An HR mystery. Any ideas?

yirara

Somewhere in my neighbourhood there are a couple of places where for some reason my HR goes down and my running suddenly becomes super easy. I've spotted these special locations in other places before (I move often). It's not terrain related as I've never lived in a place with more than a speedbump. Usually happens after 3km to 4km, often when running against the wind. Both my old Scosche Rhythm+ and my current Polar OH1 on upper part of lower arm show this drop in HR. I always supposed it was real. Yet neither my Garmin Vivoactive 4s, nor a Fenix show this. Never. Obviously I don't want to stop to test my HR by hand.
Any idea which device might be right? Why this might be happening? It's a drop of more than 20bpm, which is massive. Something certainly happens as running suddenly becomes super easy.

RunsWithBees

A mini runners high?

yirara

Possibly. I aleays called it runners high even though I’m not high but running is easier (running is super difficult for me regardless of fitness). Does hr go down then? And is my watch blind 🤣

Lietchi

I'm wondering how reliable (some of) your HR numbers are. Are they all optical sensors?
I love my Vivoactive but I know the optical sensor isn't entirely reliable, I always exercise with a chest strap paired to my watch.

NorthCascades

I would see if the same thing happens with a chest strap, but if it feels easier to you at the same time it probably isn't a sensor thing.

hipari

Are you absolutely positively sure there are no inclines, no matter how small, anywhere? Plenty of times I’ve thought my surroundings are flat terrain, until I went there with a bicycle. That thing doesn’t lie about terrain. Maybe a test ride on the same route backwards, so you’ll notice if that special location suddenly forces you to pedal an incline? Another terrain-related thing to consider might be surface material. Is that the same through your entire route?

When I was running regularly, I found it often got significantly easier around the 3-4km mark. I don’t remember HR drops that strong, I always attributed it to just being properly warmed up and my body and brain getting into a ”running mode”.

yirara

Lietchi wrote: »

I'm wondering how reliable (some of) your HR numbers are. Are they all optical sensors?
I love my Vivoactive but I know the optical sensor isn't entirely reliable, I always exercise with a chest strap paired to my watch.

Fairly reliable plus/min about 3bpm max on the optical sensors. I sometimes test them properly. Guess being very pale, little hair and very transparent skin helps. But I've not tested the Garmin yet. I'd say it's less reliable overall. I'd not use a chest strap as I'm very prone to bruising, dislocating ribs (don't ask), and everything is fairly irregular. Such a sensor just causes pain or it loses contact.

yirara

NorthCascades wrote: »

I would see if the same thing happens with a chest strap, but if it feels easier to you at the same time it probably isn't a sensor thing.

Hmm... I had a step-wise exercise test earlier this year, and kind of the same thing happened as well. But that was not a chest strap either. I'm not sure where the data came from: ear sensor or ecg. HR came up fairly quickly again due to resistance increase as compared to steady-state, but it was there as well. Still I'm uncertain which data to trust.

I'm wondering if this is real what's happening: Is the HR going down as a reaction to being able to run easier? I'd guess it's likely as it seems strange that HR crashes down, and then running becomes easier.

yirara

hipari wrote: »

Are you absolutely positively sure there are no inclines, no matter how small, anywhere? Plenty of times I’ve thought my surroundings are flat terrain, until I went there with a bicycle. That thing doesn’t lie about terrain. Maybe a test ride on the same route backwards, so you’ll notice if that special location suddenly forces you to pedal an incline? Another terrain-related thing to consider might be surface material. Is that the same through your entire route?

When I was running regularly, I found it often got significantly easier around the 3-4km mark. I don’t remember HR drops that strong, I always attributed it to just being properly warmed up and my body and brain getting into a ”running mode”.

Wow, that's interesting! Maybe it's a matter of being properly warmed up, though if I continue my HR will eventually come up again.
Flatness: well... there's maybe 50cm elevation loss over 500m on that stretch of road from last night. But, the same used to happened on a stretch of coast with no elevation change in the past. It was always the same 1.5m from the path down to the water. And a second spot near my current home possibly increases in elevation by a few cm.

hipari

yirara wrote: »

hipari wrote: »

Are you absolutely positively sure there are no inclines, no matter how small, anywhere? Plenty of times I’ve thought my surroundings are flat terrain, until I went there with a bicycle. That thing doesn’t lie about terrain. Maybe a test ride on the same route backwards, so you’ll notice if that special location suddenly forces you to pedal an incline? Another terrain-related thing to consider might be surface material. Is that the same through your entire route?

