2. Should you run a marathon before doing an Ironman?
The demands of a standalone marathon bears little resemblance to a marathon following a 2.4-mile swim and 112 miles on the bike—the only similarity is distance covered. I always urge athletes to consider triathlon as one sport, not three individual sports. You have to train to be a triathlete, not a swimmer, cyclist and runner. (If there were a single component of Ironman I would encourage athletes to do, it would be plenty of open-water swimming. Most neglect open-water training, then show up on race day anxious about the swim.)
A great reason to avoid a marathon is the extensive specific training that it requires to truly prepare for an effective 26.2 miles, coupled with the recovery needed to restore full health. It is simply not a wise use of your training preparation. Fear drives people to include a marathon, knowing that they “can do it,” but to truly establish increased confidence in your preparation you need to have a structured and progressive training plan. The only time you might want to add a marathon is at the end of a season, when you can specifically train for it, but this is for people who really wish to compete in a standalone marathon. Don’t expect it to translate to improved Ironman marathon performance.