VO2max Intervals

VO2max intervals are a specific application of HIIT aimed squarely at raising maximal oxygen uptake (VO2max). The principle is to spend as much cumulative time as possible at or very near VO2max within a session. Because a person can only hold true VO2max-level intensity for a few minutes, the work is broken into repeated hard intervals.

The archetype is the Norwegian 4×4: four intervals of 4 minutes at a near-maximal, "hard" intensity (commonly ≈90–95% of HRmax or maximal aerobic speed), each followed by about 3 minutes of active recovery. Other effective formats use shorter intervals (e.g., 30/15s or 1–2 minute repeats) that also drive heart rate and oxygen uptake toward maximum across the set.

These intervals sit above threshold work (see Tempo / Threshold Training) and below the supramaximal all-out efforts of sprint interval training (see SIT (Sprint Interval Training)). Improvements in VO2max from such training are substantial but individually variable, and VO2max has a meaningful genetic ceiling on trainability (see VO2max Trainability and VO2 Max and How Cardiovascular Conditioning Improves It). Because the intensity is high, the same warm-up, screening, and volume-limiting cautions as HIIT apply (see HIIT (High-Intensity Interval Training)).

• Goal: maximize time at/near VO2max to raise maximal aerobic capacity.
• Archetype: Norwegian 4×4 — 4 × 4 min near-maximal (~90–95% HRmax) with ~3 min active recovery.
• Also done as shorter repeats (e.g., 30/15 s, 1–2 min) that push toward VO2max across a set.
• Sits above threshold work and below supramaximal SIT.
• Gains are real but individually variable; VO2max trainability is partly genetic.