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

I already touched on this in a previous post. In all of these posts I see two kinds of arguments. There are those that say that the treadmill changes running mechanics JUST because the running surface is moving whereas the ground is not moving. Then there are those that argue about the effects of air, inclination, motors, etc. on running mechanics. I presented an example of a mile wide, mile long, treadmill to illustrate how the mechanics of running on a perfectly steady treadmill would be the same as running on the ground. I also noted that low quality treadmills with excessive friction, and/or undersized motors will have more difficulty in controlling belt speed which can affect a runner's reactions, which can alter mechanics. It is my position, however, that the belt speed variations in high quality treadmills are very, very small and insignificant for changing running mechanics. Running on crushed gravel will produce more changes than running on a good treadmill.

People also argue about the effects of air and inclination. Yes, running on a treadmill at 7mph is like running outside with a 7mph tailwind, but then there are no cooling effects either. These things primarily affect effort level, and any effects on running mechanics by these things are the same as running outside with wind and hills. I run 7 days/wk and generally run on the treadmill 2 or 3 of those days. I don't use the treadmill for just easy runs, I also like to run tempo on the treadmill because I can dial in the exact pace that I want. I can also compare workouts because the variables like wind, temperature, elevation, etc, are fixed in comparison to running outside. I also run tempos outside on the track and I typically end up doing about the same paces with the same effort level on good weather days.

I have run on crappy rickety treadmills, and sure, they don't feel the same. Maybe that's what gets people worked up about treadmills. My view is, if a person is concerned about the treadmill altering their running mechanics then they had better not run on off-road trails or crushed gravel, and instead had better stick to running on nice flat, hard cement.

me again wrote:

me have a question wrote:

If a 2% grade is used on a treadmill, how does that affect one's foot-plant? If the grade is increased to mimic the effort of a flat outdoors run, does the foot-plant difference cause any kind of effect?

Also meant to ask, why not just bump the speed up some percentage?

This. What's the point of running uphill for your entire run?

I am nominating this thread for best thread of 2018. Just too much good info in it.

As always, thank you for your deep insight mr 430miler.

-Macy from Iowa