You can calculate your own training heart rate using the Karvonen Formula, but first you'll have to determine your "Resting Heart Rate", "Maximum Heart Rate" and "Heart Rate Reserve":
1. Resting Heart Rate (RHR)= your pulse at rest (the best time to get a true resting heart rate is first thing in the morning before you get out of bed).
2. Maximum Heart Rate (MHR)= 220- your age
3. Heart Rate Reserve (HRR)=Maximum Heart Rate - Resting Heart Rate
Once you have your Heart Rate Reserve, you can calculate your training heart rate:
4. (Heart Rate Reserve x 0.85) + Resting Heart Rate = Upper end of the training zone
5. (Heart Rate Reserve x 0.50) + Resting Heart Rate = Lower end of the training zone
Example: To calculate the training heart rate of a 35 year old person with a resting heart rate of 70:
Maximum Heart Rate: 220-35=185 bpm (beats per minute)
When this person exercises, they should try to reach their training heart rate zone (127-167 bpm) and maintain it for the duration of their aerobic activity. Halfway through their aerobic activity, they should take a 6 second pulse check and add a 0 to get the one minute figure (you could also do a 10 second count and multiply by 6 or a 15 second count and multiply by 4).
Heart Rate Reserve= 185-70=115 bpm
High End of the Training Heart Rate: (115 x 0.85) + 70 = 167 bpm
Low End of the Training Heart Rate: (115 x 0.50) + 70 = 127 bpm