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HR Training in heat & humidity
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 2010-07-07 9:27 AM |
Pro  4353    Wallingford, PA |  Subject: HR Training in heat & humidityI went for an hour-ish run this morning. This plan was for a zone 2, easy aerobic run. I'm in the mid-Atlantic, right smack in the middle of a huge heat wave. It wasn't THAT hot when I ran in the morning, though (mid-80's, maybe), but pretty humid. Anyway, my question is about heart rate zones and heat. I had a heck of a time trying to keep my HR down this morning. I would be going at what felt like a comfortable pace. If I had been running by RPE, I would have called it an easy aerobic pace. But when I would look down at my HRM, I often found that I was 10 or more bpm above where I wanted to be (zones based on field testing, not formulas...). I know pace at a given HR is likely to be slower, maybe even significantly so in heat. What I'm wondering is if others have experienced the same thing - what FEELS easy shows up on the HRM as a higher zone? In that case, is it okay to let the zones shift a bit higher in the heat, or should I just really slow way down and try to keep easy runs in my established easy zone? |
| 2010-07-07 10:03 AM in reply to: #2965440 |
Champion 7036 Sarasota, FL | Subject: RE: HR Training in heat & humidity Living in Florida, we have the "opportunity" to run in the heat for a good part of the year. I do most of my runs in zone 2, and similar to your experience, I've seen my HR jump 10-12 BPM in hot weather, creating a disconnect between my HR and RPE. Usually happens at about two miles into a run. Being older (57) and having some cardiac issues (mechanical aortic valve), I normally let discretion be the better part of valor and slow down to get my HR back into my desired training range. Sometimes that means I end up walking. Best solution I've found is to get up early and run in the mornings before it gets too hot... Mark |
| 2010-07-07 10:21 AM in reply to: #2965440 |
Runner | Subject: RE: HR Training in heat & humidity Pick one and stick to it. If it's HR, then follow the HRM. |
| 2010-07-07 10:43 AM in reply to: #2965440 |
Champion 7595 Columbia, South Carolina | Subject: RE: HR Training in heat & humidity IMO, yes. I let my zones shift up a bit in high heat/humidity. I disagree a little with Scout on this one. I allow myself to use RPE and pace in the course of determining how much my zones shift due to conditions. Once I come to feel that I have a good handle on the effect of heat on my zones (i.e., after a few runs in the heat), I just use the shifted zones. |
| 2010-07-07 10:47 AM in reply to: #2965440 |
Expert 2852 Pfafftown, NC | Subject: RE: HR Training in heat & humidity As far as the beneift gained from a particular training session.....does your body CARE what pace you're running at? For example, if you're looking to run in zone 2 (and that has you running 45sec/mile slower than your normal training pace), are you getting any benefit from allowing your HR to remain elevated, even though your RPE is the same? |
| 2010-07-07 10:53 AM in reply to: #2965665 |
Champion 7595 Columbia, South Carolina | Subject: RE: HR Training in heat & humidity nc452010 - 2010-07-07 11:47 AM As far as the beneift gained from a particular training session.....does your body CARE what pace you're running at? For example, if you're looking to run in zone 2 (and that has you running 45sec/mile slower than your normal training pace), are you getting any benefit from allowing your HR to remain elevated, even though your RPE is the same? All of these methods (HR, RPE, pace) are attempts to measure (indirectly!) the level of exertion. Specifically, what your body 'cares' about is how much power it is producing, but this is not at all easy to measure directly on the run. HR is imperfect for a lot of reasons (as are the others), one of which is the topic of this post -- the heat can cause it to rise in a way that does not (entirely) reflect power-production. That's why it makes sense to allow zones to go up a bit in the heat. |
| 2010-07-07 10:59 AM in reply to: #2965689 |
