Running question

[IronFist]

Does your body adapt to running in the sense of calories burned?

Like say you're totally out of shape, and you go run 1 mile in 12 minutes. You're all tired and out of breath when you finish, and you're pulse is racing. You have just burned x calories.

Say you keep running for months and months. You get better, etc.

Now, you go run 1 mile in that same 12 minutes. Am I correct in assuming that you've just burned less calories than the first time you did it? Your heart rate is lower now when you finish, so that means less calories burned, right?

So if you want to burn a lot of calories when you run, you have to keep increasing the demand placed on your body, right?

My friend wants to know, and I don't know much about running.

Thanks,

IronFist

[rubthebuddha]

not sure it's that simple. i think it's more along the lines of your heartrate times the length of exercise. just think of the load you're putting on your respiratory system times the length it is under load.

now, this comment:

My friend wants to know, and I don't know much about running.

that friend wouldn't be the same person who quit ptp because he had no endurance and also started running on behalf of his marathonish girlfriend but wound up going into cardiac arrest just shy of 1½ miles? ;)

[Ford Prefect]

I think you adapt as your VO2 Max increases and your heart rate improves, but I think the calories burned while running are more a function of how fast/hard your legs are working and how much weight they have to move. Your legs are much bigger muscles than your heart and require a lions share of the energy (calories) to keep them moving.

In other words, I think calories used during running are more dependent on how heavy you are and how fast you're going rather than how efficient your cardiovascular system is.

[IronFist]

that friend wouldn't be the same person who quit ptp because he had no endurance and also started running on behalf of his marathonish girlfriend but wound up going into cardiac arrest just shy of 1½ miles?

No :D The friend who wants to know is the "marathonish girlfriend." :)

And for the record, the next week I ran 1.8 miles and was a little less tired when I finished than I was after the initial 1.2 miles. So there!!! :p

Ford said:
In other words, I think calories used during running are more dependent on how heavy you are and how fast you're going rather than how efficient your cardiovascular system is.

So, what if your weight is exactly the same on the two runs, and the speed and time are the same, but the only difference is that on the first run you suck are totally tired when you're done, but on the later run you're awesome and aren't very tired at all. Like this:

Run 1: Distance = X Time = Y Weight = Z Finishing heart rate = 170

Run 2: Distance = X Time = Y Weight = Z Finishing heart rate = 80

Did Run 2 burn less calories than Run 1?

IronFist

[rubthebuddha]

my gut tells me the run themselves burned no more, no less, if you assume the quality and form of the run was the same. the better then runner, more often, the less work they have to do. just comes with refinement.

moving Y lbs. X miles in theory should require the same effort. i think the bigger difference would be that, since the more in-shape person (let's call him Slim, and the less in-shape person Chubs) has a more efficient cardio vascular system, he'll be quicker to recover and be able to go a greater distance, because he wasn't as taxed in relation to HIS personal maximums.

i would also think that Slim would have a generally faster metabolism as well, and would lose weight better during resting periods. could be overgeneralizing here though.

i have a few more thoughts on this, but i can't seem to sort them out in my brain. maybe having ford or plcrane or someone else correct me on what i just said will straighten them out.

[Ford Prefect]

I think the difference would be negligable.

[TigerJaw]

Perhaps, if Chubs is unfit, he has smaller leg muscles that use fewer calories. Slim is therefore using more claories, not just when running but generally. Obviously, this wouldn't be much of a difference becasue the increase in lean mass for a runner would be relatively small but it might offset the other effect.

[Ford Prefect]

That's logically unsound though. If chubs had smaller leg muscles, then he'd in fact be working them more intensly since those small muscles would have to move his heavy body. So:

small leg muscles = less calories used but more intense work

large leg muscles = more calories used but less intense work

It would seem they would cancel each other other out and be more or less equal.

[TonyM.]

They do cancel each other out, exept larger thighs have the unpleasant fault of rubbing together when you run sometimes forcing you to run bowlegged to stop the chaffing.:D Still prefer the larger muscles though.

[IronFist]

So you don't adapt. Alright. Thanks.

IronFist

[TigerJaw]

No, you do adapt. The question is if the adatations lead to you using fewer or more calories. I suspect that there are so many factors to consider that it's not a simple linear relationship and probably depends on your age, build, gender etc. I suspect that these are in fact second order effects and as such, can be ignored.

[IronFist]

I always thought that heart rate had a big effect on calories burned, or if not, at least it was kind of an indicator.

Since an experienced runner can run the same distance at the same speed as an inexperienced runner, and finish with a much lower heart rate, I assume that meant fewer calories burned.

Since I'm so skinny I never really cared about burning calories, but now I'm curious.

So provide scientific data, please :D

(or just summarize it)

IronFist