Heart rate readings at the beginning of a race

Gravel race today and had a solid result (4th female). 1800m elevation, 86KM.

First 6km was a neutral roll out through the town before we hit the gravel and the race was on. Felt like I pushed as hard as I could sustain during the race. Verging on cramping at several points and don’t think I could have done more.

Average heart rate was 162bpm which I have sustained for long events in the past up to 9hrs. Resting HR about 55bpm. 38yrs old.

However, I was a little shocked to see the heart rate data for the first 5km (180-225BPM)! Explanation besides anxiety/adrenaline? Concerns?

Probably interference from other riders when you were still bunched up.


Ooh I hadn’t thought of that! @HLaB

What are you using for HRM? How old is it?

Well done on the result!

An erroneous heart rate reading (usually high) at the start of ride is not uncommon.

The usual cause is poor electrical contact between skin and chest strap, and the strap can pick up stray electrical signals from static electricity in the technical fabrics of your jersey. This is more common as the weather starts turning cooler, and your skin can be dry at the start of a ride.

Pre-moistening the sensor pads on your chest strap is normally the recommended solution. Once you are 5-10 minutes into a ride, your natural sweat starts taking over, as you can see from your graph where your HR settles in at a steady level.

Speaking of sweat, over time salts from sweat can accumulate in the fabric of the strap, making it easier for these stray electrical currents to travel through the strap. Regular washing can help reduce this salt accumulation. Or even just a quick rinse in fresh water at the end of each ride.


Only a year. It’s a chest strap wahoo tickr , placed a couple hours prior to the start

Data error. Without a doubt. Erase it from your memory. Nothing to worry about. :slight_smile: I see wonky HR data all the time from clients like this.

Super common when HRM is a chest strap. Error like this also happens with optical HRM’s sometimes, though it’s typically less patterned than yours was.

FYI Anxiety doesn’t cause HR elevation to that magnitude, though it sure feels like it does sometimes!

My wife had cardiac testing done (transesophageal echocardiogram) to take a better look at a relatively large PFO (hole in heart) and she has severe medical procedure anxiety. Before the test, even though she was trying diligently to remain calm, her body had decided it was fight or flight time! She was shaking uncontrollably, could barely talk, struggling to breath, etc etc). Epinephrine was likely through the roof. Her RHR is similar to yours.

Her HR at time of anxiety never exceeded 120bpm. AFAIK, it never gets anywhere near threshold HR’s no matter the degree of anxiety. I suspect folks tend to pass out before that happens but I have no evidence to back up that claim. Usually with anxiety that isn’t producing noticeable outward physical symptoms, you’re not going to see elevation >20bpm higher than what you’d expect for their current posture and activity levels. And often much less than that.

Blood pressure on the other hand, can increase dramatically with anxiety. As long as it’s transient, (ie. not all day every day) like before a race, and you’re in acceptable cardiovascular health (you are, given RHR below 50!), this anxiety-induced jump in BP is nothing to be concerned about either.

But all the above health discussion is irrelevant because that data is just HRM data error. Rest easy.


With all due respect to the post above, because bad data could be the root cause, I would report to your doctor just in case. I’ve had two incidents, one about 3.5 years ago and another a couple months ago. In both cases I believe the HRM, as explained below. Reported both to my doctor, we did some tests after the first incident and nothing found.

First time was January 2018 and I was on 20+ minute descent before a 2.5 hour climb. HR and elevation on the chart below… hit 186bpm while not pedaling at about 9 minutes into the ride. My observed max on many rides, where I sprint after a long threshold effort, is 175bpm.

It happened at the beginning, and lasted about 6 minutes total. Had no idea at the time, only saw it after the ride. This was a hard 2.5 hour climb at upper tempo / lower sweet spot, the rest of the HR data looks normal.

Temps were dropping as we descended. It was 50F at the start and 36F at the bottom. I was a bit nervous about the road, a lot of potholes, switchbacks, steep drop offs, and some incredible views while descending toward the cloud deck at the bottom. This is a pic at that mid-descent uphill:

Definitely some anxiety and excitement and adrenaline. Because I didn’t notice high HR during the ride, I didn’t attempt to confirm the accuracy of the reading. It is possibly a bad HR reading from the Wahoo TickrX used on the ride. However on mid-winter days like that (cold and dry) I use electrode gel.

The other incident was this summer, following a hard 12.5 hour week - my usual max is ~10 hours - this was a Tuesday recovery ride at 40% FTP ramping up to 50% and then short 3x3-min tempo at 85% FTP:

HR was a little high at end of 1st 3-min interval, dropped quickly during 3-min recovery, jumped above max during 2nd interval, and HR returned to normal on the 3rd interval. About 5 minutes total of abnormally high HR.

When it happened, I cross-checked HR on my Apple Watch and it was showing the same HR readings. So in this case I’m forced to believe the Garmin dual HRM strap was accurate.

My post ride notes:


The strap is about 2 years old, no problems since then. A second note I added to that ride:


Certainly the heat was a factor, although my sweat rate was unusually high for the temp. And I was experimenting with preloading different concentrations of sodium, maybe I drank too much in combination with the heat.

My family doctor is a triathlete, he told me to chill on the sodium preloading and let him know if it happened again.


In both cases there was some anxiety and some adrenaline, otherwise not much else in common (winter vs summer, descent vs flat roads). Thankfully it has only happened twice.

When I see bad data on Wahoo Tickr or Garmin HRM, my experience is the opposite of mcalista and HR is artificially too low for first 5-10 minutes during dry/cool conditions. If I put electrode gel on before a ride/workout, and get a low HR reading, it is time to toss the strap. Once a strap is done, I usually see too low HR but as referenced in the post ride note above I did see it jump to ridiculous levels in 2019. But too high (above HRmax) is unusual, its almost always too low (stays at resting HR for 5+ minutes).

The Garmin straps usually last me about 3 years, and I do wash them after each use and toss into the washing machine after every 5-10 rides. I agree with the rest of what mcalista wrote above.

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What mcalista said is probably it.

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What mcallista said is what DCRainmaker wrote about over 10 years ago:

However, I almost alway see low heart rate in dry/cold conditions. I keep logs of HR and power data, and only 4 times have I seen high HR.

Here are my post ride notes from October 2020, only the 3rd time I’ve seen high HR at beginning:

Happened in first 5 minutes of outside ride at 88F and power was 45% FTP. I would expect HR of 105-120bpm during this warmup, however HRM was showing 140s which is my tempo / sweet spot HR. And Apple Watch showing typical HR during a warmup in these conditions.

And 8 days later on windy evening at 78F, and coach feedback a few days later:

Simple endurance ride. That one started recording too low HR (below 100bpm), then briefly shot up to 95% HRmax, then immediately dropped down to zone2, and proceeded to wiggle around zone2/zone3 HR.

In general my HR data is reliable and consistent. And I’ve dual recorded with Apple Watch, and it is very accurate while on bike however there is a small lag between AW and Garmin HRM.

In my humble experience of using HRM since 2014, once an HRM starts acting wacky its best to toss it out because from that point forward it will give unreliable readings while my newer HRM remains rock solid. The HRM tossed out in October 2020 was purchased June 2017, roughly 3.3 years of use before salt build up killed the strap.

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your solution here