Welcome To Fetcheveryone

Our awesome training log doesn't hide its best features behind a paywall. Search thousands of events, get advice, play games, measure routes, and more! Join our friendly community of runners, cyclists, and swimmers.
Click here to get started
Already a Fetchie? Sign in here

Long Run woes - help please

10 watchers
Aug 2013
9:08pm, 27 Aug 2013
26820 posts
  •  
  • 0
Velociraptor
Nope, Tim, you'll train so that you can run a 1:55 half and have enough left to run a similar pace in the second half :)
Aug 2013
9:50pm, 27 Aug 2013
739 posts
  •  
  • 0
Canute
The question of positive v negative split for a marathon needs very careful consideration.

Ian W (aka Lord Fetch)) showed in his analysis of HM times that 80% of Fetchies do a positive spit in a HM. The details are in his article on Split Personality article listed on the home page. The proportion is even higher for the marathon – Stuart Mill’s analysis of those finishing VLM under 5 hours, showed that about 95% have a positive split. Because the overwhelming majority of recreational runners do a positive split in long races, it is not surprising that most recreational runners achieve their PB with a positive split. However that does not prove that a positive split gives you a better chance of a PB. It could be that they achieved a PB because they were fitter even though their race strategy was no better than usual.

In a reply to a query by Lumdoni, Ian actually revealed that neagtiv esplit was assocated with ahigher chance of a PB. Fetchies achieving a negative split in a HM had a 43% chance of a PB while those achieving a positive split had only a 36% chance of a PB. So this seems to support the conclusion that negative split gives you the best chance of a PB – but before accepting that, it is necessary to take account of the likelihood that a lot of the people with a positive split will have been under-trained, so these percentages might not apply to people who have trained well.

So far, no clear conclusion.

Stuart Mills, who is an ultra runner, has done a very thoughtful analysis of the question, and concludes that in general performance is not better with a negative split. The statistics of his argument are complex and debatable. However Mills has developed an elaborate theory based on what he calls Race Focus Energy. The argument is complex but worth reading. ultrastu.blogspot.co.uk

My own view is that for elite marathoners running faster than about 2:15, the race outcome is very strongly determined by aerobic capacity. Near equal splits with pace just below lactate turn point is the best way to harness aerobic capacity. Hence world records are usually achieved with near equal splits. But for runners taking longer than around 2:30, the duration of the marathon is too long to allow you to run on the edge of the lactate turn point for the full distance. The race starts to become like an ultra. The way the brain recruits muscle fibres when fatigued is also likely to play a large role. The ability to recruit fatigued muscle fibres can be improved by doing long runs starting with already fatigued fibres (eg a long run the day after a moderately hard session, or by back to back long runs as ultra runners do). However, it can also be improved by psychological factors. Running with a buddy with whom you share a joint belief in your race strategy is likely to be a powerful way of promoting muscle fibre recruitment in the final 5 miles.

This comment is long and I do not think the answer is clear. I suggest you read Stuart Mill’s article and see if it makes sense for you. If so, work with your buddy to make sure that you both start with faith in your race plan.
Aug 2013
10:10pm, 27 Aug 2013
7303 posts
  •  
  • 0
Boab
That's a great post Canute a d wod form the basis of a very good reply to Stuart Mills theory, which for the record, I don't believe.
Aug 2013
10:18pm, 27 Aug 2013
1115 posts
  •  
  • 0
Windsor Wool
to pick up on Canute's point on psychology - it would kill me to go out at a pace in the knowledge I was going to blow up and suffer in the 2nd half of the marathon. I think that there has to be some belief that the pace you select for the opening miles can be maintained across the run.

Tim - at the risk of being the next Paul A in your eyes......why is your race approach dictated by your training partner? You have trained for this yourself, you have to execute selfishly.

There is something immensely positive in your approach to me. Your ability to run for 2:30 on a treadmill! Astonishing! That said, I really think that MP+30 is a bit tight for your longer runs. Most things I have read advocate slower than this.

Good luck!
Aug 2013
8:39pm, 28 Aug 2013
1971 posts
  •  
  • 0
Tim of MK
Thanks for the further comments.

