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The Long Run: Marathon & Half Marathon Training

Updated: Jan 5, 2023

When you decide to take the leap into distance running, whether it’s a half marathon or a full marathon, the long run is the part of the training plan that makes most people second guess the training. The miles are long! The first time (or second, or fifth…) you see an 18-mile long run on the schedule, it can be daunting, and with reason that we’ll talk about in a little bit. But you can do it!

The most important thing to know about the long run is that it is not the end all be all to marathon training or even half marathon training. Is it important? Yes, but more mentally than physically.

Are you Overemphasizing the Long Run?

When you’re training for a distance race, you should be doing a variety of runs throughout the week that end in a weekend long run (for most people’s training plans). That means you’re doing a long run on legs (and a body) that has already done miles of running that week – and likely some hard miles with speed work, tempo runs, and some strength training thrown in.

While the long run is important to your training, it is not the only piece. If you are consistently missing your shorter easy runs or skipping strength training, you are playing a dangerous game with injury. When you consistently skip the easy runs and just keep building your long runs, overuse injuries such as shin splints, achilles tendonitis, and plantar fasciitis are close behind. You may be able to complete a training cycle, but it’s not a good plan for a long running relationship. If you are always skipping your strength workouts to get in the runs, again, you’re likely to get overuse injuries. It is better to aim for less distance or a less intense training plan that you can complete fully.

That being said, life and illness does happen. And one missed long run, or even a bad long run or one you cut short, will not drastically affect your race day outcome. The consistency over time of your training cycle is far more important. Did you miss one week when life got crazy but nail the rest of your training? Or did you miss one or two workouts every week of your training cycle? The answer to that makes a big difference in how race day will go for you.

My Experience with Focusing on the Long Run

I completed two full marathons where my focus was the long run. I would do what I could during the week, which was often a couple of 2-3 mile runs, but I got in almost every long run. I was able to finish both races. But not as strong as I wanted. In the first marathon, the Nike Marathon 2012, I pulled a muscle in my glute around mile 14 and hobbled my way to the finish line in a ton of pain and barely able to walk. It was pure adrenaline, stubbornness and determination that got me through.

Crossing the finish line at my first marathon, pulled glute and all

My second marathon, I knew I needed to run more miles during the week, so I did. But I didn’t focus on fueling for any of them, or the long run, in the way the marathon needs, so again, the race did not go the way I wanted. I hit the wall by mile 13 and struggled until about mile 18 when I finally took in enough fuel to finish the race.

I learned that the marathon is about the long run, but it’s also about all the other pieces of training – the week day runs, the nutrition, the strength training, and rest.

Why Do We Practice a Long Run?

The point in practicing a long run is to teach your body that you can. Although you physically get your body to that point through the training, you are also teaching your mind that you can too.

The long run is a physical challenge for our cardiovascular and muscular systems. We need to train them enough that they can cover the given distance at the pace we want on the given day. I think most runner’s accept that point.

But the long run on tired muscles, after a week of hard training, also teaches our brains that we can do it. The human brain is split into many parts. There’s the part that is in control of higher thinking, creativity, and metacognition. There is also the more reptile brain that is in charge of keeping us alive. This is the part we need to train.

The reptile brain is what tells us to stop when the run gets hard or long. It is what kicks in when we see a 10-mile long run or 20-mile long run and don’t even want to start.

By doing the run anyway and proving that although it is hard, we are capable, it trains our reptilian brain to know that we can do it again. And again.

It also shows the higher thinking brain that we can do this because we’ve done it before. If you want to read more about this, I highly recommend The Brave Athlete.

How long should the longest run be in half marathon training?

This really depends on your goal. To finish the race feeling good, you can train with a long run of 10-12 miles and accomplish that. If you are a more experienced runner and want to run a personal record in a race or are chasing a certain pace goal, you may want to increase your long run to a mileage of up to 15 miles. This mileage will accomplish both of the goals above.

How long should the longest run be in marathon training?

Again, this depends on your goal and what fits within your life. Anywhere from 16-20 miles as a long run will get you to the finish line of a marathon. If you’re running a 16 miler as your longest long run, I would recommend more weekday mileage so you are used to running on tired legs. One 20-mile long run can be beneficial for the mental side of training–only 10k left.

The bottom line of the long run

The bottom line is that the long run is important, but it is not everything in half marathon or marathon training. It is only a piece of the entire training puzzle that also includes easy miles, strength training, speed work, tempo runs, and recovery. You can still successfully run a race with one or two missed long runs over the course of a training cycle if the rest of the cycle is on track.

Questions about marathon or half marathon training? Send them my way,

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