The objective is to build your endurance so that on race day you can survive the 26.2 miles of the marathon.
Begin by increasing your long run by only one mile each week. Continue to build this way until your long run is up to 12 miles at a slow and even pace. This pace should be one-and-a-half to two minutes a mile slower than your 10K race pace. Finish feeling that even though you're tired, you could have gone further if you had to.
If the foundation of your program is to develop a long run, what should you do during the rest of the week? The best answer to this question is to run only as much as leaves you comfortable.
The main goal is to recover completely so that you are eager to begin the next long run. It is quite adequate to run only three or four days a week. None of your mid-week runs need exceed five miles.
During this first phase of marathon training, if your weekly mileage starts in the range of 10 to 20 miles, and stays in this range as you push the long run up to 12 miles, that will do fine.
If it grows to about 30 miles a week that will be good too, but it should not exceed this figure during the early growth period. Too much or too fast will lead to an injury.
If you have trained only for 10K's you may not have worried about keeping hydrated during your runs. When you're marathon training you must drink regularly, especially since fall marathons involve training through the heat and, in many areas, humidity of summer.
During your marathon there will be water at about three-mile intervals. Learn to drink at least as frequently during training.
It doesn't matter how you manage the logistics, but it must be built into your training plan. Use water fountains, cache water along the route, carry money and stop at soda machines or stores, or make a deal with someone on your route.
(A Maryland club uses the water cooler at a riding stable and donates a case of bathroom tissue to help support the facility.) As a last resort, carry water during your run. You can buy a waistbelt that carries plastic bottles or carry your supply by hand.
It is important to eat plenty of complex carbohydrates during marathon training. Your endurance is only as good as your glycogen supply.
During the adaptation to distance training your body learns to supplement glycogen by burning fats. In spite of this the body can't function on fats alone, and shortly before your glycogen is used up you'll become exhausted.
The only way to avoid this is to load your muscles with glycogen throughout your training. This means eat plenty of fruits, vegetables, and whole-grain cereals.
You can also reduce your rate of glycogen use by slowing your pace. You see, fats are a higher-calorie fuel than glycogen, nine calories per gram compared to four. This means it takes more oxygen to burn fats compared with carbohydrates.
The way to make sure you maximize your oxygen intake is to slow down. If you run too fast you don't have time to breathe enough oxygen to use a high proportion of fats, so your body has to draw on more glycogen to compensate.
For your first marathon train at a slow pace. This will pay handsome dividends in the last few miles of the long runs.
It is easier to train with other runners. For mutual support run with a club or a group of friends. Hold each other back to the target pace. Don't let the weekend run become competitive. For the first-time marathoner, speed kills!
Out and back training on the same route can become boring. Change the route from time to time. Another way to make things more interesting is to run point to point.
You can car pool back in a car parked before the start of the run. In some areas you can run to a pre-arranged spot and ride back in public transportation. Variety can spice up your training.