Is Calorie Burn Rate Cumulative?

Triathlon Forum
1

I can’t find a really clear answer on this, so maybe I’m not asking the right question. What i want to know is, does your rate of calorie burning increase for the longer you exercise? LIke say I cycle in zone 3 for 3 hours. Will burn 100 cals the first hour, 150 the second hour and 200 the third? Or does the rate stay constant as long as my heart rate averages the same over the entire exercise period?

The reason I ask is because looking at my diet plan from my nutritionist, I notice that the longer I exercise, the more I get to eat, however the amount of calories isnt constant. For example, if I workout 1 hour I get to eat 1500 cals. 2 hours, 1600 cals, 3 hours 2000cals, 4 hours 2500cals, etc. (these are just examples, not exact numbers.) It has me a bit confused.

Thanks.

2

Rather than cumulative you need to ask “is it linear or non-linear?”

It is linear assuming constant intensity. 1 hr run @ 8 mph for me = 800 cal. 2 hr run @ 8 mph for me = 1600 cal. Etc.

Is she giving you 1500 calories for the WHOLE DAY or for 1 hr of working out and then you have some other estimate for 0 hrs of workout = X calories?

You should ask your dietician how she came up with those calorie values.

3

I generally agree with tigerchik, who is wise beyond her years, but in order to keep the same pace over an extended period, it takes more effort and, I would expect, you will burn calories at a higher rate. Fore example, if you run at 8 mph for two hours, your heart rate will increase despite the fact that you are running the same pace. If nothing else, your body has to work harder to cool itself and as you dehydrate your heart will have to work harder. Your form will also get sloppy, which will be less efficient and require you to work harder to maintain the same pace. Of course, this is all just my theory and I have nothing to back it up.

4

in order to keep the same pace over an extended period, it takes more effort and, I would expect, you will burn calories at a higher rate.

Effort is perceived. It’s all in your head and that is not the part of your body that manufactures energy :wink:

Energy burned in exercise = Krebs cycle = you get the same number of ATP each time. And if form gets sloppy, you slow down, the energy of inefficient movement increases but as pace gets slower you burn less energy there. For this we are assuming constant intensity or else you can’t really do the problem.

Thanks for the compliment though :slight_smile:

5

Rather than cumulative you need to ask “is it linear or non-linear?”

It is linear assuming constant intensity. 1 hr run @ 8 mph for me = 800 cal. 2 hr run @ 8 mph for me = 1600 cal. Etc.

Is she giving you 1500 calories for the WHOLE DAY or for 1 hr of working out and then you have some other estimate for 0 hrs of workout = X calories?

You should ask your dietician how she came up with those calorie values.

I didn’t give the actual values because I wasn’t sure if complicated math would be involved. Basically the theory is simple. I have a base number of cals/day I eat assuming no exercise, that number was gotten from my RMR test. I eat the minimum required cals for no muscle breakdown.

The way my diet works is I add cals based on the amount I workout that day. It doesn’t matter what I do for exercise or if I do it all at once or multiple workouts in a day. The more I work, the more I get to eat, basically. Steady weight loss is the goal of my current diet plan, and it has been working as long as I stay disciplined about it.

6

I can make it look complicated. work = definite integral of yW(y) dy
where y is distance and W(y) is force. You’ll likely get an answer in joules but you can convert those to Calories and calories easily enough.

Anyway you didn’t answer my question. If you exercise for 1 hour do you eat 1500 calories for the whole day or RMR + 1500? just curious.

edit: shoot. the math doesn’t look complicated when I don’t know how to get the fancy integral sign up there.

7

Rather than cumulative you need to ask “is it linear or non-linear?”

It is linear assuming constant intensity. 1 hr run @ 8 mph for me = 800 cal. 2 hr run @ 8 mph for me = 1600 cal. Etc.

Is she giving you 1500 calories for the WHOLE DAY or for 1 hr of working out and then you have some other estimate for 0 hrs of workout = X calories?

You should ask your dietician how she came up with those calorie values.

I didn’t give the actual values because I wasn’t sure if complicated math would be involved. Basically the theory is simple. I have a base number of cals/day I eat assuming no exercise, that number was gotten from my RMR test. I eat the minimum required cals for no muscle breakdown.

The way my diet works is I add cals based on the amount I workout that day. It doesn’t matter what I do for exercise or if I do it all at once or multiple workouts in a day. The more I work, the more I get to eat, basically. Steady weight loss is the goal of my current diet plan, and it has been working as long as I stay disciplined about it.
One hour of ANY workout gets you a certain # of calories?

