Maximum heartrate
 

My wife and I have both caught the exercise bug. She has been doing it for several years while I have been doing cardio for the last 6 months. Our chosen forms of exercise are different. I bike and job on occasion. She pretty much sticks to jogging on a treadmill. Here is a question from her:

She read on a website that she should not exceed 85% of her maximum heart rate for extended periods of time since supposedly the body starts to burn muscle. Based on a website for 35-40, she shouldn't exceed 156 beats/minute. When I exercise on the bike, I typically fluctuate between 124 and 145 depending upon how hard I'm working. When I job, I'm around 145 to 162 (again depending upon how I'm pushing myself. When she jogs, her heartrate gets up to 178 beats/minute sustained only doing 10 minute miles. Even though she has been doing this for 2 years and typically runs 5 miles/day, she got a bit concerned about this. She has had genetic hypertension in the past that was controlled through medication. Once she started exercising regularly, her blood pressure reduced to regular levels.

I guess her question is if this advice on not exceeding 85% of her maximum heart rate is correct, and if she is, would this affect her weight loss? She is 5'6" 127# or so. She has been down to around 122# in the past and really wants to lose those last 5 lbs. I tell her that some of it is due to building muscle mass due to weight lifting, but she is concerned that if the website is correct and if she is burning muscle that weight loss is not occurring the way it should. She eats a very healthy diet but somewhat low on calories (in my opinion anyway).

Hey Sky...my first question would be about your wife's hydration. That could affect her HR.

Secondly...I might would check with my doc...178 seems a bit excessive for someone in pretty good shape. Although if she was pushing herself hard she could acheive this. The only problem with super high heart rates is that your heart works less effectively because there is not enough time for it to fill properly between beats. I wouldn't expect to see this unless there was something else going on such as hyperthyroid or dehydration etc.

I'm not a doc, so take that with a grain...

I would agree. Here's a link to the WebMD pulse measurement page, which has a chart for a person's target heartrate during exercise:

http://my.webmd.com/hw/heart_disease...-9531713CA348}


Is she pushing herself too hard? Getting enough nutrients in her diet? Drinking enough water?

That's great her blood pressure is down to normal. So she deffinitely doesn't want to stop exercising.

Best thing to do is to go have a check up with a cardiologist. Better to be safe.

Thank you for your answers. I'm going to have her check it out with a cardiologist. It sounds like our GP might not be the place to start.

The main effect of exceeding your MHR is that your muscles start to respirate aneaobically, which builds up. Also, its not really good for burning fat. Muscle wasting is the end product, as you rightly mention.

The fact that her heart rate reaches 178 is not the main problem, IMO.

MHR is a method that one should use to tailor your workplan. Its a zone that you should strive to exercise in. From what you say, it sounds like she's doing her set routine, and her HR is thus going above the MHR.

The cardiologist might not find anything wrong with her, in which case she should go consult a trainer who will give her a routine that will best complement her. As you mention, the excercise has yielded benefits over the last two years, with no negatives as yet. i think that a slightly less strenous cardio workout will still give her all the same benefits, plus a few more.

Vault, what are you referring to as MHR? I always knew this to be Maximum Heart Rate. What I think you are referring to, and correctly but just with the wrong name, is the Anaerobic Threashold (AT). Basically the point at which your body switches from burning Carbohydrates/Fats to burning Proteins which are harder for the body to consume. Typically this is about 60% of the MHR, if my memory serves me correctly.

Here's an article I just looked up from Triathlete Magazine that may help designing a training program:

http://www.triathletemag.com/story.c...92&pageID=1732

Nazgul, your reference seems faulted. That guy is a 52 year old with a claimed MHR of 195. His MHR calculation is also probably more precise for PROFESSIONAL ATHLETES.

Current research shows that the average UNIVERSAL way to calculate your MHR is to subtract your age from 220 (that of a newborn baby) THat would give you a close approximate MHR, good enough for exercise/gym. 85% of your MHR can be regarded as your AT.

If your AT is 60% of your MHR as you claim, and virtually every fundi states that you should keep aerobic exercise between 60% - 85% of your MHR, then you are saying that every time you work out at 60% or more of your MHR, you are burning protein. And that aerobic exercise is actually anaerobic exercise.

Which is complete bollocks, if you dont mind me saying. And if you read the initial poster's question, you would see that she is indeed concerned with going above 85% of her MHR, (crossing her AT). Her reference thus concurs with 85%, and not 60%.

To respond to this, it is actually my wife I was concerned about. This has been interesting information for us. We have actually talked extensively to people at our gym about their heartrates. She is working out near the top of where she should be working out, and I suspect it has something to do with her inability to lose a few pounds. She also has been undereating a bit which I think has caused her body to go into "starvation" mode and means she is packing on lbs rather than shedding them. She has an appointment next week with a nutritionist plus a doctor that specializes in proper exercise. She lost most of her weight (approximately 20 lbs) when she wasn't dieting or exercising as much, and she has a hard time believing that working harder and eating less doesn't have more of an effect.

Sorry Vault, didn't mean to derail the topic or get your ire up. My point was only that you were referring to the MHR as the AT or Target Heart Rate, that's all. You mention exceeding your MHR which is really not possible by definition. You were simply swapping terms of Target Heart Rate or AT with MHR. Small issue. Appologies if I insulted you.

Unfortunately this thread contains much of the mis-information that abounds regarding this topic

1. MHR is calculated most simply by 220 - age. This is very simple and only a guide! Not a rule, is can be easily skewed as can the lactate inflection point or the point where you really feel like you cant maintain the effort much longer at that rate.

2. Gluconeogenesis which is the creation of sugar for energy from non-sugar building blocks i.e. fat and protein (particularly branch chain amino acids, which happen to be most commonly in skeletal muscle) can happen in a number of ways and through all levels of intensity. Eample lactic acid made in a working muscle is taken to non-working muscle and converted to sugar.

3. The 80's circa posters outlining the "zones" is very misleading. The aerobic and anaerobic metabolic activity levels are not mutally exclusive i.e. they can both be on at the same time

4. As mentioned above, your wifes fluid levels are very important. She should weigh herself before and after exercise and there should be no change. Any loss and she is not drinking enough.

5. Rhabdomyolysis is very rare where the muscle literally melts. Gluconeogenesis is very common and can be activated by simply missing a regular meal.

Yes, having a good supply of QUALITY CARBOHYDRATES in your body is a must for anyone who runs regularly.

You'll probably want to get Nathan Pritikin's Diet For Runners (you can pick it up for cheap used at Amazon http://www.amazon.com/exec/obidos/tg...books&n=507846). It's a little outdated (he thinks all, and I mean all, fats and oils should be avoided), so don't take everything in the book as law. However, it remains and excellent source on nutrition for runners. I highly reccomend it.

Hey, no offense taken. and none meant.

:thumbsup:

good stuff, anibal.

to add on to this one, the "zones" people should be using today aren't actually based on maximum heart rate. there are two main methods today, doing it based on heart rate reserve or vo2max reserve. the american college of sports medicine (the group which sets the industry standards) goes by vo2max reserve.

Not entirely accurate there, the AT is when the body doesn't have enough Oxygen to burn carbs through the full cycle that it usually would, and switches to a partial cycle that makes energy without the oxygen requirement. The result is lactic acid buildup, which is what causes muscle cramps and the like when you've worked them out to hard, and consequently what causes chest pain if you are having angina or a heart attack.