TriPeak

Sweet spot training

For the six-hour week: the most fitness per hour available.

How the week is distributed

A sweet spot week puts roughly 55% of training time easy, 40% moderate and 5% hard. The percentages are of time, not of sessions — which is why a week with two hard sessions in it can still be 55% easy.

Easy

55% of weekly training time

Moderate

40%

Hard

5%

How it plans

• Assume hours are the binding constraint, and spend them where the return per hour is highest: 88–94% of threshold.
• Three quality sessions a week, each repeatable — hard enough to build, not so hard that tomorrow is lost.
• Keep easy sessions short and genuinely easy; there is no time for junk volume.
• Use the long weekend session for the volume the weekdays cannot give.
• Accept a smaller aerobic base as the price of fitting training into a life.

Why it is meant to work

The reasoning is arithmetic before it is physiological. Adaptation scales with both how hard a session is and how long it lasts, and the product of the two peaks somewhat below threshold — hard enough to matter, easy enough to sustain for twenty or thirty minutes at a time and to repeat within the same week.

For an athlete with six or eight hours, the polarised prescription spends most of those hours at an intensity that needs volume to pay off, and there is no volume to give it. Sweet spot converts the same hours into more measurable fitness, at the cost of a shallower aerobic base and a week with little genuine rest in it.

It is a deliberate trade, not a claim to be optimal. It is the approach with the weakest peer-reviewed comparison against the others, and the one most obviously shaped by the constraint it is designed around.

Who it suits, and how it fails

Suits

Athletes on eight hours a week or fewer, especially in winter or around a demanding job.

Watch out for

Sustained for months it flattens out: the same moderate stimulus stops adapting and leaves an athlete permanently slightly tired. Needs deliberate easy weeks and a change of emphasis two or three times a year.

Strength of evidence

Rests on the straightforward observation that adaptation scales with both intensity and duration, and that just below threshold is where their product peaks for a given hour. Well established as efficient; less clear that it is superior when hours are not limited.

The research behind it

Every citation below was checked rather than remembered, and each note says what the study found and what it does not establish.

1. Allen, Coggan & McGregor, Training and Racing with a Power Meter (3rd ed., 2019)Where the term and the zone come from. Practitioner literature rather than a trial: it argues the case from the physiology and from coaching experience, and should be read as such.
2. Comparison of Polarized Versus Other Endurance Training Intensity Distributions (2024), Sports MedicineThe relevant finding is a negative one: threshold-weighted distributions are not clearly worse, and the honest position is that nobody has shown sweet spot to be inferior for time-limited athletes, because almost nobody has tested it on them.