Marathoners aren't made overnight. Runners become marathoners with intelligent and consistent training

Due to the wonders of modern technology: wireless technology and a laptop I am currently lounging in bed listening to the wind outside and generally pondering life.
I noticed from CMJ's blog and Secret Squirrel's blog that my extract from Road Racing for Serious Runners (Pfitzinger/Douglas) seemed to cause some interest so I thought I'd dust it off and have another look to see what they say about marathon training.
I mentioned about 'stimulating the physiological adaptations that are crucial to marathon success', but what does that mean? According to my two new best friends (Pfitzinger/Douglas) marathon running requires lots of pure endurance (doh), the ability to store a large quantity of glycogen in your muscles and a high lactate threshold.
Endurance training gives you increased capillary density and increased ability to use fatty acids, i.e. to burn more fat than carbs at a given running speed. This means that glycogen (stored form of carbs in the muscle) is spared which means you can run further before depletinig your stores. Glycogen availability is a limiting factor in performance, basically, you need it!
Also, endurance training helps you to adapt to store more glycogen. Long runs deplete your glycogen stores which provides a stimulus for your muscles to store more glycogen so by increasing your long run distance and your weekly milege you increase the capacity of your muscles to store glycogen.
A high lactate threshold (lactate doesn't start accumulating in your muscles and blood until you reach a high % of your VO2 Max) can also be stimulated by the right training.
So there, it's interesting stuff...