Physics Question - Hills on Treadmill

here is you original post:

"My roommate and I were arguing about simulating hills by running on a graded treadmill. My problem is that your center of mass (more or less) is not moving up (relative to the floor). Granted, you have to have a shortened stride and bring your trail leg through more quickly to plant "higher" due to the incline. But it still seems to me that your foot is getting pulled downhill as much as you are running uphill. I would think that there is some benefit, but a fairly small amount (say less than 50%) compared to running an actual hill.

My roommate proposed that the the runner's center of mass will have the exact same vertical motion as it would on a real hill, if you use the reference frame of the treadmill, as opposed to the floor. This is a tempting argument, but still doesn't seem right to me.

I know Jack Daniels and others (I remember a Terrence / Hall video) have advocated hill running on treadmills. Has anyone actually figured out the exact PHYSICS of this and if you are getting the same benefit (and if not, what percentage of benefit) as you would on a hill of the same grade?"

You asked about the physics involved specifically, your issue was you did not find them to hold true. As you have conceded that the physics are the same, any further discussion of bio-mechanics is outside the bounds of the original question although not uninteresting. The bio-mechanical differences where never under debate.

Well, as you just posted, my original question was this: "Has anyone actually figured out the exact PHYSICS of this and if you are getting the same benefit (and if not, what percentage of benefit) as you would on a hill of the same grade?"

I would say that that is a two-part question. "Has anyone figured out the physics of this" (running uphill v. graded treadmill) and "are you getting the same benefit..." I think the second question at least is still in question, and I'm still interested in input. I know I didn't say the word "biomechanics" in my original post, but with my multiple comments about your foot being "dragged backward," biomechanics clearly weren't far from my mind. I think I was confusing the biomechanical differences (and thus the potential differing levels of work that different muscle groups are doing) with the global work done.

Albert Einstein wrote:

UHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH, no. Both of these posts below are posts of clowns.

Vegan Physicist wrote:

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this

It is just as impossible to convince the ignorant of the truth here as it is to educate the believers in Alien-created crop circles, deniers of global warming, believers in Bigfoot...

What the Heck obviously knows what he is talking about, as does Vegan Physicist, the OP's roommate, and several others who have posted. That others insist on continuing to post drivel is not something that is correctable.

Go take a physics class. Or don't.

Based on the title of the thread and the content of your post it is not unreasonable for one to imply you are only questioning the physics involved. Just because you use "and" does not mean there are two separate questions here.

I also said that the other aspects are not uninteresting, so feel free to discuss or you can just argue semantics endlessly if you want. It appears that you are the only one who has provided any input into that aspect of the benefits of graded treadmill running and I will be surprised if you get much help from anyone else on that front.

I think you fail to notice all you have really done is started another "Airplane on a Treadmill" thread.

gooner wrote:

Compare a treadmill with a set of rollers for bike training. One has a motor providing propulsion the other does not. And still the physics professors insist that treadmill running is the same as real running. If it is the same, why the heck do you need a motor.

There are treadmills without motors. They just don't regulate your speed for you.

Newton wrote:

Based on the title of the thread and the content of your post it is not unreasonable for one to imply you are only questioning the physics involved. Just because you use "and" does not mean there are two separate questions here.

I also said that the other aspects are not uninteresting, so feel free to discuss or you can just argue semantics endlessly if you want. It appears that you are the only one who has provided any input into that aspect of the benefits of graded treadmill running and I will be surprised if you get much help from anyone else on that front.

I think you fail to notice all you have really done is started another "Airplane on a Treadmill" thread.

No, it was not unreasonable for you to INFER* that I was only talking about physics. But how there are not two questions there is beyond me. The two questions cover different subjects entirely. I thought the phsyics of the situation might clue us in to the answer of the latter (the benefit question) -- hence the thread topic (which by the way, was chosen by my roommate). Semantics. Cool.

Yes, I seem to be the only one who has provided real input on the biomechanical aspect thus far. And maybe no one else will. But I think it is sufficiently related to my original questions to discuss here (and as you mentioned, "not [an] uninteresting" issue, despite your Airplane comment).

