Aabye ran his first Death Race when he was 62 years old, the oldest in that race. Brett Popplewell, author of a 2023 biography, calls Aabye "the world's oldest ultramarathon runner." Like other ultramarathons, the Canadian Death Race is a challenge for even experienced runners, with some needing to be rescued from hypothermia or treated for exhaustion. Racers are known to experience vomiting, loss of vision due to corneal swelling, and hallucinations. Aabye completed his first Death Race in 2003 in 20 hours, 58 minutes, and 16 seconds, but his fastest time was his third attempt in 2005, at 20:56:22. He last finished a Death Race within the 24-hour cutoff in 2009. He was consistently the oldest competitor in the Death Race, and has completed it a record-setting seven times. He continued participating in the Death Race every year; though he failed to finish the full 125-kilometre 24-hour race in those later years, he continued to complete the starting segment, the Near Death Marathon, which has a cutoff of 9.5 hours. His final Death Race attempt was in 2016, when he was 75.
