Let me be clear from the outset: I’m not saying that more running is always better, either for your running performance or the rest of your life. Obviously there’s a point where running more is an overall negative.
But most of us are never at risk of reaching that point. Even among longtime ambitious runners, most of us are in shape to get in shape—we’ve never really tested the limits of our running potential. And that’s fine. Certainly most of us have several other claims on our time and energy, and working twice as hard to improve another 10 percent as a runner might not make sense to you.
But it doesn’t follow from that acknowledgment that anything more than what you’ve become used to is a waste of time, or that experimenting with bumping up your set point will inevitably lead to injury or burnout. How do you know if you’ve never tried? Again, no one is saying you have to try. But if you want to, don’t be scared off by vague warnings of “overtraining” or “staleness.” Yes, when you try to push past your current limits, you might get tired. That will pass. As long as you go about advancing your running fitness intelligently, you can avoid injury while becoming fitter than you might have thought possible.