"Not all pain is significant."

The title is a quote from the first chapter of Scott Jurek’s book, Eat & Run. Jurek began the book with the story of his first Badwater Ultramarathon in 2005. In a later chapter, he’ll finish that story, with him winning the 135-mile race from Death Valley to Mt. Whitney, CA in a new course record—after he’d just run and won his seventh consecutive Western States 100 a short two weeks earlier. In this first chapter, Jurek used Badwater to introduce ultrarunning and the pain and everything else these runners endure over those kinds of distances. The chapter began with him lying on the side of the pavement, at Mile 70, puking away. It was 11 in the evening and still 105 July degrees. He then went on to matter-of-factly describe the various types of pain ultrarunners deal with, in vivid detail (e.g., tearing off toenails to relieve pressure from blistering), or ignore. “Not all pain is significant,” but, how does one know which is which?

Towards the end of my Paris morning run in August, after the last main sightseeing stop (Hotel des Invalides) and about a mile from my hotel, I felt something in the left heel. My immediate thought was that it was one of those occasional twinges that I would just run through, and it would eventually go away. I finished that run and had no problem walking quite a bit over the next couple tourist days. Four mornings later, after I'd returned home, I went out for an easy four mile run and immediately felt the pain in the heel. I was hobbling a bit the first few hundred meters but decided to keep going and see. Once I got warmed up, that heel felt better. Or, at least I thought so at the time. For the next two weeks, I pretty much couldn't run. Even walking was not normal. If I'd not run that morning and, instead, allowed my heel to recover from the injury in Paris, might I have been able to resume running sooner than in two weeks? How does one know when to run through pain and when to rest to allow faster recovery? I need more data points.