I guess that part of the problem (which is also a joy) is having shed 15kg (33lbs). It means that I've no real benchmarks. Yes, I ran say 1:55 half marathons (and indeed much faster halves) in years past. But I've not done one recently.

Perhaps I should sacrifice one long slow run and substitute with a fairly hard half marathon.
Aug 2013
8:50pm, 28 Aug 2013
5920 posts
  •  
  • 0
Bazoaxe
I read the Stuart Mills stuff and dont agree with his thinking and his analysis doesnt take the full picture into account.

I reckon their is a window either side of even pacing where a best performance will occur and thats maybe between a 1-2 min negative and 3 -5 min positive split - The trick is in being able to judge the pace accordingly based on training. The more you get it wrong, the bigger the gap will become - and that could be either way. Ive run an 11 min negative split and much bigger positive splits but only one race in the 1-3 window and one in the 2-5 window - guess what, my two fastest times.
Aug 2013
8:58am, 29 Aug 2013
741 posts
  •  
  • 0
Canute
Baz,
There is little doubt that for athletes running fast enough to be limited by aerobic capacity, near equal splits is the best strategy. I suspect that the acceptable window of variation on either side of equal becomes narrower as you get nearer to the limit. In VLM this year, the pacers got to half way about 25 sec ahead of the time required for a new world record with equal splits, leading a field with the potential to set a new world record. However even this potential positive spit of less than half a minute proved to be too much and the wheels came off the bus for everyone in that stellar field. Kebede’s winning time was the slowest for 6 years.
Aug 2013
9:18am, 29 Aug 2013
11292 posts
  •  
  • 0
Naomi P
Listen to Canute, he speaks sense as ever.

My view is that unless you have a solid background of a few years of training and racing without big weight fluctuations, injuries or anything else that gets in the way, it's VERY hard to predict your marathon pace. I would approach it from the other side if I were you, working to effort level or heart rate, not to a certain pace.

Obviously, this is easier on road than on a treadmill but you need to go with what works for you. Your long runs should be at an easy effort. When is your marathon? I'd forget about predicted times or half way splits until a few weeks out and concentrate on building up your endurance. I'd even suggest not wearing a watch in the race, setting out at a pace you honestly believe you can sustain for 4 - 4 1/2 hours and enjoying the event rather than worrying about a time. You may well surprise yourself, I know I have.

And I usually have at least one duff long run in marathon preparation, better then than in the race :-)
Aug 2013
11:21am, 29 Aug 2013
742 posts
  •  
  • 0
Canute
I am a bit worried by Naomi’s optimistic view about my opinions. We are all speculating here. In the end you have to weigh up the various opinions and decide what makes sense in light of your own situation.

But for what it is worth, here is my speculation about the question of whether you should sacrifice a long training run for a competitive HM. I think it depends on what is likely to be your greatest limitation in the marathon. Let us make the simplified assumption that there are two main limiting factors: aerobic capacity and endurance. These two are of course not completely separate. Nonetheless, there is a component of fatigue that develops even when you are running well below lactate threshold. This ‘long distance fatigue’ is important in ultras but also in marathons slower than 2:30 – 3 hrs. The evidence that you have presented us so far indicates your resistance to long distance fatigue might be a greater problem than your aerobic capacity at present. A HM will probably tell you more about your aerobic capacity than your resistance to long distance fatigue. So in the near future, long runs at a modest pace are probably crucial for you. The last very long run should probably be at about 4 weeks before the target event, so I would not be inclined to sacrifice a long run at this stage if your target marathon is soon.

Although this is speculation, I still think 4:00-4:10 is a reasonable target for you provides you have developed adequate endurance.
Aug 2013
5:56pm, 29 Aug 2013
1972 posts
  •  
  • 0
Tim of MK
This week, I've decided to do a half-marathon on the treadie at say Effort Level 6/7. That should tell me quickly enough whether I'm even capable of running 13.1 miles in 1:55 just now.

Next week, and the week after, I'll aim for two long-slow efforts of about 17 to 18 miles each.

Then, into taper.

There are doubtless some entrants who'll have done much more before race-day. Equally, there will be many who've done much less.

We'll see.

About This Thread

Maintained by Tim of Fife
I'm in training for a full-marathon. My schedule, as with pretty much every one published, includ...

Back To Top