Greg McMillian, a USATF-certified coach (His new book, YOU (Only Faster), is available on his website: www.mcmillanrunning.com) recently wrote an article in running times discussing how to fatigue proof your legs at the end of a marathon.
Excerpt from Running Times article
All marathoners know when they have power in their legs over the course of a long run or long race–and when they don’t. When leg fatigue does occur, it’s frustrating because your breathing is fine, your mind wants to push, but your legs simply won’t respond, or they cramp. Here are a few strategies to build fatigue-proof legs:
Higher Mileage Helps
If you can increase your mileage by 10 to 20 miles per week and stay healthy, your legs will be more resistant to fatigue in your next marathon.
Do Long, Long Runs
The length of a long, long run depends on the athlete. Faster runners (sub-3:00 marathoners) find that a 3- to 3.5-hour long run accomplishes the goal because this is well beyond the time they will take to finish the race. Many of us 3:00 to 4:30 marathoners find that simply running for the duration of our marathon goal time is sufficient. Because the recovery time is so great, I’m not a fan of superlong runs for slower runners, but they still must get in 3–4.5 hours to address leg fatigue.
Plan more of your runs over hilly courses and do hill workouts. This was the old-school method of strengthening the legs, and it still works. It’s also good to do some downhill training to condition the quads.
I really agree with what Greg has to say here especially from a physiologic standpoint. As a physician and surgeon with a background in athletic training, I understand how the body adapts to stress. Running 18 miles in preparation for a 26.2 mile event is not sufficiently preparing the body. I’m not saying you can’t run a marathon with one or several long runs of 18 miles ( I have done it) but the body needs more then this. Consider that you will be running almost 1 hour longer then your long run on marathon day. 1 hour! There is no logic from a physiologic standpoint to preparing for any athletic endeavor by not preparing for 25% of your race. 5k athletes run anywhere from 60-100 miles or more a week for an event that lasts for them 15 minutes. Now, I have read Hanson’s book on marathon training and it recommends not doing more then 16 to 18 miles in preparation. I just can’t agree with this. They make the standpoint to run no more then 25% -30% of your weekly mileage on a single long run. I agree on one hand, but I think you still need the physiologic adaptation from the long slow run. To make the argument more valid, I would say it would be the most beneficial and safest to reach 75-80 miles a week or more so that you long run is closer to 20 miles. The Hanson’s advanced marathon training program has the runner only peaking at 16 miles. That means you will have to go 10.2 miles farther the. What your body is physiologically adapted to and then attempt to race it! Not logical. This only leads me to believe that they are basing their recommendation on runners who are genetically gifted to run this distance.
Our bodies adapt to the stresses that are placed upon it through gradual adaptation. It’s pretty logical to say that if you want to improve your marathon time, them more miles both weekly and on long runs will increase he body’s endurance.