Runner | Subject: RE: HR Training in heat & humidity Experior - 2010-07-07 11:53 AM nc452010 - 2010-07-07 11:47 AM As far as the beneift gained from a particular training session.....does your body CARE what pace you're running at? For example, if you're looking to run in zone 2 (and that has you running 45sec/mile slower than your normal training pace), are you getting any benefit from allowing your HR to remain elevated, even though your RPE is the same? All of these methods (HR, RPE, pace) are attempts to measure (indirectly!) the level of exertion. Specifically, what your body 'cares' about is how much power it is producing, but this is not at all easy to measure directly on the run. HR is imperfect for a lot of reasons (as are the others), one of which is the topic of this post -- the heat can cause it to rise in a way that does not (entirely) reflect power-production. That's why it makes sense to allow zones to go up a bit in the heat. I guess my question is, why allow them to go up? If HR is the measurement of exertion, you are at a higher level if you let the HR rise, correct? In other words, if I hit 160 today because it's hot/humid, when I would normally run at 150, am I working "harder" than normal? And if so, is that what I want to accomplish? |
| 2010-07-07 11:01 AM in reply to: #2965440 |
Expert 1123 Falls Church, VA | Subject: RE: HR Training in heat & humidity I say stick with the HR readings.. I have tried to ignore what seemed like a bogusly high HR and just kept going by RPE.. Each time I've felt fine for a few miles, then things go south pretty quick and getting back (specially if it is an out and back route) can be quite a struggle. I have noticed that RPE/breathing pattern can lag behind what a HR monitor is telling you in real time (at least for me). |
| 2010-07-07 11:05 AM in reply to: #2965707 |
Regular 200 Stoughton, WI | Subject: RE: HR Training in heat & humidity You know when you join a gym and such it says "Before you start any exercise program, consult your physician"? I am guessing if you have heart issues already and you consult your physician - he/she will tell you to keep your HR at a certain level. I would stick with that. I don't use HR, so my RPE would be my guide and probably my HR would be higher than normal. So - to each his own. |
| 2010-07-07 11:12 AM in reply to: #2965707 |
Champion 7595 Columbia, South Carolina | Subject: RE: HR Training in heat & humidity Scout7 - 2010-07-07 11:59 AM Experior - 2010-07-07 11:53 AM I guess my question is, why allow them to go up? If HR is the measurement of exertion, you are at a higher level if you let the HR rise, correct? In other words, if I hit 160 today because it's hot/humid, when I would normally run at 150, am I working "harder" than normal? And if so, is that what I want to accomplish?nc452010 - 2010-07-07 11:47 AM As far as the beneift gained from a particular training session.....does your body CARE what pace you're running at? For example, if you're looking to run in zone 2 (and that has you running 45sec/mile slower than your normal training pace), are you getting any benefit from allowing your HR to remain elevated, even though your RPE is the same? All of these methods (HR, RPE, pace) are attempts to measure (indirectly!) the level of exertion. Specifically, what your body 'cares' about is how much power it is producing, but this is not at all easy to measure directly on the run. HR is imperfect for a lot of reasons (as are the others), one of which is the topic of this post -- the heat can cause it to rise in a way that does not (entirely) reflect power-production. That's why it makes sense to allow zones to go up a bit in the heat. My claim (I'm prepared to be proven wrong) is that HR is NOT, entirely, a measure of muscular exertion. In the heat, it goes up for reasons that are not directly a consequence of exertion. My aim is to 'subtract out' that part so that I am getting a more (but surely still not completely) accurate measure. There are studies (none come quickly to mind, but I'll look) that seem to corroborate this notion. Certainly one thing I've tried just for 'fun' is to measure my 'walking around' HR in drastically different temperatures (in this case, an over-air conditioned office building which was probably at close to 70 degrees, and then outdoors in 100 degrees), and they were quite different. I'm pretty sure this has to do with the body's attempt to cool itself in the heat. Maybe other things too. Now, it is also true that the body simply produces less wattage in the heat, so pace WILL slow down in the heat; so we can't just go by pace here either. |
| 2010-07-07 11:16 AM in reply to: #2965707 |