The thread can be "over" for you whenever you want. Just don't click on it.

Scherbatsky wrote:

No, it was not unreasonable for you to INFER* that I was only talking about physics. But how there are not two questions there is beyond me. The two questions cover different subjects entirely. I thought the phsyics of the situation might clue us in to the answer of the latter (the benefit question) -- hence the thread topic (which by the way, was chosen by my roommate). Semantics. Cool.

Yes, I seem to be the only one who has provided real input on the biomechanical aspect thus far. And maybe no one else will. But I think it is sufficiently related to my original questions to discuss here (and as you mentioned, "not [an] uninteresting" issue, despite your Airplane comment).

The thread can be "over" for you whenever you want. Just don't click on it.

OK you caught me on an editing error with infer/imply. I changed the sentence structure to place the fault on me and missed a word, but go ahead and make an ad hominem (albeit veiled) attack against me.

I won't say that you did concede the point on the physics because you did, all I am saying almost all of the weight of your original post and most of your subsequent earlier posts was placed on the physics involved. The weight slowly shifted off of that point once you began to realize your room mate was correct with regards to the physics involved.

Although you can argue that there is a small statement in your original post that encompasses these other aspects (and I am not going to dispute that), it is pretty clear that the score to be settled was the physics. It appears you are just looking for a way to argue that you were right and there is a difference in benefit between the two scenarios, which was never debated by anyone here (and I doubt was debated by your room mate).

"Oh no, please don't say you want to start this nonsense again.

"With treadmill running versus running on solid ground, you are able to run at a higher efficiency than you normally would be."

No.

"Now, when you are running on the ground vs the treadmill, the coefficient for static friction is higher than it would be if you were running on a treadmill (where the belt is running backwards as you push off, which creates more kinetic friction."

Please say you are joking.

"but I feel this makes sense"

Hey, I really want to take this opportunity to acknowledge the validity, and truly the importance, of your feelings.

BUT THIS IS NOT ABOUT FEELINGS. THIS IS A PHYSICS QUESTION.

Please go back to the above quote by "What the Heck".

And please stop posting if you lack even the most basic understanding of simple Newtonian physics."

#1, I did not ever claim to have my PhD in Physics, it will never happen.

#2. You don't have to be an d*ck, I was simply trying to bring up an idea. My use of vocabulary may not be at a PhD level but I don't think it's necessary in order to try and throw an idea out there.

#3. I was not saying "feel" as in my FEELINGS. I was simply asking indirectly if what I was wondering made sense (in terms of physics) because to ME it does. I would have been more than happy to have an explanation as to why it does not make sense than to have you be a flat out jerk.

#4. In reply to Newton, you claim that there is no change in Kinetic friction because your foot is not moving against the belt. However, the belt is moving underneath you. When you run, the ground does NOT move underneath you. SOMEWHERE in that comparison, there is a difference. I'm not quite sure if it involves kinetic friction or if it's simply a difference in the amount of GRF, or maybe there is a 3rd factor I am not thinking of. BUT, no matter how much physics I obviously have not studied, I still believe that that is where the difference lies in terms of work performed. I just don't know how to define that in physics terms.

Yes, you are one to talk on ad hominem arguments...

Not trying to argue I'm right regarding the physics. As far as global work done, I WAS WRONG about the physics. So if that's the "score to be settled," which was pretty clear to you, then yes, that score is roommate: 1, me: 0.

The subject/tone of my posts shifted not because I'm trying to argue I was right about the physics, but because I'm still interested in the differences between the two scenarios.

And yes, multiple people said there is "no difference" other than wind resistance, cushioning, etc., so those mutilpe people did "debate," at least in some sense the Benefit question. There is a difference (or so I believe). That difference is biomechanical and it affects how much work different muscle groups are doing.

Scherbatsky wrote:

The subject/tone of my posts shifted not because I'm trying to argue I was right about the physics, but because I'm still interested in the differences between the two scenarios.

And yes, multiple people said there is "no difference" other than wind resistance, cushioning, etc., so those mutilpe people did "debate," at least in some sense the Benefit question. There is a difference (or so I believe). That difference is biomechanical and it affects how much work different muscle groups are doing.

