Training: Half Marathon

In this article we look at how to create a half marathon training plan, whether you’re a new runner or an experienced PB hunter.

What is a half marathon?

The half marathon is one of the classic road running events. The length, at 13.1 miles, or 21.1km is exactly half that of the marathon distance.

It falls neatly into the gap between 10Ks and marathons and is a popular choice both for marathoners who want to step down in distance, and runners who usually do shorter events, but want to challenge themselves by pushing further.

How hard is a half marathon?

The answer depends on you, your running history, and what you want to achieve.

If you’re new to running, or if a half marathon will be the furthest you have run to date, then the distance will present a challenge. However, if you’ve trained well, and gradually increased the distance of your longest runs, then the prospect of running thirteen miles in one go need not be too scary.

If you’re an experienced runner who is looking to set a half marathon personal best (PB), then the event offers a different challenge, as you will have to try and run at a hard pace for a long way. Again, with training, this challenge can be made more achievable.

To illustrate this, we’ll introduce two example runners: George and Harriet

Introducing our example runners

George considers himself to be a beginner runner. He’s dabbled a bit in the past, but has never entered and trained for an event. However, he’s been talked into entering a half marathon and now needs to prepare.

Harriet runs a lot. She doesn’t do too many events, but enjoys the occasional parkrun. She wants to set a PB at her local half marathon to prove she’s not slowing down!

George, the beginner

Other than PE at school, George hasn’t done much running in a long time. He has done various exercise classes over the years, but struggled to stick with it and create a habit.

Even though he’s not a complete stranger to exercise, George can be considered a running beginner.

Get used to the movements and the impact

Running long distances is something that humans are pretty good at, as our bodies are well suited to the movements required. That said, for many of us, our lifestyles mean that running is a movement we’re unfamiliar with.

We might have all right muscles in all the right places, but if we’ve not used them before, we’re going to find it difficult to get them going in the way we want.

Therefore, George is first going to have to get used to running a short distance before he tries to go long.

Start small, dream big

Couch to 5K is a great introduction to running. Even if George had some fitness from other sports, running is such a specific movement, that taking the time to adapt properly and get used to it can save a whole lot of injury bother.

There are various Couch to 5K (C25K) programmes out there and one of the most popular is provided for free by the NHS. Whichever programme George chooses, the general principle tends to be the same: Start off by doing a small, manageable amount of running, followed by some walking, then repeat until the end of the session.

With each subsequent session, the amount of running will gradually increase, as the amount of walking decreases. After a while (9 weeks is typical, but it will differ for everyone), George should be able to run for 30 minutes without stopping.

George has 6 months until his half marathon, so decides to do C25K, remembering to take the time to ease off if he has a stubborn ache, building up the distance gradually and carefully.

Once he can run for 30 minutes without stopping, George is ready to start the next stage of his training – extending the distance.

Lonely Goat, Chris Henry at Torbay Half Marathon
Go further, gradually

George’s plan is going to be similar to the training that Eve, another of our example runners, did for her 10K: Take the final part of C25K as the starting point, then add a little bit more running each week until the half marathon seems possible.

It shouldn’t be necessary to run further than 10, 11 or 12 miles in training, as the excitement of the event will help to get George to 13.1 miles and over the finish line on the day.

It is worth being aware that runs over two hours will place the body under a lot of stress which will require a lot of rest. This may negatively impact on the training for the rest of the week.

Consistency is very important when running – especially in George’s case, where the goal is to try and get the body used to the movement. It is almost always better to do three slightly shorter runs a week, than one or two bigger ones that stop you training properly for days at a time.

With this in mind, George decides to limit his weekly long run to an eventual maximum of two hours, even if this falls short of the 10 to 12 miles he might otherwise have aimed for.

What does George’s training look like?

Taking the basic structure of C25K as a starting point, George opts to stick to three runs a week, spaced out as evenly as possible to allow enough rest between each run.

He has four months from the end of C25K to the half marathon, which is a nice long chunk of time to try and increase the distances run.

The two mid-week runs will gradually increase up to around an hour in length. These runs exist to remind George’s body that it is now a runner’s body, and help prompt the adaptations that will make the half marathon feel easier. George is wary of getting injured, so will cut these short or miss them out entirely if tired or especially achey.

George’s long runs

The weekend run will be a long run. This will be the most challenging run of each week as it will see George try to gradually extend the distance from 30 minutes up to 12 miles or two hours (whichever is the lesser of the two).