Champion 9600 Fountain Hills, AZ | Subject: RE: HR Training in heat & humidity Scout7 - 2010-07-07 9:59 AM Experior - 2010-07-07 11:53 AM nc452010 - 2010-07-07 11:47 AM As far as the beneift gained from a particular training session.....does your body CARE what pace you're running at? For example, if you're looking to run in zone 2 (and that has you running 45sec/mile slower than your normal training pace), are you getting any benefit from allowing your HR to remain elevated, even though your RPE is the same? All of these methods (HR, RPE, pace) are attempts to measure (indirectly!) the level of exertion. Specifically, what your body 'cares' about is how much power it is producing, but this is not at all easy to measure directly on the run. HR is imperfect for a lot of reasons (as are the others), one of which is the topic of this post -- the heat can cause it to rise in a way that does not (entirely) reflect power-production. That's why it makes sense to allow zones to go up a bit in the heat. I guess my question is, why allow them to go up? If HR is the measurement of exertion, you are at a higher level if you let the HR rise, correct? In other words, if I hit 160 today because it's hot/humid, when I would normally run at 150, am I working "harder" than normal? And if so, is that what I want to accomplish? Yep, for a Luddite SCout is exactly right on this.  HR will be elevated in the heat. It's true, Mike, that you legs are moving you at a lower speed with a higher HR, but your energy systems are trying to keep you cool so assuming your plan of a run is to stay within a certain HR zone, then you need to go slower in pace. HR is measuring total body "work" and it doesn't care what your pace is. If you go faster, you are changing the nature of that work and applying more stress than maybe you intend. |
| 2010-07-07 11:19 AM in reply to: #2965440 |
Royal(PITA) 14270 West Chester, Ohio | Subject: RE: HR Training in heat & humidity Interesting topic. I ran last night, knew it would suck cause at 8 PM it was still high 90's outside. Adjusted to keep my pace slow since I knew the HR would go crazy. Slow? Turtle slow.....about 47 min for a 4 mile loop that I can do in 39 in cooler weather. HR was 178 when I got home. I usually only get that high when I finish half marathons at race pace. |
| 2010-07-07 11:32 AM in reply to: #2965748 |
Champion 7595 Columbia, South Carolina | Subject: RE: HR Training in heat & humidity bryancd - 2010-07-07 12:16 PM Scout7 - 2010-07-07 9:59 AM Yep, for a Luddite SCout is exactly right on this. Experior - 2010-07-07 11:53 AM I guess my question is, why allow them to go up? If HR is the measurement of exertion, you are at a higher level if you let the HR rise, correct? In other words, if I hit 160 today because it's hot/humid, when I would normally run at 150, am I working "harder" than normal? And if so, is that what I want to accomplish?nc452010 - 2010-07-07 11:47 AM As far as the beneift gained from a particular training session.....does your body CARE what pace you're running at? For example, if you're looking to run in zone 2 (and that has you running 45sec/mile slower than your normal training pace), are you getting any benefit from allowing your HR to remain elevated, even though your RPE is the same? All of these methods (HR, RPE, pace) are attempts to measure (indirectly!) the level of exertion. Specifically, what your body 'cares' about is how much power it is producing, but this is not at all easy to measure directly on the run. HR is imperfect for a lot of reasons (as are the others), one of which is the topic of this post -- the heat can cause it to rise in a way that does not (entirely) reflect power-production. That's why it makes sense to allow zones to go up a bit in the heat. HR will be elevated in the heat. It's true, Mike, that you legs are moving you at a lower speed with a higher HR, but your energy systems are trying to keep you cool so assuming your plan of a run is to stay within a certain HR zone, then you need to go slower in pace. HR is measuring total body "work" and it doesn't care what your pace is. If you go faster, you are changing the nature of that work and applying more stress than maybe you intend.I agree about the pace part (go slower for same overall effort), but I'm not convinced yet on the 'don't shift your zones' part. Here's an experiment (actually done -- I'll find the reference if you care). Several people who were in decent shape and acclimatized to mild exercise in heat were exposed to various heat/humidity conditions, during which they did EXACTLY the same exercise (in this case, a combination of resting and walking at a specific pace, I assume on a treadmill). HR varied with conditions. In other words, as far as the muscular systems that were are trying to train (apart from the heart of course!) were concerned, exertion was the same. I.e., the same amount of power was being produced, in this case mainly by their legs. HR and core temp (they measured this rectally I think) rose together. My interpretation (which could easily be wrong): HR rose in an effort to cool the body. In any case, it didn't rise because of a higher production of power. That was clearly the same in all conditions, as they were doing exactly the same workout. |
