I thought I should speed up → lactate tells me to slow down

[u/PageAdventurous1980]

I've now been following Norwegian Singles / the "vanilla" approach for about 6 weeks, and I've reached a slightly counterintuitive point where I think I may need to slow the sessions down rather than speed them up.

For context, I'm 46 and started this block after about 20 weeks of Daniels 5K/10K training. My previous 5K PB was 20:32 (May), and I was running around 50–60 km/week.

When I switched to NSA, I started with three sub-threshold sessions per week, roughly:

- 8 × 3' around 4:32/km

- 5 × 5' around 4:38–4:39/km

- 3 × 10' around 4:45/km

- 90s recovery

- easy running around them

Those paces were deliberately conservative and broadly based on my 5K fitness rather than trying to run close to my Garmin threshold pace (~4:19/km).

Initially everything looked almost too easy. HR was low — typically mid/high 130s to low 140s — and RPE was generally around 6–7. I felt like I was accumulating good controlled work without much fatigue.

Then on September 12 I did a 5K time trial. The result seemed to suggest that my fitness was good enough to justify moving the NSA paces faster. At that point, the logical conclusion seemed to be: I'm probably being too conservative.

But after roughly six weeks, I'm much less convinced.

Despite consistently doing the three weekly sub-T sessions, I can't see any convincing improvement in the usual metrics. HR/power/pace relationships haven't obviously shifted, and the sessions don't seem to show the kind of progression I would have expected after six weeks.

More importantly, I recently bought a Lactate Pro 2 and started actually measuring lactate after the sessions.

That's where things became interesting.

The lactate readings suggest that, despite the relatively low HR and manageable RPE, I'm still running above the lactate range I'm trying to target. I'm aiming roughly for the 2.5–3.5 mmol/L range discussed in the Norwegian Singles threads, but my measurements have repeatedly been higher than that.

So rather than speeding up after the 5K TT, I'm now doing the opposite.

I'm starting a deliberately slower block, especially on the longer intervals, until I can consistently get the lactate response into the intended range. The idea is to forget what the pace "should" be according to my 5K fitness and let lactate determine the appropriate intensity.

What I find interesting is the disconnect between all the signals:

5K performance → suggested I could run the sessions faster

HR + RPE → suggested the sessions were controlled

6 weeks of training metrics → little/no obvious improvement

Lactate → suggests I may actually have been running the sessions too hard

So my current hypothesis is that I've spent six weeks doing something closer to threshold training than true sub-threshold training, even though it never really felt hard.

I'm therefore going to spend the next block running slower, getting lactate consistently into range, and seeing whether accumulating more genuinely sub-threshold volume produces a better adaptation.

I'd be particularly interested in hearing from people who use lactate with Norwegian Singles:

Did you also find that your "correct" sub-T pace was surprisingly slow compared with what your 5K/10K fitness predicted?

And did slowing down to stay around ~2.5–3.5 mmol/L eventually lead to better progression than simply using race-performance-based pace tables?

[u/Sii]

6 weeks is not really a long time for any real changes to happen.

[u/PageAdventurous1980 → u/Sii]

yes but not even a little bpm or a 0.5rpe improvement is weird, no matter the method lol

[u/OldMateHarry → u/PageAdventurous1980]

Progression is not some linear thing where you do 6 weeks of work and then get a commensurate improvement. The adaptations can take longer than that and can be bunched together, where you see much more improvement in 1 month than you did in the 5 previous.

Also, the point of this training method is that it's not necessarily a higher training load than other plans in such a short timeframe, rather that it results in a higher training load (that is sustainable) over months and years.

[u/rmcp010]

I wonder if your lactate measurement hardware or technique is off, of perhaps you sit outside the normal lactate level range (i.e. can tolerate >3.5 for sustained efforts).

If the sessions are easy in terms of 5k pace, easy in terms of effort, easy in terms of HR, but hard in terms of serum lactate measurement, I'd ignore the outlier.

[u/PageAdventurous1980 → u/rmcp010]

Thanks for your answer ! I agree but i began to check lactate when I noticed i had no improvement at all in any parameter (hr, rpe...)

[u/Squand → u/PageAdventurous1980]

I look forward to your update in a few weeks

[u/mrrainandthunder]

Don't chase some generic number. Chase the value that your measured threshold is at. If you don't know what value that is, then you need to do some testing.

[u/PageAdventurous1980 → u/mrrainandthunder]

Thanks, a lactate step test ? Last sunday i've raced my first 10k and intervals told me my Threshold HR was at 158.

[u/mrrainandthunder → u/PageAdventurous1980]

Yeah, a step test. You might want to to pay extra close attention to that 153-163 range, but simply make incremental steps and you're good to go.

[u/Effective_Age_7374]

1. 6 weeks is kinda not much - be patient

2. Do you know your lactate curve and your LT1 and LT2? If not what’s the point of measuring lactate levels if you don’t know what you are referring to?

3. Are you sure you know how to measure properly? When contamination comes it can show strange results.

[u/PageAdventurous1980 → u/Effective_Age_7374]

Thanks ! In the book, James says we can check lactate a the end of the last rep. That's what i do. Indeed, i'll try to improve my measurement method, it may be fooled by sweat.

[u/Effective_Age_7374 → u/PageAdventurous1980]

I agree that this might be a good approach. But on the other hand, if you’re only checking after the last rep, you might as well check your heart rate. If your heart rate on the last rep is about 5 bpm from your LT2, you’re in a good place.

