Concept
Zone 2
A low-intensity aerobic training range. Its exact boundary depends on the zone model and the quality of the underlying heart-rate estimate.
What Zone 2 means
Zone 2 usually describes controlled aerobic work where breathing remains stable and conversation is still possible. It is useful because the effort can be repeated frequently.
Why beginners use it
It helps build aerobic capacity and weekly volume without turning every run into a hard workout. Walk breaks are valid when they keep the intended effort.
Why the number varies
Five-zone systems, three-zone systems, maximum-heart-rate formulas, and threshold-based zones do not produce the same boundary.
Zone 2 and fat loss
Zone 2 can support fat-loss training because it is repeatable, but long-term fat loss still depends on overall energy balance and consistency.
Use conversation, breathing, and recovery to verify the range. Slow down or walk when heart rate and effort keep rising.
Zone 2 is not a magic fat-burning zone, and staying one beat above or below a boundary does not determine whether a run works.