I've mountain biked up a mountain a few times with a heart rate of 80%+ for over 2 hours. No symptoms, just exhaustion at the end of the day after a morning ride. I'm interested to know if there are any cyclists (on or off road) that exert heart rates for this period of time and whether or not this has any long term effect on the heart muscle. I'm not in peak shape and I'm hoping for a reduction in heart rate as I get fitter. Thanks..!

EDIT - I need some proof in the form of experience or links with studies, not general speculation. So you would need to be a doctor/specialist or runner/cyclist, please.

  • How did you determine what your peak heart rate is? Many cyclists and runners use RPE (rating of perceived exertion, scale 1-10) to get at how intense something is--which seems to relate roughly to % max heart rate. Apr 10, 2013 at 15:46
  • @BerinLoritsch - I run on a field flat out for as long as I can after an easy warm-up. Check the heart rate and that will be max. The 220-age is not the right way. I'm 45 and can get my HR to 190, so 175 is not my max. My resting HR is 58 and my jogging heart rate is around 130. Apr 10, 2013 at 17:54
  • We agree on the 220-age thing. So 80% of 190 would be in the 150 bpm range. I can't think of any reason why that would be a major issue. Spending too long in the 180-190 range will have you quit before you get lasting damage. Apr 10, 2013 at 18:15
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    If you're really after medical advice about heart health and high intensity endurance training, you may need to go to a pure cycling forum, or a medical forum (or a doctor). :( The people on this site tend to be strength-training focused, and tend to give good answers on health and heavy weight lifting... I think your question falls a little outside of what the people here tend to be best at, but I may be wrong.
    – DavidR
    Apr 10, 2013 at 18:26
  • @DavidR - your comment above answer my question to a degree. thanks and appreciated. Apr 10, 2013 at 18:40

4 Answers 4


I think that cyclists might do that, but it isn't necessarily optimal training. When I was cycling more (on road) I was advised to spend a lot of time (read: up to 4+ hours at a time) at <70% of my max heart rate, then once I was conditioned, include short bursts of speed at rates above my lactic threshold. There was a notion from more experienced cyclists that what you're trying to do (which is very common) is simultaneously too much and too little. Its too intense to train your aerobic capacity, but also too moderate to really train your lactic threshold, V02 Max, or max leg strength.

That being said, that's only comparing it to an optimal training schedule for experienced road bikers. If you're having fun and feel like you're getting better, keep doing it.

I would recommend that you try and be aware of signs of overtraining - if you feel like you're not recovering between rides, or you're starting to pick up aches and pains that feel like their not going away before its time to ride again, or if you just find that you're getting slower and less explosive, you may want to reduce your pace or weekly mileage.

I'd recommend that you research beginner training plans for cyclists. I know that Bicycling Magazine published a nice small book for beginning road bikers, and they may have a good one for mountain bikers too. You'll get a lot better if you're following an established training plan than if you just go out and beat yourself up. :)

EDIT - I can't speak to the potential long term negative effects of keeping your heart rate that high for that long. Whether it exists at all, or to what extent it does / doesn't matter to people of different ages. That's outside the scope of the training literature I read, or my experiences of those of the other (20-something) cyclists I used to know. The only thing I could say is that if you're feeling short term symptoms of overtraining, your odds of doing something bad are likely higher.

  • thanks for this. I am trying to condition myself slowly, but the occasional weekend ride puts me at a high heart rate. I was interested to know if I have no symptoms whether I'm damaging myself and whether other cyclists doing uphill keep heart rate at this level for this duration. Apr 10, 2013 at 3:42

Assuming you are saying your heart rate is 180% of normal, like 110-120, then yes that seems normal, and no it is not bad for the heart muscle, though 2 hours without a break is a little harsh. Might want to limit it to 45 min with 10-20 min breaks in between (But not like stopping breaks, more like getting off the bike and walking slowly with it, then hop back on...), if you make this a pattern for a long enough time this will improve, and you will be able to ride longer with less stress on the heart.

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    by 80%, he probably means 80% of his max heart rate, something like 150-170 beats per minute. Many cyclists would consider 110-120 to be a casual pace, and 170 or so a serious effort.
    – DavidR
    Apr 9, 2013 at 13:46

Usually you should not keep it max for more than 2 hours per day. If your glycogen storages are empty, then your body may burn some muscles.

It doesn't matter when doing it a few times.

For marathon runners it is said to be the main reason for heart operations after 10 years (less muscles at heart, then rebuilding, and again the same, every time.. so there are rumors that their heart gets some blood supply problems)

I think that is also the reason why HIIT training is getting more popular.

So, if you are unable to keep your speed, then maybe it is a feedback that you are running low on energy, and a break would be useful


One of the training evaluations that many endurance athletes use is called the Rating of Perceived Exertion. In practice this kind of maps out to a rough % of your max heart rate at whatever your current level of fitness is.

Even with Zone Training the RPE can be mapped to the training zones. It would map out like this:

  • Fitness Zone: RPE 6-7 (60-70%)--can sustain for hours
  • Aerobic Zone: RPE 7-8 (70-80%)--can sustain for hours
  • Anaerobic Zone: RPE 8-9 (80-90%)--can sustain for minutes
  • Red-Line Zone: RPE 9-10 (90+%)--can sustain for seconds

As long as the exertion is Aerobic, there is absolutely no danger to your cardiovascular health whatsoever. Venturing into the Anaerobic zone also does not pose any danger, only that you will lose energy much more quickly.

Any potential danger lies in the red-line zone. This is where you can pass out if the heart rate gets too high. Peaking into the red-line zone occasionally during training isn't a major issue, but if you start to feel light-headed it's time to end the training, and do a cool down.

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