On a relatively cool 65 degree morning in San Francisco, Kurt laced up, found a hill-less six-mile stretch and destroyed his old personal best (50:12) for a 10K. The new PB: Just under 46 minutes, around a 7:25 mile pace. According to all the expert coaches I'm following, that means Kurt's VDOX is around 44. Potential marathon time around 3:32 to 3:40, depending on who you read, if the endurance training is in place and weather permits. Weather is always the biggest factor in reaching potential.
More important, the 10K time translates to a 8:37 MP pace at a comfortable 75% effort, or even an easier 9:03 at 70% effort, just to break four hours. However Kurt wants to run Chicago, the potential is there for a fast time if he stays uninjured (doesn't overtrain) and puts in the remaining longs -- a couple more 20s and a couple more mid-distance runs in the 13 to 15 range. Followed by a good taper. Should be good to go.
Boston qualifying time for late 40s is 3:30. That's a game day decision, based on weather, and a dangerous one at that. Running at that fine line between aerobic and anaerobic thresholds (80% effort) brings the Wall into play around 20 with lactic acid-soaked legs. You could end up at 4:15. But if you can drive that 10K down to 44-45.....the potential is there. I tried once from there (40:30 10K), ran 8s through 20, hit the Wall and ended up with a 4:02. You take your chances.
Training note: With a month to go before the taper, the tempo runs and longer MPs, where my legs are learning to efficiently move out lactic acid, would be key weekly runs, along with the longs.