Let me tell you something you already know. The marathon is not the half marathon. When training for a marathon, don’t train the same way you did for the half marathon. You’ll wish you hadn’t, at mile 20, while walking, and cursing the marathon. That was my experience for my first few marathons. Someone once told me that I was training for the marathon the same way I trained for the half and I didn’t make the connection.
The half marathon requires a lot of LT/Tempo paced runs. You need to get good at buffering all that lactate and the more tempo you do the better. The marathon on the other hand is less about lactate threshold. You’re not running nearly as close to LT pace during the race so pushing the envelope isn’t important. I’m convinced what is important, is building up endurance and efficiency at marathon race pace. VO2max and LT help, but they’re just a part of the equation.
It’s the same thing as comparing the 5k to the half marathon. You might have the speed to run an awesome 5k, but if you don’t have the endurance you’re going to flame out before you cross the finish line. I’ve done that too. I’ve run a 1:20 while taking a couple walk breaks.
More mileage! Shock, you need to run more to prepare for the marathon. Even if it’s junk miles, it’s slow, it’s that extra 45 minutes you had laying around. Every mile helps. You need to run longer runs as well. I think I ran mid-week 5 milers for my first marathon. I thought it was a lot at the time because it was. Now my mid-week runs are in the 7-12 mile range. I can run 10 miles at an easy pace and feel completely normal within a couple minutes of stopping. Just getting used to being on your feet that long does amazing things for your endurance. And that kind of endurance that makes the marathon distance manageable.
I guess I should include the obligatory paragraph on how your body can’t actually store enough energy to get you through the marathon. This is why efficiency is so important. The better your body gets at working at race pace, the less energy you burn and the longer it’ll be before you hit the wall. If you’re good enough, you’ll take in enough gels to offset the difference and you may not hit the wall at all!
I’ve always been a speed guy. The endurance has taken a lot of time and effort. If you’re a speed guy/girl too, just keep packing on the miles and you’ll eventually get there. Take the time to build the efficiency and you’ll knock your marathon out of the park!