In Part 1, we looked at the argument around Sweet Spot, polarized training, and the so-called black hole.

The short version was this:

The middle is not automatically the problem. The uncontrolled middle is the problem.

That distinction matters, because it changes the entire conversation.

If you treat the middle as a vague “comfortably hard” zone, it quickly becomes a trap. Easy days become too hard. Hard days lose quality. Fatigue accumulates. The athlete feels productive, but the training week slowly loses shape.

But if you treat the middle as a controlled sub-threshold stimulus, it becomes something very different.

That is where Bakken and Copeland are useful.

Bakken gives us the high-control model: threshold training guided by lactate, repeatability, discipline, and a refusal to turn every good-feeling session into a harder session.

Copeland gives us the practical adaptation: Norwegian Singles. A way to apply some of that logic for runners with normal lives, normal schedules, and no desire to build every week around double-threshold days.

The idea is not to copy the Norwegians.

The idea is to understand the principle.

The most useful version of this training sits in what I like to call the controlled gutter: the space between easy aerobic running and true threshold-and-above work.

It is not jogging.

It is not racing.

It is not a heroic tempo session.

It is disciplined, repeatable, sub-threshold work.

In Bakken’s model, the classic structure is built around controlled sessions, often separated by several hours, with intensity kept in a manageable lactate range rather than drifting into maximal threshold work. His public explanation of double-threshold training describes work commonly held around 2 to 3 mmol/L of lactate, with the broader purpose being to accumulate quality without creating excessive fatigue.

That number should not be treated as magic.

For some athletes, the right cap may be closer to 2.0 or 2.5 mmol/L. For others, especially well-trained athletes using consistent testing methods, it may sit a little higher. The exact number depends on the athlete, the sport, the testing protocol, the day, the heat, the fueling state, and the accumulated fatigue in the legs.

The principle matters more than the number:

Stay below the point where the workout starts to run away from you.

That is the whole game.

When you drop the intensity just enough, the character of the session changes. You are still applying a strong aerobic stimulus. You are still asking the body to work. But you are not creating the same recovery debt that comes from repeatedly drifting into threshold, VO₂ max, or race-effort territory.

This is why controlled sub-threshold work is so powerful.

Not because it is magical.

Because it is repeatable.

Bakken’s system is often discussed through the lens of elite runners and double-threshold days.

That can make it feel inaccessible.

Most adult athletes are not going to run twice in a day, prick their finger after every interval, and build a week around carefully managed lactate dynamics. They have jobs, families, stress, poor sleep, limited time, and an injury history!

That is where James Copeland’s contribution is useful.

Copeland’s Norwegian Singles Method takes inspiration from the threshold-controlled logic of the Norwegian model, but adapts it to a more realistic training structure for recreational and time-constrained runners. Instead of double-threshold days, the emphasis is on regular sub-threshold sessions performed as single daily workouts, surrounded by genuinely easy running.

That makes the model less exotic and more practical.

You do not need to copy Jakob Ingebrigtsen.

You need to understand the principle.

Keep the easy days easy. Keep the moderate work controlled. Progress by accumulating more repeatable work, not by turning every session into a test.

The mistake many athletes make is asking, “What is my Sweet Spot pace?”

That is too blunt.

And it is something I have been guilty of myself.

It is tempting to take one pace, one power number, or one percentage of threshold and treat it as the answer. It feels clean. It feels coachable. It feels like the complexity has been solved.

But a 3-minute repetition, a 6-minute repetition, and a 10-minute repetition should not all be run at the same intensity. The longer the interval, the more conservative the pace needs to become.

The better question is:

What pace can I hold for this specific interval duration while staying below the point where fatigue starts to snowball?

That gives us a simple step-down architecture.

These can be crisp and controlled.

They may feel close to 10K or half-marathon effort, depending on the athlete, but they should never become a VO₂ max session in disguise. The short duration lets you touch a faster rhythm without letting the metabolic cost rise too far.

The key word is touch.

Not attack.

These sit one step lower.

The pace should feel strong but settled. You are working, but you are not bargaining with yourself. Breathing is active, rhythm is clear, and you should be able to repeat the interval without needing a long psychological reset.

This is where many athletes go too hard.

They feel good on the first rep, push slightly above the target, then spend the rest of the session managing the damage.

That is not controlled sub-threshold work.

That is ego with a lactate problem.

These are the real test of discipline.

