Marathon training: at what pace should you do your long runs?
By David Chalfen
One of the most common questions you hear from those training for marathons – particularly those targeting a specific time – is how fast or slow should they take their long training runs. Coach David Chalfen gives his view.
In many of the glossy running magazines, you will find advice on what the pace of your long runs in marathon training should be. The most common advice isthat your long runs should be done at marathon pace (MP) plus about one minute per mile – sometimes described as MP plus 20%.
This seems to be based on what works for elite runners, particularly men, extrapolated to the amateur runner. For an athlete racing at five minutes per mile (a 2hr 11min marathon), six minutes per mile will often be their pace for a solid steady-state run; whereas target MP – that is, five minutes exactly – will, in most stages of training, be quite a test for more than about seven or eight miles.
When you get to a three-hour marathoner – 6 min 52sec per mile – the numbers don’t work quite so well. If you add one minute per mile, you get to 7min 52sec. If you add 20%, you come to 8min 14sec per mile – and I don’t personally know any three-hour types who would feel that 8min 14sec was a “steady” long-run pace, but rather a pretty slow one. Indeed, many would feel that even 7min 52sec was somewhat relaxed, and certainly their perceived effort at that pace would be much gentler than a 2hr 11min runner knocking out six-minute miles. Equally, for a three-hour marathoner to do an eight-mile run at their MP of 6min 52sec (taking almost 55 minutes) would be somewhat more comfortable than for our elite chap clocking it in 40 minutes at his MP.
Move the bar – or the clock – a little further and the formula really goes awry. For a 3hr 45min marathon, aiming for a MP of 8min 35sec per mile, the formula works out as a long-run pace of either 9min 35sec or, on a 20% basis, about 10min 20sec per mile. I’ve never yet coached a 3hr 45min type who feels right moving at a 10min20sec pace– this would be almost 50% slower than such a runner’s typical 10k race pace.
So, what’s going on here? Are the slower runners too inexperienced or headstrong to run at a sensible pace? I think that’s not the full story. It’s true that your average 3hr 45min runner will actually run very little of a marathon at their MP. They will typically run about 15 miles notably quicker than this, then, as things start to fall apart, about four or five miles at about that pace, then spend the last six miles with major payback for the overzealous opening miles.
Generally speaking, the quicker you run a marathon, the less variation you will have in your mile splits as the race unfolds. Whereas the very large majority of the 3hr 30min - 4hr runners that I coach, if they closely adhere to the target pace we have agreed, spend the second half of the race, and particularly the last six miles, passing hundreds of runners while barely losing any places to people outpacing them.
The main principle here is about physiology and a bit of maths. Go back to the 2hr 11min whippet. At six minutes per mile, he is running at about a notional five or six-hour race pace – that is, a pace he could, notionally, if he trained for it, sustain for five or six hours. Very few of the 2hr 11min guys will put themselves through such an ultrarun, but if you look at the very sharp end of the South Africa Comrades marathon – more than 56 miles – the numbers stack up.
But the further your own time drifts from the 2hr 11min elite, the more your own MP starts to approach your own notional five to six-hour race pace – and so, it follows, the closer the physiological demands of what your “steady” long-run pace should be.
The same principle applies to some of the specific training sessions you do. For example, for the runners I coach, I suggest some sessions where for 90 minutes you switch in five-minute blocks between 10k race pace (or slightly slower than 10k pace for the fastest runners) and a pace slightly slower than your MP. The swifter the runner, the closer to MP the average pace of the session will be – even though none of the session is actually run at that pace. That’s the purpose, to finesse the fine balance between the carbohydrate and fat burning at these paces.
So, in a 90-minute session of this sort of effort, a 2hr 20min runner is covering more than 16 miles, whereas a 3hr 45min marathoner might cover less than 12 – so the link to their likely MP is much looser.
For runners who are looking to target an MP of seven minutes per miles, I usually suggest some long runs at a pace of about 7min 20sec/7min 35sec per mile; for 7min 30sec runners, about 7min 45sec/eight-minute miles. As experience at covering this distance grows, I then suggest doing blocks of long runs at MP. This is, of course, assuming a fast, flat road, good mild weather, and a well hydrated and reasonably rested runner. Deviating from any of those and, of course, pace should and will drop.
Many runners aren’t targeting any time at all, just hoping to finish, and won’t cover those 26.2 miles in such a structured way. But even without specific targets, only doing three or four runs beyond the half-marathon distance in preparation for a marathon does leave you underprepared – and you may need to acknowledge that when you set your own expectations.
And I do believe that many people make the mistake of taking their long runs at too easy a pace – and that their achievements on race day will pay the price.
A final point worth noting is that for those expecting to finish in more than four hours, it’s my view that doing long runs beyond about 3hr 15min overtips the balance between training benefits and injury risks. It does make the last four to six miles of the marathon something of a lottery – but then, that can be the case for anyone ...