When I was running regularly, I found it often got significantly easier around the 3-4km mark. I don’t remember HR drops that strong, I always attributed it to just being properly warmed up and my body and brain getting into a ”running mode”.

Wow, that's interesting! Maybe it's a matter of being properly warmed up, though if I continue my HR will eventually come up again.

Yep, same here, or at least it started feeling harder again. Figured it’s the sweet spot after getting warmed up and into ”running mode”, before getting tired. I have no scientific background for this, just my own experience.

yirara

hipari wrote: »

yirara wrote: »

hipari wrote: »

Are you absolutely positively sure there are no inclines, no matter how small, anywhere? Plenty of times I’ve thought my surroundings are flat terrain, until I went there with a bicycle. That thing doesn’t lie about terrain. Maybe a test ride on the same route backwards, so you’ll notice if that special location suddenly forces you to pedal an incline? Another terrain-related thing to consider might be surface material. Is that the same through your entire route?

When I was running regularly, I found it often got significantly easier around the 3-4km mark. I don’t remember HR drops that strong, I always attributed it to just being properly warmed up and my body and brain getting into a ”running mode”.

Wow, that's interesting! Maybe it's a matter of being properly warmed up, though if I continue my HR will eventually come up again.

Yep, same here, or at least it started feeling harder again. Figured it’s the sweet spot after getting warmed up and into ”running mode”, before getting tired. I have no scientific background for this, just my own experience.

Thanks a lot. That's really interesting. Yes, it does get more difficult again. If I do longer runs and things really work out then I get constant small fluctuations: moments where my HR goes down and things get easier, and then up and more difficult again, and then down again, etc. Smaller fluctuations than those, but my log looks seriously funny.

heybales

I've seen the same thing when half or marathon training, because it seemed to take about 8-10 miles to hit that point. Not 20 bpm improvement, but the feeling of running better with HR taking a bit of nosedive.

At first I wondered if it was a warmup aspect, and there is a short blip to that for short time in, even though I walk for 5 min to literally warmup the muscles first.
But even though my muscles seem to be warmed up (unless it's cold out), I'm not at best flexibility it appears, and it takes a little while running to reach that point where form improves and efficiency is better and since I don't speed up it's just not as intense, so HR can lower.

I've wondered if that 8-10 miles is just another similar point, where maybe some other muscle/tendon/ligament finally loosened up enough for form to get better yet again.
Maybe that's the point my hamstrings have gotten tired enough there is better glute activation finally and form is better, really don't know.
I just hate it takes that long to get the feeling - not often running that distance, nor that pace it would matter.

Or now that I think about it - perhaps because I do try to keep the HR down to a training zone and it is slower than potential - maybe that's the point form improved for that slower pace finally. Hmmmm, can't wait to start running again to test that one.

I know on treadmill running (to remove incline and wind factors) years ago I tested HR against changes in turn-over and pace, and found sweet spots of efficiency based on HR either being lower or not increasing nearly as much as the pace increase would indicate. Then would use that on normal outdoor training when flat and it worked great.

For long cardio events though usually HR follows a drift up based on blood getting thicker, more heat to dissipate, tired, ect - all reasons for it to normally just keep increasing despite the intensity/pace being exactly the same.
Perhaps you are hitting a moment body turned something on to get cooler and it worked, or water released from stored glycogen being used is now free to be pulled into blood stream.

yirara

Wow, I'm so glad I made this post. There are so many interesting angles to this. Thanks a lot for your as ever fantastic insight, Heybales. And to everyone else as well.

Jthanmyfitnesspal

I don't see what you mean from you data. You warmed up then stayed very sustained with a slight overall increase until the end of the run. There are one or two little glitches in there which I doubt are real.

yirara

Jthanmyfitnesspal wrote: »

I don't see what you mean from you data. You warmed up then stayed very sustained with a slight overall increase until the end of the run. There are one or two little glitches in there which I doubt are real.

The upper graph. That's from my hr sensor, with data uploaded to smashrun. The lower graph is from my garmin watch for the same run. Horizontal scale is very slightly different. Should have stretched out the upper graph a bit more.

heybales

EKG sensor for the win when comparing data - unless you have like static issues and inflated HR readings.

I've never seen occurrence of it lowering by some amount - but I've sure seen that issue cause inflated by an almost set amount.
Until I put hand on poly shirt flapping around and held to HR sensor then reading takes a nose dive for 5-20 bpm, until I let it flap again.
But reading low...... hmmm