Aerobic Threshold (AeT)
Aerobic threshold (AeT) marks the upper range of easy aerobic work, useful for Zone 2 training, base building, and long-session pacing.
Aerobic Threshold (AeT)
You can think of Aerobic Threshold (AeT) as the boundary where “easy aerobic” starts to become “moderately aerobic”: breathing becomes more noticeable and you begin relying more on glycogen over long durations.
Key characteristics
- Breathing: easy; you can often breathe through your nose or talk comfortably.
- Perceived effort: feels like “I could do this for hours”.
- Lab definition: often near the point where blood lactate first rises above resting baseline (commonly around ~2 mmol/L).
Practical ways to approximate it
Without lab equipment, it’s usually better to use repeatable, practical signals than chase a single “exact” number:
- Talk test & feel: an intensity you can hold for a long time while still speaking in full sentences.
- Heart rate (rough range): many athletes use “below LT by a step” as a starting point, but individual variation is large.
Training relevance
AeT is often used as the “upper edge” of base training:
- Below AeT: easier volume and recovery; great for building consistency.
- Above AeT: glycogen cost and recovery cost tend to rise faster, so it’s best used intentionally.
Joe Friel makes a similar point: in the real world, it’s more useful to find an intensity you can repeat consistently than to obsess over a perfectly precise lab line (see reference).
How Trainingload.ai uses aerobic threshold
- Easy-session guardrail: AeT helps identify the upper edge of easy aerobic work.
- Long-session review: when pace or power stays steady but heart rate drifts above the intended range, Trainingload.ai can flag the session for context review.
- Base training context: AeT is interpreted alongside heart-rate zones, aerobic decoupling, EF, and recent load.
Related tools and docs
References
Aerobic Capacity
Aerobic capacity describes the upper range of oxygen use during hard efforts, commonly represented by VO2 Max and interpreted alongside thresholds, economy, and training load.
Lactate Threshold (LT)
Lactate threshold is the intensity range where lactate begins to accumulate more steadily, used to anchor threshold training, heart-rate zones, pace zones, and power zones.