Calories burned running: is speed a factor at all?

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mikeyrp
mikeyrp Posts: 1,616 Member
in Fitness and Exercise
Yesterday I did a the following running training session:
2 miles warm up @ 9 minute miles
3 miles @ 7 minute miles
1 mile cool down @ 9 minute miles

So I logged my calories burned follows (based on MFP calc):

27 minutes at 9mm: 377 cals
21 minutes at 7mm: 373 cals

In other words - speed has virtually no impact on the number of calories burned per mile ~ (125)

On one hand this seems logical - the amount of work exerted is a factor of weight x distance - this how levers and pulleys function after all. On the other hand, you would think that running outside your comfort zone is going to offer more resistance - a good analogy would be that a car travelling at 70 mph burns more fuel per mile than one travelling at 50 mph because there is additional wind resistance to be overcome by the faster car.

Does anyone know the answer to this?
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Replies

  • SanyamKaushik
    SanyamKaushik Posts: 215 Member
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    Good question and excellent examples. Bumping!
  • Shadowsan
    Shadowsan Posts: 365 Member
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    The amount of energy expenditure as your speed increases for running exponentially reduces, because you carry momentum.

    Which is also why interval training burns more energy - because you are constantly increasing/decreasing your speed from slow to fast, fighting against inertia.
  • mirandamayhem
    mirandamayhem Posts: 772
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    I read the distance is the thing. So if i'm walking 2mph it will take me longer than you running 7mph. So you can do far more distance in an hourrunning 7mph than I can walking 2mph. So in an hour you'll burn far more because you went further. So it makes sense to me. And if you're pushing yourself, you are going farther, and so going to burn more calories.
    Obviously carrying extra weight etc, changes the amount of calories burnt too?
  • IdunAbelone
    IdunAbelone Posts: 45
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    I've been told that if I walk 5 miles I burn exactly the same amount of calories as if I run 5 miles.

    I'm just done a lot faster running :)

    I've read several successtories in papers etc. of people losing huge amount of weight by "just" walking. Never hit the gym or ran, just walking - every day.
  • rotill
    rotill Posts: 244 Member
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    I am absolutely certain you'll have a lot of better responses to this, but as far as I understand it's not about speed, but about your effort. So an out-of-shape person who runs for one hour at top speed will burn as much as or even more than the really fit person who runs twice the distance.

    This is why people go the whole length of heart-rate monitors, etc, in order to figure out how much effort they put into the exercize, and to get a better idea about how many calories they burn.
  • BarbaraC47
    BarbaraC47 Posts: 175 Member
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    I thought it would be more the number of steps taken rather than the speed - I just walk and walk and walk... gonna join a gym for the variety and expertise I need but am happy plodding along, putting one foot in front of the other
  • JDUR19
    JDUR19 Posts: 60 Member
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    You did 27 minutes running three 9 minute miles then 21 minutes running three 7 minute miles. It will show a bigger impact if you run the same amount of time. For example, If you had run (hypothetically) seven 9 minute miles making 63 minutes and it burned x calories then running nine seven minute miles (same amount of time) would burn off many more calories than x (lets call it y). So "y" which is the amount burned in 7 minute miles is greater than "x", the amount burned in 9 minute miles.

    It doesn't really show because you ran at the different speeds for a different length of time.
  • mikeyrp
    mikeyrp Posts: 1,616 Member
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    Its about effort x time - so you cant compare a fit person and an unfit person of the same weight running at the same speed - but you can compare two people of the same level of fitness running the same distance at different speeds. I find it hard to believe that both have the same efficiency level.
  • NCJB
    NCJB Posts: 10
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    If you compare two equal amounts of time, not distance, you will burn more calories moving faster. You have a 6 minute difference in your comparison.
  • mikeyrp
    mikeyrp Posts: 1,616 Member
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    OK - I'm going to rephrase the question because I think some people are missing my point- if my target was to burn, say, 500 calories running - would I always go the same distance irrespective of the speed I was running at?
  • Shadowsan
    Shadowsan Posts: 365 Member
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    No.

    You can burn 500 calories running faster, which will mean for X amount of time you would cover more distance potentially. This difference increases and so becomes more noticeable the further you do this for.

    However, this is comparing apples and oranges really. They both achieve the same thing, albeit via different methods with different secondary effects (like increasing your VO2 Max etc).
  • mirandamayhem
    mirandamayhem Posts: 772
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    yes
    and that magic distance number will be dependant on a load of factors such as current weight,
  • mirandamayhem
    mirandamayhem Posts: 772
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    No.

    You can burn 500 calories running faster, which will mean for X amount of time you would cover more distance potentially. This difference increases and so becomes more noticeable the further you do this for.

    ah, well i obviously think differently. lol
  • rkr22401
    rkr22401 Posts: 216 Member
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    Ooooh, Ooooh, teacher, I know! I know! [he said with arm raised]

    Here is the physics answer:

    Work/energy (i.e. calories) is force times distance. Increase calories by going greater distance or using greater force. Distance is obvious. Regarding force, a heavier person will burn more calories going the same distance. Also 5 miles uphill will burn more calories than 5 miles on a flat or downhill surface.

