physiology experts: why exactly is it easier for me to run on the treadmil than it is on motionless surfaces?

paul72 wrote:

areusure? wrote:

Hey All,

Biomechanics professor here. So OP are you asking why it is for YOU...or do you mean anybody?

1. No air resistance on TMs. There's plenty of research that has looked at the metabolic cost comparison and it takes a 1-2% incline to equal the no air resistance factor. Drafting while running typically shows a 7% reduction in O2 consumption to maintain running velocity.

2. The push-off phase. Once the COP passes the COM in the AP direction (i.e., the force vector is perpendicular to the ground) the TM "pulls" your leg through the push-off phase effectively lowering/minimizing the metabolic energy it would have taken to propel your body through that phase. That results in freely gaining the SEC and PEC's strain energy contribution to the forward swing of the trail leg (leg that just toed off).

These are research conclusions not just my opinion.

agree-both are primary factors-i did a kinesiology degree in the 90's and I remember we discussed in biomechanics classes why it is easier. The reaction force required to push off is less since the belt is motion...to compensate we discussed that the force vector had to be increased by increasing the grade (increasing the vertical component of the force vector) to about 2% making it equivalent to running on a flat motionless surface with no wind---indoor track slightly better than indoors with no wind but at least you are running on a fixed surface-that's why in my opinion "treadmill marathons" are really not the real deal if you are running at 0% grade.....that being said the boredom factor makes it about even to a real marathon...

theJeff wrote:

live the Lagrangian life wrote:

Exactly. If you were in a bottomless box being dragged along a stationary rubber belt at your running speed, you'd be running on the ground but think you were running on a treadmill. If you were running on a 30 ft wide asphalt treadmill and were just looking down, you'd think you were running on the ground.

In fact, when running outside, you are running on a surface that's moving 1000 miles per hour west to east. Is it different running east or west?

Like it's all relative, man.

I disagree with this. Running on a level treadmill is closer to running on a decline outside, because of the tendency for the end of the stride to flick your foot up into the air, making it easier to increase your stride length with no added effort. (I didn't verbalize that very well, but I hope you get the gist.) This also explains why most people advise setting the incline of the treadmill to 1-2%

live the Lagrangian life wrote:

Bad Wigins wrote:

that makes no sense. In the frame of reference of a runner, the ground does precisely the same thing.

Treadmillers may find it easier to free themselves from the fallacy that they have to keep pushing themselves forward, rather than merely minimizing braking force to preserve their momentum, thus focusing on efficiency and good form rather than effort. But the mechanics are equivalent, except for the wind.

Exactly. If you were in a bottomless box being dragged along a stationary rubber belt at your running speed, you'd be running on the ground but think you were running on a treadmill. If you were running on a 30 ft wide asphalt treadmill and were just looking down, you'd think you were running on the ground.

In fact, when running outside, you are running on a surface that's moving 1000 miles per hour west to east. Is it different running east or west?

Like it's all relative, man.

It IS all relative wrote:

live the Lagrangian life wrote:

Exactly. If you were in a bottomless box being dragged along a stationary rubber belt at your running speed, you'd be running on the ground but think you were running on a treadmill. If you were running on a 30 ft wide asphalt treadmill and were just looking down, you'd think you were running on the ground.

In fact, when running outside, you are running on a surface that's moving 1000 miles per hour west to east. Is it different running east or west?

Like it's all relative, man.