To make this jump in one go would not work, as it is a massive increase in distance and would be four times longer than what George has done so far. However, with four months to go, those extra 90 minutes of running can be divided into 5 or 6 minutes of additional running time each week.

Just as the long run will increase each week, so the total weekly mileage will get bigger, with the highest weekly mileage coming three weeks before the event.

Keep the pace easy

All of the runs will be run at an easy pace. That is, a pace at which George could just about hold down a conversation if forced to do so. The reason for this is that George’s primary goal is to get across the finish line. The speed doesn’t matter. “Time on feet” is what is important, and running at an easier pace will allow George to maximise this.

Tapering for beginners

With two weeks to go, George will probably be feeling tired from the cumulative effect of six months’ training, but will hopefully be at the point where the thought of doing the half marathon is no longer as scary as it once was. This is the point where George gets to taper.

The taper is the final part of the training plan (often two weeks, sometimes more or less, depending on the runner and the event) where the training distance is cut back. This allows extra time to rest, which means George will get to the start line feeling fresh with a bounce in his step, rather than heavy-legged from all the training.

More experienced runners will be better able to judge what mileage is right for them when tapering, but George opts to adopt the following rule of thumb: Chop a third off his peak weekly mileage in the first week of the taper (two weeks before the event); then chop again for the second week (one week before the event).

This should get George to the start line in top condition.

Lonely Goat, Michelle Kennedy at the Frozen Phoenix Half Marathon
Harriet, the PB hunter

Harriet isn’t usually excited by races, but has decided to try and get a half marathon PB to try something different. She has just over three months to train.

A little structure

Harriet’s running mostly consists of heading out the door a few times a week and doing as much she feels like. This ticks the boxes on her goals – keeping physically and mentally fit – but Harriet recognises a bit more structure will be helpful if she is to break her half marathon PB.

Harriet has just over three months to train before the half marathon.

One run a week will be a long run, one will be an interval session, and one will be a tempo run. There will also be some easy runs (1 to 3, depending how Harriet feels), run at a relaxed, comfortable pace, to add to the general mileage.

There won’t be any planned ‘recovery weeks’, where the mileage is reduced. Instead, Harriet will listen to her body and cut back on the running for a few days if she has a niggle or ache that won’t go away, or if she finds she’s constantly exhausted.

Harriet’s long runs

The half marathon requires a high level of endurance to be able to cover the distance quickly. Seeing as Harriet has run further before, 13.1 miles is not the intimidating proposition that it would be for George, for example.

It is not unreasonable for Harriet to run further than the race distance in training, provided she is able to do so without injury. The maximum will be 15 to 16 miles, or two hours of running, whichever is further.

Initially, during the first month, Harriet’s long runs are an hour long, which doesn’t represent an increase on what she would usually do, as she gets into the rhythm of structured training.

During the second month, the long runs increase slightly each week until Harriet is out for up to two hours.

During the third month, Harriet will hold the long runs at their maximum, before cutting down to 90 minutes a fortnight out, and 60 minutes the week before the half marathon.

These will all be run at an easy effort. The pace isn’t too important, as these are all about getting the body used to being out for a long time, so that covering the distance on race day doesn’t feel too difficult. Running the long runs over hills or varied terrain can help with overall conditioning and leg strength.

Intervals and speedwork

The purpose of these faster runs is to get the body used to running quickly, so that the pace required to set a PB feels a little bit easier.

During the first month, Harriet will insert half a dozen or so short hill sprints into one of her weekly runs. After each sprint, Harriet will walk back to the start to recover. If half a dozen feels comfortable, then she might choose to increase the number or reps up to 10 or 12. The idea isn’t to push beyond her limits, but to stay smooth at a faster speed and get the body used to quicker paces while improving leg strength.

In the second month, the speedwork gets harder with interval sessions. The aim is to run the fast intervals at somewhere around 5K race pace, or whatever feels comfortable, topping out at around 30 minutes of total fast running.

The recovery periods inbetween the fast repetitions (‘reps’) will be whatever is needed to get through the session. Each week, as she gets fitter, the reps get longer, and the recoveries get shorter.

Example sessions include:

  • 12x 60 secs hard (60 secs recovery);
  • 8x 3 mins (2 mins recovery);
  • 5x 5 mins (3 mins recovery).

During the final month, the intervals might top out with a couple of extra hard sessions, followed by a reduction in volume over the final two weeks for the taper.

