Heart Rate Connundrum - Can't get it up (even in Intervals)

ejwme

Background:

I'm a long time runner (off and on, mostly on, for 20 years). I'm 32yr old, female, a very healthy weight, and have been running ~20-40 miles a week for the past 9 months (averaged ~20 miles a week for most of my life). My resting heart rate is, and always has been, between 52-60 bpm. My pace depends on the distance, but for a 5k I like about 7-8 minutes a mile, and long slow distances are 10-12 minutes a mile. I figured that means I'm healthy, but now I'm wondering.

Heart Rate Monitor:

I used a heart rate monitor to do a 1 hour Lactic Threshold Heart Rate test about 10 years ago, it was ~178-181. This seemed to jive with my fitness level. Fast forward 10 years, and I've recently picked up a garmin 310xt to help with my long runs (I like to get lost, until the end of the run when I can't get home). I'm a comparable fitness level, but even during intervals, I can barely get my heart rate over 164. Charging as fast as I could up a super steep, quarter-mile long hill, I hit 171 near the top. I also thought my arms and legs were going to fall off, though my heart never felt like it was pounding at all.

Questions:

1) Yes, I'm 10 years older, but does that really translate into a 10bpm drop in lactic threshold heart rate? If the trend continues, in another 20 years my lactic threshold heart rate will be below my current 5k racing heart rate (~150bpm)? What?

2) Assuming my max heart rate is up where it should be, around 190, why can't I get my heart rate up above 170? Have I spent too much of my life eschewing intervals in favor of long slow distances, and thus my heart is healthier than my arms and legs? I'm hoping this is the answer, just "do more intervals", but I never used to do intervals and could get my heart rate up just fine.

3) Non-fitness, non-age factors that I could find were things like bradychardia (but I thought that affected resting heart rate too, mine is normal), and beta blockers (I don't take them). I'm not on any meds, never had any gland or hormone disorders, and honestly feel pretty darn terrific (excepting a new, slight anxiety over the heart rate).

So what's up with that? My heart rate for distance runs appears very healthy, as does my resting heart rate, so I'm really confused as to why I simply can't get my heart rate up.

Any ideas would be helpful.

scottb81

It could be that it has dropped a few beats in 10 years. Its possible that your aerobic fitness has improved greatly and that your legs cannot keep up with your heart. You can likely figure out which it is after reading this: (Look at the relationship between your race times at various distances.) http://www.angio.net/personal/run/hadd.pdf

Another explanation is that you were tired. Unless you are pretty rested it is nearly impossible for the legs to push the heartrate real high in an aerobically trained runner.

If you have done a max effort 5K race sometime recently and you ran it rested than your max heart rate is probably no more than 5 beats higher than what it was in the sprint at the end of the race.

If the max heart rate has dropped either due to age or increased aerobic fitness that doesn't mean you will race slower.

ejwme

hmm... that's some good reading, thank you! I'll need to dig up my actual race results (pre-watch), or just run some new ones (properly) and see where things lie. I tend to run races as social events, and train hard independently. Kind of the opposite of normal, but speed was never a goal, and I'm notorious for getting friends hooked on running (meaning I'm often keeping pace with newer runners for races well below my "race" pace).

Maybe I need to switch it up and see if I can't get my heart rate up biking or doing something else... it seems obvious, but I didn't think of it being sport related.

Does sleep deprivation really have that big an effect? I was coming off a bad round of insomnia but felt good. Something else to track and see, I didn't realize it would affect things that much.

thank you!

mirthfuldragon

A couple of things:

HRM vary; good ones vary less, but a 3-5bpm margin of error might be in place.

A 10bpm drop in ten years seems reasonable, depending on how you were training. The classic formula (which isn't 100% perfect by any means) for max HR is 220-age, so a ten year age increase with a 10bpm drop is not out of line.

Maximum heart rate is variable by activity, and is not set by formula; the classic 220-age is a good baseline, but it really helps to actually go find it.

Lactic threshold is also very trainable. Long, slow distance running (presumably mostly in zone three) will help with endurance, but you aren't getting near lactic threshold in terms of power production, so you probably aren't building lactic threshold ability in the last 9 months. Intervals will help train lactic threshold for you.

Sleep, training strain, and a variety of other factors will effect your maximum HR on any given day. For example, I did a "typical" 5k on a treadmill on Friday, and couldn't get much above 160bpm; that was after a four days of continuous training in swim, bike, and running at least once a day. This morning, coming off a day of rest, I was hitting around 171bpm. My running speed is about the same, with my 5k times within 60 seconds of each other (34ish minutes - yeah, I'm slow, but I've been running for only two months now).

http://www.beginnertriathlete.com/cms/article-detail.asp?articleid=53 and http://www.beginnertriathlete.com/cms/article-detail.asp?articleid=54 are good articles on the subject.

ejwme

yee gads, the first few paragraphs of that tri article describe me perfectly. "Ooo, pretty new pictures, look what I did!... uh... wait..." I look forward to reading the rest (I do love that site, I'm amazed I hadn't found it before).

