Are brief dips in heart rate when exercising a cause for concern?
May 18, 2020 6:40 PM   Subscribe

I've been riding my stationary bike regularly lately, wired up with a power meter and heart-rate monitor, so I can just sit there and watch my stats scroll by. I've noticed that during low-intensity periods my heart rate will occasionally dip about 10 bpm and then bounce back: one of these episodes lasts about 10 seconds from the baseline departure to return.

I've seen this happen 1–3 times in a one-hour workout. It's never during a high-intensity interval. I'm reasonably sure it's not a hardware glitch. In general, I'm in good health (I think). Is this something I should worry about? I acknowledge YANMD.
posted by adamrice to Health & Fitness (8 answers total)
How are you measuring your heart rate? Chest strap or otherwise?
posted by Special Agent Dale Cooper at 7:46 PM on May 18, 2020

I've found the monitors (both the fancier chest monitor I bought and the ones on various workout machines) to be better as an average over time than as anything super accurate. If they don't detect a beat I've seen them vary more than that often. So my first thought would be the sensor just missing a beat here or there. But if your insurance has a nurse line you can call for free, I've found them reassuring more than once, too.
posted by ldthomps at 7:59 PM on May 18, 2020 [3 favorites]

I'm not a doctor, but I think high heart rate variability is a sign of health.
posted by pinochiette at 8:11 PM on May 18, 2020

I'm not a doctor, but I think high heart rate variability is a sign of health.

It's actually the opposite (lower HRV == moar fitness), and even that applies only to the heart rate at rest.

I'd say you heart rate monitor is dropping out. If it's a chest strap, you can try some electrode gel from Amazon to help get better readings if the problem is between the sensor and your skin. My Wahoo Tickr seems to go a weird default of like 110 BPM if my skin doesn't have enough moisture in it, so I use the gel. With optical, I'm not sure you can really do anything.
posted by sideshow at 8:32 PM on May 18, 2020

This is probably a device issue (as discussed above) but first a long shot: Have you ever been checked for valve abnormalities? On me they can make my heart flutter in a way that is ineffectual in pumping, causing a momentary drop in apparent pressure/bpm if the measuring device is sufficiently stupid.
posted by aramaic at 9:30 PM on May 18, 2020

The real question to ask here is: is your heart actually slowing down as recorded? If you're cranking and then stop (the road-bike equivalent of waiting at a light) and you can actually feel your pulse go from boomboomboomboom to boom........boom........boom, yeah that might be a problem. You would likely feel a little lightheaded from the sudden drop in pressure. If you have good pulse points, you may be able to check your neck real quick and see if the HRM is telling the truth.

If you are actually getting a sudden drop like this, certainly talk to a doctor.

If it's just a recording error, it's just a recording error.
posted by notsnot at 5:19 AM on May 19, 2020

If your HR monitor is on your wrist, like a FitBit or a Garmin, I think there's some algorithmic adjustment of the numbers based on movement patterns. For instance, if I ride a stationary bike until my heart is beating fast and I'm breathing hard, my FitBit Alta won't read my heart rate accurately because my hands aren't moving and so it thinks I'm not working hard.
posted by Sublimity at 5:28 AM on May 19, 2020

This is using a chest strap. I'm familiar with the concept of HRV, and I don't think what I'm describing is related to HRV, which is measuring beat-to-beat syncopation (also, AIUI, higher HRV indicates better health).

I can't say for certain that this isn't a hardware glitch or dropout, but I can watch my heart rate steadily dip and then steadily rise. If it were a glitch, I'd expect to see a discontinuous change.

I've never been checked for valve abnormalities per se, but I've been told my EKG is "textbook."

As to measuring by hand while measuring with the HRM—it's not realistic. I only have a ~10 second window to do it, and I don't know I'm experiencing a dip until it's halfway over. And there would be no way to get two accurate counts in 10 seconds anyhow.
posted by adamrice at 6:27 AM on May 19, 2020

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