Kenny Moore is largely remembered for as a writer but just how great he was as a marathoner is often forgotten. He had a lifetime best of 2:11:36, set in 1970, held the American Record in the event before a fella named Frank Shorter came along to break it. He finished 4th in the 1972 Olympic Marathon, one of two he competed in. Kenny had some of the more interesting marathon training I have seen. Coached by Bill Bowerman who made each athlete an experiment of one rather than fitting guys to his program. Kenny was not nearly as exceptional at the shorter distances though he was an effective runner he was truly world class in the marathon.
This long run was one that Kenny would do in his marathon build ups. It is super hard and should not be attempted unless you are very fit. It is a great session for both the aerobic system and for teaching the body to burn more fat while running marathon pace.
Kenny would run 30 miles, not a typo, at about 7min pace as a consistent 2:11 to 2:13 marathoner this can only be described as a very easy pace. After 30 miles of very easy running he would run 6 miles at 5:00 pace, his marathon pace. This workout is not the most intensive you will ever find but it is one of the toughest extensive type workouts you can do. You will completely run your tank dry on this one for sure.
Most people will not be able to just go from regular long runs and traditional workouts to completing this session. I would suggest that in building up to this session you should do at least one 30 mile long run in advance of this session. Also you should do a "Rothlin" long run, http://nateruns.blogspot.com/2015/01/sunday-long-run-rothlin.html
Finally you may have to do the 6 miles as a 10x1k or 6x1mile at marathon pace the first time you do this session. Frankly you have to be quite close to ready to run your marathon at goal pace before you can succeed at this session so it isn't worrisome if it takes you a few workouts to build up to completing this session.
Why do this workout? The 30 miles of easy running burns the vast majority of your glycogen stores and tires you out muscularly, mentally and emotionally. In short it simulates the kind of exhaustion you can expect late in the marathon. When you shirt gears and start trying to run marathon pace your body is very aware that its glycogen stores are very low so it will automatically try to run the pace as efficiently as possible, meaning burning as much fat as it can. Once your body learns it can run a pace on more fat it will likely run that pace that way in the future. This will enable you to avoid the dreaded "wall" where you run out of glycogen and are reduced to training pace in the final miles of the marathon.
So if you are getting ready for a marathon and you are really fit why not give the Kenny Moore a try. Just be sure you have plenty of time to recover. You don't want to be doing a hard 36 mile workout a couple weeks out from your marathon. That would be a recipe for disaster. However 3 to 6 weeks out this may just be your secret weapon to fly by "the wall" to the finish.