Which burns more calories, 5mi run in 30min or 40min?

Sounds likely

Would you use more gas travelling ten miles at 120mph or travelling 10 miles at 50 mph?

Faster speeds generally are less efficient and use more energy.

There is nothing wrong with saying "burning calories". Look at the first definition in the dictionary:

"1 a : to consume fuel and give off heat, light, and gases "

Note how the example describes the fire as burning, not the substrate. Same thing here: calories are interchangeable with "fire" in the example as a calorie is just a unit of energy, which is exactly what the fire manifests.

EoT Boom.

treole wrote:

There is nothing wrong with saying "burning calories". Look at the first definition in the dictionary:

"1 a : to consume fuel and give off heat, light, and gases "

Note how the example describes the fire as burning, not the substrate. Same thing here: calories are interchangeable with "fire" in the example as a calorie is just a unit of energy, which is exactly what the fire manifests.

EoT Boom.

Really? Fire is a measure of energy?

No. BTUs are the measure related to fire. Would you start a fire in your fireplace, and then say "I'm burning BTUs in my fireplace"?

substrate, not calories wrote:

treole wrote:

There is nothing wrong with saying "burning calories". Look at the first definition in the dictionary:

"1 a : to consume fuel and give off heat, light, and gases "

Note how the example describes the fire as burning, not the substrate. Same thing here: calories are interchangeable with "fire" in the example as a calorie is just a unit of energy, which is exactly what the fire manifests.

EoT Boom.

Really? Fire is a measure of energy?

No. BTUs are the measure related to fire. Would you start a fire in your fireplace, and then say "I'm burning BTUs in my fireplace"?

I would if I were burning BTUs.

The faster pace would burn more due to :

1. More vertical motion when running faster.

2. Slightly more wind resistance while running faster.

3. Potentially less efficiency with the body running faster and heating up.

If there was no vertical motion, wind resistance, or efficiency issues, the energy expended would be the same. Energy is a function of distance traveled and not the speed you do to get there (in a vacuum with no wind resistance). Power is a function of speed.

Energy = Force x distance, Power = Velocity x distance. Power is the derivative or time rate of power. Energy is the time integral of power.

If you go twice as fast to get somewhere you will take 1/2 the time to get there. Energy is the same given the assumptions I stated.

From a mechanical engineer.

Anon wrote:

The faster pace would burn more due to :

1. More vertical motion when running faster.

2. Slightly more wind resistance while running faster.

3. Potentially less efficiency with the body running faster and heating up.

If there was no vertical motion, wind resistance, or efficiency issues, the energy expended would be the same. Energy is a function of distance traveled and not the speed you do to get there (in a vacuum with no wind resistance). Power is a function of speed.

Energy = Force x distance, Power = Velocity x distance. Power is the derivative or time rate of power. Energy is the time integral of power.

If you go twice as fast to get somewhere you will take 1/2 the time to get there. Energy is the same given the assumptions I stated.

From a mechanical engineer.

Power is the derivative or time-rate of "energy". I'm a mechanical engineer not an English major. Didn't proof read careful enough.

The discussion doesn't include physiological effects of calories burned after the run.

Anon wrote:

If there was no vertical motion, wind resistance, or efficiency issues, the energy expended would be the same. Energy is a function of distance traveled and not the speed you do to get there (in a vacuum with no wind resistance). Power is a function of speed.

Energy = Force x distance ...

Um, what force is that exactly? Gravity is vertical and movement is horizontal. Back to the drawing board for you. For a human, if there were no vertical motion, there would be no horizontal motion. The way the body moves is by pushing off at an angle to the ground. We would need to measure both components to know the energy consumed. It's easy to imagine an inefficient bounding stride that uses way more energy to travel the same distance.

3hr marathoner wrote:

luv2run wrote:

EPOC (the "afterburn") is a pretty small amount of energy above normal.

If by pretty small, you mean smaller than the workout then, yes, we agree but those papers you cite do show a trend toward larger afterburns for more intense exercise. That was my point, calories per mile doesn't change much with pace, but the afterburner does especially when you cross above VO2max.

You expend very little energy per minute at rest. So a 10% increase is not much. You burn something on the order of 1 kcal/min at rest. So a 10% increase means 1.1 kcal/min. Maybe 6 more kcals/hr. So 120 kcals/d (at rest). A small candy bar takes care of that.

luv2run wrote:

3hr marathoner wrote:

If by pretty small, you mean smaller than the workout then, yes, we agree but those papers you cite do show a trend toward larger afterburns for more intense exercise. That was my point, calories per mile doesn't change much with pace, but the afterburner does especially when you cross above VO2max.

You expend very little energy per minute at rest. So a 10% increase is not much. You burn something on the order of 1 kcal/min at rest. So a 10% increase means 1.1 kcal/min. Maybe 6 more kcals/hr. So 120 kcals/d (at rest). A small candy bar takes care of that.

I should note that a large person will expend more energy per min at rest than a smaller person, but even a 200 pounder is maybe going 1.3 or 1.5 kcals/min.

Alan Bennet wrote:

Anon wrote:

If there was no vertical motion, wind resistance, or efficiency issues, the energy expended would be the same. Energy is a function of distance traveled and not the speed you do to get there (in a vacuum with no wind resistance). Power is a function of speed.

Energy = Force x distance ...

Um, what force is that exactly? Gravity is vertical and movement is horizontal. Back to the drawing board for you. For a human, if there were no vertical motion, there would be no horizontal motion. The way the body moves is by pushing off at an angle to the ground. We would need to measure both components to know the energy consumed. It's easy to imagine an inefficient bounding stride that uses way more energy to travel the same distance.

He knows, he is just explaining the physics that relates distance travelled to energy for other Letsrunners.