It doesn't matter whether you've just escaped your sofa like some sort of fitness butterfly, or whether you're training for your umpteenth race – the long run is the foundation upon which all training plans are built. And it can be just as beneficial whether you're training for a 5k or a marathon.
First up, there's the obvious benefit of becoming accustomed to being on the move for long enough. For marathon training, this really is a no-brainer, but when you're in the last five minutes of a sharp 5k, it can be reassuring to draw on the mental toughness that you get from the drawn-out discomfort of longer runs. Of course, you don't need to scale the same heights to complete a 5k, but the endurance benefits from long slow running will undoubtedly help.
A regular long run is also the perfect opportunity to practice everything you need to get right on race day. That jazzy shirt you got for Christmas might be great on shorter runs, but the never-ending repetition that can cheese-grater your extremities, and the multitude of weather conditions you might experience on a longer run will encourage you to focus on finding the most comfortable options.
It gives you the opportunity to experiment with different ways to fuel and hydrate – during and before your run. Find out where the fuelling stations will be on race day, and what's on offer - then try a similar set-up on your long run to see how you cope. If it doesn't work out, you need to think about how to fuel at the times that work for you. It's an opportunity to find out what will work best for you, and what will leave you hallucinating about custard creams by mile eight.
The most common newbie mistake is to run too fast. Save it for the race! The golden rule of training for a purpose is to remember the purpose of every run. Long runs help your body adapt to harness and optimise a lot of important systems. It's improving its ability to make use of fat, increasing its capacity to store more glycogen, and strengthening your heart, so it can help deliver oxygen to hard-working muscles. A minute slower than marathon pace is plenty fast enough to do all of this. Any faster and you're just wasting energy.
By avoiding the urge to burn rubber during your long run, you'll be able to give your full attention to that speed session later in the week. But do make sure you spread out your key training sessions. Planning intervals on the day before, or the day after a long run just isn't sensible. Equally, make sure your schedule allows for a scaled back week each month, to avoid burning out.
Increasing distance should also be a sensible, gradual process. Adding an extra 10-15 minutes each week to your running time will get most runners to where they want to be. If you find the idea daunting, then try sticking with a favourite route, but add a few small diversions along the way. I find that it can be helpful to add the extra miles to the start of your route, rather than the end. As you approach home, and tick off the landmarks, it's good to know that you've already got the miles under your belt.
When planning your run, it's useful to choose a route with potential shortcuts home, just in case things don't go to plan. Similarly, look out for corner shops and petrol stations, and places where you could use the loo if you need it. And if you want a drink on the route, but don't want to carry it, scout out some safe places where you could hide a bottle the previous day.
It can also be extremely helpful to do your long runs with friends or club mates. Not only do you encourage and look out for each other, but you can take turns holding the water bottle, and it can be a fantastic shared experience.
Most importantly, long runs can give you a wonderful feeling of liberty as you eat up the miles using just the power of your own body. Running fast feels good, but there's nothing like that sense of equilibrium you can reach on a long run where it feels as though you could run forever.