Question for trainers re: cardio

kmbrooks15

I work out on the elliptical machine (just started a week ago). The first few workouts, I could not keep my heart rate at the target (target for my age is 143--highest it got was about 160); it kept going higher. I know it was because I was SO out of shape. With each workout, it's getting better, and today, for the first time, I stayed right at it (really concentrated on this today-highest it got was 146). My question is this: Today, when I kept my heart rate right at the target, I actually burned MORE calories than I did when it was too high. Why is that? I'm just curious about this more than anything.

I was THRILLED that I was able to keep it at target today because it means my heart is getting stronger!

ninerbuff

I work out on the elliptical machine (just started a week ago). The first few workouts, I could not keep my heart rate at the target (target for my age is 143--highest it got was about 160); it kept going higher. I know it was because I was SO out of shape. With each workout, it's getting better, and today, for the first time, I stayed right at it (really concentrated on this today-highest it got was 146). My question is this: Today, when I kept my heart rate right at the target, I actually burned MORE calories than I did when it was too high. Why is that? I'm just curious about this more than anything.

I was THRILLED that I was able to keep it at target today because it means my heart is getting stronger!

How are you measuring your heart rate? And were both durations equal?

kmbrooks15

Both were 25 minutes, and I'm going by the monitor on the elliptical machine. The 25 minutes where my heart rate was too high, I burned 200 calories. I burned 250 in 25 minutes when my heart rate was at the right rate. I was kind of shocked today when it happened and was just curious why that might be.

Melanie12081

I'm interested to hear the theory on this. I always push my heart rate above the machines target...

ninerbuff

Both were 25 minutes, and I'm going by the monitor on the elliptical machine. The 25 minutes where my heart rate was too high, I burned 200 calories. I burned 250 in 25 minutes when my heart rate was at the right rate. I was kind of shocked today when it happened and was just curious why that might be.

The same exact machine or was it a different one with the same brand name? If different then it's a calibration issue. The numbers don't add up correctly.

jazzy020106

I'm interested to hear the theory on this. I always push my heart rate above the machines target...

Me too..

jazzy020106

I also try to do the elliptical on the highest level with the most resistance.. and I actually found that I burn more cals when I DONT do that.. instead of having both settings on level 10 if I put one on 10 and the other on like 8 I burn more.. so weird.. and the duration of the workout is always the same.

luvgreen25

I've never paid attention to the differences by keeping my heart rate in the target area, but I'm interested in seeing what people have to say about this.

ninerbuff

I also try to do the elliptical on the highest level with the most resistance.. and I actually found that I burn more cals when I DONT do that.. instead of having both settings on level 10 if I put one on 10 and the other on like 8 I burn more.. so weird.. and the duration of the workout is always the same.

That's resistance training and yes if you train at a high resistance your pedaling will be slower, which means less "distance" traveled. So yes you would burn more calories on distance covered by a lower setting since you can pedal a little faster.

kmbrooks15

Both were 25 minutes, and I'm going by the monitor on the elliptical machine. The 25 minutes where my heart rate was too high, I burned 200 calories. I burned 250 in 25 minutes when my heart rate was at the right rate. I was kind of shocked today when it happened and was just curious why that might be.

The same exact machine or was it a different one with the same brand name? If different then it's a calibration issue. The numbers don't add up correctly.

Same machine.

After thinking about this today, I seem to remember reading, a long time ago, something about when your heart rate is too high, you're not burning the right thing? Does that ring a bell?

MikeSEA

Is it possible that even though your heart rate was lower that you were going faster. If the duration was the same, but you burned more calories, the first place my mind goes to is to conclude that you simply did more work in the same amount of time (went faster). The fact that your heart rate was lower is cool, but may not indicate that you worked less.

Azdak

When I read topics like this, I really start thinking that HRMs may do more harm than good--they seem to promote more MISinformation than useful information.

OK, I exaggerate--but not much.

Heart rate is a RELATIVE indicator of work intensity.

Let me repeat that: Heart rate is a RELATIVE INDICATOR of work intensity.

Just to make sure we are clear: HEART RATE IS A RELATIVE INDICATOR OF WORK INTENSITY.

Meaning that exercise heart rate reflects the percentage of maximum fitness level at which you are working. It is NOT a measurement of the absolute workload.

