What does it mean when your MHR drops 15-20 beats when you're in shape?

getting into better shape, when your really out of shape and morbidly obese your heart beats so fast even when doing the simplest activities that you get a heart attack.

Large increase in plasma volume during training may be the reason your max is much lower when you are fitter.

Do you sweat a lot?

Actually I do. I'm 150 when fully hydrated but I commonly drop near and even below 140 on long runs in hot weather, even when I carry water. My weight doesn't change when I detrain but presumably I'm losing muscle and gaining fat. Is prodigious sweating always indicative of large plasma volume? Hadn't thought of this--please tell me more. Thanks!

Max HR dropping once you improve your fitness is what normally happens. This is because the left ventricle increases in size, thus allowing the heart to increase its stroke volume. with a larger stroke volume your heart does not need to beet 205 times a minute like it does when its out of shape. basically its your body maximizing its cardiac output by finding the best ratio between BPM and SV!

15-20 is a very large jump however. but that may just be normal for you. i wouldnt be that worried about it. how did you test your MHR? was it after a hard day of running?

It might not be a bad idea to monitor your waking pulse.

Also, have you tried to do your daily runs at a much easier pace? If it's really hot, then just go very slowly.

My MHR estimates generally come from the max reached in racing or in the sprint at the end of a long hard hill session. So it's probably low but it would be a similar bias both in and out of shape. I regularly monitor my resting pulse as well and it also drops 15-20 beats when I'm in shape, but I think this is more normal. This MHR thing wouldn't bother me except that I regularly have very bad races (much slower than training would indicate) and it's always correlated with a low race MHR. I ran a PR 5K last fall and hit 180; last month I tanked in a 5K and hit 173. I've tried cutting out speedwork for a month or more before racing. I took three months completely off last year because I thought it might be long-term overtraining. I just tried a very long (nine-day) taper with nothing but a few miles daily of slow flat running and had another bad race (and 175 max). Running out of ideas... Thanks for the suggestions--much appreciated.

Take off the HR monitor. It obviously isn't working for you, and is just making you paranoid.

Find some part of your training that feels different than from when you set your PR. Then go and work on it. Taking off 3 months after a PR and expecting to return to better than PR shape in less than 6-9 months is rather optimistic, depending on age and ability.

Very normal...

After training for weeks on end your body (and heart) are tired. The heart rate is limited when you are training so that you do not injure your body (or heart) The areas of the brain that tell the heart how fast to beat acts as the "decision maker" at all times, as far as heart rate. Then of course there is the heart's ability to "expand" and pump more blood per beat. This is "governed" by certain areas of the brain as well.

As long as you have no heart pains and it beats regularly relax. You can't analyze what's happening because we don't really know how this all works. Dr. Timothy Noakes has his "central Governor" theory that makes a ton of sense to me....

I'm 44 and am having the same problem. My Max HR is 195 but in recent 5k's I've maxed at 180 and avg 175 in a race. Even lower in longer distances. I've tried surging in races to try to kick my HR into another gear but nada. (I've found sometimes running faster when your HR is higher is actually more comfortable.) I also wouldn't care if it meant my times were under 18:00 (PR is 17:20) but I'm only at ~18:30. Same low HR in workouts.

FWIW I sweat like crazy.

Meeeee 2 wrote:

I'm 44 and am having the same problem.

Well, the problem is you're thinking it's a "problem". When you're old, gimpy, and out of shape like I am then just taking a dump is going to raise your HR, so strenuous activity will get you closer to your MHR a lot faster.

When you become more efficient at running and in better shape you're going to have to be chased by a pack of wild dogs with a steak hanging around your neck to get anywhere close. Other things will top out before you hit your heart's max stroke rate.

That's NOT a problem, but a good sign of progression through fitness levels.

As far as trying to raise your HR to increase comfort, I think your correlation factors are just a tad off.

I've actually experienced an opposite situation, and it has happened at the very start of a morning run three times since I got my HRM. My heart rate goes straight to max. (187 for me, I am 45) within the first mile, and then goes back to normal (110-120) within the 2nd mile. I think it is just my heart "waking up" and the max. stroke volume isn't achieved until about 10-12 minutes into the run, so the heart compensates with high HR. If I wasn't wearing the HRM I would never even know it was happening.

Incidentally, my doctor, who is a cardio specialist (and a runner), per his charts says 187 is my predicted max.

