What are split times?
Once you've got an idea of your estimated finish time for the marathon, you need to work out your 'split times'. Split times are simply the amount of time it takes you to complete any given section of the course – it could be each mile or kilometer, every 10k, or the first and second half of the race, depending on how much information you are willing to cope with.
Use your training to work out splits
When projecting your finish time and splits, think about the times and speeds you have accomplished in your training. If you know, for example, that you have run 18 miles at a speed of nine minutes per mile in training – and felt shattered afterwards – let’s face it, it is unlikely that you’ll be able to run a further eight miles at the same speed on race day. But by slowing your pace by an extra 30-60 seconds a mile will make the race far more comfortable, and your likelihood of success greater. If this is your first marathon, be conservative in your target – the idea is to complete, not compete.
Once you have established your target time, calculate what that equates to in terms of consistent split times for each mile (bearing in mind that you will undoubtedly be slower on the first two or three miles, as you jostle for space with the thousands of other runners).
Working out your split times
Convert your target time to minutes
Divide by 26.2. (If you want km splits instead, you'll need to divide your target time by 42.165 instead).
You’ll end up with a 'decimal' number, which you then need to convert to minutes and seconds to give you a split time for each mile.
Target time: 3 hours 40 minutes = 220 mins
220 divided by 26.2 = 8.4 mins
8.4 mins = 8 mins 24 secs per mile
Finally work out the accumulative time for each mile. For example: 8 mins 24 secs per mile means that at mile 3, your watch should read 25:12 (i.e 3 x 8 mins 24 secs)
Many experts advocate a ‘negative split’ for marathon running, in which you aim to run the second half of the race slightly faster than the first half. Whether you go for a negative split or even splits, you certainly don’t want to be slowing down as the race progresses – a sure recipe for hitting the dreaded wall.
Stay on track
To monitor your progress and see if you are on target with your splits you could use a sports watch or even a phone app and set alerts which would go off should you be falling behind the targets you have set. A more simplistic approach that doesn’t rely on technology is to work out your splits and get them printed out on a band, which you laminate to protect them from sweat and/or rain, so that you can manually check your times as you progress. It should show you the times you need to be at for each distance - you can choose whether you want this to be every mile or km or less frequently.