However, unless you're a serious athlete preparing for high-level competition, you should not spend any time in this zone.
The training zones offer a simple means for determining fitness and developing an effective exercise program. Start by calculating your zones with the age formula, the Karvonen heart rate reserve method, or the lactate threshold method. The age formula is very simple. You determine your maximum heart rate using the MHR = 220 - your age formula, and then apply it to the five training zones.
For example, if you're a 40-year-old male, your estimated MHR is 220 - 40 = 180. This would yield the following zones:
- Zone 1 = 90 to 108 beats per min (bpm)
- Zone 2 = 108 to 126 bpm
- Zone 3 = 126 to 144 bpm
- Zone 4 = 144 to 162 bpm
- Zone 5 = 162 to 180 bpm
This approach can work well for many individuals, particularly beginning exercisers; however, the age formula can miscalculate MHR by 8 to 12 bpm so it's not a completely accurate method. Another approach is the Karvonen heart rate reserve method. Heart rate reserve is the difference between MHR and resting heart rate (RHR). It represents the working heart rate range within which all activity occurs.
While the Karvonen method incorporates the age formula, it can be more effective because it takes your current physical condition into consideration (i.e., lower RHR is correlated with increased aerobic fitness). The Karvonen formula is (MHR – RHR) x Desired Intensity + RHR = HR (determine RHR by wearing a heart rate monitor overnight). You can use this formula to identify a target heart rate zone for your workouts, ideally between 60 and 85 percent of MHR.