Heart Rate - what's the big deal?

What does the heart rate monitor say about ones cycling? I find i can’t make reliable sense of the heart rate data. When i’m tired and have gone on for awhile, my body will feel the pain but my heart rate will not rise to indicate my suffering. I’m assuming my heart will show the stress with additional beats…i sure feels like it does. 

They say the heart rate data is like a tachometer in the car. But the heart rate data’s reliability gets less reliable when you’re getting tired???

If you ride at the same wattage over a long period of time your HR will start to raise. Here is a very good article on it: https://help.trainingpeaks.com/hc/en-us/articles/204071724-Aerobic-Decoupling-and-Efficiency-Factor

You can also monitor your resting HR to see if you are fatigued. 

You can also train by HR zone so you put out more power in Z2 over time.

To add to Paul’s comment, find your resting (minimum) heart rate and your maximum heart rate (after a long sprint or end of an FTP test for example). With these values along with your age, you can find your heart rate zones. There are web sites that can help you with calculating your zones. 


With your heart rate and FTP in Zwift, you can effectively get the most out of your workouts or determine what target zone you were in during a normal ride. I’d recommend having these values up to date in any cycling app you use (Zwift, Strava, Garmin, TrainingPeaks, etc.). 

Personally, I’ve seen my VO2 max increase over time using these values. An oversimplification of this is view the same workout from months, or even years ago. Compare your power and your heart rate for both. If you’re training well, you most likely are able to put out more power at a lower heart rate. If you only had power, you’d only have one part of the equation = not enough data to analyze your fitness.

If your heart rate monitor is faulty, you should replace it as it adds valuable data when training with power.

Put simply, when you are exhausted with tired legs, your ability to maintain a given wattage will drop. And so your heart rate will drop too. Your heart doesn’t care if your legs are hurting and your exhaustion is causing you stress, it only knows that your muscles and cardiovascular system have eased up and so it takes a break.

Similarly at the end of a long run when I am utterly spent and hobbling the last mile my heart rate will drop a little - simply because I’m running slower.

Well If you look up at the screen when your peddling and there’s no heart rate, it’s shown you you died in your shed on a turbo trainer and you are now a ghost rider…

A lesson to us all I think to keep a fully charged HRM.




Paul Firth - thanks for the comment. I think i get it now…so the heart doesn’t care how much pain/suffering there is. I just thought ones heart would beat faster under duress.

So the heart would beat as fast as the body needs it to pump blood.

say my max heart rate is 180 and i’m into a long ride…it’s tiring and the legs have started to feel like lead…and my heart rate is 145. Can I say that i’ve got capacity to push it more…since its only 145 versus my of 180.

vice versa…if my heart rate is 175 i know that i’m close to hitting my limit?..

Edward - Well, you’d have the heart capacity to keep on pushing at 180 but the the build up of lactic acid in your muscles and your screaming tendons might force you to ease up a bit. Having the ability to push through that is what separates the pro athletes from us amateurs. Half a packet of jelly babies will only get you so far without specific endurance training.

As for your max heart rate - that depends on your age and fitness – I’m not sure there is a ‘limit’ (within reason). If you push the limit a little, the limit usually increases a little.

PS: I’m not an expert - train at a pace you’re comfortable with.