The cornerstone of any good training regime (after you've mastered wearing shorts) is your long run. Aside from the obvious benefit of becoming accustomed to being on the move for long enough, long runs also help tune up your aerobic systems - your heart, lungs - everything that helps to deliver oxygen to your muscles. Lots of headline-grabbing training programmes focus on improving your ability to handle lactic acid with fast-paced runs and interval sessions - but there's a lot to be said for quietly nudging up your fuel efficiency and endurance whilst everyone else runs themselves into the ground.
But how long is a long run? Every training plan puts a number on 'long' - and if you look at enough, you'll start to develop some rules to work to. I'm in the fortunate position of overseeing millions of miles of data from thousands of runners, training for all sorts of distances, and it's a lot of fun looking for rules on a large scale.
A database of this size requires careful weeding. A simple question like 'what's the typical longest run for a marathon runner?' isn't as simple to answer as you might think. Take someone like David Bayley who's run ten marathons in ten days for the Brathay Trust, every year for the last five years. As awe-inspiring as that is, if he was your only example, then you'd be forced to infer that the best training for a marathon is to run one every single day. In a sport where every other person is plotting something beautifully ludicrous, it's easy to lose sight of the norm.
Running has an inbuilt tendency to push the limits of what we can achieve. Before Roger Bannister ran the first sub-4 minute mile in 1954, it was thought to be nigh-on impossible. Within a year, four more runners achieved it, and by the end of the decade, 25 runners had joined him. I bet there are plenty of you who could go out right now and run a 10k at the pace you ran your first one, without too much trouble, but a much smaller percentage who could go out and PB right now. We are often confined by what we know to be possible, and when we know we can, it becomes that little bit easier. On that basis I focused my search on the times where runners pushed themselves beyond that which they'd already achieved.
The yellow columns in the first graph shows the typical longest run in marathon training, whilst the white columns shows the longest run when training for a half marathon. So for example, if you aim to complete a marathon at 8 min/mile pace, you'll probably get up to a maximum of 22 miles, whereas if you're looking to run a half marathon at that pace, a longest run of 15 miles is typical. The turquoise column represents 5k and 10k - the figures were virtually identical.
But just as one torrential downpour doesn't make a summer, one long run doesn't make you an endurance king. Bruce Tulloh once suggested that when training for a marathon, your five longest runs should total a hundred miles. If we all did that, then perhaps we'd be as fantastic as Bruce - but just like so many rules of thumb, it needs a bit of work to make it fit everyone. The second graph shows the typical 'five longest runs' figures. If you're aiming to run faster than 8mins/mile at marathon distance, Bruce has nailed it - but if you're closer to 10 mins/mile, then 90 miles will give you as good a chance as anyone else.
Whilst marathon training clearly requires extra commitment, what is perhaps more revealing about these graphs is that the volume of long runs doesn't drop excessively whether you're training for a half or a 5k. Incorporate more speed work sessions for shorter races by all means, but don't neglect the distance.
It's also worth considering the pacing of long runs. As I suggested initially, long runs are mainly about improving your endurance and aerobic capacity. If you go at them too hard, not only do you run the risk of not improving your aerobic fitness, you also lengthen the time it takes your body to recover. This means that when it comes to your speed sessions, you're less effective there too.
The final graph shows how the long run pace relates to race pace. A runner who does a marathon at 6 min/mile will do his or her long runs nearly a minute slower than race pace - but a 10 min/mile marathoner will actually run faster on long runs than on race day. There's a clear tendency across all distances for faster runners to take it easy on long runs. So if you want to be a faster runner, slow down on your long runs and save your Billy Whizz impersonation for speed work.
Please remember that I've presented here are typical figures, not concrete goals or promises. Follow a plan or speak to a coach and you may end up doing something completely different - and there's usually a reason for that - but I hope that being able to see the middle ground will encourage you to explore those reasons, as it can only be of benefit to your running to understand more about what you're doing.