Why is my marathon long run heart rate so high?

Is it colder now than it was a month ago? Is your hr monitor on your wrist or a chest strap? Could be picking up cadence instead of heart rate.

If these are real numbers, impossible to say without at least knowing max heart ratr.

Hey,
So, a few things. HR monitors can give false readings just like other tech (GPS watches, for example). In general, chest strap monitors are less susceptible to issues than wrist ones. Moisten the chest strap before strapping it on for best contact.

All that said, the next part is data accumulation and interpretation. First, your HR number means nothing by itself. You need at least an approximate max HR and then you can figure out percentages of your max. Formulas for calculating your max HR are never correct. The only way to do that is get out there and push it to the max. However, until you get a better idea of what your max HR is, just pay attention to the data AFTER your runs. After 30-50 runs, you'll be getting an idea about correlations between your pace and your HR under different conditions. Once you have a reliable max and a good baseline of performances, you may choose to structure workouts based on effort measured by HR rather than pace.

Hope that helps.

Which product is it, model too?
Consider going to see your Dr if you have to get a referral to a cardiologist for a full EKG. Getting a measured VO2 max test would be best, if they’ll do it, they typically just try to get away with a stress test that estimates VO2. from treadmill speed and grade, and they typically don’t use protocols designed for athletes. Measuring VO2 would also give more accurate threshold values, including heart rate at thresholds. Those heart rates would be more accurate than the zones & max your device is using.

Device zones are reasonably close (percentage based), but that doesn’t mean they match anyone’s actual threshold heart rates because each person is different with fitness levels too.

But the main thing is the high heart rate, is it a bad device or something to have assessed. Heart rate also drifts higher later in runs due to heat & hydration.

Unexpected high heart rate data can be caused by:

1. Strap or wristband problems (loose, dry, damaged, low battery, etc.)
2. Dry and/or low-sweat conditions with a chest strap
3. Static electricity from your shirt
4. Maybe RF interference (overhead power lines, etc.)

It can also be a real measurement of heart rate that is high for reasons that may be confusing:
1. Overtraining
2. Sickness or temporary decrease in fitness for the effort you are making
3. Emotional effects like thinking about something stressful (like seeing a high HR number on your watch) or exciting
4. All kinds of other weird things that effect HR

It can also be a real measurement of electro-cardio activity that is not purely "heart rate." If you have this you will need to go to a cardiologist to figure it out.

HRMs can cause a lot of unnecessary trouble but they are just one more form of feedback, not a substitute for staying in touch with your breathing and how you feel during and after your runs.

Are you using a Garmin 235 with wrist sensor?

My advice, throw away your heart rate monitor, or put it in a box in the closet.

It's picking up your cadence instead of heart rate.

"Averaging 15-30 miles a week while taking a week off here and there." That's not near enough miles for marathon training, then run 20 at an 8:30 pace. I'm surprised you are able to walk today.

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Agingrunner wrote:

"Averaging 15-30 miles a week while taking a week off here and there." That's not near enough miles for marathon training, then run 20 at an 8:30 pace. I'm surprised you are able to walk today.

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So you've done 20 miles around your pb pace and it felt easy.

I'm not sure, the race will tell us if really was easy.

Just get the training in a and stop overthinking.

Thanks for all the responses.

To answer one of the questions posed - yes, it is a Garmin 235 HR monitor. Is that a model known to have HR problems? I think on my next run I'll stop periodically and take my HR manually and see how it compares to the monitor. It sounds like these HR monitors can be more hit and miss than I thought, so I'll take the readings with a grain of salt.

For what it's worth, while for the last couple years I have just done 15-30 miles per week, I am doing a proper marathon training cycle now--in week 12, averaged 35-45 miles per week so far. I thought maybe it could be the big increase in miles (for me). I suppose it is also possible I am in for a rude awakening in the race, but I think for now I guess I just agree with the advice to go by feel and not obsess to much about the monitor.

I think perhaps I will also go do a really hard run and see how high I can get my HR (my best idea short of trying to get doctors involved) to see if that will help me get some more info. about where my HR training should be.

Thanks again.

Garmin 235 has wrist based optical heart rate sensor (not HR strap that uses ECG-like approach to HR measurement).

It is well known fact that devices with optical heart rate sensor uses accelometer to correct errors in HR readings due to cadence. If your watch with optical sensor is loose on the hand it will very easily pick up the cadence as HR. In fact to get correct readings you might need to strap the watch very tightly.

So most probably what you see as HR in your runs, is actually cadence.

Do you think knowing your max HR may be relevant to this topic?

I don't think the problem is your HR monitor. You need to find out what your max HR is. I'm guessing you just have a high max and so 175bpm is a HR you can hold for a long time while not working too hard.

I will normally do a max HR finder workout by doing longish hill sprints after a very thorough warm up or look to see what I hit during the final sprint of a 5K race. I am an example of a high HR runner and at 46 yrs old can still hit 195 or so and average about 180 for a half marathon. None of the stock formulas I've seen indicate I should be able to hit those numbers. The link below gives you a workout idea, but treat it like an all out effort race (it should hurt like hell!) to get the most accurate # (ie. rest up before and after):

https://www.polar.com/blog/calculate-maximum-heart-rate-running/

This link shows you how to calculate zones based off your max & resting HR:

https://support.polar.com/us-en/support/Heart_Rate_Reserve__HRR

FYI I have no association with Polar, they just had the best summaries I could quickly find.

Good luck!

OP, based on your perceived effort level at 175 bpm, your max HR is probably around 200. The formula 220 minus age can be off by more than 30 beats. In my case 220-age=150, but my Max is 186.

A better way to use HR monitors is the Joe Friel Method. Do a search for Joe Friel Lactate Threshold Heart Rate to learn how to find your LTHR (Lactate Threshold Heart Rate) that is the exact point (give or take a couple of beats) where your body switches from aerobic to anaerobic work.

Finding LTHR is easier than finding your Max HR, which is somewhat irrelevant anyway.

...follow up to my previous post...

You have a wrist monitor for HR? That's a problem. Get a chest strap monitor. I've tried a couple of wrist monitors and I couldn't get a reliable reading on either one.

I have a 235. Some days, the HR monitor is wacked and there isn't anything that fixes it no matter how tight you make it . Love it when it works, but for consistency I think the chest band is necessary.

Your watch is definitely reporting your cadence. As suggested, make sure it is not loose on your wrist. Also make sure that it is t directly on your wrist bone - you’ll need to wear it a little higher up your arm. Finally, I’ve run with the 235 since it was released, and I think the HR sensor is garbage for getting consistent readings. If you’re really serious about HR training, pick up an HR strap to use until you feel comfortable with your baseline values. Then you can pretty quickly eyeball if your optical sensor is trying to sell you a line of bull or not.

I have a 225 and the HRM has been pretty off since the weather changed last week. There are other times that I can I will see it going crazy, but for the most part it gives consistent readings. That being said, I'm 35 and had my max heart rate measured at 190 last summer. My heart rate is upper 160s for a marathon and low 170s for a half.