# Was my heart rate really 237 bpm today? **URL:** \ **Category:** Factual Questions\ **Created:** [September 22, 2011, 4:00am UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155 "2011-09-22T04:00:25Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [September 22, 2011, 4:00am UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/1 "2011-09-22T04:00:25Z")
I have a Polar heart rate monitor that consist of a chest strap with sensors, a wireless transmitter, and a receiver that sits on my bicycle handle bars. My theoretical max heart rate is 183 bpm using the 220 - age rule of thumb and my resting heart rate is around 60 bpm. My bike rides are around 60 km long and include some hill climbing. My heart rate during a ride normally tops out in the 170s when hill climbing and drops to the 120s when descending for an average of about 155. up until today my maximum recorded heart rate was 183 which seemed to validate the rule of thumb. Today was different, while descending a hill I noticed that my heart rate was 205 bpm, shortly afterward it dropped instantly to the usual 120s, a little while later it was back up over 200. When I finished my ride my max recorded heart rate was 237 bpm. Through the heart rate changes I felt normal and as far as I could tell by feeling for my pulse in my neck it wasn’t racing. Because the changes were apparently instant and I felt normal my conclusion is that the monitor is giving false readings, but what would cause that? I would have thought that the only false reading it could give would be if it wasn’t picking up all my heart beats in which case it might under read, what would cause it to over read? ---
**Author:** ![Shmendrik](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@Shmendrik](https://boards.straightdope.com/u/Shmendrik)\ **Post date:** [September 22, 2011, 4:09am UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/2 "2011-09-22T04:09:54Z")
I’m not sure how the heart rate monitor works, but maybe it was picking up the two heart sounds as separate heartbeats. ---
**Author:** ![Dag\_Otto](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)\ **Post date:** [September 22, 2011, 4:51am UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/3 "2011-09-22T04:51:03Z")
False reading. The polar units are good, but every now and them (maybe once or twice a year in my experience) they get a buggy reading. I don’t recall the exact number, but when it happened to me it was in the 230 range. Well beyond what I could do. ---
**Author:** ![smithsb](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/smithsb/32/12107_2.png) [@smithsb](https://boards.straightdope.com/u/smithsb)\ **Post date:** [September 22, 2011, 2:25pm UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/4 "2011-09-22T14:25:24Z")
False reading; the strap may be getting wet or saggy; different humidity (air, your skin); your bike shirt may be loser/not helping the strap keep the contacts against your skin as effectively; batteries starting to fade; etc… on the mechanical side. From the paranoid perspective, I first exhibited my A-Fib ([Atrial **fibrillation** - Wikipedia, the free encyclopedia](http://en.wikipedia.org/wiki/Atrial_fibrillation)) while hill climbing as an avid bicyclist. If you notice a physical sensation of accelerated heart beat (not just the heart unit reading something high), see a doctor for a checkout. ---
**Author:** ![heavyarms553](https://avatars.discourse-cdn.com/v4/letter/h/779978/32.png) [@heavyarms553](https://boards.straightdope.com/u/heavyarms553)\ **Post date:** [September 22, 2011, 2:53pm UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/5 "2011-09-22T14:53:12Z")
You would have very poor cardiac output with a pulse that high unless you had an extensively remodeled heart from extensive training. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [September 22, 2011, 3:53pm UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/6 "2011-09-22T15:53:41Z")
> [@heavyarms553](#): > > You would have very poor cardiac output with a pulse that high unless you had an extensively remodeled heart from extensive training. Ex-EMT checks in > **[Pulseless electrical activity](https://en.wikipedia.org/wiki/Pulseless_electrical_activity)** > > Pulseless electrical activity (PEA) is a form of cardiac arrest in which the electrocardiogram shows a heart rhythm that should produce a pulse, but does not. Pulseless electrical activity is found initially in about 20% of out-of-hospital cardiac arrests and about 50% of in-hospital cardiac arrests. > Under normal circumstances, electrical activation of muscle cells precedes mechanical contraction of the heart (known as electromechanical coupling). In PEA, there is electrical activity but insuffi... If your pulse was actually that fast, your heart chambers would be unable to fill properly before contracting again. ---
**Author:** ![11811](https://avatars.discourse-cdn.com/v4/letter/1/9d8465/32.png) [@11811](https://boards.straightdope.com/u/11811)\ **Post date:** [September 22, 2011, 7:41pm UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/7 "2011-09-22T19:41:21Z")
Another fun thing is that you may lose signal altogether when riding close to power lines. MLK Drive in Philly does this to my HRM. ---
**Author:** ![AndyLee](https://avatars.discourse-cdn.com/v4/letter/a/898d66/32.png) [@AndyLee](https://boards.straightdope.com/u/AndyLee)\ **Post date:** [September 22, 2011, 9:09pm UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/8 "2011-09-22T21:09:19Z")
If you’re pusle was that fast, you’d know it. I find when my hand get sweaty or wet, while I put my hands on the sensors at my gym, the pulse indicator, goes way off. It usually goes up past 200, when it’s about 125 in reality ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [September 22, 2011, 9:56pm UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/9 "2011-09-22T21:56:45Z")
You rode under a set of power lines. I see this all the time with my HRMs both Polar and other brands. ---
**Author:** ![JustinC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/justinc/32/8083_2.png) [@JustinC](https://boards.straightdope.com/u/JustinC)\ **Post date:** [September 22, 2011, 11:29pm UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/10 "2011-09-22T23:29:56Z")
In the gym I’ll be on the treadmill with my hands on the pulse monitor and sometimes it’ll go WAY up to eleventy. At the time I’m not particularly exerting myself, ‘blowing’, or feeling ill. Usually I just grip the sensor a little tighter and the reading comes back down to normal. I put it down to a bad connection caused by sweat or just the sensor being full of gremlins. ---
**Author:** ![Ca3799](https://avatars.discourse-cdn.com/v4/letter/c/9f8e36/32.png) [@Ca3799](https://boards.straightdope.com/u/Ca3799)\ **Post date:** [September 22, 2011, 11:42pm UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/11 "2011-09-22T23:42:18Z")
Sometimes the monitors at work “split” or “double” heart rates. If we are not certain, we check the pulse manually or by stethoscope. Also, does the monitor have a battery? Maybe the battery is getting old. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [September 23, 2011, 1:56am UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/12 "2011-09-23T01:56:34Z")
Some good ideas here. I don’t know that it would be because the contacts got too wet, they’re supposed to be wet, you should moisten them before putting the strap on and after that sweating takes care of the rest. Could be the battery. Could also be power lines, but then why has this never happened before? I was riding a standard route. It may have been getting loose I suppose though it felt tight enough, I’ll see if it happens again. ---
**Author:** ![MobiusStripes](https://avatars.discourse-cdn.com/v4/letter/m/d6d6ee/32.png) [@MobiusStripes](https://boards.straightdope.com/u/MobiusStripes)\ **Post date:** [September 23, 2011, 2:04am UTC](https://boards.straightdope.com/t/was-my-heart-rate-really-237-bpm-today/597155/13 "2011-09-23T02:04:23Z")
Most likely a bad reading. It happens. Also wanted to point out that the formula for calculating heart is terribly accurate. In fact, it’s most likely wrong for any given individual. ([Heart rate - Wikipedia](http://en.wikipedia.org/wiki/Heart_rate#Formula), or linking to a more scientific cite: [http://faculty.css.edu/tboone2/asep/Robergs2.pdf](http://faculty.css.edu/tboone2/asep/Robergs2.pdf))