Because this type of training is new to Harriet, she’s going to err on the side of caution and hold back if too much fatigue creeps in. After all, having not done much speedwork before, any faster running is going to be beneficial.

Tempo runs

To run a half marathon PB, Harriet is going to have to hold a relatively hard pace over a long distance. Tempo runs are a great way to prepare for this challenge.

There are different ways of doing tempo runs, and different ways of progressing them over the course of a training plan:

  • ‘Top Down‘: Do the same distance every week, but try and do the run slightly quicker each time.
  • ‘Bottom up‘: Pick a pace (perhaps 10K to half marathon pace) that you’ll use for each of your tempo runs and try to run slightly further each week.
  • ‘Progression runs‘: Start your run slowly, then gradually speed up over the course of the run until you’re finishing quickly. Over time, try to make the quick bit longer or faster.

Harriet is likely to find she prefers one of these approaches over the other, but the best way to incorporate tempo runs into her training is probably to use all three, and vary which one she does each week. This variety will not just offer a broader range of training benefits by stressing the body in different ways, but will also keep training more interesting.

For many runners, an hour’s duration is a sweet spot for tempo runs, as it has an endurance element, but also allows for some faster running.

Rather than stress too much about the pace, Harriet should aim to be aware of how she feels and get a sense for judging the amount of effort she can give. This will help on race day when it will be important to lock into a pace that can be sustained all the way to the finish line.

Total mileage

How far Harriet runs in a week is entirely dependant on how her body copes with the training. It is difficult to say how many miles a week are needed to run a half marathon PB, as it will be different for each runner. What matters is that enough running is done to progress, but not so much that the runner gets injured.

Given that Harriet is incorporating structured h training sessions into her plan for the first time, she may even find she is better off reducing her mileage below her normal level to compensate for the extra hard runs


Like George, Harriet will taper her training down in the last couple of weeks before the half marathon. Fitness can’t be added in the last couple of weeks, so the goal is to preserve the fitness that’s there and get the body ready to run hard.

The distances will reduce, but the general pattern of runs throughout the week will stay the same. The idea, is to get to the start line with fresh legs, full of energy, and ready to go.

Lonely Goat, Anne-Marie Jane Pollard-Vearnals after the Manchester Half Marathon

For both George and Harriet, what they eat and drink starts to become more important as the distances increase.

There are so many different ways to approach running nutrition that it is beyond the scope of this article to summarise them here.

Instead, George and Harriet need to remember the following principles:

  • Eat enough before running that they’ll have enough energy to get through the run;
  • Consider if they’ll need to eat anything during the run to replace the energy expended;
  • Eat after running so the body has what it needs to repair itself.

A similar approach is required for hydration. Both runners need to make sure they drink plenty of water as part of their daily routine. When running, they won’t need to drink lots (as ‘over-hydrating’ can cause serious problems), but drinking a little bit, to avoid thirst, should help.

If they both practice their ‘nutrition and hydration’ strategies when training, they’ll soon learn what works well for them.

Cross training

The best way to train for a running event is to run. If that proves impossible or impractical, then there are cross training methods that can help. Anything that is predominantly aerobic or involves lots of different muscle groups should be considered: swimming, cycling, rowing, elliptical cross trainers, etc. Just bear in mind, that the half marathon is a long event, so the duration of any cross training activities should reflect that.

Some runners like to do other sports or activities too. If these add variety that can help the runner to keep focused on their training, then that’s a good thing. They can also assist with general fitness and conditioning. However, cutting back on risky activities close to the race can ensure unexpected injuries don’t cause problems.

In summary

Whether you are a beginner like George, or a PB hunter like Harriet, the main difficulty of running a half marathon is covering the distance. Your approach to training for this will depend on whether you just want to finish, or want to finish in a particular time.

  • If you just want to finish, then the primary focus of your training should be on improving your endurance.
  • If you want to finish in a particular time, then add some faster running to your training so that you’re in a better position to push the pace and do so.

Think about what you want to achieve, then think about what you need to do to prepare yourself to do that. That might be more long runs, or it might be more speedwork. It might even be less running if you keep getting injured. After all, if you’re too injured to get to the start line, then you’re definitely not going to get to the finish line in the manner you want.

And if you’re struggling to work out what you need to do to smash your half marathon goals, remember there is a massive, friendly community of other Lonely Goats that you can ask for advice. Check out our social media channels – Facebook, Instagram and Strava – and get in touch.

The Lonely Goat running training series

Check out the rest in this series of training articles…

…plus our other articles on different aspects of running training.

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