A Bowling Green football player who died after becoming ill at practice last week died of a condition related to sickle cell disease, a coroner said Tuesday.

Aaron Richardson, 18, died last Wednesday of hemoglobinopathy associated with sickle cell, said Wood County Coroner Douglas Hess. The condition prevents blood cells from carrying enough oxygen to the body.

Richardson passed a physical Aug. 23. The university requires new athletes to complete a health history questionnaire and health insurance form before scheduling the physical. Hess said Richardson didn’t list sickle cell on his medical records. It is possible for people to carry the trait for years and not know it until they have a health crisis, Hess said.

The day of his death, Richardson had run half-speed sprints for 10 minutes and complained of calf cramps. He left the field with an assistant coach and went to the locker room. He later became unresponsive and was pronounced dead at Wood County Hospital.