Monday, January 24, 2011

Heart rates and pool running

When running on land, I regularly use a heart rate monitor.  I'm not one of those people who "trains" by heart rate zones -- I think that there's too many other variables that can come into play.  For example, I can bump my heart rate up by nearly 10 beats per minute just by daydreaming about the last race I ran.

When running, I do like to get some HR feedback, though.  I've had workouts where a ridiculously high HR has convinced me to bail (where otherwise I might have struggled through and dug myself into a hole), and I've had other workouts where a low HR reinforces my perception that I can up my training paces the next time round.

The one time that I do "train" by heart rate zone is on my non-workout, easy days.  There, I program a HR ceiling into my monitor, so that it squawks at me any time I push the pace.  It's a nice way to ensure my easy runs stay easy.

Usually, my heartrate hits the following ranges when running:

very easy run -- under 150 (this is hard to do)
aerobic (a bit slower than marathon pace) - around 160-165
tempo - between 172 and 182
speedwork - peaks at about 190-193.

My resting HR is in the low 40s (when in bed, drifting off to sleep), and my max HR is somewhere near 200 (though I haven't seen a true 200+ reading in about 2 years, so it may have lowered a bit with age, as max HRs can do).

All of that is when I'm running.  Which I'm doing little of right now.  

I haven't been using my HR monitor while pool running.   I use a Garmin 310xt as my HR monitor, and while both the monitor and the strap are waterproof, the strap can't transmit to the band while submerged -- the signal fades in the water.  So, I've been pool-running off of perceived effort (which is how to do it).

Until today.  Today I had a rare flash of insight -- if the components both worked, but the signal couldn't traverse the distance in the water, then the device might work if I held my wrist right next to the chest strap.

And it did.  So while I can't get continuing information, I can do spot checks as often as I like, and it's easier to do so than to take a pulse (I can never find mine anyway).

So, here's the results:

a) my "easy pool run" HR seems to range between 128-135 BPM.
b) an "aerobic" HR in the pool is around 150 BPM
c) my HR peaked at 176 BPM during my last, hardest "drive the HR up as high as possible" interval this morning.

Each of which correspond to about 15 BPM below my land HR for the same effort.  Which matches everything I've read about heart rates in the pool -- that they are depressed by 15-20 BPM in the water due to three reasons:
  1. pool running is not fully weight bearing
  2. the coolness of the water keeps your HR down
  3. the pressure of the water acts like the best compression suit evah, meaning that the heart works much less hard to circulate blood at the same velocity.
Neat.   Now to try it on my next tempo.


  1. Good insight. I've found about the same variation. In fact, I just wrote an article about cross-training, including lots of info about pool running, and I made note of the fact that getting your HR up to "running" levels is really hard to do in the pool.

  2. WHOA! How did you hold the device to get it to read from the HR monitor? You may have just changed the world for me.

  3. Very useful information! This adds a whole new element to your training. I found the three reasons why HR is lower to be interesting. I have also heard, and found to be true, that you are hungrier after a pool workout due to the affects of the water temperature on your metabolism.

  4. My HR is much lower in the pool than yours, my monitor works in the pool. I know I'm older, not as elite as you, & my max HR is lower than yours, but my resting is 42 and that it makes me wonder.
    @Elizabeth, it's so true, I'm definitely hungrier after pool running then regular running!

  5. Thanks so much for this blog. Very useful info for those of us who've been forced to become pool runners (but have also come to recognize the benefits!) - My HR is also much lower in the pool than yours. I'm 43 - and I find that my HR at something approximating tempo pace is more like 122.

  6. Jo -- that's the thing about HRs -- they're so unique (and have no relationship to effort between individuals, though they do indicate effort within an individual).

    Mine peaked on my track tempo this morning at 182, which is about where it should be (races should hit the 190s). For many others, that's ludicrous.

    (122 is me walking around :))

    I'm glad you find the blog helpful!

  7. I use the 310XT whilst pool running too. I have worn the HRM a couple of times and did a spot check by lifting myself out of the water. Next time I'll just hold the watch close to it instead. Thanks for the advice.