Running outside, or on a treadmill?

Question

Basics I want to know how much of a difference in energy consumption there is between running the same distance through open air, or on a treadmill - I'm guessing it's quite a bit tougher outside, but I want to know how much.

We are assuming that the terrain is completely flat, and that the wind speed outside is very low. I really want to know how much of an effect the air resistance makes. Obviously one would be running at the same speed.

Answer 1

I have looked through my books and online and have not seen anything that directly answers that question.  A lot of research is done on a treadmill because you can eliminate factors such as weather, temperature, speed, incline, etc.

Just looking at the differences, I believe the consumption would be very similar to a point.  Arguments for the treadmill:

1.  Pace is consistent.  Outside running you can vary your pace much more easily.  So if you run on the treadmill, you may burn more calories because you are working hard.  That is assuming that you pick a difficult pace.  Even if you try to run at the same speed, it is very difficult to.

2.  Belt is cushioned.  Though this can be good for the joints, with proper form, you may actually work harder.  Newton's law states that every action there is an equal but opposite reaction.  If the belt has some cushion, that means that less reaction force from the belt will be transferred back into pushing you forward.  

Arguments for Outside:

1.  Heat and humidity are very big factors.  The hotter and more humid outside, the more your body is going to have to work to keep your body temperature normal.  Studies of marathoners have shown that even small differences in temp/humidity can slow down world class marathoners 3% and 3 hour pace marathoners 10-13%.  Basically still burning calories but the body is battling over where to utilizes its resources - cooling the body or running.

Given your conditions, I believe that air resistance is going to be fairly low.  True humans are not very aerodynamic, but we are not going so fast that it will make a tremendous difference especially as the distances increasing.  This is why sprinters tend to wear close fitting clothes and distance runners where more loose clothes.

I would say that all things equal, both expend about the same amount of energy. I have been working with clients for over 15 years and have anectodal evidence that supports both being difficult.  The main factors that I usually see are weather and form in energy consumption.  Many people run inefficiently on either surface which to me is where the caloric consumption is larger.  A person with better form is able to train longer and rest less so they are able to burn more calories.

Hope that helps!

Answer 2

the air resistance wont make much of a difference but tar is a lot worse on your knees. a treadmill is not taht good either. you not going to be so much harder running 1 mile outside then inside maybe if its teh Boston marathon then ya but not for just going out for a daily run

Answer 3

I would say run outside.  Just because of scenery.  It depends though on your terrain which would be tougher because you can put the treadmill on incline but they also do not always acurately show your speed or distance.  Also, if you are indoors on a treadmill, then you will probably have the AC on right?  Well this will mean that running outside will be hotter and you will get more tired! The air resistance won't make much of a difference if the wind is not blowing.  But I don't like treadmills because my shins seem to hurt when I run on them.  Plus it is hard to pick up the pace when you need to or whatever.  Just do whatever is better for you and if you have the oppurtunity to do both, then try each.

Answer 4

Definitely run outside, it is so much nicer than getting stuffy in a room. I love sightseeing while im running :)