We did what the coaches called a "virtual" 20 mile workout yesterday morning. We actually only ran about 9 or 10 miles, but it was supposed to give you the same benefit as a 20 miler without the pounding damage to your legs. We started out by running around the top of Kezar at top speed for 25 minutes, and then did a 10K through Golden Gate Park at our marathon pace. The hard, fast run at the start of the workout was supposed to simulate a much longer distance at marathon pace. I don't know about 20 miles, though. It felt more like a "virtual" 13 or 14 to me.