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D's word of the week: HRR - Heart Rate Reserve

When planning an aerobic training session, the most important metric you should consider is your heart rate. Sure, time and intensity markers like minutes/ km and watts are important, but how hard you're stressing your heart should be the first thing you determine and should correlate to the workout's objective.

The reason you'll want to plan your heart rate range is due to the close relationship between the heart rate and oxygen consumption, especially when the heart rate intensity is above 50% of your functional capacity, which is your VO2Max or also know as your heart rate reserve (HRR). The most accurate way of programming intensity

The most accurate way would be to get your VO2MAX tested in a laboratory and determine how it relates to your lactate threshold, which will give you an accurate layout for zone training intensities - something the other calculations don't take into consideration, making them much less accurate. This type of testing is quite expensive. Unless you're training for a specific event like a marathon or triathlon where you'll want to have these zones dialled in as accurately as possible, I don't think you really need it.

Another way is to utilize your age-predicated max heart rate: 220 subtracted by your age and multiplied by the zone intensity. I'm not a fan of using this method, because I don't feel as though its personalized enough. I'm the same age as two of the greatest athletes of all time, Lebron James and Eliud Kipchoge - do you really think we should be using the same numbers for our conditioning? I don't.

Heart rate reserve (HRR) is a much better metric to utilize, because it takes into consideration your resting heart rate. To calculate your HRR you'll take the max heart rate and subtract your resting heart rate. Then, use the Karvonen formula to calculate your training zones. Here is the Karvonen Formula:

(220 - age - resting heart rate) x intensity + resting heart rate = Target heart rate

When you're planning your session, you should plan for a range of heart rates within one specific zone. Here is a simple chart outlining the different training zones:




% of Max Heart Rate


Very light


50 - 60%