Less Calories Burned for Same Workout?

Cruz2Fit

Ignoramums fitness question of the day: Is it normal to start burning less calories doing the same workout over time?

I've been running for a couple of weeks now and have noticed the number of calories burned is not as high as it was when I started. I measure with an HRM. I've also noticed my heart rate does not get as high as it did initially for the same type of exertion. This is so, even when I'm doing the exercise in less time.

Cruz2Fit

I thought so, but wanted to confirm. BTW, if that's you in the profile pic, CONGRATULATIONS on those great abs!!!

ryno0618

Yes, to me that would make sense over time. For one thing, you are doing the same exercise in slightly less time. Less time means less calories burned. But even more important, and less obvious is that you are conditioning and adapting to that form of exercise, your body is improving. Your heart rate is no longer as elevated for the same workout. But you can compensate for this by doing the exercise longer, pushing yourself further, etc.

Also, as you lose weight adjust the weight setting on your HRM. I change my weight on my HRM every 5lbs lost. When I was 45lbs heavier and not as conditioned to my running schedule my calories burned were quite a bit higher than they are now. But I can run longer and faster now and so I achieve the same burn just takes more time to reach it.

Azdak

Unless you have lost weight, or you are running for a shorter period of time, then the answer is likely NO. What you are seeing is an anomaly of HRMs, not a change in what is happening in your body.

This provides more explanation: http://www.myfitnesspal.com/blog/Azdak/view/calories-burned-during-exercise-it-s-the-intensity-not-the-heart-rate-that-counts-26524

When heart rate decreases for a given steady-state workload (in this case a particular running speed), it's because you are working at a lower percentage of your maximum. Why? Because the training has increased your maximum (right? that's why you are training). The actual energy cost (calories burned) has NOT changed--it's the same as before. It just feels easier because you are more fit.

HRM readings go down because they are based on heart rate--which is a very indirect way of estimating energy--not the energy cost of the activity itself. The HRM only knows that you are working at "X%" of your maximum, and it assumes the maximum is whatever you set it to be when you set up the monitor. If you don't (or cannot) adjust the settings to let the HRM know your maximum has increased due to training, then it will assume you are running slower and thus give you a lower calorie burn.

The problem is NOT that you are burning fewer calories--the problem is that your HRM is operating with outdated information -- garbage in, garbage out.

It's one of the most widespread pieces of misinformation in fitness.

lemonadem

Unless you have lost weight, or you are running for a shorter period of time, then the answer is likely NO. What you are seeing is an anomaly of HRMs, not a change in what is happening in your body.

This provides more explanation: http://www.myfitnesspal.com/blog/Azdak/view/calories-burned-during-exercise-it-s-the-intensity-not-the-heart-rate-that-counts-26524

When heart rate decreases for a given steady-state workload (in this case a particular running speed), it's because you are working at a lower percentage of your maximum. Why? Because the training has increased your maximum (right? that's why you are training). The actual energy cost (calories burned) has NOT changed--it's the same as before. It just feels easier because you are more fit.

HRM readings go down because they are based on heart rate--which is a very indirect way of estimating energy--not the energy cost of the activity itself. The HRM only knows that you are working at "X%" of your maximum, and it assumes the maximum is whatever you set it to be when you set up the monitor. If you don't (or cannot) adjust the settings to let the HRM know your maximum has increased due to training, then it will assume you are running slower and thus give you a lower calorie burn.

The problem is NOT that you are burning fewer calories--the problem is that your HRM is operating with outdated information -- garbage in, garbage out.

It's one of the most widespread pieces of misinformation in fitness.

Great share, thank you!