Expert gives tips: Why half marathon training is not automatically enough for the marathon

If you've already successfully run a half marathon, you have a solid foundation—but the leap to a marathon is bigger than you think. Traditional half marathon training plans are usually tailored to a manageable distance: The long runs often stay under 90 minutes, and the weekly distance settles at 30 to 40 kilometers. That's perfectly sufficient to comfortably manage 21 kilometers. But anyone who attempts the full distance with this level of preparation is entering dangerous territory.

By kilometer 30 at the latest, the marathon reveals its true colors. Your reserves dwindle, your mind gets tired, and if you don't have a clear strategy, you're no longer fighting for a good time—you're fighting to finish. Without extended training runs, during which your body and digestion learn to cope with gels, drinks, and increasing fatigue, a slump is almost inevitable. And the so-called "tapering"—the targeted reduction of training in the final weeks—is completely missing from many half-marathon plans.

Long runs are far more than just crunching the miles. They're a key element of your marathon preparation, because on these runs, your body learns to work more efficiently. Your ability to use fat as an energy source noticeably improves, and glycogen consumption is optimized. The better your body can do this, the longer you'll stay in the "green zone" without premature exhaustion.

But it's not just about your metabolism. Long runs also train your gastrointestinal tract. Because during the marathon, you need to replenish energy, for example, in the form of gels or drinks. What works well at rest can quickly become a problem under intense exertion if you haven't practiced it regularly. And last but not least: your mind learns along with you. The sheer duration of the exertion challenges you mentally – and makes you more robust for what awaits you on marathon day.

The rule of thumb is: Longer isn't automatically better. In practice, long runs of no more than three hours have proven effective. Anything significantly longer often does more harm than good – because the risk of overexertion, exhaustion, and injury increases disproportionately. Instead of running extremely long distances once, you should regularly incorporate runs of between two and a half and three hours – ideally with integrated sections at your planned marathon pace and with genuine fueling training. This way, you'll not only strengthen your endurance but also train all the small but crucial details that determine your success over the 42.195 kilometers.

Your performance depends not only on running, but just as much on what you do outside of training sessions – especially how well you recover and how cleverly you supply your body with energy.

In the 36 to 48 hours before the race, you should specifically fuel yourself with carbohydrates (carb loading) – around 10 to 12 grams per kilogram of body weight per day. Sounds like a lot? It is – but it fills your glycogen stores to a maximum, which provides you with crucial energy during the race.

You also need to refuel during the run: 60 to 90 grams of carbohydrates per hour is considered optimal. It's best to combine glucose and fructose – this increases absorption while also being gentle on your stomach. Sounds technical? Maybe. But it makes the difference between a controlled finish and the dreaded "man with the hammer."

With all that training, don't forget about recovery. The more you train, the more you should focus on getting enough sleep, high-quality protein, and taking real breaks. Your body doesn't rebuild during training, but in the hours afterward. If you neglect recovery, you risk not only a drop in performance but also injury.

Tapering is especially important. In the last three weeks before the race, you systematically reduce your training volume – without completely inactive. Studies show that a well-structured taper leads to measurably better finish times. So, you won't get worse, but rather fresher. And that's exactly what you need when things get serious on marathon day.

A half marathon is a great milestone – no question. Competing 21 kilometers requires discipline, endurance, and willpower. But the marathon? It's in a league of its own. It's not just twice the distance – it's a different race, with different demands, a different pace, and a dynamic all its own.

If you're thinking about taking the leap to the 42.195 kilometers, you need some well-thought-out training.

Give yourself the time to truly prepare. Then you'll not only reach the finish line, but cross it with your head held high. Not exhausted, but proud. Not just a finisher, but someone who has truly mastered the marathon.