Hrm. It would be nice to see some of the numbers, because for sure the numbers you gave don’t add up. (For most people, 1500 cals is a base level, i.e. all you did all day was breathe. :D)

And, 1 hour of cycling at 15mph is much different than an hour at 22mph, likewise an hour of swimming will have different calorie burn rates than 1 hour of running.

Basically, you want the formula to look like: BMR requirements + daily activity (brushing teeth, walking at work, etc) + exercise = calories in. If you want to lose weight, then subtract about 500 calories from the right side of the equation for ~ 1 lb per week of loss.

Edited to add: Also, no, it’s not really cumulative. You may burn more during certain parts of the workout (Such as when doing intervals, strides, whatever), but basically you determine total calories for the entire effort as an average. So if you do a warmup on the bike for 30 mins at 16mph, then an hour at 24mph, then another 30 mins at 16, you’ve done 40 miles in two hours, and you’d use that for your total determination. Nobody that I know of tracks it on a piece by piece basis.

John

8

I must disagree tigerchik. There is a reason why one’s heart rate increases (cardiac drift). It’s because it, and your body, are having to work harder to maintain the same pace. I think it is more complicated than w = f x d.

9

Edited to add: Also, no, it’s not really cumulative. You may burn more during certain parts of the workout (Such as when doing intervals, strides, whatever), but basically you determine total calories for the entire effort as an average. So if you do a warmup on the bike for 30 mins at 16mph, then an hour at 24mph, then another 30 mins at 16, you’ve done 40 miles in two hours, and you’d use that for your total determination. Nobody that I know of tracks it on a piece by piece basis

How many times do I have to say “assume constant intensity”?

10

I can make it look complicated. work = definite integral of yW(y) dy
where y is distance and W(y) is force. You’ll likely get an answer in joules but you can convert those to Calories and calories easily enough.

Anyway you didn’t answer my question. If you exercise for 1 hour do you eat 1500 calories for the whole day or RMR + 1500? just curious.

edit: shoot. the math doesn’t look complicated when I don’t know how to get the fancy integral sign up there.

It’s like 1561 cals/day with no exercise. Add calories baed on total exercise time from there. I get Breakfast, lunch and dinner choice with no exercise and add snacks as my exercise time goes up.

11

HR is under nervous system control

Yes there is a reason for cardiac drift - http://www.medscape.com/viewarticle/499173
second paragraph under “introduction” - scroll down

If you burned a different amt of energy in the second hour of exercise than you did the first, assuming constant pace, and it were SIGNIFICANT, I would have, in an exercise science major, learned how to calculate it. I can calculate energy burn based on pace, body weight, incline of treadmill or ground, watts produced on a bike… nowhere in that equation is there “is it the second mile or the 20th? If it’s the 20th add 50 calories cuz the runner’s tired” or something like that.

12

Edited to add: Also, no, it’s not really cumulative. You may burn more during certain parts of the workout (Such as when doing intervals, strides, whatever), but basically you determine total calories for the entire effort as an average. So if you do a warmup on the bike for 30 mins at 16mph, then an hour at 24mph, then another 30 mins at 16, you’ve done 40 miles in two hours, and you’d use that for your total determination. Nobody that I know of tracks it on a piece by piece basis

How many times do I have to say “assume constant intensity”?
Oh, get over yourself, tc. I hadn’t read your entire post when I responded.

John

13

Tigerchik, would you agree that as you get tired your form deteriorates (whether swimming or running)? And would you agree that as your form deteriorates you become less efficient? At mile 20 isn’t your form less efficient? If so, wouldn’t you have to expend more energy (and burn more calories) to keep the same pace (say 8 mph)? In swimming, as you get tired and become less efficient, doesn’t it take more effort (energy and calories) to keep the same pace? If not, I guess form in swimming really doesn’t matter after all.

14

This would imply a 2d order differential…she ain’t there yet…

15

The reason I ask is because looking at my diet plan from my nutritionist

Dude cannot help out with the question, but your ex did not take you for much if you can hire a nutritionist. Did you get your healthcare provider to pay for it somehow?

16

I can’t find a really clear answer on this, so maybe I’m not asking the right question. What i want to know is, does your rate of calorie burning increase for the longer you exercise? LIke say I cycle in zone 3 for 3 hours. Will burn 100 cals the first hour, 150 the second hour and 200 the third? Or does the rate stay constant as long as my heart rate averages the same over the entire exercise period?

The reason I ask is because looking at my diet plan from my nutritionist, I notice that the longer I exercise, the more I get to eat, however the amount of calories isnt constant. For example, if I workout 1 hour I get to eat 1500 cals. 2 hours, 1600 cals, 3 hours 2000cals, 4 hours 2500cals, etc. (these are just examples, not exact numbers.) It has me a bit confused.

