QT2.0 Build/TH Block Comments

QT2.0 Build/TH Block Comments

What This Phase Is Actually About

The Build/TH training block is where we work to reduce wasted space in your fitness.

By the time we enter this phase, you typically already have a solid aerobic foundation. What we’re addressing now is how efficiently your sustainable performance (Critical Power / Critical Speed) sits relative to your high-end capacity (power or speed at VO₂ Max).

This block is about bringing those two closer together.

1. Muscle Fiber Utilization

Training the crossover that defines threshold

During a Build/TH block, we continue to support Type I (slow-twitch) fibers, but the primary focus shifts toward the transition zone between:

  • Type IIA - Oxidative fibers

  • Type IIA - Glycolytic fibers

This crossover point is critical because it largely defines where your threshold lives.

In this block:

  • Sub-threshold work pushes the oxidative side of Type II fibers to behave more aerobically

  • Slightly above-threshold work recruits higher-force fibers and teaches them to sustain effort more efficiently

  • Small amounts of work above Critical Power / Speed lightly engage Type IIX fibers, not to build raw anaerobic power, but to help lift the ceiling that threshold is anchored to

The goal is not to increase anaerobic contribution - it is to convert usable capacity into aerobic sustainability.

2. The Athletic Architecture Model

Closing the gap by raising the ceiling

We typically enter a Build/TH block when:

  • Critical Power relative to pVO₂ Max power, or

  • Critical Speed relative to sVO₂ Max speed

falls below ~85%.

This usually means:

  • You have more anaerobic capacity than you need right now

  • Your sustainable output is not keeping pace with your high-end capability

  • There is “attic space” above threshold that isn’t being used effectively

From an architectural standpoint:

  • Threshold sits at the ceiling

  • Power/Speed at VO₂ Max defines the roof

  • The space between them is potential - but also inefficiency

This block works in two directions:

  • Just below threshold work pushes up on the ceiling

  • Just above threshold work pulls the ceiling upward from above

The result is not just higher numbers, but a tighter, more efficient structure where sustainable performance occupies more of your available capacity.

3. Quality, Duration, and Fatigue Accumulation

More intensity means more protection

Compared to Base/Durability:

  • A greater portion of training stress comes from higher-intensity work

  • Duration matters, but quality matters more

  • Sessions carry clearer execution demands

Because of this:

  • We are more deliberate about protecting workout quality

  • Fatigue accumulation is managed, not maximized

  • You should feel challenged, but not crushed

This is not a brutal block, and it is not designed to overwhelm you. The intensity is purposeful and controlled - but it does require that you show up able to meet the demands of the sessions.

As a result:

  • CTL still rises

  • Fitness becomes more specific

  • But overall load increases more conservatively than during Base/Durability

This is refinement, not volume-driven expansion.

The Big Picture

Build/TH is where fitness becomes usable.

We are:

  • Reducing inefficiency

  • Improving sustainability

  • Teaching your system to operate closer to its true potential

If Base/Durability made the structure bigger, this block makes it tighter, cleaner, and more functional.

That’s the job of threshold work in QT2.0.