Bit of a disappointment

What's blood lactate levels got to do with running a marathon?

800m track race perhaps.

The marathon is 99% plus aerobic.

Nearest most runners get to raising blood lactate levels in a marathon is when they start chatting on their phones or eating their lunch.

I think it's best not to take any of these tests, then you have no preconceived glass ceiling.

Just run and listen to your body. Why did it all get so technical and complicated? Just run...

Your freebie blood lactate test probably says you're not capable of a 46 minute 10k...

your 10k and half times are way better than mine and i managed a sub 4.......it depends of course on how well your training is going..how many long runs you have fitted in and are likely to fit in and how it all goes on the day.........

i agree with Phil...i bet they would say you are not capable of your 10 k time

good luck

If this is your first marathon then I would suggest you be conservative with your pace ambitions. It is frustrating to finish a marathon feeling you could have gone quicker but this frustration is nothing compared to the pain of running out of steam at 20 miles and hobbling the last few miles. I would base my expectations on my training pace in my long runs. You still have a fair amount of time left to get some miles in. Just completing your training without injuring yourself and running the whole 26 miles is a challenge in itself! Science is great but interpreting it is a pain in the arse!

Your times are certainly compatible with a 4 hour marathon, perhaps the person testing wasn't properly equipped or trained?

I listened to Tony Audenshaw on this week's marathon talk podcast talking about lactate threshold and testing.  Didn't sound like it was the kind of thing you'd get for free. I asked my friend at our club who is a sports science lecturer for one and she said I'd need a morning off work and she would run me till I was sick to get the different levels.  Audenshaw went on to say that his lactate threshold session was the biggest contributor to his improved times, so I think it's well worth working on

Oh you are more than capable of doing a sub 4.  Your 10k and HM PBs are near identical to mine were when I did a 3:54 in October (2nd marathon) (10k was 46:14 and HM was 1:44:17)  My first marathon was 4:06 but that was Manchester and pretty horrific conditions (my HM PB at that time was 1:45).  

Agree with Also Ran re P&D book, I am currently following their plan and am definitely shifting my training to easier paces than ever before - I made mistake of doing too much steady and threshold running for my last marathons and it is a huge error.  It is an aerobic event so doing lots of aerobic running at an easy pace with a few miles a week ran at lactate threshold in a tempo run will help you hugely.

You should be fine with sub 4. The blood test - did they take just one sample at rest? Unless they took several samples at increasing levels of effort I don't see how they can detirmine your lactate threshold and pace.

That's not how lactate testing is done for running if I went and paid for it tomorrow - generally blood samples are taken multiple times over increasingly fast speed intervals.

If you are going to make use of this type of stuff, then it only really makes sense with regular retesting. Thats why I just run threshold sessions at an approx pace of 5 - 10 seconds per mile faster than I think I can currently do a HM in, and ask myself, is this pace comfortably hard - can I keep it up for an hour. 4 to 7 miles at this intensity is the typical P&D threshold session. For a fast distance runner, then the pace is going to be close to half marathon pace.

So in conclusion, if you want to go down the science route, you need a load of pricks to test yout LT. One prick is not enough.

If you are doing 13 miles relatively easily I doubt it is really at tempo pace. As you get fitter as long as you are doing intervals/threshold runs your long runs start to be at a lower percentage of you maximum (as your max increases). As long as you can do the long runs at an even pace and are not too tired to do the rest of the training you will be ok but don't get too hung up about LSR pace - it is mainly about time on feet/endurance. You may even revise your target time. For my second my original target was sub 4 and training went well so I revised to 3:45 and did 3:41. (down to 3:15 now )
Probably right about drumming up trade for a full test.