There are two interrelated, but at this point, independent reasons for this.
First, I sprained the posterior deltoid ligament on the inside of my right ankle in mid-February. Since then, I have potentially re-aggravated it twice, once by running Zumbro and withdrawing after tweaking it going down Ant Hill (after getting medical clearance twice to run the race, the second time agreeing to pull the plug at the slightest change in ankle circumstances). The second aggravation came on May 5 after I had run a couple days to test the ankle - a kind of "if you're going to run Bighorn, you need XX many hours/wk for X weeks before race day" mentality to see what I could do physically. After 3 days of slow 90 minute trail runs, the ankle did not appreciate me and had swollen in the front - a new location - and I decided to shut training down, do only ankle exercises, and wait for the sucker to heal.
Second, I have not run consistently since about mid-February. This was caused by issue number one, but I did try several times to consistently hike or otherwise be active. I eventually shut this down on May 5 after a series of three runs left my ankle swollen and stiff in areas not initially injured.
My plan was before today to shut down training for the rest of May, and see how I felt and wait as long as possible to make the decision to start or DNS. But doing that shows no respect for the course, other runners, or the race directors and their volunteers. Bighorn is a mountain 100 that starts a 3,000 feet and spends much of the race at or above 7,000 ft. I live and train at 900 ft above sea level. It is a qualifier for Hardrock - the board of which having tightened their standards in recent years - for a reason. I have not paid my dues to run this race in 2017.
Regardless of the condition of my ankle now or on any day for the next five weeks, I am in no shape to attempt toe the line at Bighorn. I lack the requisite physical fitness and preparation my mind demands of me, and that is but one more hole in a 100 mile racer's armor that the course and conditions will exploit with every step. I will not subject myself or my family to a race I have no expectation of finishing (of course, excepting the Barkley Marathons here...).
What other options were there? 1) Do nothing and race if it felt good on our departure day, the Sunday before the race; 2) Do nothing and pick an arbitrary other day in June or perhaps May by which I needed to make this decision; 3) Train more and risk re-injuring the ankle? None of these are particularly palatable. Throw in my planned family vacation to coincide with this (going to Mt. Rushmore and Black Hills, and in/around Sheridan and the Bighorns etc. in the week before the race), and you add more complexity to this - my decision affects myself and my family, and I don't want them left holding the bag for a DNF. It is a long drive back from Dayton/Sheridan, Wyoming to the Twin Cities metro area.
What other potential outcomes were there? 1) start and finish the race with no ankle complications. This outcome was not viewed as likely; 2) start the race, DNF for ankle injury, or even finish with an ankle injury. This outcome was viewed as much more likely, and it risks throwing out my entire season, or worse, putting me in this same situation for Superior 100 - being healthy, or believing I'm healthy, but without a summer's worth of training to show for it. None of these options was good.
What's next? Back to the doctor, me thinks after I have taken four full weeks off of this ankle. I fear he'll either a) tell me to do nothing until I can do certain movements without discomfort, however long that takes; or b) send me for an MRI and then who knows what the radiologist will say.