Anaerobic Capacity

You can think of anaerobic capacity as how much short-duration high-intensity work you can produce above sustainable intensity, and how long you can keep that effort going. It shows up in sprints, surges, and short steep attacks.

Key characteristics

• Short duration: often seconds to tens of seconds (many people anchor it around ~30 seconds).
• Different from “steady fitness”: it’s not the same as threshold or aerobic base.
• Typical scenarios: finishing kick, sudden accelerations, short steep surges.

Training relevance

For long-distance endurance athletes (marathon, triathlon), anaerobic capacity is usually less central than aerobic base, threshold, and durability. For sports that require frequent surges, attacks, or finishing kicks (road cycling, trail running), anaerobic capacity can strongly influence decisive moments.

It is not sustainable in the way threshold work is, but it can matter when a race or workout demands a sudden change in intensity.

How Trainingload.ai uses anaerobic capacity

• Short-effort context: identifies sessions with repeated surges, sprints, or high-intensity work above threshold.
• Power-model connection: in cycling, anaerobic capacity is closely related to W′ / anaerobic work capacity.
• Training balance: interpreted alongside threshold, VO2 Max, and recovery so short-effort work does not crowd out the main goal.

Related docs

• Anaerobic Work Capacity (W′)
• Critical Power
• VO2 Max
• Anaerobic Threshold

References

• Joe Friel: Common But Confusing Training Terms