The target is critical power itself: the highest power a rider can hold without continually fatiguing. By moving one minute over it and one minute under it for ten minutes at a time, the session loads both sides of the boundary, the aerobic production that sits just below and the fatigue management that sits just above.

The minute at 90% of CP is where the adaptation happens. It is hard enough to keep aerobic demand high and just easy enough for partial metabolic recovery, so the lactate produced in the minute at 110% is cleared while the rider is still working. Three blocks with five-minute recoveries give thirty minutes of that transition in an hour.

In Vekta the over and the under are both written against CP, and because CP is derived from every ride, the boundary the session targets is today's boundary. The W′ balance trace afterwards should show a sawtooth that never reaches the floor; if it does, the over was too far over.

A build-phase staple, twice a week at most, indoors or out. When the last block matches the first, move the over to 112–115% or lengthen the blocks.