Zone 2 cardio
Redirected from "Zone 2 training"
Also known as: Zone 2 training
Zone 2 cardio is low-intensity aerobic training performed close to, but generally just below, the first lactate or ventilatory threshold. That is the preferred definition reached by an expert panel on Zone 2 training in 2025. At this effort, breathing and energy demand are elevated but a physiological steady state can usually be maintained for a relatively long time.
"Zone 2" does not have one universal heart-rate percentage. Watches, machines, laboratories, and coaches use different three-, five-, or seven-zone models, and the second band in one system may not match the second band in another. Age-predicted maximum heart rate also has substantial individual error. More broadly, a review of exercise-intensity prescription found that fixed percentages of maximum heart rate or aerobic capacity often fail to place different people in the same physiological intensity domain.
Laboratory measurements of the first lactate or ventilatory threshold provide the most individualized boundary. Without testing, a talk test and perceived effort are useful approximations: in the commonly intended low-intensity Zone 2, you should usually be able to speak in full sentences while breathing more deeply than at rest. Heart rate can add context, but heat, dehydration, fatigue, caffeine, and cardiac drift can change it at the same pace. Use a range and the session's feel rather than treating one beat-per-minute value as an absolute cutoff.
Zone 2 overlaps with LISS cardio, but the terms answer different questions. LISS describes a continuous easy format; Zone 2 describes a target intensity and, according to the expert viewpoint, can also be trained with variable or interval-type work. It is much easier than HIIT, which deliberately reaches high intensities separated by recovery. Both can improve endurance, but they differ in fatigue, time commitment, and the specific stimulus.
Zone 2 is useful because it can accumulate aerobic work at a manageable cost, not because it occupies a uniquely magical zone. The 2025 expert panel noted that expected adaptations are not necessarily exclusive to this intensity. A higher proportion of fat used as fuel during an easy session also does not guarantee more body-fat loss; long-term energy balance remains decisive. Choose duration and frequency that complement the rest of your training rather than copying an elite endurance athlete's volume.