1. Zone 2, often called aerobic base, is a steady-state effort at about 60 to 70 percent of your maximum heart rate. 
2. At this intensity, your body primarily burns fat for fuel while improving cardiovascular efficiency and aerobic endurance. 
3. You should be able to hold a comfortable conversation during your workout. 
4. Examples of zone 2 training include easy runs, cycling, or swimming.
5. Training in Zone 2 increases stroke volume, the amount of blood pumped per heartbeat, which in turn raises cardiac output, the total blood volume your heart pumps per minute (calculated as Stroke Volume × Heart Rate). Higher cardiac output delivers more oxygen to working muscles, supporting endurance and recovery.
6. Improved efficiency as a result of regular zone 2 training contributes to lower resting heart rates in fitter athletes, because their hearts can supply the same blood volume with fewer beats.

The Bottom Line: Zone 2 training is the foundation of aerobic fitness. By focusing on steady, moderate effort, you strengthen your heart, improve endurance, and prepare your body to handle higher-intensity workouts more effectively. It’s slow but powerful work that pays off in the long-term.