Thanks.

It seems the answers you have might still be confusing you. It shouldn’t be so complex. With a little rehashing, this might help:

If you ride at a constant intensity (forget about heart rate here. If you want calories burnt then refer to work, or eg, Watts – ie a direct indicator of calories burnt), you are burning a set amount (or rate) of calories. Eg, ride at ~200W for 1 hour, and you burn ~850 cal/hr. Keep going for another hour at 200W, and your burn rate is still 850/hr for the second hour.

Obviously therefore, number of calories burnt is cumulative, but burn rate is not, at a constant intensity.

The key point you might be missing is that the numbers given by your nutritionalist vary because the intensity you exercise at for a given time period will likely vary, and the numbers given are for the entire exercise period, not per hour. Eg, if you go for one hour, you exercise harder than you would for 2 hours, therefore the amount recommended to eat for 2 hours of training is not double the amount given for one hour. Other minor factors are at play here, but that seems to be the main gist of it.

Since you will likely experience some drift in HR during longer sessions, therefore decrease work rate to maintain the same HR, your burn rate will vary (ie maybe fall a little as you go longer), but not by much - eg maybe cycle at 200W for 1st hour, then 185 for the second, your cals burnt will drop from ~850 cal/hr to ~800 cal/hr. This difference is probably smaller than the error in calculation of recommended cal intake from your nutritionalist, so the issue of HR drift is not really something to be concerned about with respect to cal intake numbers.

17

Tigerchik, would you agree that as you get tired your form deteriorates (whether swimming or running)?

Depends on the athlete and his/her fitness. You can be tired without a deterioration in form.

“At mile 20 isn’t your form less efficient?”
See above.

“If so, wouldn’t you have to expend more energy (and burn more calories) to keep the same pace (say 8 mph)?”
You would: an inefficient runner vs an efficient runner, at the same pace - the inefficient runner burns more energy. BUT now you’re making assumptions that your form does deteriorate at the end of _____ some certain amount of time. And I can tell you that the extra caloric burn for that is going to be negligible.

In swimming, as you get tired and become less efficient, doesn’t it take more effort (energy and calories) to keep the same pace? If not, I guess form in swimming really doesn’t matter after all.
Ah, you brought swimming into it :slight_smile: Remember that in swimming, water is far less forgiving a medium than air. Any inefficiency is magnified as far as you slowing down and it taking more effort and energy. Form in swimming matters a bunch.

Does that help?

18

This would imply a 2d order differential…she ain’t there yet…

Yeah I don’t know what that is. Right now in calc we just had a quiz over the various ways to find volumes of objects by “washers” and “slicing” and revolving eqn around axes. And now we’re into a section on all these physics/engineering problems like “if there’s a spherical tank r = 50 ft and it’s 200 ft above the ground, how much work is required to fill it with water” and other engineering problems. Since we’re now combining physics, stuff in calc I only half understand, and engineering, I usually want to stand up and scream I AM NOT AN ENGINEER CAN WE GET BACK TO THE THEORETICAL STUFF PLEASE.

What’s a 2d order differential?

19

The reason I ask is because looking at my diet plan from my nutritionist, I notice that the longer I exercise, the more I get to eat, however the amount of calories isnt constant.

Here’s my answer to explain part of what you’re seeing, if not all of it.

The longer and harder you work out, the more calories you burn afterwards. And I don’t believe that this effect is linear at all.

Q: Is it true that your body continues to burn extra calories for 12 hours after you’ve worked out?
A: Yes. “After vigorous exercise, we’ve seen caloric expenditure increase for up to 48 hours,” says exercise physiologist Tom R. Thomas, Ph.D., director of the exercise physiology program at the University of Missouri in Columbia. The longer and harder you work out, the greater the post-workout metabolism increase and the longer it lasts. Subjects in Thomas’ research burned 600-700 calories during one hour of running at about 80 percent of their maximum heart rate. During the next 48 hours, they burned about 15 percent more calories – 90-105 extra – than they otherwise would have. About 75 percent of the post-workout metabolism increase occurs in the first 1 2 hours after exercise, according to Thomas.
http://findarticles.com/p/articles/mi_m0846/is_8_21/ai_83911021/

20

**What’s a 2d order differential? **

Its defined by the highest form of derivative in the equation. At the moment, you’re still using first derivatives…if you think a bit further on, say through velocity as the change of position of a particle, and acceleration as the change in velocity - the second derivative of its position function could be defined as acceleration also.

Edit: I’m just a farmer, and as such, should not be allowed to think…