The pace should be almost boring in the first few minutes. You should feel like you are waiting for the work to arrive. By the second half, focus is required, but the effort should remain stable.

If the first 10-minute rep feels exciting, you are probably going too fast.

The goal is not to win the first rep. The goal is to make the final rep look almost identical.

This is where Copeland’s book is useful, because it makes the idea concrete without turning every athlete into a lactate-testing project.

Rather than treating “sub-threshold” as one fixed pace, Copeland uses a pace table that steps the target down depending on the interval length. The shorter 3-minute repetitions are faster. The 6-minute repetitions are slower. The 10-minute repetitions are slower again.

That sounds obvious, but it is exactly where many athletes get this wrong.

They take the pace they can handle for a short controlled repetition and then try to stretch it across longer intervals. Suddenly the session is no longer sub-threshold. It has become threshold work, or worse, a disguised race effort.

Here is a small sample of the logic, using 5K time as the reference point.

Copeland built these kinds of targets from thousands of lactate-test proof points, which is what makes the table useful for runners who do not have access to regular testing. It gives you a practical starting point so that you do not have to turn every session into a lab exercise. But the numbers are still targets, not commandments. If you have access to a lactate meter, use it to check your own response. If you do not, cross-check with breathing, RPE, heart rate, and how well the session repeats.

The value of the table is not that every athlete should copy the numbers blindly. The value is the principle it teaches:

The longer the repetition, the more conservative the pace needs to be; and easy runs are exactly that, very easy.

For many runners, the biggest surprise is how restrained the longer targets look. A 20-minute 5K runner, for example, is not being asked to run 10-minute repetitions at 10K pace or even close to it. The 10-minute target is 4:29/km, and the easy pace is 5:43/km. That is a long way from the kind of “comfortably hard every day” running that gets people into trouble.

That restraint is not a weakness of the system.

That is the point.

The aim is not to prove that you can run fast. The aim is to stay in the right physiological lane long enough for the work to accumulate without dragging the rest of the week down with it.

A good sub-threshold session often feels a little underwhelming at the end. You should finish knowing you could have done one or two more repetitions. Not five more, but one or two.

That feeling is not a sign that you missed the workout.

It is usually the sign that you got it right.

The pace table explains the intensity, but it also helps to see where the work sits inside a normal week.

Copeland’s 6.5-hour example week is useful because it shows that Norwegian Singles is not built around one heroic session. It is built around repeatability: three controlled sub-threshold sessions, genuinely easy running around them, and enough restraint that the athlete can come back and do it again.

The week typically moves from longer, more restrained sub-threshold work early in the week toward shorter, slightly quicker controlled repetitions later on.

The important point is not the exact day of the week. The important point is the relationship between the sessions.

The 10-minute repetitions are the most conservative. The 6-minute repetitions sit in the middle. The 3-minute repetitions are the crispest. But all three remain controlled.

That is the practical lesson: the sub-threshold work only works because the rest of the week allows it to work. The easy days are not filler. They are what make the controlled days repeatable.

When the middle is dismissed as a marketing gimmick, we lose sight of the adaptations that matter for long-distance performance.

Controlled sub-threshold work trains the body to produce, clear, and reuse lactate more effectively, without letting it accumulate uncontrollably.:

You become better at holding a strong pace without the effort steadily deteriorating.

Long-distance performance is not only about how high your ceiling is.

It is about how much of that ceiling you can use for a long time.

A huge VO₂ max is valuable, but it does not automatically make you durable. Marathoners, long-course triathletes, swimrunners, ultra-runners, and gravel cyclists all need the ability to sit at a high percentage of their aerobic capacity without tipping into a cost they cannot repay.

That is exactly what controlled sub-threshold work trains.

It pulls performance up from below.

A controlled middle session should usually feel like this:

The next day, you may feel that you worked, but you should not feel like the session has taken ownership of your week.

That is the difference between productive sub-threshold work and the black hole.

The black hole leaves you flat.

Controlled sub-threshold work leaves you better.

The lesson from Bakken is that threshold work can be powerful when intensity is tightly controlled.

The lesson from Copeland is that the same principle can be adapted for normal runners with normal lives.

That is the real message.

Not “train harder.”

Not “live in Sweet Spot.”

Not “copy the Norwegians.”

The message is simpler and more useful:

Easy should be easy. Hard should be hard. And the middle only works when it is controlled.

Master that, and the so-called black hole becomes something very different.

It becomes one of the most repeatable ways to build the engine.