Heart Rate Target

*Originally published on my first blog, Exercise Navigator.

I am often asked for a “target zone” for a client’s heart rate.  

Let me start by saying that there are many reasons to have a target zone and many ways to get it.  In my mind, the most compelling reasons are avoiding “badness”, a term coined by one of my grad school professors.  It simply means bad things that you want to avoid, like heart symptoms, pulmonary symptoms, or other damage to your body.  If you know that you have health problems that put you at risk for “badness”, please see your MD or Exercise Physiologist to have the appropriate tests that will give you your target heart rate zone.  The gold standard is a graded exercise test (GXT) where you will be wired up to monitor your EKG, breathing, blood pressure, and symptoms.  Then you will know for sure what your target is.

The rest of us use heart rate as an indirect indicator of how much oxygen we are using, also known as the percentage of maximal oxygen consumption (VO2 max).  This lets us know if we are working hard enough to get a “training effect”, or benefit, from our exercise.  Heart rate and VO2 max are very well correlated and it is much easier to measure the heart rate than to wear the contraption that measures our gas consumption and release as we exercise.  Heart rate and VO2 max have an almost linear relationship until maximal exercise, when it becomes curvilinear.  This was described by Pollock, Wilmore, and Fox in 1978. 

Our VO2 max decreases as we age, which explains why the charts we see describing how high our heart rates should be are based on age.  Of note, though, these are estimates.  They are based on research, like that by M.J Karvonen in 1957.  Your results may be different, but it gives you a place to start.  FYI, the Karvonen formula is ((heart rate max-resting heart rate)*desired percentage)+resting heart rate.  This is also known as the heart rate reserve formula.

Personally, I like to use heart rate to track my progress, not necessarily to shoot for a certain point.  As we get more fit, we are able to do the same amount of work with a lower heart rate because our body has become more efficient at pumping blood, using oxygen, and extracting it.  M.J. Karvonen also showed this effect in 1957.  Therefore, I know that if my heart rate is usually 132 at a certain speed of exercise, and after several weeks, it is 126, then my training is working and I am getting fitter.  I can increase my speed to keep encouraging my body to adapt. 

So if you’re still wondering how hard you should exercise, my advice is to listen to your body.  Use the “talk test” (http://www.cdc.gov/physicalactivity/everyone/measuring/index.html).  If you cannot talk, you’re going too fast and you need to slow down.  If you can sing, then you need to speed up.  This is correlated with approximately 82% of maximal heart rate (Quinn and Coons, J Sports Sci. 2011 Aug;29(11):1175-82.) Once you have found your “talk test” speed, take your pulse and make a mental note.  This is likely within your personal “training zone”. 

P.S.  If you don’t want to deal with heart rate, then don’t.  Every movement counts, whether you’re in your “training zone” or not.

Here’s to happy and smart training!