Are you Putting Too Much Emphasis on the Long Run as Part of Your Marathon Training?
The marathon long run is overrated.
In my experience, too many beginner runners (those training to run slower than 3:45) focus on trying to get in multiple 20 or 22 milers in their training segment at the expense of improving more critical physiological systems. More importantly, scientific research has shown that runs of over 3 hours offer little aerobic benefit compared to runs of 2 hours while significantly increasing injury risk.
As such, rather than cramming your marathon training schedule with multiple 20-22 milers that increase your injury risk and recovery time without decisive aerobic advantages, you should focus on improving your aerobic threshold, teaching your body to use fat as a fuel source, and building your overall tolerance for running on tired legs through accumulated fatigue.
Since the long run is such an ingrained element of marathon training, and suggesting they are overrated sounds blasphemous to many veterans, I am going to provide you with scientific research, relevant examples, and suggestions on how to better structure your training to help you run your next marathon faster.
The science of the long run
Most beginner runners training for the marathon are averaging anywhere from 9 minutes to 12 minutes per mile on their long runs (3:45 to 5-hour finishing time). At a pace of 10 minutes per mile, a runner will take roughly 3-hours and 40-minutes to finish a 21-mile run. While there is no doubt that a 21-mile run (or longer) can be a great confidence booster, from a training and physiological standpoint, they don’t make too much sense. Here’s why:
Research has shown that your body doesn’t see a significant increase in aerobic development, specifically mitochondrial development, when running over 90 minutes. The majority of physiological stimulus of long runs occurs between the 60 and 90 minute mark. This means that after running for 3 hours, aerobic benefits (capillary building, mitochondrial development) aren’t markedly better than when you run for only 2 hours. Therefore, a long run of over 3 hours builds about as much aerobic fitness as one lasting 2 hours.
Furthermore, running for longer than 3 hours significantly increases your chance of injury. Your form begins to break down, your major muscles become weak and susceptible to injury, and overuse injuries begin to take their toll. This risk is more prevalent for beginner runners whose aerobic capabilities (because of cross training and other activities), exceed their musculoskeletal readiness. Basically, their bodies aren’t ready to handle what their lungs can.
Not only are aerobic benefits diminished while injury risk rises, recovery time is significantly lengthened. The total amount of time on your feet during a 3-hour plus run adds considerable fatigue to the legs, which leads to a significant delay in recovery time. In the long-term, this means you can’t complete more marathon specific workouts throughout the following week, which I believe, and research has shown, are a more important component to marathon success.
Why is the 20-mile long run so popular
Given the overwhelming scientific evidence against long runs of over 3 hours, why are they so prevalent in marathon training?
- First, many people have a mental hurdle when it comes to the 20 mile distance. The marathon is the only race that you can’t easily run in training before your goal race.Therefore, like the 4 minute mile and the 100 mile week, the 20 mile long run becomes a mental barrier that feels like an obtainable focus point. Once you can get that 2 in front of your total for the day, you should have no problem running the last 10k, or so your mind believes. Unfortunately, this just isn’t true from a physiological standpoint.
- Second, the foundation for marathon training still comes from the 1970’s and 1980’s at the beginning of the running boom. Marathoning hadn’t quite hit the numbers it has today (you could sign up for most marathons, including Boston, the day before the race) and the average finishing time at most races was closer to 3 hours (today that number is near 4 hours). As such, the basis for how to train for a marathon came from runners who averaged close to 6 minutes per mile for the entire race. Therefore, 20 and 22 milers were common for these athletes as a run of this distance would only take them about 2.5 hours to finish at an easy pace.
- Moreover, the 20-mile distance is synonymous with “hitting the wall” or “bonking”. Hitting the wall frequently occurred at 20 miles because your body can store, on average, two hours of glycogen when running at marathon pace. Two hours for a 6-minute per mile marathoner occurs almost exactly at 20 miles.
In short, the basis for a lot of our understanding of marathon training is passed down from generation to generation without regard for the current paces of today’s marathoners. Therefore, we also need to reassess where the long run fits into the training cycle and how we can get the most benefit from training week in and week out.
How to train smarter
I suggest that you downplay the role of the long run if you’re training to run 3:45 or slower and focus instead on improving your aerobic threshold (the fastest pace you can run aerobically and burn fat efficiently) and utilize the theory of accumulated fatigue to get your legs prepared to handle the full 26 miles, without needing to run the full distance.
For example, you should focus on stringing out your workouts and mileage over the course of the week, rather than having 40 to 50 percent of your weekly mileage come from the long run, which increases the total amount of quality running you can do and decreases the potential for injury.
The question still remains, however, about how do you get your legs prepared to run for 26 miles?
The answer lies in the theory of accumulated fatigue.
- By shortening your long run to the 16 to 18-mile range and buttressing it against a shorter, but steady paced run the day before, you’re able to simulate the fatigue you’ll experience at the end of the race.
- In addition, when you have shorter long runs, you’re able to increase the total quality and quantity of tempo and aerobic threshold workouts throughout your training week. Instead of needing four to five days to fully recover from a 3-hour plus run, with a shorter long run, you can recover in one or two days and get in more total work at marathon pace or faster. Developing your aerobic threshold is the most important training adaptation to get faster at the marathon distance because it lowers the effort level required to run goal pace and teaches your body how to conserve fuel while running at marathon pace. The more work you can do to improve aerobic threshold and your ability to burn fat as a fuel source, the faster you can run the marathon.
- Finally, with a focus on shorter, more frequent long runs, you can implement faster training elements, such as fast finish long runs or surges, which allow you to increase the overall quality of your long runs. Running your long runs more intensely teaches your body how to run marathon pace while tired, and also increase your body’s ability to store energy for the end of the race and use fat as a fuel source more efficiently.
When you balance out the gains you can get from finishing a long run fast and upbeat with the potential drawbacks from an extended, 3-hour plus long run, you can see why a shorter, faster long run is the better training option for almost all marathoners aiming to finish over 3:45.
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