Which is harder: a 5K or a marathon? Ask a runner who specialises in either, and they’ll likely say it’s the other one. The truth is, both these distances can be seriously challenging — and training for one can help you improve in the other.

Here’s the secret: Even though the distances are wildly different (the marathon is equal to about 8.5 consecutive 5Ks), the training fundamentals for both are pretty much the same, says Nike Run Coach Jes Woods. “You’re going to have easy runs, you’re going to have a speed run, and you’re going to have a longer run,” she explains. “The workouts themselves will look different, because you want to train for the distance you’re racing, but the essentials don’t change.”

What it really comes down to is the difference between speed and endurance. For most runners, the 5K can feel like a sprint, where you’re red-lining right off the bat and holding on to goal pace for dear life.

A marathon, on the other hand, is a test of physical and mental stamina. That’s why Woods recommends starting with 5K training — even if your long-term goal is a marathon. “If you can work on your speed and get in shape for a 5K, that’s your jumping-off step-by-step point for longer distances,” she explains. “You can always layer on more miles and more time on feet, but really good 5K fitness gives you the freedom to explore the marathon distance.”

Wherever you are in your running journey, it’s helpful to know the key differences (and similarities!) between the two distances so you know what you’ll be up against in training and racing. We spoke with run coaches to compare the 5K versus the marathon side-by-side when it comes to training, race day, and everything in between.

“For a 5K, the key workouts are somewhere between your VO2 max and faster than threshold pace,” says Evan Schwartz, a certified coach. Your VO2 max pace is one that you can only sustain for up to about 10 minutes at a time, while threshold pace is one you can hold for up to about an hour. “The goal is to get comfortable at those efforts and then extend them,” he adds.

For the marathon, the main focus is on volume at a submaximal effort, meaning you’re pushing hard but not reaching your absolute limit. This allows you to rack up more volume with less recovery time, increasing your endurance. “The marathon is generally a test of duration, so the long run is the most important workout,” says Schwartz. “We’re trying to train your fitness to be at such a high level that it makes holding that planned race pace as easy as possible for as long as possible.”

In a workout, the volume may look similar, but the execution is different, says Woods. Take 1K repeats, for example: “If you’re training for 5K, you’re going to be running those 1K repeats at race pace or faster, with longer recoveries — two to three minutes — in between because it’s about nailing those splits versus building an aerobic base,” she explains. “Whereas a marathoner is going to do those 1K repeats closer to half marathon pace with shorter rest, like 90 seconds, because it’s more about hitting tempo pace and settling in.”

Even at 100-percent effort, “a 5K just isn’t going to beat you up as much as a marathon or even a half marathon would,” says Schwartz. “You could race every weekend and experiment with different types of pacing — going out at PR pace and seeing how long you can hold on one week, versus trying to negative split the next week.” (That’s not to say recovery isn’t important in 5K training; training at a higher intensity actually means prioritising recovery is crucial to avoiding burnout and preventing injury, adds Woods.)

The difference is in the runway with which you have to make adjustments. “In the 5K, there’s not a lot of margin for error and you really have to lock in,” Woods says. “But you have so much more time for strategizing and problem-solving in the marathon depending on the variables that pop up over such a long distance.”

One other main differentiator: the warm-up. “I really don’t like having marathoners warm-up for more than eight minutes with a really light jog; we don’t need to expend that extra energy,” says Schwartz.

On the flip side, if you’re running a 5K, you can benefit from warming-up with a “mini-workout.” “This will help you get off the line already feeling comfortable at 5K pace,” Schwartz says.

• Jog for 10 minutes.
• Run for 3 minutes at a pace that’s somewhere between marathon and half marathon pace.
• Run for 1 minute to recover.
• Run for 2 minutes closer to 10K pace.
• Run for 1 minute to recover.
• Run for 1 minute between 10K and 5K pace.

For example, while nutrition is important for all runners, it’s a crucial piece of the puzzle during marathon training. The average 5K runner finishes in about 40 minutes and a marathoner takes an average of four and a half hours to reach the finish line — way past the body’s time limit for storing the energy needed to keep running without slowing down or bonking.

Because of this, marathoners need to practice fueling strategies in training that will help them stay energised for the entire distance. On the other hand, 5K runners can avoid hitting the wall just by fueling at mealtimes and not going out too aggressively.

Also, while 5K runners may be training at a higher intensity more frequently, marathoners are typically racking up more volume (especially in peak weeks), which means their muscles, joints, and bones are subject to more repetitive impact. Because marathoners use more energy and sustain that higher impact for longer workouts, they need to be more proactive about recovery, which includes rest, but also nutrition and hydration.

It’s not just about how you treat your body. Whether you’re running a 5K or a marathon (or any other distance), mental training can be just as important as physical training. In both scenarios, you have to get comfortable being uncomfortable — in the 5K, that’s due to the intensity, while the marathon is all about duration/time on feet.

“Doing a 5K every other week for a summer lets you get better at the mental conditioning you need to push back against the part of your brain that says ‘I don’t want to’ — and you can easily compare your performance week over week,” says Schwartz. “With the marathon, being able to do good marathon pace work in your long runs is going to help a lot psychologically.”

Strength training is also key for both distances, but “it’s going to look different if you’re including that in your training for a 5K versus a marathon,” says Woods. Higher-intensity running warrants higher-intensity strength sessions, which means you need to include plyometrics for explosive power, along with heavy resistance training. Meanwhile, while you might do plyometrics when training for 42.2, it’s more about having a consistent strength training routine to support running a marathon so you can better handle the later kilometres of the race.

You may need a different mindset, but shifting your focus from the 5K to the marathon or vice versa can help push you out of your comfort zone. “It’s fun to do something different,” says Schwartz. “Switching things up lets you discover a different approach” — and that can potentially unlock new PBs in any race.

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