Runner, 24, texted her father 'Ow ow' before collapsing and dying two miles from the New York marathon finish line

Rachel Apa, a 24-year-old former Division I field hockey player from Lewisberry, Pennsylvania, died from rhabdomyolysis — a rare condition in which muscles break down and release toxic proteins that overwhelm the kidneys, causing organ failure within hours. She had no prior health problems and had spent months training for her first marathon, fundraising for the Parkinson's Foundation in memory of her late grandfather.

When Apa collapsed at mile 24, bystander Michaela Nicholas, a hospital social worker, was quickly at her side, holding her hand and assuring her she was not alone, while two doctors carried out CPR until medical personnel arrived with a defibrillator.

Steve Apa had been sending words of encouragement to his daughter at every mile marker and had told her not to 'overdo it'; the final message she sent him — 'Ow ow' — arrived at mile 19, and she fell silent after mile 23.

Rhabdomyolysis proves fatal in five to ten per cent of cases; doctors warn that its early symptoms — swelling, weakness and dark urine — are easily confused by athletes with ordinary race fatigue.