Heart Rate and Exhaustion

by Evie
(Melbourne)

I am a fit 25 year old with a BMI of 22 who has now been running for 2 years. I have estimated my maximum heart rate at 205 bpm.

When I run at a pace generally 6 minute kilometers (talking pace) my heart rate sits between 175-185. Is this normal?

I run with my friends who are similar size and fitness and their heart rates sit between 140-150.

My concern is exhaustion. Previous half marathons I have competed in my heart rate sits over 180 the whole race and I generally finish my last 3 kilometers over 200 bpm even though my pace slows.

I want to work up to a full marathon but see this as impossible because I hit the runners wall by the 18km mark.

Is this because my heart rate is so high?

And if so what can I do to bring it down? I don't feel that I run fast therefore I don't want to drop my pace.

Thoughts would be appreciated.

Answer by Dominique:
Hi Evie,
Thanks for your question about heart rate and exhaustion.

Assuming your measurements of your max heart rate and your normal heart rate are accurate, your heart rate is intriguingly high.

My thoughts on this are:

1. Pace and heart rate during training
2. Pace and heart rate during a race
3. Building endurance

Pace and Heart Rate During Training

Heart rate is personal and so much subject to change based on factors like weather, stress levels, fitness etc. Generally I would recommend here to drop the pace somewhat. I can see you do not want to do that, so maybe do not do it on every run. But what I have seen in some people as they are developing their aerobic fitness is that they have either a low heart rate while exercising, or high. With not much in between.

It would be interesting to experiment with starting your run very easy, e.g. walk for the first 5-10 minutes, then break into a jog, then slowly increase the pace to the pace you normally run at and monitor your heart rate throughout.

At the moment, provided you are feeling fine otherwise, I don't think your heart rate is a severely limiting factor. And as you run more and vary your pace more, I do think it will settle at a lower level.

Pace and Heart Rate During a Race

What you are experiencing during your half marathons is pretty normal. When you are doing a half marathon you are pushing the pace a bit more than you would do on an easy run. Even if you are not, a race brings out some adrenalin and excitement and generally sees you run with a higher heart rate.

And as you get to the end your heart rate will drift up towards the maximum. For shorter races you would see the same things happening. Towards the end your heart rate will go towards your maximum. It's just a sign you have given it absolutely everything.

So, I would not assume that just because this happens you would not be able to run and finish a marathon. Regardless of where your normal heart rate while running sits, you can expect this.

Building Endurance

Now, how do we deal with this wall you hit at about the 18km (11 mile) mark? I'd love to get a look at your current training, but I am assuming that you need to increase the length of your long run.

Without further insight into your mileage levels it is hard to get specific, but I think your long run and general length of your runs should be pushed up a bit. Ideally, when training for a half marathon, you are able to push your long run to about the length of a half marathon, or even a bit beyond that.

That really should help avoid hitting that wall. Hitting the wall should not happen in a half marathon, unless you are somewhat undertrained.

Building up to the Marathon

For now, I'd recommend sticking to the half marathon. Work on your overall mileage, build up your long run and get through one or two half marathons without hitting the wall.

Then set your sights on the marathon. Marathon training is demanding and will require even longer, long runs so you really first want to get a bit more comfortable with that half marathon distance, before pushing on to the marathon.

For further half marathon training advice, check out the training for a half marathon page. And when you are ready to step up to the marathon, check out my marathon training tips for the info you need.

Hope this helps.
Kind regards,
Dominique