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

Bad Wigins wrote:

areusure? wrote:

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

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.

I wonder if you're overstriding. It seems to make sense to me that the biggest advantages to running on a treadmill come from someone overstriding.

This is a very interesting post to me because I've always felt the exact opposite...

For me, it's always felt more difficult to run the same pace on the treadmill as I run outside. I understand all of the reasons stated as to why the treadmill should be easier but for reasons that I cannot understand it is much more difficult on the treadmill for me.

For example, a typical run for me outside at an easy effort might be somewhere between 8:00 and 8:30 pace. My HR at this effort will float around 130 bpm. What's strange is, when I run what truly feels like easy effort on the treadmill, I'll have the speed set to somewhere around 6.5 mph which is well over a 9 minute mile. Oddly enough, my HR will be closer to 120 at this speed. In fact, my HR seems to correlate very closely between my speed on the treadmill vs my pace outside despite it feeling more difficult on treadmill. In other words, forcing the speed on the treadmill up until the point that my HR begins to settle around 130ish bpm will result in approximately the same pace/speed as I would experience outside despite the fact that it just FEELS like so much more effort on the treadmill (even though my heart rate response can't tell the difference). I know this sounds crazy but it's my experience.

Just wear a heart rate monitor and train by heart rate forget the speed.

How is your momentum propelled forward on a treadmill because the belt is in motion?

The belt is going backward with respect to you. You have to combat that. I agree, though, that the TMill

is easier, and not just because of the fact that your torso and head are not going through the wind (your arms and legs are

moving through the still air of the gym). I think that the belt pulling your foot back after contact may involve less energy cost or maybe you can just trick the tmill by a bouncier stride that is in the air for more of the belt's motion, making it seem that you are running further than you actually are. This may be a particularly big issue when you set the TMill to a high speed. That might be what allows me to do 5M tempos @1% in high 25 to low 26 when I'm in shape, while never having run sub 26:40 on the ground.

Bad Wigins wrote:

areusure? wrote:

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

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.

Actually no it doesn't. Think about what is happening in the time interval when the foot is in contact with the ground. This time interval is not zero.

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...

Depending on where you are, running on the road or treadmill, the ground beyond your feet could be moving at hundreds of meters per second due to the Earth rotation. The reason you don't feel that is that your body is at rest relative to the surface of the Earth just below, because you move at the same speed.

Assuming that you run at constant speed, it should make no difference at any point during the motion whether you are stationary above a moving surface, or moving above a stationary surface. The difference (apart from air resistance, different surface etc.) would have to come from the fact that, when you are running on a road, you do not run at exactly constant speed throughout your stride, while the treadmill is always moving at constant speed underneath you.

You lost all creditiihillbilly when you opened with "so, ............"

Just stop with the "treadmill pulls your leg/foot back" please.

It doesn't.

If you think it does - try an experiment:

Set the treadmill to 6:00 pace while standing on the side, then hop on the treadmill with only one foot and exert no energy once you land. How far does it pull your foot back in this case?

hossrunr wrote:

Just stop with the "treadmill pulls your leg/foot back" please.

It doesn't.

If you think it does - try an experiment:

Set the treadmill to 6:00 pace while standing on the side, then hop on the treadmill with only one foot and exert no energy once you land. How far does it pull your foot back in this case?

The treadmill aids in pulling both of your legs back and helps you throw every single stride.

That being said, I think that's the main reason why treadmills are so extremely easier; low and behold.......we are omitting the almighty and powerful factor of treadmills having easy access to bottled water. You don't have access to a nice cold water when you are running outdoors. I'd say this adds 4 percent to the easiness, to where the electrical belt helping you throw each stride helps you another 96 percent.

God bless.

Cool, if you're not a troll (you are) - go ahead and do the experiment and post a video showing us how far back the treadmill pulls your one leg.

I would've thought running on the ground is harder simply because you have to push the ground to move forward while on a treadmill you just have to turn your legs over to keep up. When your foot lands on a moving treadmill your leg could even rest somewhat because it only has to support your weight and doesn't need to push at all.

maybe I'm slow wrote:

I would've thought running on the ground is harder simply because you have to push the ground to move forward while on a treadmill you just have to turn your legs over to keep up. When your foot lands on a moving treadmill your leg could even rest somewhat because it only has to support your weight and doesn't need to push at all.

EXACTLY

.[/quote]

Can't tell if you're an idiot or a good troll[/quote]

True gold here at LRC.

Shieeeeet.

Someone’s gotta draw a force diagram! I ain’t a physics major, but I met someone really special in my introductory physics class.

Shieeet. Shieeeeeet. It completely devastated me though.

Shieeeet...

I hope to have time to read the responses to this later. For now, I will hypothesize that most of the decrease in difficulty comes from the absence of air resistance, and you can more closely replicate outside running by having a large fan blowing at your front while treadmilling.

No, you're not the only one. Treadmill running requires slightly more conscious effort for me, but this increased "effort" doesn't correlate with increased HR (or any other physiological cues that my body's working harder). It might be psychological.

I'm the exact same way. I've documented it at a variety of paces and effort levels as well. I'm assuming that it has something to do with something in our biomechanics and perceived effort since the heart rates correlate to what you would actually see. For example, if you ran over 9 min pace on the roads your heart rate would probably drop closer to 120 bpm. I'm assuming on the biomechanical side that something with how we run is thrown off by the treadmill but it really doesn't make any sense to me. Hopefully the thread continues and suggests something that makes sense.

Also, a lot of treadmills these days have fans. Not sure if that's sufficient enough airflow to overcome the lack of wind resistance while running but it probably does something.