Negative Split in Marathon - does it work?

I’m an experienced marathon runner but I have never dared to run a faster second half of a marathon than the first half. I guess I haven’t enough self discipline or not enough faith that it will result in getting me a good time. I’d be interested in hearing from anybody that has planned a negative split as part of their race strategy and whether it proved a success or disaster in the their marathon. Thanks.
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  • SHADESSHADES ✭✭✭
    It doesn't suit everyone and the only time I've done it was when I had a tough first half and only felt better in the 2nd half so was able to run on.   I run better with a positive split and if I'm running well I would expect to be no more than 5 minutes slower in the 2nd half, my PB is 4:24, these days I run about 5 hours and try not to be slower than 5 to 8 mins in the 2nd half.   

    I think the best strategy is to aim for even paced all the way and accept that you might lose a minute or two in the last few miles
  • Negative is better than positive. Even is better than both.
    With Even pacing you know where you are and all you have to do is stay there. Everyone else has to get faster than you, which is the hard part. Negative pacing allows you to conserve energy to get faster when every one else is sprinting away. If  you plan right you can beat the Positive runners and maybe the Even paced runners,  but the odds are they are stronger than you. Positive pacing is the risky one. You shoot off and can't maintain. You're allowing nerves to get the better of you.  You get passed by the evens who are strong and the Negs who still have a tank full and more importantly are controlling their nerves.
    I would recommend you watch a few races to see what I mean. parkruns are good to see what those at the front are doing as apposed to those in the middle and those at the back. 

  • rodeofliprodeoflip ✭✭✭
    Dunno. Even pacing works for me. I find that whatever pace I set in the first few miles, I settle into that rhythm and keep that pace throughout. It's easier for me to just maintain my rhythm than to try to speed it up in the latter stages. I understand the theory of negative splits and conserving energy, I just physically can't bring myself to do it.
  • I'm not sure that actually starting with the intention of running a negative split is the way to go, unless you're out for a bit of a jolly in the first half, like pacing a mate then heading off on your own.  For me, best bet it to start at a pace you think you can maintain throughout, like rodeoflip says.  If you've got that exactly right you'll run even splits, obviously.  If you've been a bit cautious or are fitter than you think it'll be a negative split.  Usually though you'll be a bit over-optimistic and end up with a slight positive split.  If you've really over done it or haven't done the miles in training to sustain any pace for that long it'll be a big positive split.

    The only reason for actually planning a positive split IMO is if you really haven't done the mileage, and it's a case of being realistic and getting round with damage limitation.

  • OuchOuchOuchOuch ✭✭✭
    Interesting, I've only ever run one when taking it easy in the first half and speeding up in the second - generally I have a 3-5 minute fade which I put down to generally starting too fast but also race factors such as a rising temperature, less runners/ groups to run with.  Just heard a guy speak on an older edition of marathon talk and his analysis of recent London marathons show that the quicker the less the fade but even the elites (top 1,000 of the London marathon on his analysis) typically fade in the second half by 4-5%.  
  • rodeofliprodeoflip ✭✭✭

    I guess the fade towards the end is probably an inevitable result of fatigue, having run a stupidly far distance. You just have to look around you in the last 4 miles and compare how people are running with what you saw in the first 4 miles - the spring in the step is long-gone, everyone has stopped chatting to each other, every step looks like an effort. The running form has usually disappeared as well (I include myself in all this!)

    If I was planning a 3:30 marathon I would probably want to hit half-way in around 1:44, no quicker than 1:43. That leaves a small allowance for "fade" without having a massive positive split. I would then set off and try to run at constant pace for a 1:44 half and try to maintain that rhythm right to the end.

  • I’ve done it twice, both PBs, both times training has been improved considerably from previous efforts.

    i had previously ran 4 road maras between 3.44 and 3.47 since autumn 2015 and was hoping for a small pb on Sunday at Manchester.

    Aim was to even split it, wanted to go half way in 1.50 (went 1.48) but then got faster and Neg split 1.44 to finish 3.32.29.

    neg splits are possible and a good pb one will be subject to a good bank of training on most occasions 
  • SHADESSHADES ✭✭✭
    Robert - that's a great result, well done
  • T RexT Rex ✭✭✭
    I'm reasonably good at doing negative splits and it is my preferred method to get a fast time.

    It takes a lot of guts to deliberately do a negative split but the psychological boost you get from overtaking so many runners in the second half and the sensation of finishing strongly leaves you feeling very good.

    You have to know yourself and know that you can go that small amount faster in the second half and not panic because you haven't got a 'cushion'. 

    Knowing what pace you need to do in the first half comes from experience.  Too slow and you might have too much left in the tank at the end and underachieve.  Too fast and you'll get too tired to keep the pace up and end up with a sizeable 'positive' split and likely not achieve your target.

    In training runs that are an out-and-back type I always aim to return quicker than I went out and if I finish feeling it was a bit too easy doing the negative split, I increase the pace of the first half slightly the next time.  It's quite a good training method for developing strength when you're tired.

    In marathons I always divide my target time in half and aim to be at halfway no sooner than that time.  I am about 4 hours these days so in Llanelli this weekend, for example, I will aim to be at halfway no sooner than 2:00:00.  And then I'll see what I can do.  Might not be able to do the negative split for various reasons such as lack of training, early in the season, etc, but it'll be worth the try.

    A good way to keep yourself going in the second half is to keep a tally of all the runners you overtake and try not to be overtaken, or if you are try to keep that person in sight and get them before the finish!




  • T-Rex I like that thought of dividing the time that you want to do in half, although I never thought like that I had kinda subconsciously was going along those lines on Sunday.

    I also start hunting down runners in front of me too, too many to count on Sunday 570ish from the 30km point to the finish. 

  • My fastest marathon was a 3 minute negative split. My slowest (and the one that really hurt) was a 7 minute positive split. Negative feels a lot better. I ran Manchester last week and had a particular time in mind (to qualify for Boston) and just made sure I stuck to it each mile. My first half was 4 seconds slower than the second so I was very pleased to have ran do evenly even though I am getting slower with age.
  • I've never managed this - I think you have to be a very good runner with enough miles in the legs not to fade after 20 miles plus.  It's impressive that some people can do it - but I think they're probably a single figure percentage of marathon runners as a whole. 
  • T RexT Rex ✭✭✭
    I think I'd better only post on here again when I actually achieve a negative split!

    I had a few issues on Sunday and it wasn't happening.

    The most important thing is have a realistic target finish time!  I pulled 4:00 out of thin air when, after a rather poor winter of training and a knee problem, it actually took 4:24.  So my first half 2:01 got me into all sorts of trouble in the second half.

    It's a good thing to aim for.  If you don't do it next marathon, slow the first half even more on the one after.  If you do a negative split too easily run the one after faster in the first half.

    Where you'll finally end up is an even-paced marathon throughout, at your maximum performance.

    That's my theory, anyway.  All the best.
  • Sub17ParkRunSub17ParkRun ✭✭✭
    edited April 2018
    Run the first half 10 minutes slower than a recent HM time. Then you will have legs fresh enough to be able to run a good second half and achieve an even or negative split marathon. This strategy will work for casual hobby joggers not worried about finish time. This strategy will not work for experience runners aiming for a time goal or elite runners that run Marathons at a fast pace.
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