced dead at around 9:40 p.m.

'Perfect health, perfect shape, 24 years old — it's unfathomable,' said her father Steve, who had been texting her words of encouragement at every mile.