Joy Johnson, of San Jose, was the oldest woman to complete Sunday's marathon.
Her sister Faith Anderson said Johnson stumbled and hit her head on the road at about the 20th mile.
Anderson told the Daily News (http://nydn.us/1hgv0Hg) that medics wanted to take Johnson to the hospital but she insisted on continuing the race.
On Monday, Johnson felt tired and lay down on her bed at her hotel. She never woke up.
She was pronounced dead at Bellevue Hospital.
The city medical examiner's office said Tuesday that Johnson died of complications of blunt trauma.
Organizers said Sunday's race was Johnson's 25th New York City Marathon.
