The 20 mile run can actually be a step back in your training, leaving you in need of a recovery period that may take longer then the time left before your marathon.

The principals of training are basic. Stress the system, and then recover. During this recovery the body builds back up to a level stronger than previous to the workout. The body comes back to the next workout ready to easily take on the load of the previous workout. Actually, the body overcompensates during recovery preparing you for even harder workouts than before. Physiologists have shown that with a run of about 16 miles the body over compensates and prepares you to cover 26 miles. Depending on the individual, the recovery time for a run of 16 miles is about 2 weeks. The complete recovery time for 20 miles can be over 3 weeks.

Should I run 20 miles? Now that Ive laid down the argument for a 16 mile long run my answer is yes, go run 20. The marathon is a daunting distance at any pace. The mental and physical energy necessary to cover the distance is huge. 16 miles will prepare you physically but perhaps not mentally. I believe the 20-mile run is worth the risk. (Remember; it is a risk.) Talking your self through a 20-mile run during your peak training period when all systems are maxed will make for an easy 26.2 race day.

Randy Step

"People become what they expect themselves to become."
---- Mahatma Gandhi