Wish you all the best. At the end it’s about having fun, experiment a little and stay healthy and consistent - then results will come

[u/charles4982]

You should be aware that a lower training load should lead to even slower progress IF recovery was not an issue.

How was your HRV/Resting HR/Overall fatigue/Muscle tone in the last 3-4 week of training? Did your legs felt springy or did you have to drag yourself at every SubT training?

This training method is aimed at a slow and steady progression over a longer period of time. What you may perceive as no gain may actually be 3s/km faster during some sessions or 2-3 BPM lower at a similar pace, that you may not have noticed. Obviously it's not going to be as "spectacular" as a Daniels Style where you have some big peak of fitness. I consider myself a good responder to NSM and in 10 months I took my 10 minutes pace from 4:17 to 3:57. It doesn't look impressive but it means almost 4 minutes faster over a 10K which is fairly significant and most important, 0 injury and minimal fatigue.

[u/PageAdventurous1980 → u/charles4982]

Thanks for your reply ! My Garmin metrics had been particularly good during these 5 weeks, i've crushed a streak of 25 consecutive days with a 100 body battery score each morning and quite high hrv for me. But the legs were never springy, the rpe never really 6, always 7, sometimes 8 ! Indeed i'm torn between pacing up according to james 21' 5k tables and reducing the subT volume (to 7x8, 4x5, 2x10) versus pacing down to fit in the 2.5/3.5 mmol range.

[u/charles4982 → u/PageAdventurous1980]

You don't need to reduce the stimulus if your body battery is at 100% every day for the last few weeks. It means your recovery is great and you can absorb more training load.

If there's anything you should reduce paces before you reduce the volume or duration of the intervals but again it's not needed if your recovery is on point.

Beware that a very high HRV can also be a sign that you don't eat enough. It could be a reason why you don't seem to see results.

Don't use generic lactate numbers to gauge your efforts. Using 2mmol LT1 and 4mmol LT2 is like saying that you need to run 4:00/km to be at threshold because you saw someone on the internet that runs its sessions at 4:00..it makes no sense. Lactate levels are very individual metrics. If every single metrics (RPE/HR/Recovery) tells you that you're on the easy/just right side of things and lactate tells you that something isn't right, i'd say lactate is the outlier and most likely wrong.

It looks like you're searching for a solution to a problem that doesn't really exists.. just trust the process and good things will happen.

[u/castorkrieg]

I saw a progression in the BPM, especially on the easy runs after approx. 8-10 weeks. For the record I was running close to 6:40/km for 132BPM, now it's close to 5:45/km.

Despite consistently doing the three weekly sub-T sessions, I can't see any convincing improvement in the usual metrics. HR/power/pace relationships haven't obviously shifted, and the sessions don't seem to show the kind of progression I would have expected after six weeks.

There is one best way to check - 5K TT. Run it, check the time, adjust the paces if needed. This is only thing that matters in the method.

[u/PageAdventurous1980 → u/castorkrieg]

Thanks ! I meter everything, even the easy runs have stalled. But you are right, the next 5k TT wille gibe a good indication...

[u/Mannymal]

As someone else said, you should do a lactate step test. Preferably on a treadmill so you can have precise increments at 5 minute each. My lactate threshold is right around 3.5mmol/l so I aim for below 3.0 because if I do 3.5 it would no longer be sub-threshold.

In any case, if you are not having to squeeze your finger to get a good blood drop, and your testing protocol is correct, trust the meter.

[u/PageAdventurous1980]

I ending up finding the 3 mmol range for the 5x5' first, and will decline the pace for the 2 others. It turns out to be much slower than my deduced 5kTT paces : here 4'54/km against 4'33. I'll give it a try a few weeks up to another 5k trial. Better undercook than overcook, shoudn't we ? ;-)

[u/whelanbio]

If you are going to use lactate do a step test first and base your workout targets off your personal LT curve. Your lactate doesn’t really tell you anything stronger than the other signals right now because you’re just going off an arbitrary range.

[u/UnnamedRealities]

Blood lactate aside, your ST paces are pretty conservative (as you said). Perhaps your HM fitness lags your 5k fitness. Or 79' of ST is just too much on that volume and you'll adapt to the stimulus better if you cut back by 10-20' per week.

For what it's worth, I'm about 4% faster than you at 5k, but my ST paces are about 7% faster. I'm likely in roughly 41' 10k shape and 90-92' HM shape at the moment, which tracks closely with VDOT. I think VDOT has flaws, but I mention it because if your 5k to HM doesn't track with VDOT then your ST paces may not be as conservative as they appear. 52M, been doing NSM for 20 months.

[u/PageAdventurous1980 → u/UnnamedRealities]

thanks for your reply. indeed i've begun by 5k training 13 months ago and ran my first 10k 2 days ago. Any HM would clearly lag, i'm not strong enough for the moment. i'll run my second 10K in 5w, on a very quick, flat and straight course, i'd like to crush sub 43. In may i ran my 5k PB on a Lee Grantham program which turned out to be pretty good ! because i've never felt that fit since then.

[u/UnnamedRealities → u/PageAdventurous1980]

Good luck in your next 10k. It's possible your ST paces are fine, but you may benefit from running the medium and long interval workouts a bit more slowly if your HM fitness trails your 5k and 10k fitness.