Last fall, I decided to run a cross-country season for the first time in a few years. I started hammering a weekly over-hill-and-dale interval session with friends, and partway through one of these workouts—stop me if you’ve heard this one before, fellow middle-aged people—I felt a faint pop in my right hamstring. It didn’t feel terrible, but I’m a cautious guy. After a few seconds of denial, I stopped running and headed home.
The next morning is when the hard decisions started. I could feel the tweak in my hamstring, but was still capable of running if I wanted to. My target race was just over five weeks away. How should I weigh the risk of making the hamstring worse—perhaps bad enough to end my season entirely—with the loss of fitness that would begin to accumulate if I took time off? I’ve been running long enough to know that a few days off isn’t the end of the world, but I didn’t have a precise sense of how much fitness I’d lose with each passing day, which made weighing the pros and cons difficult.
There are a few different ways you can approach this. One is to model your individual training…
