Using your training log, compare the pace of your daily training runs and long runs now to those you did when training for your first marathon. This will give you a good idea of your current fitness. If your mileage and long runs are better now, you should also see improved race times at a variety of distances. A good measuring stick is the half-marathon. Assuming decent weather, double your half-marathon time and add 10 to 20 minutes for an idea of your marathon potential.
23. I've heard that the worst thing you can do in a marathon is "go out too fast." On marathon day, how will I know what is "too fast" and what will happen if I don't pace myself right?
If you go out too fast, two things will happen. One, you will increase body heat and thus dehydrate more quickly, and two, you will waste glycogen (stored fuel supplies) and thus run out of energy sooner. Going out too fast in a marathon sets you up for failure. Don't think you can build up a big time cushion by starting faster; this strategy usually backfires. The likely result is a long struggle over the last several miles or dropping out. A good bet for most first-time and casual marathoners is to start out at the pace you averaged for your last long run. Most experienced marathoners should start out at the pace they think they can average plus or minus up to 10 seconds per mile. If you start slightly faster than you think you can average and maintain that effort, your pace will slow a bit as the race progresses. That is, you will run with even effort but not at an even pace. If you start at the pace you think you can average, you will have to really hold back early on and work increasingly hard to maintain that pace. If you start slower than the pace you plan to average, your strategy should be to pick it up after you warm up and maybe even run negative splits (a faster second half than first half). With experience, you will learn which pacing strategy works best for you.
24. In the three marathons I've run, I've hit the wall and slowed dramatically the last 5 miles-particularly from mile 24 on-and felt terrible at the finish. I followed a schedule that included long runs, speed workouts, and a good taper. What can I do to prevent this from happening in the future?
You need to ask yourself whether your training-particularly your mileage and long runs-was adequate to support your goals. Look back at your training log and be honest. If you train and taper properly, carbo-load wisely, don't start too fast, and take in adequate fluids and fuels before the start and during the race (sports drinks and energy gels can be helpful, though you should try them first on long training runs), then you greatly minimize your odds of hitting the wall.