Moving from the 10K to the half marathon: how should you adapt your training?

What is the difference between a 10K and a half marathon?

Your running experience and recent 10K races have given you the confidence to step up in distance? Congratulations on your progress. A new adventure awaits over the half marathon distance. Moving up in race distance can be both challenging and motivating, as well as stressful. That is only natural when you are doubling the number of kilometres, right? By definition, a half marathon is half the distance of a marathon (42.195 km), or 21.0975 km. That is the main difference between the two race formats. More kilometres inevitably mean a longer time on the course. The 10K world record is held by Uganda’s Joshua Cheptegei in 26:38. The half marathon world record is held by his compatriot Jacob Kiplimo in 56:42. The duration of the effort is therefore more than twice as long, even for the world’s best runners.

When you run for longer, your race pace also changes compared with your 10K pace. The pace you work on during half-marathon-specific sessions will not be the same as your 10K pace. If you did not usually have a fuelling strategy for the 10K, you will need one for your first half marathon. Finally, although there are some similarities, 10K and half-marathon training are different, as is the recovery period after the race. You will need to devote a little more time to your half-marathon preparation and increase your weekly mileage gradually.

How long should half-marathon training take?

If you have already trained for a 10K, you probably spread your preparation over several weeks. Naturally, the length of the training cycle depends on many factors, particularly your running experience. For this relatively accessible distance, six weeks may be enough to complete a 10K. The half marathon requires a little more. Coming from the 10K, you have already built up a certain amount of mileage and gained race experience. To give yourself enough time to prepare for your half marathon, make a successful transition, avoid injury and enjoy race day, it is recommended that you follow an 8- to 12-week training plan. You can follow a specific training plan through the various coaching options available to you. This 8- to 12-week plan will allow you to build your mileage progressively and complete half-marathon-specific sessions at your target race pace. Naturally, depending on your availability and your profile, you may do more or fewer training sessions each week.

Adapting your training to increase the distance

Let’s take a closer look at how to adapt your training for your first half marathon. If you followed a plan for your previous 10Ks, you already have some understanding of how to train for a multi-kilometre road race. The foundations of half-marathon training remain fairly similar to those of 10K training: building endurance, working at race pace, long runs, rest, a taper and recovery.

➜ Easy running accounts for around 70% of your weekly volume. These sessions will help improve your endurance, meaning your ability to hold a pace over time. These are simply your easy runs.

➜ Specific sessions are essential for working on your race pace. For example, if your goal is to run a two-hour half marathon, your race and training pace will be 10.5 km/h, or 5:41 per kilometre.

➜ Long runs allow you to progressively increase your weekly volume. They are crucial because they get your body used to running for almost as long as your expected race time. During long runs, you can include some half-marathon race pace, for example 15 km with 20 minutes at half-marathon pace.

Moving up to a longer distance does not mean you should abandon speed sessions. Maintaining a few high-intensity workouts with shorter work intervals is strongly recommended. This will allow you to continue developing your maximal aerobic speed and, consequently, improve your various paces, from easy running to race-specific work.

The biggest risk when increasing the distance is injury: doing too much, too quickly, too soon. Do not neglect rest periods or progress gradually when increasing your training load. Including strength training is highly relevant for reducing injury risk and improving your muscular capacity.

Common mistakes to avoid

When moving from the 10K to the half marathon, it is easy to make certain mistakes. Here are the ones to avoid at all costs before your first half marathon:

✗ Increasing your mileage too quickly: the main risk is injury. It is better to do slightly less and complete your training successfully than to do too much and get injured before race day.

✗ Neglecting recovery: half-marathon training is much more demanding than 10K training. You will increase both the duration of your runs and your overall mileage. Do not forget to take rest days.

✗ Failing to test your fuelling strategy: arriving on race day without having tested your nutrition can lead to unpleasant surprises, such as digestive issues or energy dips. Use some of your long runs to test different products.

✗ Starting too fast on race day: remember, you are committing to an effort that will last considerably longer than a 10K. The first few minutes may feel easy, but that does not mean you should speed up. Stick to the pace you have practised in training and stay consistent from kilometre to kilometre.

✗ Ignoring the long run: if you think half-marathon preparation is all about intervals, think again. Long runs are essential for getting your body used to efforts lasting 90 minutes or more.

✗ Neglecting strength training: strength training is often the most overlooked part of training, even though it is so important. Reducing injury risk and improving your muscular capacity, strength, power and resilience are all good reasons to include it in your plan.

✗ Underestimating the importance of the mental side: when your legs can no longer carry you, your mind takes over. You can work on your mental game by using visualisation techniques with a mental coach.

The half marathon is much more than just another race: it is an ideal stepping stone between the 10K and the marathon. By taking on 21.1 km, you will discover a new dimension of endurance, learn to manage your effort more effectively and build a solid foundation for perhaps running a marathon one day. Do not hesitate to work with a coach as you make the transition from the 10K to the half marathon and enjoy a rewarding sporting experience.

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