Example: starting a fitness program, your maximum fitness level is 10 METs (MET is a measure of aerobic intensity). You are working at 7 METs, a 70% effort level. At 70%, your heart rate is 150 bpm. After some training, your maximum fitness level increases to 12 METs (that's the whole point of exercise training). While maximum fitness level has increased, maximum heart rate remains unchanged. So your 70% heart rate is still 150.

Since maximum fitness level has increased to 12 METs, however, now at that 150 bpm heart rate, you can work at 8.4 METs (70% times 12 METs).

Caloric expenditure is a product of WORKLOAD INTENSITY x BODY WEIGHT. So someone working at 8.4 METs will burn more calories than someone working at 7 METs, if weight is unchanged.

So, not only is it perfectly reasonable that you would burn more calories at a lower heart rate, it is expected. This is only an anomaly in people's minds because they confuse relative intensity (heart rate) and bogus HRM calorie numbers with absolute intensity (METs).

In your case what has happened is not that your fitness level has improved that quickly, it's that you have become acclimated to the exercise movement. Basically, the numbers from the first few workouts don't really count because your body wasn't responding in a consistent way (that's why research studies always include a "habituation" period of several workout sessions before testing people on new pieces of equipment).

This is why machines can sometimes give a more accurate picture of calorie burn than HRMs. Machines measure ABSOLUTE workload--the actual intensity of the work being performed.

Some machines -- esp elliptical trainers -- use inaccurate formulae to translate that workload into calories, however changes in those numbers reflect real changes in total aerobic work performed--even if the actual number is overstated.

By that I mean that a certain elliptical model might give a reading of 500 calories in 30 min when you actually burned 400. However if, over time, the calorie reading on the machine increases from 500 to 550 in 30 min, that likely represents a 10% increase in total work performed (and actual calories burned). If fitness level increases, your heart rate will stay the same and the HRM calorie count might stay the same or even decrease, but that's a shortcoming of the HRM, not a problem with the machine.

rawfitness

Do you have to enter variables like weight?

mariabee

Ya, what Azdak said...

ninerbuff

Same machine.

After thinking about this today, I seem to remember reading, a long time ago, something about when your heart rate is too high, you're not burning the right thing? Does that ring a bell?

Has to do with glycogen being used at higher intensities. You burn fat a lower intensities, but overall it's the total calories burned that count. Plus interval and high intensity training raise resting metabolic rate where low intensity cardio doesn't.

kmbrooks15

OK, what Azdak said makes sense to me.

Part of the reason I was working a little less to try to keep my heart rate at the target was because my mom was concerned that my heart rate was going so much higher than the target. Is this something to be concerned about? Even when it got up to 160, I didn't feel bad, I could still breathe, etc., but if it's harmful, I'll work to keep it at the lower rate. It was mainly a matter of lowering my speed a little to keep the heart rate close to the 80% target.

Azdak

OK, what Azdak said makes sense to me.

Part of the reason I was working a little less to try to keep my heart rate at the target was because my mom was concerned that my heart rate was going so much higher than the target. Is this something to be concerned about? Even when it got up to 160, I didn't feel bad, I could still breathe, etc., but if it's harmful, I'll work to keep it at the lower rate. It was mainly a matter of lowering my speed a little to keep the heart rate close to the 80% target.

Listed target heart rates are not very worthwhile. It's gotten to the point where, unless I am working with someone on an ongoing basis and can observe their HR response to exercise, I often don't even use target heart rates.

There is a lot of variability in maximum heart rates--which is the basis for those "target" numbers. For someone your age the range of "normal" max HR might be 165-205. In the absence of any underlying cardiac issues, when you are starting out, you should always compare the heart rate number with your rate of perceived exertion. If it feels like a comfortable challenge but not a strain, then the workload is likely OK, regardless of the actual HR. Over time, you will learn your individual HR response to different levels of exertion--then the HR numbers will make more sense.

kmbrooks15

Thanks, Azdak. Sometimes sorting through all the information about target heart rates and calorie burns and nutrition and...blah blah blah...can get frustrating. Thanks for clarifying for me. I just wanted to be sure I wasn't doing something that's dangerous or would sabotage my health.

Melanie12081

Wow...very interesting!