The author, who ran his 2:29 PB in the first London Marathon in 1981 and has since run every London since 1984, looks at what is required to break the various time barriers in the marathon

Eliud Kipchoge smashed his world record at the BMW Berlin Marathon with a time of 2:01:09 – effectively just a mere 1.66 seconds per kilometre away from achieving the first sub-two in a genuine competition.

Other time targets may be a little bit more attainable for those participating in the TCS London Marathon.

London may not be quite as fast as Berlin or Chicago but the number of world records previously achieved in the capital show that it is one of the fastest and best marathons in the world.

The target should be based on a number of factors. Your previous best, your age, the volume of your training and your recent half-marathon times. So if you struggled to break two hours in a half-marathon then a 4:30 to 5:00 marathon is more likely than a sub-four.

Plenty of 20-mile training runs may slightly make up for the lack of speed at shorter distances but you need to be realistic in your time target.

Going for a sub-4:00 when 4:30 is more of a realistic and attainable target could ultimately see you nearer or even outside five hours.

Age does come into it, even if performances like Nigel Rackham’s UK M60 record at Berlin of 2:41:16 suggests that you can still run very fast at an older age. However, he ran faster when he was younger and, as you get older, you lose speed even though your stamina is maintained but don’t expect to run as fast at 50 as you did at 40 unless your training has progressed.

Pacing is the most important factor. Kipchoge himself went a little too fast on the first half in his world record run. His 5km splits were 14:14, 14:09, 14:10, 14:12, 14:23, 14:32, 14:30 and 14:43 and his 10km splits were 28:23, 28:22, 28:55 and 29:13 which is hardly a great slowing down.

The slightly quick first half certainly did not cost him a sub-two but he may well have run a sub-2:01 had he been a little more controlled.

For London, the first half contains the quickest section with a longish downhill around the 5km mark and the anticipated brisk westerly wind will make it slower than it would have been, especially on the second half.

Obviously apart from pacing, fuelling and hydration is vital, although you only may realise you have got it wrong in the closing miles by which time, gels and liquids will be too late to make a difference.

Drink and fuel regularly but sensibly as too much water or gels or jelly beans might not necessarily make you faster and could have consequences.

Many say the half-marathon mark in a marathon mentally is 20 miles rather than 13.1 as the first half is relatively easy and the key to a good time is getting to 20 miles (32km) as relaxed and fresh as you can so you can maintain a solid pace for the last 10km and are strong enough to fight the fatigue.

Even pace is what many say is the desired goal but the vast majority of runners are not capable of running fast with 20 miles in their legs however quick they have gone in the early stages.

That does not mean you need to get lots of time hand in the first half while you feel good as that will tire you earlier and make it harder than it should be.

However, if you are aiming for a sub-three and it is a realistic and achievable target, a 1:28:30 first half shouldn’t really take that much more out of you than a 1:29.

Kipchoge’s halves of 59:50 and 61:19 are effectively near even-pace running with a slight slowing which is what the vast majority of successful runners achieve.


Kilometre pace required: 2:50.6. Mile pace required: 4:34.8. Suggested first 10km: 28:15-28:30

Ideal 10km PB requirement: 26:30. Half-marathon requirement: 57.00

While it has been done by Kipchoge with a mass of pacemakers, and it only requires only a 0.94% improvement, the lack of someone able to challenge him through the last 10km, and the fact that at the age of 37 he is not improving his speed, suggests it might be a while coming.

Could the future be Commonwealth 5000m and 10,000m champion Jacob Kiplimo?

Aged just 21, the world half-marathon champion and world record-holder could be the athlete to push Kipchoge all the way or even eventually break the Kenyan’s record.

Certainly no one will come close to this barrier at London even if it was perfect conditions and while Kipchoge has now run a sub-hour first half in competition, no one has come close to producing a sub-hour second half with 13.1 miles at a fast pace already in their legs.

INEOS 1:59 Challenge in Vienna


Kilometre pace required: 3:33. Mile pace required: 5:43. Suggested first 10km: 35:30-36:00

Ideal 10km PB requirement: 32:00. Half-marathon requirement: 70:00

Less than 150 runners broke this barrier in 2021 which is less than did it the first London in 1981, despite the great advancement in shoe technology and training and diet knowledge over the last 40 years.

Ideally a halfway time of around 73-74 minutes is required and most who achieve this barrier have run a sub-70 half-marathon.

There won’t be a large number of runners at this pace so it does require concentration and the ability to set your own pace independent of others.


Kilometre pace required: 4:15. Mile pace required: 6:52. Suggested first 10km: 42-42:30.

Ideal 10km PB requirement: 39:00. Half-marathon requirement: 1:23

The sub-three is the traditional target of a quality club runner and there will be a number of runners trying for this goal but the pacers at this speed invariably end up with few of the followers who were with them at halfway still there in the last 5km.

While it has been known for some to break this barrier with a 1:27 half-marathon PB, those are a rarity and even a sub-1:20 half does not guarantee beating this time barrier but does gives a very good chance with 1:23 being a possible chance.

Steve Smythe pacing a sub-3 in the 1999 London Marathon


Kilometre pace required: 4:58. Mile pace required: 8:00. Suggested first 10km: 49:00-49:30

Ideal 10km PB requirement: 43:00. Half-marathon requirement: 1:30-1:35

As the pace gets slightly slower, the numbers on the road increase in intensity and space is at a minimum, meaning you may not always be able to run at the pace you had intended as others get in your way.

However, the staggered starts nowadays do allow a little more room as athletes in this popular time bracket attempt to maintain a sub-5min/kilometre pace throughout.

Athletes generally in this time bracket can run a time of around 1:30 for the half-marathon a minute a mile quicker than the target pace but a well-trained athlete with natural stamina may be able to achieve the target with a 1:35 best.


Kilometre pace required: 5:41. Mile pace required: 9:09. Suggested first 10km: 55:00-56:00

Ideal 10km PB requirement: 48:00. Half-marathon requirement: 1:45

It is extremely crowded at this pace with the highest concentration of runners with sub-four the target of the average competitor.

An average pace of around nine-minute is required so it helps if you have sustained a pace of around a minute of mile quicker in a half-marathon.


Kilometre pace required: 6:23. Mile pace required: 10:18. Suggested first 10km: 62:00-63:00

Ideal 10km PB requirement: 53:00. Half-marathon requirement: 1:55

It is still very crowded around this time barrier though a sub 4:30 is less of a desired target than the even hour 3:00 and 4:00 barriers.

It requires a 10-minute mile pace throughout and again a minute a mile quicker should be doable over the half-marathon distance so the pace feels comfortable.

2019 London Marathon (Getty)


Kilometre pace required: 7:06. Mile pace required: 11:27. Suggested first 10km: 69:00-70:00

Ideal 10km PB requirement: 60:00. Half-marathon requirement: 2:15

Running even-pace around this pace is not easy as a higher proportion of competitors walk in the second half and requires the ability to side step others in the manner of Ryan Giggs at his peak as they suddenly stop and slow.

I have some experience of this pace as, unhealthy and unfit in 2021, I ran a roughly two-hour first half and walked a near three-hour second half and hopefully was not too much of an obstruction for those maintaining a better pace.

» Steve Smythe ran his first sub-three hour marathon in 1976 and his last in 2017

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