Help me understand heart rate.

Take your resting heart rate first thing in the morning, before you even get out of bed. To be most accurate, take it for a full minute (rather than 15 seconds and multiplying by 4). Your RHR is partially determined by genetics, so having a faster heart rate doesn't necessarily mean you are less fit than someone with an extremely low heart rate.

To determine your ranges, I like using the Karvonen formula, which you can find here: http://www.briancalkins.com/HeartRate.htm
Most running experts agree that it is more accurate than using a calculator based on age only.

When I first started running with a heart rate monitor, it was really hard to stay within the recommended range! But you don't want all of your workouts to be hard workouts at the top end of your range - save that for speedwork or hills once or twice a week, depending on your level of fitness and goals. The bulk of your running should be at about 70% of max heart rate. Otherwise, you risk burnout and injury, and slow down recovery time. If you stick with the moderate pace runs, your body will adapt and you will see that you need to run at a faster pace to maintain the same heart rate.

I don't know what kind of watch you have; but my Garmin triathlon watch allows me to set a min and max heart rate for my workout, and alerts me if I stray from it. I don't wear the monitor on every run - just for speedwork, and to "check in" once in a while to make sure I am not pushing too hard on my easy runs

Your Polar is telling you what the 65 to 80% range is of your MHR (maximum heart rate).

When you go over 80%, you are in the anaerobic state. This is not a sustainable zone and in the world of sports, sprinters are the best example of anaerobic activity.

If you stay within 65 to 80%, you can sustain that for hours and hours and hours depending on what sort of shape your muscles are in, your cardiovascular system, etc. Marathon runners are a classic example of athletes who perform in this zone.

The 65 to 80 range is the ideal place to be to burn fat. In the first 20 to 30 minutes, your body is using the glycogen in your blood stream as fuel. (This is why you'll read that you should do weights before you do cardio work. Burn the glucose with iron. Burn the fat with treadmill.)

In the anaerobic state (over 80%) you will not sustain for long and you will not burn fat for as long as you can.

Now, as you get more and more fit, you will find that you can run faster, farther, whatever and still stay in the 65 to 80 zone. Polar HRMs are a fantastic device to gauge your level of FITNESS.

If you want to burn fat, stay at 65 to 80. If you want to get faster or build endurance, inject periods of anaerobic activity (running and injecting a spring, running and injecting a sprint, etc.) every few minutes.

I hope this helps.

>>When you go over 80%, you are in the anaerobic state. This is not a sustainable zone and in the world of sports, sprinters are the best example of anaerobic activity.

If you stay within 65 to 80%, you can sustain that for hours and hours and hours depending on what sort of shape your muscles are in, your cardiovascular system, etc. Marathon runners are a classic example of athletes who perform in this zone.

The 65 to 80 range is the ideal place to be to burn fat. In the first 20 to 30 minutes, your body is using the glycogen in your blood stream as fuel. (This is why you'll read that you should do weights before you do cardio work. Burn the glucose with iron. Burn the fat with treadmill.)

In the anaerobic state (over 80%) you will not sustain for long and you will not burn fat for as long as you can.

Now, as you get more and more fit, you will find that you can run faster, farther, whatever and still stay in the 65 to 80 zone. Polar HRMs are a fantastic device to gauge your level of FITNESS.

If you want to burn fat, stay at 65 to 80. If you want to get faster or build endurance, inject periods of anaerobic activity (running and injecting a spring, running and injecting a sprint, etc.) every few minutes.
>>

That ^ was a great explanation. Thank you.

Heartrate is a good indication of overall health. Measure your resting heartrate right when you wake up for accuracy. You'll also have a "walking" heartrate which is just your average daily kind of sorta resting heartrate. In terms of "zones" it's not that big of a deal unless you're training your body to use different forms of fuel. Marathoners and Ironman racers, for example, train around 150bpm-ish because in that zone their body is burning 50% fat and 50% carbs for energy so they can replace carbs easier during races. If you're outside of that "fat burning zone" you're still burning calories. You're actually burning more calories (faster HR = more calories). You're just burning more carbs than fats. When your HR gets up to a certain point you're destroying muscle which is then repaired by the food you take in. The "fat burning zone" is just really good because it's usually walking pace and can be maintained for the longest amount of time but if you go into a Tempo zone and burn more carbs then your body needs to replace that glycogen in your muscles somehow. It'll do this by either using the carbs you take in directly, taking from fat stores if there are no carbs available or in a process called glyconesis to use proteins. Ideally you want to replace carbs with carbs.

Glycogen in the liver is not easily accessible. In the first twenty minutes, you burn the glycogen in the blood stream. Beyond that, your body is using fat for fuel. If the scientific community has come up with a new study, I am not aware of it.

I am in the supposed anaerobic zone about 95% of the time when running, if my app is to be believed.

Then your maximum heart rate is probably set too low for your body. The zones are based on your listed max heart rate. The default is usually a formula that maybe works for averages but is often high or low for individuals. I have the opposite problem and after some tweaking of my max heart rate setting my zones became more correct for me. There are tests in labs that will estimate this pretty accurately, and there are tests you can self administer at home that will estimate this (probably not as accurate as a lab, but cheaper). I started by looking at the highest heart rate achieved during very vigorous workouts (I used stair laps 5 floors up and down) and added 10 bpm to that max. That still seemed a little high, but better than the formula estimated. If you can comfortably sustain a heart rate for a period of time it isn't anaerobic for you. I suppose it is possible if your running is short sprints, of course.

I am in the supposed anaerobic zone about 95% of the time when running, if my app is to be believed.

Then your maximum heart rate is probably set too low for your body. The zones are based on your listed max heart rate. The default is usually a formula that maybe works for averages but is often high or low for individuals. I have the opposite problem and after some tweaking of my max heart rate setting my zones became more correct for me. There are tests in labs that will estimate this pretty accurately, and there are tests you can self administer at home that will estimate this (probably not as accurate as a lab, but cheaper). I started by looking at the highest heart rate achieved during very vigorous workouts (I used stair laps 5 floors up and down) and added 10 bpm to that max. That still seemed a little high, but better than the formula estimated. If you can comfortably sustain a heart rate for a period of time it isn't anaerobic for you. I suppose it is possible if your running is short sprints, of course.

If I use your max-number-plus-10bpm idea, I'm probably in the high 190's I guess. Which seems closer. If we assume that I shouldn't be able to sustain anaerobic threshold for more than 3 minutes or so, then I would guess that equates to a 180bpm heart rate based on my experience running intervals, and so that's pretty close.

Glycogen in the liver is not easily accessible. In the first twenty minutes, you burn the glycogen in the blood stream. Beyond that, your body is using fat for fuel. If the scientific community has come up with a new study, I am not aware of it.

There have been many studies on glycogen depletion. If we burned only fat for fuel after 20 minutes, there would not be the infamous "wall" in the marathon. I am an ultramarathoner who has been running for over 35 years, and I have seen a lot of change; but research results on glycogen depletion have been pretty consistent. The focus of research now is how to get your body to burn fat sooner.

I'm not an ultra marathoner. I only run the little 26.2 marathons. Only have 24 under my belt.

Deplete the body of carbs and fat will be the source of fuel. It takes time and training to get to this point. Replace sports drinks with water and Nuun or salt tablets, and you'll be fine. Run slow and avoid the lactate threshold and you'll never see the Wall.

I'll never win a marathon as long as I win.

But I'll never come in last.

*wink*