Where did I say you still thought you were right about the physics? My point was you were trying to show that you were right in the fact that there is a difference between the two scenarios(not necessarily the physics) which was never being debated. No one ever refuted that claim.

Thank you for the good example of a "tu quoque" argument as well.

Scherbatsky wrote:

I guess I'm convinced that the amount of work done, globally, is uniform between a graded treadmill and the road hill. I think that the biomechanics side of it is what is confusing to me... The fact that different muscles may be doing different amounts of work in the two scenarios. I found a fairly useful article (that reviews some other studies/papers) that addresses some of these points, including what I meant by the treadmill "pulling" your foot backwards to some extent.

Yup. Your biomechanics change on a treadmill just as much as they change when climbing a rope that is being continuously lowered from the ceiling.

Holy cow, folks! Get a clue.

Neliah2507 wrote:

#4. In reply to Newton, you claim that there is no change in Kinetic friction because your foot is not moving against the belt. However, the belt is moving underneath you. When you run, the ground does NOT move underneath you. SOMEWHERE in that comparison, there is a difference. I'm not quite sure if it involves kinetic friction or if it's simply a difference in the amount of GRF, or maybe there is a 3rd factor I am not thinking of. BUT, no matter how much physics I obviously have not studied, I still believe that that is where the difference lies in terms of work performed. I just don't know how to define that in physics terms.

First of all, yes the ground is moving underneath you, or you are moving over the ground. This is exactly what has been discussed several times in this thread regarding frames of reference, so I am not going to get into it again. There is no difference.

It has been very clearly described and a few people on your side of the argument have realized through the surprisingly civil discussion that the amount of work performed is the same. Your admission of lack of physics knowledge and your belief that there is a difference are in direct opposition of each other. If you do not understand physics, by your own admission, then your "belief" does not hold wait as a physics based argument. It is an unfounded "belief".

Yuppers wrote:

Yup. Your biomechanics change on a treadmill just as much as they change when climbing a rope that is being continuously lowered from the ceiling.

Holy cow, folks! Get a clue.

That is kind of an apples to oranges comparison.

Newton wrote:

Yuppers wrote:

Yup. Your biomechanics change on a treadmill just as much as they change when climbing a rope that is being continuously lowered from the ceiling.

Holy cow, folks! Get a clue.

That is kind of an apples to oranges comparison.

Not really. Please see the following expert opinion and note the absolute correctness of the final four words:

"First of all, yes the ground is moving underneath you, or you are moving over the ground. This is exactly what has been discussed several times in this thread regarding frames of reference, so I am not going to get into it again. There is no difference."

Yuppers wrote:

Not really. Please see the following expert opinion and note the absolute correctness of the final four words:

"First of all, yes the ground is moving underneath you, or you are moving over the ground. This is exactly what has been discussed several times in this thread regarding frames of reference, so I am not going to get into it again. There is no difference."

From a physics standpoint there is no difference between a treadmill and the road, from a bio-mechanical standpoint there is most certainly a difference. Please read Scherbatsky's posts about the bio-mechanical differences.

Newton wrote:

Yuppers wrote:

Not really. Please see the following expert opinion and note the absolute correctness of the final four words:

"First of all, yes the ground is moving underneath you, or you are moving over the ground. This is exactly what has been discussed several times in this thread regarding frames of reference, so I am not going to get into it again. There is no difference."

From a physics standpoint there is no difference between a treadmill and the road, from a bio-mechanical standpoint there is most certainly a difference. Please read Scherbatsky's posts about the bio-mechanical differences.

Ummm.. No. There is no difference. Biomechanics are just physics.

After all, how do you know that the treadmill is even moving (and the hill is actually stationary)? You don't. It depends on your frame of reference.

Don't want to believe it? OK, then how come your biomechanics are not so effected when you run near the equator where you are actually traveling at roughly 1000 miles per hour?

Or how about if the treadmill was truly stationary (in the sense that most folks here think) but the earth magically started moving backward at 8 mph (with the treadmill NOT moving backward at 8 mph). Is there any conceivable way to distinguish this scenario from the 8 mph treadmill and the non-moving earth? So there you are running on a completely stationary surface but your biomechanics are going to differ relative to running on a (wait for it) completely stationary surface?!?!?

