I was just thinking about back when my dad was an endurance super athlete. He would run 15-20 miles a day. Every year he would do at least a dozen marathons as well as a handful of adventure races. The adventure races would involve running, biking, swimming, kayaking, and orienteering and would total 100-200 miles depending on race. Most people who do adventure races divide up the task as a team, one person does running, one person does biking, one does the kayaking, etc. He would do them solo, and beat out many of the teams. In some small town races hosted by the local YMCA he would beat out all of the teams solo. He beat teams from all branches of the military. It must have been embarrassing to be a young Marine and have your squad badly beaten by some middle aged shop teacher from the sticks. He had a resting heart rate in the low 40’s.
In an unrelated note now all of his joints are artificial.