| 2010-07-07 11:48 AM in reply to: #2965440 |
Champion 9600 Fountain Hills, AZ | Subject: RE: HR Training in heat & humidity No, that's right, you are not producing the same "power" or "pace" for the same HR value's as one would when it's cooler, however, if for the same pace you HR is ten BPM higher, you need to slow down otherwise you will begin to suffer. You are applying too much stress to your entire system as it tries to lower your core temp. Ignore that at your own peril. It's anywhere from 103-110 here right now and will be for the next 2 months. If I go out and run at my "normal" pace, my HR will be greatly elevated and my body will try and force me to slow down to stay ahead of the requirement of keeping cool. You can't excercise the same in extreme heat, you can't ignore it and run by pace. A HR of 160 for me, even if I am running at a pace that when it's cool is usually 150, "feels" just as bad. Here is an interesting thread over on ST on how wattage also decreases with excessive heat. http://forum.slowtwitch.com/cgi-bin/gforum.cgi?post=2896570;sb=post... Edited by bryancd 2010-07-07 11:54 AM |
| 2010-07-07 11:56 AM in reply to: #2965876 |
Pro 4353 Wallingford, PA | Subject: RE: HR Training in heat & humidity bryancd - 2010-07-07 12:48 PM No, that's right, you are not producing the same "power" or "pace" for the same HR value's as one would when it's cooler, however, if for the same pace you HR is ten BPM higher, you need to slow down otherwise you will begin to suffer. You are applying too much stress to your entire system as it tries to lower your core temp. Ignore that at your own peril. It's anywhere from 103-110 here right now and will be for the next 2 months. If I go out and run at my "normal" pace, my HR will be greatly elevated and my body will try and force me to slow down to stay ahead of the requirement of keeping cool. You can't excercise the same in extreme heat, you can't ignore it and run by pace. A HR of 160 for me, even if I am running at a pace that when it's cool is usually 150, "feels" just as bad. The thing is, with my run this morning, I was definitely at a slower pace, but at the higher heart rate, I didn't really FEEL like I was working that hard. It FELT like how I feel when my HR is in Zone 2 in cooler weather. However, as soon as I recognized that my HR was that much higher, I did slow down and try to get it back in the zone I was shooting for. But that's kind of where my question lies.... do zones shift a bit in high heat conditions? It sounds like, at least among responders to this thread, there may be some disagreement on the answer.... |
| 2010-07-07 12:00 PM in reply to: #2965440 |
Champion 9600 Fountain Hills, AZ | Subject: RE: HR Training in heat & humidity You said it was mid 80's and humid, but that's not too bad, your relative perception will not be too extreme. If it was 95+, you would likely "feel" a lot different. You can fudge your zones a bit for heat, but be very careful to understand the toatl amount of "stress" you are applying beyond you muscular system. Edited by bryancd 2010-07-07 12:01 PM |
| 2010-07-07 12:00 PM in reply to: #2965440 |
Elite 3913 far northern CA | Subject: RE: HR Training in heat & humidity Are you getting sick? HR tends to rise before coming down with an illness. |
| 2010-07-07 12:03 PM in reply to: #2965907 |
Sensei Sin City | Subject: RE: HR Training in heat & humidity I'm a RPE guy who keeps tabs on my HR... If that makes sense. They usually have a pretty consitent relationship for me. However, when I run/bike here and it's 100-110 degrees, it will be higher during the middle/later part of my workout but I still run at what feels like the effort I set out to do that day and just realized HR will be elevated when I download my workout. |
| 2010-07-07 12:03 PM in reply to: #2965440 |
Champion 9600 Fountain Hills, AZ | Subject: RE: HR Training in heat & humidity What is true is that your LT doesn't change due to heat, it's just that you need to elevate your HR very high to reach it and that potentially isn't a good thing depending on how high. |
| 2010-07-07 12:08 PM in reply to: #2965919 |
Pro 4353 Wallingford, PA | Subject: RE: HR Training in heat & humidity bryancd - 2010-07-07 1:00 PM You said it was mid 80's and humid, but that's not too bad, your relative perception will not be too extreme. If it was 95+, you would likely "feel" a lot different. You can fudge your zones a bit for heat, but be very careful to understand the toatl amount of "stress" you are applying beyond you muscular system. Hah! Good point... heck, I feel like crap walking from my house to the car when it's 95+... |
| 2010-07-07 12:10 PM in reply to: #2965440 |
