For example, using the Karvonen method and assuming a RHR of 70 bpm, the target heart rate zone for a 40-year-old man would be 136 to 164 bpm. Lactate threshold is the most effective approach you can use to create training zones because there's a very strong connection between lactate threshold (the highest intensity, measured by average heart rate, that you can maintain for 60 minutes) and athletic performance.
There are a variety of ways to determine your LTHR, but two common examples include the 30-minute cycling time trial and the 3-mile run.
For the time trial, you simply ride your bike as hard as possible for 30 minutes (make sure you get a thorough warm-up). Measure your heart rate for the last 20 minutes of this effort and it will be a close estimate of your LTHR. Use this number to calculate your LT training zones based on the percentages described above.
For the running test, warm up thoroughly and then record your average HR for a hard, 3-mile run. This number is approximately 101 percent of your LTHR. For instance, if your average HR during the field test is 180, your estimated LTHR is 178 bpm (180 divided by 1.01). Research has shown that running LTHR is typically 5 to 10 beats higher than cycling LTHR. If you know one, you can easily estimate the other.
For example, if your cycling LTHR is 160, your LTHR for running will be between 165 to 170 bpm. Conversely, if your running LTHR is 170, your cycling LTHR will be between 160 to 165 bpm. Remember, testing for lactate threshold is very strenuous.
Make sure your physician has cleared you for rigorous exercise before participating in any of these tests.
More: How to Create a Heart Rate Training Program
Find a fitness activity and stay in shape.