    Power is work/energy per unit time. Going equal distance in shorter time will burn the same energy in less time (more power).
  • Shadowsan
    Shadowsan Posts: 365 Member
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    No.

    You can burn 500 calories running faster, which will mean for X amount of time you would cover more distance potentially. This difference increases and so becomes more noticeable the further you do this for.

    ah, well i obviously think differently. lol

    Think about it a second.

    If I burn 50kcals/mile running at 5mph and run for 1 hour, then I burn 250kcals.

    If I burn 60kcals/mile running at 6mph and run for 250kcals, then I only have to run 4.16 miles to get the same kcal expenditure.

    I get this by doing 250/60.

    But if I run for the same amount of time at the faster pace...

    Then I burn 60*6=360kcals in an hour, and cover 6 miles.

    If I choose to run for the same distance (5 miles) at that faster pace...

    Then I burn 300kcals.

    I get this by doing 60*5.

    Make sense?

    Note - the kcals/mile were figures pulled off the top of my head as an example. They're by no means definitive, it was just to give you an example.
  • mikeyrp
    mikeyrp Posts: 1,616 Member
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    OK - I just did an experiment with MFP exercise calorie calculator - I took the pace and entered the same value for the minutes of exercise (eg 6 minute mile pace, 6 minutes) - which means that the output is the number of calories per mile. As my weight is a fixed quantity and MFP doesn't know my fitness level we can assume that there are no other factors changing.These are the results.

    pace / cals
    6 / 122
    7 / 124
    8 / 127
    9 / 126
    10 / 127
    12 / 122

    As you can see, there is no linear correlation between pace and cals per mile shown here - meaning either MFP has incorrect values (possible) or that there really is no correlation and that the body doesn't have a peak efficiency in terms of running speed.

    Note that I would define efficiency here in terms of calories burnt - obviously muscle fatigue sets in over a shorter distance at higher speeds.
  • SanyamKaushik
    SanyamKaushik Posts: 215 Member
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    mikeyrp. As per Newtons laws : Word Done (or calories burnt) = Mass * Acceleration * Distance
    (where mass relates to weight, acceleration is resistance whilst running and hence its directly proportion to distance)

    However, I understand your point of efficiency as well and that bit is somehow built into the acceleration bit.

    I'm also looking for answers...
  • mikeyrp
    mikeyrp Posts: 1,616 Member
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    No.

    You can burn 500 calories running faster, which will mean for X amount of time you would cover more distance potentially. This difference increases and so becomes more noticeable the further you do this for.

    ah, well i obviously think differently. lol

    Think about it a second.

    If I burn 50kcals/mile running at 5mph and run for 1 hour, then I burn 250kcals.

    If I burn 60kcals/mile running at 6mph and run for 250kcals, then I only have to run 4.16 miles to get the same kcal expenditure.

    But if I run for the same amount of time at the faster pace...

    Then I burn 360kcals in an hour.

    If I choose to run for the same distance (5 miles) at that faster pace...

    Then I burn 300kcals.

    Make sense?

    Yes - but (apparently) you burn the same cals per mile at both speeds.
  • Shadowsan
    Shadowsan Posts: 365 Member
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    OK - I just did an experiment with MFP exercise calorie calculator - I took the pace and entered the same value for the minutes of exercise (eg 6 minute mile pace, 6 minutes) - which means that the output is the number of calories per mile. As my weight is a fixed quantity and MFP doesn't know my fitness level we can assume that there are no other factors changing.These are the results.

    pace / cals
    6 / 122
    7 / 124
    8 / 127
    9 / 126
    10 / 127
    12 / 122

    As you can see, there is no linear correlation between pace and cals per mile shown here - meaning either MFP has incorrect values (possible) or that there really is no correlation and that the body doesn't have a peak efficiency in terms of running speed.

    Note that I would define efficiency here in terms of calories burnt - obviously muscle fatigue sets in over a shorter distance at higher speeds.

    This means that the calculator is wrong really.

    Although how wrong is debatable. Obviously to increase speed, you may be able to do that simply by increasing your stride length which would result in nearly the same amount of muscle contractions as the slower speed.

    Which ties in to what I originally said - as your speed increases, the difference in expenditure begins to result in an inverse exponential curve - diminishing returns.
  • mirandamayhem
    mirandamayhem Posts: 772
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    No.

    You can burn 500 calories running faster, which will mean for X amount of time you would cover more distance potentially. This difference increases and so becomes more noticeable the further you do this for.

    ah, well i obviously think differently. lol

    Think about it a second.

    If I burn 50kcals/mile running at 5mph and run for 1 hour, then I burn 250kcals.

    If I burn 60kcals/mile running at 6mph and run for 250kcals, then I only have to run 4.16 miles to get the same kcal expenditure.

    But if I run for the same amount of time at the faster pace...

    Then I burn 360kcals in an hour.

    If I choose to run for the same distance (5 miles) at that faster pace...

    Then I burn 300kcals.

    Make sense?

    Not really, I don't think the calories vary as much as you think.

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