What Is Heart Rate And Why Is It Interesting?
Your heart rate is how often your heart beats in a minute. The harder your body is working, the faster the heart has to pump to get oxygen and energy to the areas that need it, and to remove carbon dioxide and waste products. The harder you exercise, the more your heart rate increases. The heart is a muscle, so the more you train the more efficient it becomes.
Resting Heart Rate
I love resting heart rate as a statistic to track. Especially when you start out on your running journey (or return to it), your resting heart rate will gradually drop as you get fitter, which is a great metric to track your progress with.
Resting heart rate is also a good indicator as to how your body is coping with training and life. I can often tell if my body is “up to something” if my resting heart rate is higher than usual. A higher than usual resting heart rate prompts me to ask myself a few questions; am I coming down with a cold, am I worried about something, have I overdone it with my training this week? If your resting heart rate is higher than usual, take some time to work out the reason. Tracking your resting heart rate in your training diary can be a handy way to make sure you aren’t pushing things too hard in training.
You can measure your resting heart rate by having a relaxing lie down for 20 minutes and, without getting up, measuring your heart rate. You can use fitness trackers to do this, or there are free smartphone apps that take heart rate by getting you to put your finger over the phone camera flash.
To ensure consistent results (and a fair comparison), try to test your resting heart rate at roughly the same time each day.
Maximum Heart Rate
Maximum heart rate is a bit more tricky to work out. The most popular formula is 220 minus your age. So for someone aged 35 that’s a maximum heart rate of 185 beats per minute. When this method has been researched, though, it has been shown to be up to 20 beats per minute out either way, so a massive 40 beats per minute range…! In fact, some studies suggest that this measure is as likely to be wrong as right, so it’s best to take this calculation with a pinch of salt.
In my research I’ve found 6 other formulas of increasing complexity for working out maximum heart rate, which all have different errors in practice. When I plug my age in I get a variation of 12 beats per minute across the formulas.
The moral of the story here is that everyone is different and these formulas only give averages. I’ve seen people happily train far below and far above their suggested “maximum heart rate” from these formulas. The only totally accurate way to ascertain your own maximum heart rate is to get yourself tested in a lab.
Heart Rate Zones
This lack of accuracy around maximum heart rate poses a bit of a problem with heart rate zones, as maximum heart rate forms a pretty key part of calculating your training zones!
Please excuse the “science bit”, or more accurately “the maths bit”!
Take your maximum heart rate and minus your resting heart rate; So for me this is 185 (ish!) – 60 = 125
This gives you the working range of your heart; as you don’t want to go below your resting rate and not above your maximum.
Then say you want to do a tempo session at 70% effort; you take 70% of this working range; So for me this is 70% of 125 = 87.5
Add this number back on your resting heart rate, and you get the heart rate you should be working at for a 70% effort section of your run. For me this would be 87.5 + 60 = 147.5 beats per minute for a 70% effort.
As our heart rate varies all the time it’s easier to turn this into a zone to work within; say 60-70% effort, or between 135 and 147.5 beats per minute for me.
But as these calculations are based on the slightly flawed maximum heart rate calculation, do take them with a pinch of salt! Many GPS watches these days give you your heart rate zones and show the stats afterwards. This can be a good way of tracking effort on your run, but don’t get too worried if you spend time in the “wrong” zone; your maximum heart rate probably just doesn’t match the average used in the calculation.
The great thing about heart rate based training is that the pace you run at for a given zone will gradually increase as you train, meaning the runs are always challenging you the right amount for your fitness. It’s a great way to make sure you are running your long and recovery runs slowly enough – it’s incredibly common to see these types of runs being run at much too fast a pace!
An alternative to heart rate zones is to work on effort-based pacing, linked to your breathing (see these blog posts for more information on effort-based running pacing and running training paces). The benefit of the effort-based approach is that it gets you to tune-in with how you are feeling more closely.
What Can Impact Heart Rate?
Your heart is powering your whole body, so it’s not just training that can cause your heart rate to vary. Here are some examples of what impacts heart rate; it shows that lots of things that go on in life have a profound impact on your body and how it will cope with training;
– Illness; if you are ill or coming down with an illness, your heart rate will usually increase
– Dehydration can increase your heart rate by 7.5%
– Heat and humidity can increase your heart rate by 10 beats per minute or more
– Altitude can increase your heart rate by 10-20%
– Stress and anxiety can increase your heart rate
– A large or rich meal and alcohol can also increase heart rate, as your body works hard to break it all down!