HR Zones

Heart rate zones are ranges of heartbeats per minute that correspond to different exercise intensities. There are typically 5 zones: Zone 1 (recovery), Zone 2 (aerobic base), Zone 3 (tempo), Zone 4 (threshold), and Zone 5 (VO2max). Training in different zones targets different physiological adaptations.

The simplest formula is 220 minus your age, but this is an estimate. The Karvonen method, which also accounts for resting heart rate, gives more personalized zones. For the most accurate result, consider a lab-based stress test.

Zone 2 is a low-intensity aerobic zone (typically 60-70% of max HR). Training in Zone 2 builds your aerobic base, improves fat oxidation, and increases mitochondrial density. Most elite runners spend 80% of their training time in Zone 2.

The Karvonen formula calculates target heart rate using heart rate reserve (HRR): Target HR = ((Max HR - Resting HR) × intensity%) + Resting HR. It provides more personalized zones than simple percentage-of-max methods.

Measure your resting heart rate first thing in the morning, before getting out of bed. Track it weekly for trends. A declining resting HR over weeks indicates improving cardiovascular fitness. A sudden spike may signal overtraining or illness.

Yes. As your fitness improves, your heart rate at the same pace will decrease. Recalculate your zones every 3-6 months, or after significant fitness changes. Your max HR decreases by roughly 1 bpm per year with age.

Initial heart rate spikes are normal. Your cardiovascular system needs 2-3 minutes to adjust to the increased demand. Warm up with 5-10 minutes of easy jogging before looking at your heart rate data for training purposes.

Yes. As cardiovascular fitness improves, your heart becomes more efficient. Resting heart rate typically decreases, and you can sustain higher intensities at the same heart rate. Recalculate zones every 3-6 months.

Heart rate drift is the gradual increase in heart rate during prolonged exercise at constant effort. On runs longer than 60 minutes, heart rate may rise 10-15 bpm due to dehydration and heat. This is normal and doesn't mean you should slow down if effort feels steady.

Heart rate responds with a 30-60 second delay, making it less ideal for short intervals (under 3 minutes). For short intervals, use pace or perceived effort instead. For longer tempo runs and threshold work, heart rate zones are excellent guides.