I went along as handler for a friend at a couple of Old Dominion 100s in the 1980s. The then course took the runners over Massanutten Mountain somewhere around 80 or 85 miles in, and the one year runner could be accompanied for the last 25 miles, the other year for the last 33. The first year I didn't need to accompany for my friend dropped out because of the brutally hot weather. The later year, I split the companion duties with my brother.

The thing about ultra-distance races is that the exhaustion can affect the judgment, and the runner and the race are better off having somebody with judgment unimpaired along.