Perceived exertion, heart rate, and calories burned..

numinousnymph

So maybe the answer to this question is pretty obvious, but I just thought it couldn't hurt to get others' input. I was wondering if your body burns more calories if you feel like you're working harder. I'll give myself as an example. l do a run on the treadmill at 3.0 incline and 6 mph. Some days this feels manageable, and my heart rate (which is mostly connected to exertion, correct?) is in the mid-to-high-150s. Other days it feels almost miserable, and my heart rate is in the high 160s or low 170s (according to the 220 minus your age rule, my max heart rate is 196). It sure feels like a huge bummer to think that, on the "bad" days where I can't wait for the exercise to be over and I feel like I must be burning 1,000 cals an hour (exaggeration of course), I'm still only burning the same amount as the "good" days. But, according to the math, this must be pretty much true, right?

martinel2099

At the end of the day any number you use for calories burnt is going to be an estimate. This is why some folks prefer not to log / eat back exercise calories.

I'd recommend consistency and watching your trends over 4-6 week periods. If you notice a stall it could be because you are burning less calories during exercise than you think you are.

Azdak

Yes, it's pretty much true. Exercise calorie burns are based on the actual workload, not heart rate per se. Heart rate can be an indirect indicator of calories burned because during steady-state exercise, heart rate reflects the workload. However, some factors--fatigue, illness, heat, etc--can cause HR to rise without any increase in workload. In those cases, even though HR is higher, calorie burn is not.

There have been a number of studies where subjects have exercised on different pieces of cardio equipment, but set the workload according to their feelings of perceived exertion. They directly measured oxygen uptake (which measures actual calories burned). At the same perceived exertion, calories burned varied by as much as 20%, depending on the type of equipment.

SpecialKH

Yup. I've found that true looking at the daily bar charts from my body media uploads. I can see how many calories I burn minute by minute.

I learned that my period affects how I feel during a workout (but not my calories burned) and my hydration level REALLY makes me feel exhausted like I've worked super hard even when I really haven't. That's probably my biggest factor. Also back to back workouts - if I run two days in a row they won't be good. If I skip one day and just walk the day in between I'm much better and if I skip TWO days between runs, I will have a great run. So body fatigue is big for me, too.

In the end the calories out are pretty much the same for the same duration and activity, though, even when it feels like I'm having to work so much harder at it.

_Waffle_

Perceived exertion has little to nothing to do with calories burned other than it's easier to continue the exercise and perhaps keep it up longer if your perception is different. Mostly your cardio calories is a matter of weight moved at what speed for how long. Your perception of that energy used doesn't change how much energy was used.

Your body can be more efficient at using energy but that's a different story. On a day to day basis you're burning the same amount yesterday when it felt easy as you are today when it feels harder.

numinousnymph

_Waffle_ wrote: »

Your body can be more efficient at using energy but that's a different story. On a day to day basis you're burning the same amount yesterday when it felt easy as you are today when it feels harder.

Would you be able to explain this a bit more to me? Does that mean that, even if mathematically speaking you burn X amount of calories at a certain weight, the calorie burn becomes less because your body gets used to that activity? How does that make sense, when perceived exertion apparently has little or no effect on calorie burn?

Mouse_Potato

I think I get what he's saying. I walk my dog pretty much every day and we take one of three paths. I can go the exact same path at (more or less) the same pace, but if it's hot I will feel I am working much harder than when it is cool. However, it took my body the same amount of energy on both days. I don't burn more calories moving my body when it's sweating than I do when my ears are going numb from cold. I hope that makes sense.

Wronkletoad

^ but is that the path less traveled?
(cuz I've read that that makes all the difference)

_Waffle_

numinousnymph wrote: »

_Waffle_ wrote: »

Your body can be more efficient at using energy but that's a different story. On a day to day basis you're burning the same amount yesterday when it felt easy as you are today when it feels harder.

Would you be able to explain this a bit more to me? Does that mean that, even if mathematically speaking you burn X amount of calories at a certain weight, the calorie burn becomes less because your body gets used to that activity? How does that make sense, when perceived exertion apparently has little or no effect on calorie burn?

That's speaking about adaptations you gain over time doing the same activity over and over. Now you're getting into the realm of sports conditioning and endurance. Even then you still end up burning a similar amount of calories. You're just more effective in applying the calories to actions.

Mostly it's still weight and distance for calories running even if you're better at running. Also with these adoptions you're able to burn more calories because you can challenge yourself more.