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5 reasons why we do the long run slow

When I take on a new online run coaching client, one of the first things I ask about is previous running experience and future goals. This is to try to determine appropriate training paces. I use realistic race paces to set specific training sessions. For example, you might do 4 x 1 mile at Half marathon pace, with 3 minutes recovery jog in between.

The training pace I find most people ignore, is quite possibly the most important of all the training paces! And this is the long run, or ‘easy run’ pace. Which is generally set to be a minute OR MORE slower than your realistic target marathon pace. So, if you are targeting a 4 hour marathon, with an average pace of 9:09 per mile, then your training pace for a Long slow run ought to be 10:15 per mile or slower.

Why so slow?

The truth is, there are multiple reasons why this slow pace is important. Some are physiological, some are nutritional, some are psychological. Read on to find out more.

Reason 1: Training aerobic energy system

Running is about using both the aerobic and anaerobic energy systems at the same time. The slower you run, the more you use the aerobic system, and the faster, the more anaerobic it becomes. The greater your aerobic capacity, the faster you can run, as you are able to run faster before you are forced to rely on the anaerobic system. The more you run slow, the more you develop the aerobic system, and improve your overall running capacity.

Physiological adaptations take place when running slowly to make the aerobic energy system more efficient:
Increased capillaries
More mitochondria in muscle cells

The Lydiard approach to training physiology is demonstrated in the following diagram.  It shows that the greatest volume of your training should be done at a slow, aerobic pace, in order to build a strong base before you add faster sessions into the mix.

Lydiard Training method

Reason 2: Pacing/ pace control

This is relevant particularly in the longer runs, and longer race distances. Learning to control your pace is crucial to make sure you don’t use up all your glycogen stores early in a race. If you are able to maintain a slow pace. That is, start slow and control it, then you are much more likely to be able to control your pace at the start of a marathon or half marathon. This also helps you to develop efficiencies in your running. If you can run at one pace for 2-3 hours, you are able to ‘zone out’ mentally, and can sometimes experience being ‘in the zone’. Its really nice to complete a long run not knowing where the time went.

Reason 3: Time on feet

The slower you do the long run, the more time you have on your feet. This is especially important if you’re marathon training. Your longest run will not be marathon distance, but it may well be time on feet for as long as your target time. This is not for physiological adaptations, but helps psychologically.

Reason 4: Injury/ overtraining risk

The chances are that you have several runs in the week. Whether its 3 runs or 6, its important that the long run doesn’t stop you from doing the other runs. If you do it too fast, you risk overtraining, or hurting yourself. This might mean you do not complete the other training sessions in your training week. If your goal is to improve performance, frequency of running is very important, so the long run really shouldn’t stop you from doing your other training.

Reason 5: Nutritional/metabolic adaptations

The aerobic energy system can use fat as its main fuel source. If you get used to using fat for fuel, it means at faster paces, you will be able to do this, thus saving your glycogen stores and your chances of hitting the wall. In addition, the long run is an opportunity to practise your nutrition strategies for your longer races. Running slowly helps from a practical perspective, of being able to chew and/or swallow whilst running!

In summary, just because you CAN run faster, doesn’t mean that you should. There are lots of reasons to do the long run slow, however, as you move through a training programme, you may choose to vary the pace of your long runs to help you prepare psychologically to the demands of racing.

To learn more about other run speeds and their relevance, check out my blog on training quality vs quantity, or read my book, How to Run Your Best Marathon.

To help you better prepare for your next marathon or half marathon, why not download the marathon prep checklist HERE.

Checklist image

Happy Running!

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Angela Isherwood

Angela Isherwood is the founder of I Run Success
She is a REPs Level 3 Personal Trainer, a Run England Running coach, and a multiple marathon runner. She is a London Marathon Good for Age runner, a Boston Marathon Qualifier, a parkrun Run Director and Trainer for Goodgym Colchester.

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