How to progress from 10K to half marathon

Thinking of progressing from 10K to half marathon? Here are the key ways to achieve it

10k to half marathon

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The half marathon is one of the most popular race distances for runners. For many, it represents the sweet spot of being a significant endurance test while also fitting in to a runner’s wider life more easily than training for a marathon. That said, the step up from 10K to half is still significant and requires respect. Whether you’re coming off the back of recent 10K training and preparing for your first half or searching for a PB, this article includes my top tips to achieve your best 21.1K.

The demands

10k to half marathon

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Good-quality 10K training shares many of the same components as half marathon training, or even marathon training. Both distances rely to a large extent on aerobic energy production and thus are tests of endurance as opposed to speed.

As such, a general foundation is required before we worry too much about the differences in sessions and training structure. This would include a good pattern of easy runs between 30 and 75 minutes at a low intensity (where conversation is easy). It might include some short, fast hills over eight to 12 seconds to help build speed and power. Regular strength training or even a circuits session can be a great addition to this foundation period. Occasionally, you might include a run where you increase your effort to ease yourself into the faster training later in your plan. Despite these similarities, there’s no doubt that, being over twice the distance of the 10K, the half marathon has some specific demands runners need to prepare for.

Below the tipping point

Running a 10K and a half marathon impose some slightly different metabolic demands due to the differences of intensity and duration of each. For most experienced runners, a 10K is actually run at an intensity that pushes beyond the ‘lactate turnpoint’. This means that, during a 10K, you’ll be burning quite a lot more carbohydrate and generating fatigue at a much more rapid rate than during a half. A half, for all but the fastest athletes, is run slightly below this ‘turnpoint’, which means that finding and developing your ‘maximal lactate steady state’ should be one of the priorities in your training. This is an effort faster than your normal running pace, but where you’re still able to stabilise your effort and not find each kilometre feeling harder than the previous one.

Top tip: Threshold runs can be a very effective tool in half marathon training and help you get more comfortable with running for longer periods around your maximum lactate steady state. Start with 20 minutes of effort where you can speak four words or so at a time, at around a pace you feel you could hold for 60 to 70 minutes in a race. As the weeks go by, build this up to 30 to 40 minutes of work either as a straight run or broken into blocks (eg, 3 x 10 minutes with short recoveries).

Threshold runs are all about intensity regulation. If you’re struggling to stay in control during a 60-minute race effort, back off by 10 to 15 seconds a kilometre and focus on building up minutes you can spend while still in control.

Build fatigue resistance

Callusing yourself to the rigours of the extra kilometre is obviously a key part of successful half marathon training. The extended duration means more repetitive strain on your muscles and a greater likelihood of fading in the latter stages of the race. As such, the core of your plan to build from 10K to half should be about increasing volume. You might consider starting to add more time to your long run, including another short 30-minute run in your plan or adding 10 to 15 minutes on to some of your existing runs.

Top tip: The long run plays a much more central role in half marathon training than it does when preparing for the 10K. Start by building five to 10 minutes on to your easy or steady long run every 10 to 14 days, building to long runs of 90 to 120 minutes. In the final eight to 10 weeks before the race, consider adding some blocks of race-pace running into the final 45 minutes of some of your long runs. If you feel that your body isn’t ready for more running volume, remember that cross-training, such as cycling, elliptical training or swimming, can boost your endurance with less impact.

Extend your speed

10k to half marathon

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As you build from 10K to half, your goal should be to extend your speed for longer. This is a key concept of progression and overload in training. Your training mix should include some running at your current half marathon pace, but also your goal pace, layering this up over time.

Top tip: While the core of your half plan will be made up of easy and steady running, longer runs and threshold runs, some occasional quicker interval efforts can certainly help. Interval work in half marathon training should be about control, running just a little faster than your goal half pace. Most runners are likely to benefit from 10 to 12 x 3 minutes run at 10K pace. As you get closer to race day, focus on building the length of your efforts or number of repetitions rather than worrying too much about running them at higher intensities.

The importance of adaptation

An increase in running volume and including longer sustained interval and threshold efforts requires respect. Changes to your training plan will only bear fruit if you can
adapt to the training.

Top tip: Place as much focus on your recovery and nutrition as you do your training plan and make an honest assessment about how ready you are to step up the training volume. Consider moving beyond a weekly structure with your plan. For many runners, trying to squeeze a mix of different types of run and a long run into seven days is too much. Consider planning your training over a 10- to 14-day cycle, allowing you to build in two or three easy or rest days between each harder run.

Taper right

Tapering is essentially the process of cutting back your training to make sure that you’re recovered enough to perform your best when race day comes. For the 10K, this
is less of a critical factor. Certainly, you might be looking for a lighter three or four days or so before the day of the race, but you’re unlikely to be undertaking a structured taper. The half is a bit different.

Top tip: Plan a period of lighter training and decrease wider life stress for up to seven to 10 days before the race. Aim to trim back your long run a week before the race to 60 to 70 minutes maximum, and tick over in race week with 30- to 40-minute runs and a handful of efforts at race pace.

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