Hmmmm..Somehow I don't think so. Please have a bit more confidence in the laws of physics than you do in "expert" testimony.

I am 95% sure I am falling into a troll trap here but oh well. Since you refuse to go back one page here you go.

"A study by Riley et al., (2008) comparing HSR and TMR at the same speed (approximately 13.8 km/h) found that stride frequency was significantly higher and stride length shorter on a treadmill when compared to HSR. These results confirmed those of Schache et al., (2001) and Frishburg (1983) who likewise found increases in stride frequency and decreases in stride length when TMR.

Furthermore, both of these latter studies found a decreased swing phase and an increased stance phase when TMR versus HSR (Frishberg, 1983; Schache et al., 2001) indicating an increased period where the foot is in contact with the treadmill belt.

Biomechanical - Muscular Interactions and Differences:

As the tread belt rolls backward it drags the foot backwards, eliminating the need for the Gluteals and Hamstrings to pull the upper body forward thus making the movement easier; hence its potential lower energy cost (Frishberg, 1983). The Hip Flexors however, now have to work harder to bring the limb, which is being dragged backward, forward. Furthermore, the Frishburg (1983) study found that the lower limb was required to move through a greater range of motion in the stance phase when TMR (X=60.6 vs 54.5 deg). Similarly, Schache et al., (2001) found TMR to have a lower angle of hip flexion at initial contact and considered the increased hip extension position to be caused by the treadmill belt dragging the foot rear-ward. With this in mind, if the Hip Flexor muscles are tight, the increased hip range of motion requirement on a treadmill may cause the pelvis to rotate or the lumbar spine to hyperextend to release the tension on the hip as the limb is dragged backwards. This increased pelvic rotation and/or lumbar hyperextension, which typically occurs with fatigue (which increases stance phase duration) and at high speeds, places strain on the hips and lowerback and has the potential to cause a number of injuries.

It should be noted however that a study by Riley et al., (2008) found no significant differences in hip flexion/extension ranges or pelvic rotation between HSR and TMR. The subjects in this study (n=20) who were regular runners and ran at least 15 mi (24 km) per week, were, however, only assessed over a short period (no more than 15 consecutive gait cycles). Hence these runners would not have been subject to the impact of fatigue.

With the belt moving backwards, the ability of the gastroc-soleus complex (calf muscles) to push off is reduced (Riley et al., 2008; Baur, Hirschm, ller, M¸ller, Gollhofer, & Mayer, 2007) and these muscles must work harder in order to achieve an effective push off. This is one of the reasons why you tend to power walk when you transition from the treadmill back onto hard surface – your calf muscles have been activated more than usual for hard surface locomotion. Furthermore, research has shown that running on the flatter, predictable surface of a treadmill requires less ankle stabilization than that required for running across land, with muscles like the peroneals found to be less active when TMR (Baur et al., 2007)"

Unbelievable. Just unbelievable.

OK, my friend, go ahead and analyze what was already posed:

"Or how about if the treadmill was truly stationary (in the sense that most folks here think) but the earth magically started moving backward at 8 mph (with the treadmill NOT moving backward at 8 mph). Is there any conceivable way to distinguish this scenario from the 8 mph treadmill and the non-moving earth? So there you are running on a completely stationary surface but your biomechanics are going to differ relative to running on a (wait for it) completely stationary surface?!?!?"

After all this thread I didn't see anyone who actually WENT OUT AND TRIED IT. Thats what I just did I went outside theres a hill near my house thats at an 8% grade and 427m long I went out and ran up it in 98 sec so thats 9.74 mph so I rounded to 9.8mph and hit my treadmill at 8% incline and did the same thing and RUNNING UPHILL WAS HARDER. A lot harder actually and I know why.

What many of you are missing is that IT TAKES ENERGY TO LIFT AN OBJECT. The basic fact remains that the force due to gravity is overcome completely and then some to accelerate you upwards when you are on a real hill but the normal force of the treadmill overcomes some of the gravitational force and you only match it so it takes far less energy