Champion 9600 Fountain Hills, AZ | Subject: RE: HR Training in heat & humidity Here's a good analogy. Heat should be considered in much the same manner as alttitude. It becomes progressively more difficult to produce the same amount of power (pace or wattage) as you gain elevation. The O2 limitations cause your body to perfrom differently. Same with very high temps. The need to manage core temp is redirecting energy from your muscles to your heart and blood flow in an attempt to move blood to your extemeties where it can cool more effectively. That has a material impact on perfromance and should be heeded. Edited by bryancd 2010-07-07 12:12 PM |
| 2010-07-07 12:24 PM in reply to: #2965440 |
Champion 7036 Sarasota, FL | Subject: RE: HR Training in heat & humidity Think of your heart as the engine in your car. Besides driving the wheels it also powers the radio, lights, stereo, A/C, etc. All of the additional functions divert some power from the primary task of propelling the car forward. When running in the heat your core temperature starts to increase and your body diverts blood to your skin to help dissipate heat (like a car radiator). Just like turning on the A/C in your car, this adds to the load on the engine/heart. This is where the disconnect between HR and RPE starts to kick in. Your leg muscles are turning over at the same rate, but the additional need for cooling causes the heart to pump faster to satisfy both requirements. Whether you slow down to maintain a specific HR or run at the same pace with a higher HR, becomes a choice based on the individual (assuming that in either case the runner is wise enough to avoid heat stroke or exhaustion). In my case, I'm more concerned about my cardiac fitness and want to focus on maintaining a target HR. On the other hand if someone else is training to maximize their running performance under hot conditions, they may chose training pace as the primary objective over HR (while at the same time training their heart to work at a higher load level). Mark
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| 2010-07-07 12:33 PM in reply to: #2965440 |
Member 115 Chicago, IL | Subject: RE: HR Training in heat & humidity Great thread. My HR goes through the roof with the heat/humidity, so I slow the pace down to accomodate and keep my BPM in the right zone. But, I extend my runs a little longer than planned so that my leg muscles don't get short-changed because of the slower pace. |
| 2010-07-07 12:54 PM in reply to: #2965951 |
Extreme Veteran 1996 Halifax, Nova Scotia | Subject: RE: HR Training in heat & humidity bryancd - 2010-07-07 2:10 PM Here's a good analogy. Heat should be considered in much the same manner as alttitude. It becomes progressively more difficult to produce the same amount of power (pace or wattage) as you gain elevation. The O2 limitations cause your body to perfrom differently. Same with very high temps. The need to manage core temp is redirecting energy from your muscles to your heart and blood flow in an attempt to move blood to your extemeties where it can cool more effectively. That has a material impact on perfromance and should be heeded. Well said. This is why many more people die of natural causes in heatwaves than at any other time, including cold snaps. Folks with with lower cardiac fitness (typically the elderly and those with health issues, known or not) have hearts that can't handle the stress of internal temperature regulation. Same goes for athletes. |
| 2010-07-07 1:35 PM in reply to: #2965440 |
Runner | Subject: RE: HR Training in heat & humidity People keep saying the "disconnect between HR and RPE". I don't see it as a disconnect between the two methods, I see it perhaps as a perceived difference. Truth is, "easy" is "easy", objectively speaking. I know what my easy feels like. And I know when I am not running at that level anymore. Does it really matter what my pace, or HR, or whatever else, are going to be at that specific point in time, assuming I do not follow them? Not really. The same holds true if I'm using HR. If it's hot, the assumption is that I will be going slower to stay within the same zone. RPE and pace should not really come into play in terms of deciding when to back off the effort or increase it. Follow your training. I cannot equivocally state that my HR falls within specific ranges when I run easy, no matter what. And to be honest, I don't think it matters. As long as I remain solid in my understanding of what my easy feels like, and remain brutally honest with myself about how I feel, then it should all come out the same in the end. The feeling of easy should be the same, no matter what. I do think we tend to lie to ourselves, though. |
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