Exactly +1. Suppose you and a friend are standing in the middle of a treadmill that is a mile long and a mile wide and the treadmill is going along at 7mph. Your body is moving along with the treadmill so there is no sensation of motion. You can run in any direction away from your friend and your friend will not see any difference in your mechanics or speed. If you happen to run in the opposite direction of the treadmill then an observer that is stationary to the ground will see you remaining in a fixed position, and your friend who is just standing will appear to whiz away at 7mph. Now shrinking the treadmill down from a mile long to just 6 feet long doesn't change a thing. It becomes a visual illusion that makes people think that the belt is helping to throw feet around. For a perfectly steady treadmill there are no biomechanical differences between running on a treadmill versus running on the ground. However, treadmills are not perfectly controlled so there may be very slight differences that have to do with slight variations in belt speed. For cheap treadmills that have lots of belt friction, or inadequately sized or controlled motors, then the belt speed may be affected by the loading of the runner, and these may induce slight changes in biomechanics. These effects are very slight and insignificant. Running on a crushed gravel surface will produce more changes in biomechanics from stride to stride than running on a treadmill.

The effort level on a treadmill is extremely dependent on the elevation setting. One treadmill can feel much easier than another mill at the same elevation setting just because its level is off by 1%.

Sorry for the duplicate post. I had forgotten to show the posts that I was in agreement with.

live the Lagrangian life wrote:

Bad Wigins wrote:

that makes no sense. In the frame of reference of a runner, the ground does precisely the same thing.

Treadmillers may find it easier to free themselves from the fallacy that they have to keep pushing themselves forward, rather than merely minimizing braking force to preserve their momentum, thus focusing on efficiency and good form rather than effort. But the mechanics are equivalent, except for the wind.

Exactly. If you were in a bottomless box being dragged along a stationary rubber belt at your running speed, you'd be running on the ground but think you were running on a treadmill. If you were running on a 30 ft wide asphalt treadmill and were just looking down, you'd think you were running on the ground.

In fact, when running outside, you are running on a surface that's moving 1000 miles per hour west to east. Is it different running east or west?

Like it's all relative, man.

not really wrote:

It IS all relative wrote:

Exactly +1. Suppose you and a friend are standing in the middle of a treadmill that is a mile long and a mile wide and the treadmill is going along at 7mph. Your body is moving along with the treadmill so there is no sensation of motion. You can run in any direction away from your friend and your friend will not see any difference in your mechanics or speed. If you happen to run in the opposite direction of the treadmill then an observer that is stationary to the ground will see you remaining in a fixed position, and your friend who is just standing will appear to whiz away at 7mph. Now shrinking the treadmill down from a mile long to just 6 feet long doesn't change a thing. It becomes a visual illusion that makes people think that the belt is helping to throw feet around. For a perfectly steady treadmill there are no biomechanical differences between running on a treadmill versus running on the ground. However, treadmills are not perfectly controlled so there may be very slight differences that have to do with slight variations in belt speed. For cheap treadmills that have lots of belt friction, or inadequately sized or controlled motors, then the belt speed may be affected by the loading of the runner, and these may induce slight changes in biomechanics. These effects are very slight and insignificant. Running on a crushed gravel surface will produce more changes in biomechanics from stride to stride than running on a treadmill.

The effort level on a treadmill is extremely dependent on the elevation setting. One treadmill can feel much easier than another mill at the same elevation setting just because its level is off by 1%.

Sorry for the duplicate post. I had forgotten to show the posts that I was in agreement with.

There is actually a sensation of motion because you are plowing through the air at 7 mph standing on the treadmill. It is hard to breath in a vacuum.

You are also assuming that the runner is always moving at a constant speed like the treadmill which is incorrect. They are not using a motorized wheelchair.

not really wrote:

It IS all relative wrote:

Exactly +1. Suppose you and a friend are standing in the middle of a treadmill that is a mile long and a mile wide and the treadmill is going along at 7mph. Your body is moving along with the treadmill so there is no sensation of motion. You can run in any direction away from your friend and your friend will not see any difference in your mechanics or speed. If you happen to run in the opposite direction of the treadmill then an observer that is stationary to the ground will see you remaining in a fixed position, and your friend who is just standing will appear to whiz away at 7mph. Now shrinking the treadmill down from a mile long to just 6 feet long doesn't change a thing. It becomes a visual illusion that makes people think that the belt is helping to throw feet around. For a perfectly steady treadmill there are no biomechanical differences between running on a treadmill versus running on the ground. However, treadmills are not perfectly controlled so there may be very slight differences that have to do with slight variations in belt speed. For cheap treadmills that have lots of belt friction, or inadequately sized or controlled motors, then the belt speed may be affected by the loading of the runner, and these may induce slight changes in biomechanics. These effects are very slight and insignificant. Running on a crushed gravel surface will produce more changes in biomechanics from stride to stride than running on a treadmill.