I'm starting to think that my sleep deprivation played more into things than I thought. Feeling "fine" is relative, and I might not have recovered as much as I'd hoped.

Thank you guys for the sanity check - I have not discovered a new problem, I have discovered a new measurement I don't understand yet. Thankfully the solution - run more to get more data - is one I like very much.

Azdak

Long-term endurance training (you are 32 and have been running for 20 years? started young, I guess), can affect the nervous regulation of the heart.

Endurance training increases parasympathetic activity (which has a lowering effect on heart rate) and can decrease sympathetic activity.

Basically, it becomes harder and harder to reach high heart rate levels. Don't know how significant this is. I am a lot older (59) and have been running off and on for almost 40 years (although the last 15 years have been mostly off).

I find the same thing. My age-predicted HRmax is 161-165. Even back in graduate school 30 years ago, I never went above 170 in max testing.

Now, I rarely go above 155-160, although I can maintain mid-140s for 30-60 min). Even doing all-out intervals, my HR rarely gets above 130-135 during a 20-30 sec interval at 100% effort.

Here is a reference that might lead you to more info:

http://www.ncbi.nlm.nih.gov/pubmed/12477376

scottb81

Even doing all-out intervals, my HR rarely gets above 130-135 during a 20-30 sec interval at 100% effort.

That's another good point. If you are well trained aerobically your heart rate rises slowly and falls pretty quickly.

I am fairly well trained aerobically and doing hill repeats like the OP described, when I am tired, gets my HR up only into the low to mid 140s. WIth a couple of minutes recovery it is below 100 again before the next repeat. For reference, my max is somewhere in the range of 167 to 172 and I'm pretty sure my LT is around 156.

The OP may need either longer repeats, up to 5 min, or much shorter recoveries, in order to get the heart rate up to the desired level.

scorpio516

Long-term endurance training (you are 32 and have been running for 20 years? started young, I guess)

Just pointing out that that isn't too out of line.
I'm 34 and I started running competitively in 7th grade, which would have been 90/91, 22 years ago.

ejwme

I did start really young - impressing the cross country coach was the only way to get on the soccer team in 7th grade, and getting on the soccer team was the only way to see my (soccer playing) friends for like most of the school year. Used to get in trouble for waking up too early to run by myself at a nearby track before school, mom hated me being alone in the dark at 6AM at 12, but I realized if I ran earlier - to get home and in the shower before she woke up, she wouldn't know. I was a jerk of a kid. Never made the soccer team, but got hooked on running.

I heard about the parasympathetic stuff, but figured that applied only to elite runners. My paces aren't elite, even by the most liberal definitions. I've only just recently decided to see how fast I can run, having gotten bored with sorting out how far I can run (super far, it's a mental and training game for me). Thus the new interest in intervals and heart rate stuff, since I'm pretty stagnant at my current paces on my previous "yay, lets run over there now!" training program.

ejwme

on the intervals/recoveries...

My "fartlek" runs were short sprints followed by comfortable jogs as long as my training partner let me rest (we took turns picking when to start/stop so that whoever picked when to stop didn't pick the next start). But we both hate intervals, so our bursts were likely too short, and recoveries were definitely too long. Add in our mismatched strengths (he's got better strength and sprinting, I've got better endurance)

Farting around with programming intervals in my garmin watch, I started doing 5 minute intervals keeping my HR between 150 and 165 (usually closer to 150-155) followed by easy jogging/brisk walking until my heart rate hit 125 (sadly, only about 15 seconds if walking), then immediately ramping back up again for 5 minutes. I found that if I did 4:30 instead of 5, and follow hitting 125 with 30 seconds of maintaining 125-135, I went farther overall for similar heart rate profile for the same number of runs. I assumed farther was better.

I find I'm able to do better interval training with the watch because I simply do what it beeps at me to do - training partner can bargain and rationalize, and I tend to turn my mind off while running so making decisions about pace is not my forte. Unfortunately, I'm also the one programming the watch, and I'm still pretty dumb at this

Flamenquero

http://www.amazon.com/Training-Lactate-Pulse-Rate-Peter-Janssen/dp/9529006683

See the link above and try and get a copy of the book. Sounds like you just need to get a new Conconi test. http://en.wikipedia.org/wiki/Conconi_test Janssen's book tells you how to do this.

ejwme

yeah, I was planning on doing another LTHR test, but postponed it ... I didn't want to do one without sorting out why my heart rate was so low (I don't know why, but I feared a super low result, like "lactic threshold inadequacy issues" or something). I'm tempted to do a few more weeks of intervals before I do, just to get used to intentionally getting my heart rate up and to make sure I'm getting real results, and not getting skewed numbers (like insomnia, or crap diet, or abrupt weather change, or something else odd I haven't thought of).

Flamenquero

Go to a track. Wear the HRM. Try and run a 600-yd at an all out sprint and put yourself into oxygen debt. Look at your HRM when the riggy sets in. That will estimate your threshold.