My name is Katie, and I’m planning on running across the U.S. from Boston to San Diego starting this March! I’m 23 and have been an avid runner since high school. I train on my own now and am deciding whether to run 9-12 miles a day or kick it up to an average of 20 miles a day. I’d like to understand what the effects of the two choices would be. Under the 20 mile plan, I’d run long, slow distance with some walking. The 9-12 mile plan would be the same with less walking. If I’m going slow, would covering the extra 10 miles a day be harmful to my body? What is the risk of injury and long term health/bone problems if I did 8 months of 100 mile weeks compared to 12 months of 60 mile weeks?
Thanks, Katie, for your questions. While I absolutely applaud your ambition and dedication, I’m afraid my answer is going to rain on the parade. Although you may have a very compelling reason to go the distance (I’d love to know), I have to say that there’s no way this effort (either way you describe really) can be constructed as healthy. The only considerations left then are how you can mitigate the damage of your trek. Any elite/endurance athlete faces health compromises  as I’ve described in the past, and your case would definitely be subject to some of the hardest of those health concessions.
Some key questions come to mind also as I think about your situation. What’s your running background (e.g. distance training)? Are you trying to break a record? If not, is there a necessary time frame? If not, could you extend the duration and just walk? I’m particularly interested in your training plan and the inevitable toll it will take on you before you even leave Boston. Let’s say you train 100 miles a week for 8 months. In this case you’ll run some 3300 miles (more than the trek itself) just in training. The training, logic says, could be more damaging than the event itself.
I also wonder about your plans for fueling yourself. If you walked the trek, you could go 30-40 miles a day and manage it on a lower carb diet with careful planning and some dietary “training” (so your body can rely on fats and ketones). Otherwise, you’ll likely need a hefty amount of simple carbs to get you through your trek. Working at high levels of exertion day after day, month after month (the ultimate chronic cardio ) inevitably depletes natural glycogen stores and leaves you dependent on carb loading. Constant fueling with simple carbs, of course, boosts inflammation. The results? Loss of bone density and muscle mass, and increased susceptibility to just about everything under the sun. You asked about the risk for health problems. Check out my friend Art De Vany’s article that offers a detailed vision of what your body goes through in endurance training and events .
Everything from serious muscle damage, spine degeneration, kidney damage, and a shifting of biological markers that indicate cardiovascular stress, brain trauma and higher risk for cancer.
All this said, I understand there may be a reason compelling enough to convince you to move ahead with your plans (e.g. raise money for a loved one who has a disease). In good conscience, I have to caution you against the trek for health reasons that go far beyond usual athletic “primal” compromises. If other motivations keep you committed to the task, however, I’d urge you to take it slowly and use the PB to inform your diet and exertion plan along the way. In fact, this would be my ultimate suggestion to someone that wants to traverse the country by foot. Consider turning this into a truly Primal event. Imagine the goal is to migrate (instead of race) across the U.S., stopping periodically for push-ups and doing sets of sprints every few days along the way. This way you could stay on a high-fat diet to fuel your efforts and turn an unhealthy endeavor into something that is perfectly Primal. (And, it goes without saying, make sure you seek out expert medical observation throughout the trek.) Good luck to you, Katie.
As always, thanks for your questions, and keep ‘em coming!