The effort level on a treadmill is extremely dependent on the elevation setting. One treadmill can feel much easier than another mill at the same elevation setting just because its level is off by 1%.

Sorry for the duplicate post. I had forgotten to show the posts that I was in agreement with.

There is actually a sensation of motion because you are plowing through the air at 7 mph standing on the treadmill. It is hard to breath in a vacuum.

You are also assuming that the runner is always moving at a constant speed like the treadmill which is incorrect. They are not using a motorized wheelchair.

the430miler wrote:

so, we are all aware of the different discussions about treadmills, many of which have discussed the distance and how accurate treadmills really are in terms of how far you have ran on them. however, we have not discussed another aspect of treadmills.......

for some reason, obviously a scientific reason, running on the treadmill is much easier for me than running on motionless surfaces. now, I am NOT referring the the hardness of the surface; obviously there has been much discussion on letsrun about treadmills being hard on your legs. I am simply referring to the amount exertion that I feel when running.

does the moving belt cause an actual physiological differential when it comes to each stride, as compared to having to throw each stride on a non moving surface? please dont misunderstand me. I am also not referring to any weather related issues, as obviously indoor treadmills have no windage factors involved. I am simply asking does the belt being in motion, somehow on a physics level, affect your cardiological and physiological EXERTION as compared to running on a motionless surface.

obviously it is a physics issue. I took tons of physics in college, but I am still baffled about why running on a non incline treadmill is still extremely easier for me as compared to running outside at this age (lower 30s). I personally do not hypothesize that it has anything to do with being "forced" to stay on the treadmill due to threat of being injured hath I stopped running on a moving belt, as compared to stopping while running outside. just want to head additional physiological explanations.

thank you for your ANALyzation of this issue, and please remember......

mentality>physicality

UphillOllie wrote:

the430miler wrote:

so, we are all aware of the different discussions about treadmills, many of which have discussed the distance and how accurate treadmills really are in terms of how far you have ran on them. however, we have not discussed another aspect of treadmills.......

for some reason, obviously a scientific reason, running on the treadmill is much easier for me than running on motionless surfaces. now, I am NOT referring the the hardness of the surface; obviously there has been much discussion on letsrun about treadmills being hard on your legs. I am simply referring to the amount exertion that I feel when running.

does the moving belt cause an actual physiological differential when it comes to each stride, as compared to having to throw each stride on a non moving surface? please dont misunderstand me. I am also not referring to any weather related issues, as obviously indoor treadmills have no windage factors involved. I am simply asking does the belt being in motion, somehow on a physics level, affect your cardiological and physiological EXERTION as compared to running on a motionless surface.

obviously it is a physics issue. I took tons of physics in college, but I am still baffled about why running on a non incline treadmill is still extremely easier for me as compared to running outside at this age (lower 30s). I personally do not hypothesize that it has anything to do with being "forced" to stay on the treadmill due to threat of being injured hath I stopped running on a moving belt, as compared to stopping while running outside. just want to head additional physiological explanations.

thank you for your ANALyzation of this issue, and please remember......

mentality>physicality

The real reason is that when you plant your foot on the treadmill it causes a slight deflection in the base under the belt. It is a slight hole. The belt pulls your foot back out of the hole or essentially up hill. Since your push off foot is now higher the other foot is going downhill to it's plant position. To summarize you are always running downhill.