The marathon is uniquely challenging. It is well more than twice as difficult as a ½-marathon and, in many ways, more difficult than an ultra. Still, for many runners, it’s the pinnacle of achievement. Why is it so hard?
Things start to happen between 13.1 and 26.2, both in the race and the training.
Seemingly well-fitting shoes and socks can develop hot spots and lead to blisters. Unnoticed imbalances can lead to twinges then to excruciating pain and injury.
Then there’s the wall. The wall is muscular as well as physical. While many can power through or fake it for 13.1, that’s very hard to do in a marathon. Almost inevitably your muscles will fatigue. Most marathoners aren’t adequately trained to run a full marathon strong. While you can survive a marathon at 30 miles per week (mpw), most runners need to do 60+ to be able to run strong (more on marathon training below). Lacking adequate training, your muscles will fatigue significantly, and you will struggle over the waning miles.
The other part of the wall is metabolic. While many can get by with little or no calories in a ½-marathon, almost everyone needs calories in a marathon. Even with frequent aid stations, it can be challenging to absorb enough and the right kind of calories to fuel your effort. You need to take in enough of the right kind of calories to keep the engine going strong without upsetting your stomach.
Just like in racing, things start to happen when you increase your mileage from 30 to 60+. Good shoes start to cause problems. Muscle imbalances and weaknesses are exposed. There’s a much greater risk for illness and injury. It takes a while to adapt to the increased training load. I would argue that it’s not just the mileage, the training load in your current racing season that matters, but as you move up to a marathon, it’s the accumulation of training over a few years that’s determinant to marathon success. In other words, the jump from ½ to full marathon may be best done over a few years. However, many make the jump more quickly.
Increased training means increased stress. That means your body needs more rest and sleep. Elites, running 100+ mpw (plus strength and form training) typically sleep 10-12 hours/day, and they are resting much of the rest of the time. Running is their job, their life. With the rest of us, running comes in addition to the many other activities and stress in our lives.
Proper pacing is difficult in a marathon. You may have a goal pace, but how do you know that’s the best pace for your fitness level? At the marathon distance, you have few if any opportunities to test your pace, your fitness level for a full 26.2. What seems good for 10, 15, or 20 miles (hopefully you’re not doing many that long at race pace) may not be good for 26.2, Even if you do get your goal pace right, it can be hard to get that pace right on race day. Crowds and excitement can make early paces hard to hit. Even if you do hit the early miles on target, those so-called accurate early splits may involve a lot of fatiguing varied pacing weaving through a crowd. It’s been said that every 10 sec/mi too fast you go the first mile causes you to slow 1:00/mi in the last 6mi.
Bottom line, training for and racing a full marathon adds significantly increased difficulty and risk over a ½-marathon.
Certainly, finishing and doing well in a 100mi race is harder than a marathon. However, there are elements of it that are easier to handle. By ultra I’m generally talking about distances well beyond a marathon, 50 miles and beyond, not just a “mere” 50km.
At faster paces and higher efforts, getting in and absorbing sufficient calories can be more challenging in a marathon than in an ultra. The harder your effort, the harder it is to digest, to handle the volume and types of calories you need. In 100 milers, I’ve eaten things like pizza and pb&J, things I would never consider nor could handle in a marathon.
If you crash in a marathon, you have less time to recover than in an ultra. Crashing is almost expected when you’re racing for 10, 20, 30+ hours. Many ultra runners learn to handle it and can come back to finish strong. That’s not the case with sub-ultra where once you crash, once you bonk, once your muscles fatigue causing you to slow or walk, your goals go out the window and it’s just about survival/finishing.
A marathon is difficult to get right. It deserves respect and eyes wide open going in. Understand the challenges and risks going in, and be prepared to deal with them, and you have a better chance for success.