At the same power and the same 30 minutes of work, breaking the ride every 5 minutes with a 30–90-second pause lowered lactate by 1–1.5 mmol/L and removed its drift; the lactate steady state then sits 22–32 W higher
Key Findings
At the same power, lactate after 30 minutes of work was 6.0 ± 1.3 mmol/L continuous against 4.9 ± 1.4 with 30-second and 4.5 ± 1.1 with 90-second interruptions every 5 minutes.
Lactate drift over the last 20 minutes was 1.2 ± 1.0 mmol/L continuous against 0.2 ± 0.7 and −0.3 ± 0.7 with interruptions.
The power at maximal lactate steady state was 277.8 ± 24.4 W continuous against 300.4 ± 30.4 W and 310.0 ± 31.2 W with 30- and 90-second interruptions (73.7% vs 79.2% and 81.5% of peak); the steady-state lactate itself was unchanged.
Nineteen men in two experiments (n = 10 and n = 9).
Practical Application
At one fixed power, splitting threshold work makes it a smaller metabolic load: 6 × 5 minutes with short pauses is easier than 30 minutes straight, and by the same logic 4 × 10 is somewhat easier than 2 × 20 (the 10- and 20-minute comparison itself was not tested).
To keep the same internal load with shorter reps, raise the power — here by roughly 20–30 W. That is what lactate-guided threshold intervals do REF-301.
So "2 × 20 or 4 × 10" is not one question: at the same watts the long reps are the harder session; at the same lactate the short reps carry more watts.
Limitations
Only 5-minute blocks were tested; training status is not stated; no RPE or heart rate in the abstract; acute (abstract only was read).