question on calorie burning

NothinToLose · #1 (**permalink**) February 2nd, 2006, 06:17 AM

Ok, I have a question on calorie burning during exercise.

When a person first starts exercising, and they ride 2 miles at 8 miles/hr, they are huffing and puffing and sweating and their heart rate is way up, etc... Then a month later or two later, with built up strength and stamina, the same person does exact same ride - 2 miles at 8 miles/hr, just broke a sweat, heart rate is just slightly up, breathing almost normal... Let's say his weight is the same. Does this person burn the same amount of calories those 2 rides, because their muscles did the same amount of work? Or does the first ride burn more calories, because the respiratory and circulation systems are working so much harder?

I made example with a bike, but my question is really general, related to all the exercise... Hope its clear...

wonderwoman · #2 (**permalink**) February 2nd, 2006, 11:04 AM

i want to say that since the weight is the same that it would burn the same amount since calories burnt during an activity is all according to what you weigh at the time. but if he isnt in his target heart rate range the 2nd time since he has more endurance, i'm not really sure! thats a good question..i will have to bring in sean on this one i think.

Korrie · #3 (**permalink**) February 2nd, 2006, 11:07 AM

Oh man...too much thinking involved here for me

NothinToLose · #4 (**permalink**) February 2nd, 2006, 12:03 PM

NB, I do tend to overthing things all the time... But this question keeps coming back to my mind...

Thanks, WW, I hope Sean can help!

AllCdnBoy · #5 (**permalink**) February 2nd, 2006, 12:05 PM

that is a very good question and the inherent problem with the calorie counting system on bikes ... but, it's the best it can do.

Weight is only a guideline for calories burnt ... but it should take into account body type and height for better calculations. There is no straight answer for these reasons ... the simple answer is, maybe

:

1) lets ignore calories as we are interested in burning fat .. so:
2) your heart rate is lower so you aren't working as hard, so you are burning fat more efficiently, but maybe not as much **see point below, if this got your head spinning
3) if you are the same weight, that means you have added some muscle mass ... and, since muscles are your best source of fat burning (which is why you want to add weights to your workouts), you have again increased the effeciency of your fat burning ... but again, the change is hard to measure. You could be burning more ... could be slightly less.
4) the real benefit actually comes after the workout and in your daily activities. The better shape you are in, the more your body continues to work after the workout and while you are performing other activites. People who are in tip-top shape can eat whatever they want because their bodies become fat burning machines ... their BF% is so low, that whenever there is an excess amout of fat laying around the muscles eat it right up.
5) also, since you are in better shape, you will have less fat stores to burn off ... so, your body may compensate and slow things down to conserve what is there ... i believe that in this scenerio, if you are doing everything right and are in really good shape now, you would be burning more fat then before ... you are in better shape and your body is more attoned to burning fat ... however, it really depends on the shape that you were in before, the shape that you are in now ... the intensity of your workout ... your natural metabolism ... the food stores that you have in your belly at the time (which relates to your regular eating habits) ... on, and on, and on

** high heart rate means you are out of the fat burning zone. But you are still burning more fat, but you also start to burn protein
** a lower heart rate (from a speed walking or slow jog), optimizes fat burning, but is a slow process ... walking an hour every day (7 days) will not be as optimal as running an hour 4xweek
** for best results in fat burning, use HIIT: High Intensity Interval Training ... 20 second sprint with 40 second light jog ... any interval where the slow down period is twice the sprint period will get the job done. It keeps the heart generally in the fat burning zone, but kicks the body into high gear long enough to burn more fat, but not get too far into the protein burning mode.

NothinToLose · #6 (**permalink**) February 2nd, 2006, 12:14 PM

AllCdn,

You are a wealth of information!

So what you are saying is that 2nd bike ride 2months later would burn more fat then 1st one because of lower heart rate, but not necessarily more calories, because the higher your heartrate is the more calories is burned per minute(but now calories come from fat and protein)?

AllCdnBoy · #7 (**permalink**) February 2nd, 2006, 12:21 PM

... clear as mud, right? ... i'm guessing this doesn't answer the question very well.

Realistically, if you are no longer huffing and puffy, and that's what you were wanting to achieve in the first place, you should be increasing your intensity anyway.

... i'll try another approach too: everyone knows that the more out of shape you are, the more weight you will lose faster. So, the better shape you are in, the slower the progress. I think relatively, according to the fat stores and the shape you are in, the fat burned in the beginning and the end are the same ... even though the values may be different ... that make sense?

AllCdnBoy · #8 (**permalink**) February 2nd, 2006, 12:24 PM

nothintolose ... kind of. i think if you were to measure the exact fat calories burned, it would be less than before, but that is only because you are in better shape and, in relation to your current fitness status, you have less fat to burn. Now that i think about it, you probably will burn more fat, relatively, because you are in better shape ... just not quantity wise.

NothinToLose · #9 (**permalink**) February 2nd, 2006, 12:44 PM

Thanks, AllCdn!

I think I understand it now. Metabolism is faily complicated subject, with so many variables, more for biologists and scientists, so it is probably hard to explain in layman terms.

Yeah, I realize that this is a very hypothetical example. In real life the person will start pedaling faster, so they will probably burn more calories when they are fitter then when they are out of shape.

Thanks!