The Karvonen Formula is a mathematical formula that helps you determine your target heart rate zone. The formula involves using your maximum heart rate (MHR) minus your age to come up with a target heart rate range (which is a percentage of your MHR). Staying within this range will help you work most effectively during your cardio workouts.
This method of calculating your target training zone is based on your maximal heart rate and resting pulse.The correlation here is more directly linear: 60% to 80% of your Heart Rate Reserve, HRR, equals 60% to 80% of your functional capacity. 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:
To determine your target training zone with HRR, do this: Take your resting pulse three mornings in a row, just after waking up. Add all of them together, and divide by 3, to get the average.
Let's say your average is 70 beats per minute and age 35 years.
(220) - (your age) = MaxHR
(MaxHR) - (resting heart rate) = HRR
(HRR) x (60% to 80%) = training range %
(training range %) + (resting heart rate) = (your target training zone)
220 - 35 = 185 (MaxHR)
185 - 70 = 115 (HRR)
115 x .6 = 69 (60% training percentage)
115 x .8 = 92 (80% training percentage)
69 + 70 = 139 (target training zone, in beats per minute)
92 + 70 = 162 (target training zone, in beats per minute)
So, your target training zone, in beats per minute is 139 to 162. Of course, to get a 15 second target simply divide each number by 4. That would be 35 to 41 beats over 15 seconds. Here is a rough guide to different heart rate zones and the adaptations they elicit
Recovery Zone - 60% to 70%
Active recovery training should fall into this zone (ideally to the lower end). It's also useful for very early pre-season and closed season cross training when the body needs to recover and replenish.
Aerobic Zone - 70% to 80%
Exercising in this zone will help to develop your aerobic system and in particular your ability to transport and utilize oxygen. Continuous or long, slow distance endurance training should fall under in this heart rate zone.
Anaerobic Zone 80% to 90%
Training in this zone will help to improve your bodys ability to deal with lactic acid. It may also help to increase your lactate threshold.