2K Test and falling heart rate

[dave2013]

During the last 300m of a 2K test, my heart rate dropped from a steady 168 bpm to 157 bpm in just under a minute. Less than 30 seconds after stopping it was back up to 162 bpm.

I have experienced similar behavior before. My heart rate will fall rather than rise during the sprint at the end of an intense erg piece. This only appears to occur during hard 1K and 2K pieces, never on longer pieces (e.g., 5K and 10Ks).

What could account for this behavior?

Since turning 60 years old I have done a 2K every year on my birthday. Looking back at the metrics I can see a drop in heart rate over the last 400m each year for which I have heart rate data. These drops are not as extreme as this most recent example (11 beats) but a falling heart rate at the end of an intense piece has been a recurring phenomenon.

I do not feel dizzy or lightheaded during the time the heart rate is falling and I actually feel quite strong and focused. I do not appear to suffer any after effects.

I should note that I full medical exam by a cardiologist (EKG and stress test) in the fall of 2016 and got a clean bill of health.

Attached is a link to a video that shows the last 300m of the most recent 2K test along with the PM5 monitor and heart rate data:

https://www.youtube.com/watch?v=sIBBn2u ... e=youtu.be

The specific data points are shown below:

Heart Rate (bpm) Distance Remaining (m) Time Interval (seconds)
167 291m 5:59
166 171m 6:24 0:25
165 133m 6:31 0:07
164 104m 6:37 0:06
163 81m 6:42 0:05
162 62m 6:46 0:04
161 49m 6:49 0:03
160 37m 6:50 0:01
159 20m 6:55 0:05
158 10m 6:57 0:02
157 1m 6:59 0:02
158 0m 0:09 0:10
159 0m 0:13 0:04
160 0m 0:17 0:04
161 0m 0:21 0:04
162 0m 0:26 0:05

[Ombrax]

I should note that I full medical exam by a cardiologist (EKG and stress test) in the fall of 2016 and got a clean bill of health.

Given the potential gravity of the situation, I don't think it's too soon to have another one. (Or at least a basic physical by your PCP and see what s/he says.)

Good Luck

Caveat: I know next to nothing about heart-related health stuff.

[ccooper]

I often see the same behavior. I doubt that it is anything to be concerned about.

Chris Cooper

[lindsayh]

I often see the same behavior. I doubt that it is anything to be concerned about. Chris Cooper

Yes my thoughts too - to take it further maybe talk to an exercise physiologist

[NavigationHazard]

I agree that for peace of mind, if nothing else, you absolutely should consult a trained physiologist and/or cardiac specialist.

Keep in mind that HR on an erg is affected by a number of things including subtle changes in posture. It may be that you're doing something different posture-wise (or for that matter in terms of sequencing and/or muscle fibers committed) in a final effort/sprint that's connected to the apparent HR fall.

[jamesg]

I often see a drop in HR; this a.m. from 120 to 112, then up again over 10-15s. Probably due to one or two skipped beats. Would seem the HRM averages over the last 10 seconds or beats, but never seen any supplier describe how they do the sums.

I know I miss beats, I can hear it. Doc seemed unfazed but didn't tell me to stop wasting her time.

[Allan Olesen]

I know I miss beats, I can hear it. Doc seemed unfazed but didn't tell me to stop wasting her time.

Heh, when I experienced that for the first time, I freaked out and had my wife drive me to the ER.

As you say, it doesn't really impress the doctors. I was told that they are actually not skipped beats, but extra beats, which come too early with a nerve signal in the wrong place on the heart, don't really do any usefull work, and mess up the next regular beat too, hence causing the sensation of a skipped beat. I was also told that an average person have 600 of those extra beats in 24 hours.

Still it feels very unpleasant. The next "good" heartbeat after the extra/skipped heartbeat feels like a jumpstart as if it has to make up for the wasted effort of the previous beat.

[Mark E]

This book (and a bunch of associated articles that can be found with a search) is worth a look, especially for anyone who has done regular aerobic training for several decades.

https://www.velopress.com/books/the-haywire-heart/

[johnlvs2run]

You were using a lower than optimal rating for most of the distance, then raised the rating -
helping your cardiovascular system circulation to be more efficient, which is very easy to see on the video.
This is nothing to be concerned about, but simply shows you used more effort than was necessary for most of the distance.

[lancecampeau]

You were using a lower than optimal rating for most of the distance, then raised the rating -
helping your cardiovascular system circulation to be more efficient, which is very easy to see on the video.
This is nothing to be concerned about, but simply shows you used more effort than was necessary for most of the distance.

I have never used a heart monitor, so find this response intriguing... could you clarify a bit? When you speak of effort, how are you comparing pace VS spm VS heart rate?

[dave2013]

Thank you everyone for all the useful comments. I appreciate you input and advice.

Chris Cooper: It looks like I'll get to meet you tomorrow morning in Long Beach at 10:35! (You're erg #47 and I am #49.) Best of luck tomorrow!

[ukaserex]

When many of see the BPM from our hr monitors, we're seeing a measurement of how many times our heart beats within that 60 seconds. What were not seeing is the time in between heart beats, known also as HRV. There is a Polar chest strap that detects this, but it's the only one I know of. There is also a Whoop! wearable, and a few others that are also worn on the wrist. Only Whoop tracks it all day when you're wearing the wrist strap. The others, just when you're sleeping. So, that 150 bpm you see may have more uniform time between beats, while the 160 bpm may have less; the heart slowing down for whatever reason, then picking up speed to catch up. Or, vice-versa. There's still a lot we don't know! Hydration (cardiac drift) could play a part in this, inadequate warm-up, a number of things.

Ultimately, when the heart slows down a bit, it's nothing to be worried about and is quite normal. Happens to me, too, throughout pieces that are longer than 1k, at least, that's when I notice it. Still, good on you for noticing it, and given it's your health, if you've got the time and money, go see your cardiologist and remove all doubts. I know I'm not a doctor.