MM - How long have you been using the HRM? I've used one off and on for about four years and it's taken me a while to figure out some of the nuances (as in, it isn't a perfectly reliable tool at all times and for all workouts, though very useful once you get the hang of it.) Shoot me an e-mail if you want so we don't clutter up this thread.

I don't base my training on the monitor output; I use it diagnostically. If I didn't use the HRM I'd have the same erratic race performances but no extra information. I think it's a valid question as to why my MHR should fluctuate so much, especially since my racing speed is so well correlated with it. One consistent observation is that if I do a lot of hard training (long intervals at ~5K pace), my resting rate drops a lot. If I see it much below 40 (I've seen 33 before) and I've got a race in the next week or so, I'm screwed: bad race, low MHR, even if I've stopped running completely for four or five days before.

Interesting. I find the lower RHR to be quite reassuring, means I'm in shape and rested, ready for a race or good workout. But if I've done a really hard workout around 5K pace, my RHR will often be a little high for a day or so.

My MHR probably comes down somewhat when I'm in shape, but I never push hard enough to get near max when I'm out of shape. I also don't race when I'm not in at least OK shape.

I know people who find that if they can't get the HR up much on the warmup, that is a sign they are stale and have not tapered and eaten enough in the days beforehand to be really ready to go. They will not be able to get the HR up in the race, either. I almost never have that problem; often it is the reverse.

I dont think any of us can answer this question with as little information as we (us and you) have.the only thing i can think is that a) you should stop doing as many long vo2max workouts that you have been doing that seem to bring on the problem. b) dont worry about it, as MHR is 1 of only about 100 other things that could be actually wrong. cardiac output is what you need to look at if you want to corelate heart problems with poor performance, not just MHR.

I had a very similar problem that related to fatigue. my heart rate is very high even running at 6:30 pace (im a 1:50 800 guy) so lots of distance made me fatigued because it was a lot of stress on my body running at high end for so long. i used a heart rate monitor to keep my HR below about 155 on my long runs (which was at around 7:15-7:30 pace. which is really slow, but i had to listen to my body. i was able to keep my long runs, while improving my interval workouts because i wasnt tired.

You're right that there can be many problems that limit performance and therefore heart rate, e.g., insufficient carbs, tired legs, etc. After all, speed and heart rate are very nearly linearly related. The question is then why my resting rate plummets after too much speedwork and is always followed by low race MHR. Cutting out the fast stuff for a couple of months tends to give me a better shot at a high race MHR but I'm absolutely convinced that it's these workouts over the years that have provided all my long-term improvement (I have a very fancy model that tells me so unambiguously--I'm a physics/math dork). So I can improve over the long haul but race crappy, or race well but never better... Thanks for the info about your long run pace. And congrats on that 1:50.

pretty normal wrote:

Max HR dropping once you improve your fitness is what normally happens. This is because the left ventricle increases in size, thus allowing the heart to increase its stroke volume. with a larger stroke volume your heart does not need to beet 205 times a minute like it does when its out of shape. basically its your body maximizing its cardiac output by finding the best ratio between BPM and SV!

15-20 is a very large jump however. but that may just be normal for you. i wouldnt be that worried about it. how did you test your MHR? was it after a hard day of running?

So far, this is the only correct explanation. Good job.

Stroke volume times heart rate is equal to cardiac output. Increasing the strength of the left ventricle increases the amount of blood pumped per beat (stroke volume). To maintain the same cardiac output... which is what your body does to maintain its efficiency... it lowers the heart rate. Race performance is dependent upon a number of variables and not just heart rate. Cardiovascular fitness and muscular fitness/development are two different subjects. The heart has multiple automatic pacemakers and receives input from parasympathetic and sympathetic innervation. Contractility, however, is more of an intrinsic property of the heart muscle itself (Frank Starling's law of the heart). But, there are positive and negative inotropic agents. Quit overanalyzing and blaming your performance on your heart. Unless it is starting to hypertrophy, then you'll be okay. Try finding a different body part to blame it on. Oh, and this subject isn't a black hole.

question asker, tell us more about this model (I too am a maths dork)...

I don't agree that heart rate and speed are "very nearly linearly related". I'd like to see this model as well. I know a guy by the name of Lambert demonstrated that workload and heart rate have a pretty constant relationship... but that's only if you can control all other variables.