Help Me Decipher a Heart Rate Result

[Bill Been]

Daughter Kid (swimmer, age 18) has been on the SSLP since February with reasonable compliance within the bounds of largely-preposterous swim programming. We recently got a Concept 2 and a Rogue Butcher, as we all wanted to add some cardio so we don't die of heart disease by tomorrow afternoon and cuz everybody knows the definition of wellness is "does cardio". So we buy all this equipment. Today Girl Kid decides to get started. By going for a run. Apparently, swimming 8000 yards 4 times a week is inadequate cardio in Teenkid Land, and you need to go for a run. Anyway, I made her wear the super cool new heart rate chest strap and iPhone App I bravely confronted the App Store to obtain. She ran at a pace of 12:30ish/mile for just over a half hour for around 2.35mi or so. This struck me as a pretty leisurely run until I saw the heart rate history: most of the time she was at 185 beats per minute. On the down hills it dropped to 165.
Now this seems entirely "off" to me.
Is there some reason she'd "need" such a high rate with such a pedestrian pace?
Does a high heart rate signify anything in and of itself, or are we looking for accel/decel rates?
Am I showing my ignorance by being stunned by completely normal HR data for running?

[hollismb]

185 is indeed high, unless she was sucking wind the whole time, even accounting for the higher max HR of an 18yo. Sometimes you get bad data and spikes if it's not making a good connection, like if you don't moisten the strap first. For example, here's some info from Garmin. So try those things first, and see what happens. Might also want to just try checking her heart rate manually after a short jog to compare.

[Dan Miller]

It could be a specificity thing. She might be well adapted to swimming but not running, hence the high running HR.

[CJ Gotcher]

It's pretty unlikely that she sustained about 90% max rate heart for 30 minutes. Heart rate monitors can be pretty finicky- I'd check the user's manual for any step that hasn't quite been followed, and if there's a function on the device to see HR in real time, I'd do a manual comparison to what it was putting out once or twice mid-run.

If it's still wonky, I'd look at getting a replacement.

[Viola]

Many people have higher than average maximum heart rates. The equations out there to calculate MHR are not accurate for everyone. Plus what Dan said. Swimming cardio does not equal running cardio . I would ask her how it felt. In my experience when the heart rate strap isn't reading correctly, the results are very spiky. Or very low.

[nanson]

Many people have higher than average maximum heart rates. The equations out there to calculate MHR are not accurate for everyone. Plus what Dan said. Swimming cardio does not equal running cardio . I would ask her how it felt. In my experience when the heart rate strap isn't reading correctly, the results are very spiky. Or very low.

Agree with this. My observed max is 197 at 38 years old (at the end of a 5k), I could hit 230 as a teenager (manually taking pulse, so may not have been all that accurate). The formula has a large standard deviation (~12bpm) and if you aren't in the 68% that fall within one standard deviation it gets worse.

Also how hot was it? My heart rate can be quite high relative to my perceived effort if it is hot and or humid, or if I am running in direct sun, particularly in the spring when I'm less adapted to the heat. My heart rate will jump up 5-10 bpm going from shade to full sun. And this afternoon (86deg, 55% humidity) my heart rate running in the shade was ~175bpm at a pace where I would normally be <150 bpm.

Dehydration can also significantly raise heart rate, even mild dehydration. Blood volume lowers and the heart has to beat faster.

You need more data to draw any conclusions. If she uses the heart rate monitor whenever she is running she can compare the number to how she feels and get a feel for what is normal for her at various effort levels.

[Bill Been]

Thank you all for the thorough responses. I'll check her resting heart rate and see if it's rational, but the strap is brand new and has been used on my sons and myself as well, all without issue. That's part of the reason I was so concerned - my 19 y/o rugby player son barely scrapes 180 on about his 6th or so interval on the Prowler, and I (age 52) only hit about 150 late in my much less intense Prowler work. All those results seem pretty much down the middle. I'll check real-time resting HR with the manual technique nonetheless.

Heat and humidity: it was a bit humid, but not too terribly hot. I'll ask her about hydration, but she tends to do a pretty good job with that.

[Bill Been]

And the last piece of the puzzle is Wifey Girl getting on the C2 wearing the monitor today. Her HR sitting down was 85, after the first 20 second interval is was over 170, never dropped below 165 during the 1+40 recovery phases, and topped 180 every interval thereafter.

So, evidently like mother like daughter.