5-15 Seconds Slower Than T Pace —
TT's Four-Week Sub-Threshold Pilot

If tempo sessions repeatedly drift above their planned intensity, running faster may not be the answer. Lowering the target can make the repetitions easier to control.

What TT means by sub-threshold

Physiological lactate threshold is not one universal pace. The boundary varies with the definition and test. TT's T pace is a training reference calculated from a trusted current VDOT. It is not the same as a laboratory measurement of LT2.

TT sets the pilot target 5 to 15 seconds per kilometer slower than that T pace. Because the app does not measure blood lactate, heat, hills and fatigue can still push the effort too high. Slow down when breathing or form is no longer controlled.

The Norwegian model combines a large low-intensity base with lactate-controlled threshold sessions. Elite examples include two threshold sessions on the same day. TT's NSM pilot is a conservative, once-a-day product adaptation inspired by that model. Norwegian Singles Method is a product label here, not the official name of a standardized training protocol.

Why lower the intensity?

Controlling intensity may make planned work more repeatable than turning every session into a maximal test. Norwegian elite practice also places non-exhaustive threshold work between high volumes of low-intensity training.

That does not guarantee a faster race after four weeks. The pilot aims for consistent execution at a conservative target rather than promising a specific adaptation or result.

In other words the goal is not to run well today. It is to repeat the work for four weeks without missing.

Setting your target pace

This is where most attempts drift. "A bit slower than threshold" means something different to every runner.

The reference is VDOT. The server prioritizes PBs. When no PB is available, it can use recent wearable VO₂max or a recent-run estimate. The data-poor default does not unlock this pilot. TT then calculates easy (E), marathon (M), threshold (T), interval (I) and repetition (R) training paces.

The sub-threshold target is one step further: 5 to 15 seconds per kilometer slower than T.

The gap looks small on paper. It does not feel small. At T pace you are hanging on by the end; at sub-threshold your breathing and form hold through the final rep.

This range is a VDOT-based proxy. Measuring your actual lactate response requires separate testing.

How the four weeks are built

Weeks 1 to 3 default to two sub-threshold sessions. Everything else is easy running and the long run. Week 4 reduces both distance and quality frequency.

• Week 1 — two sessions plus long and easy days
• Week 2 — same shape, only the rep format changes
• Week 3 — two sessions, plus a short third one if you qualify
• Week 4 — one session with weekly volume pulled back to 90% of recent average

That third session in week 3 is only for advanced or elite runners covering at least 45km across six days. Everyone else stays at two.

The week 4 cutback is part of the implementation: weekly distance drops to 90% and the second quality session becomes an easy run.

Three session formats

Different lengths, same purpose: accumulate time at a controlled intensity.

Four things to protect

1. Never turn the last rep into a test.
   The better you feel, the more you want to push the final one. That is the moment this becomes an interval session.
2. Keep easy days genuinely easy.
   Two quality sessions a week only work if the rest of the week recovers. Holding easy pace matters as much as holding session pace.
3. Do not extend the long run.
   For these four weeks the long run stays comfortable and the same length.
4. Do not make up missed days.
   Stacking a skipped session onto the next day breaks the structure.

Who can start

These are product entry rules. They are not universal medical safety thresholds. They keep the current session structure within recent training volume.

• A trusted current VDOT that TT can verify
• Intermediate level or above
• 30km or more average weekly volume over the last four weeks
• At least one run of 8km or more in the last four weeks
• Able to run five or six days a week

Now available in TT as a 4-week pilot

TT calculates the target from a trusted current VDOT and keeps the four-week schedule inside your recent training volume. The app and server both validate the entry rules and weekly structure.

Open the NSM four-week pilot card in Analysis or choose NSM pilot while creating a training plan.

Frequently asked questions

Evidence and limits

This article does not prescribe the elite Norwegian model. That model combines a high volume of low-intensity training with lactate-controlled threshold work. TT does not measure lactate and instead applies a conservative product rule to VDOT T pace.

• Casado et al., 2023 — review of lactate-guided threshold intervals and the Norwegian model
• Sandbakk et al., 2025 — survey of training organization among Norwegian world-class coaches
• Weber et al., 2023 — individual responses varied under the same fixed lactate workload