Treadmill vs. Real Hill: Which is harder to run - Steve Mould

Just based off of the thumbnail, it makes sense

I used to run rc cars and trucks back years ago, and battery life really was influenced by the combination of terrain/surface and the tires.

Let's say that with flat rubber tires on asphalt, you get five minutes of run time on a specific battery.

If you change the tires only, to something with a tread, you end up losing an almost unnoticeable amount of run time, but if you're timing your runs, the difference is there.

Leave the same tires on, but switch to something like packed clay, and not only do you lose run time, but you can clearly see the loss in traction; you'll be sliding more in the corners, and likely having some degree of spinning on starts (depending on your setup). Switch to treaded tires, your run time notches back up a little, and you're slipping less.

If you're doing hill climbing, or rock climbing, you'll see a similar shift in run times based on grass vs loose soil, vs packed soil, etc. no matter what tires you're running, with the tires serving to shift run times upwards depending on how little slippage you get during a run.

Now, you might not notice any of that in timed trials, but if you're just out there fucking around for fun, and you only bring X number of batteries, and someone else is running the same surfaces with different tires, but a similar build otherwise, there's a decent chance that one of you will run out of batteries sooner than the other consistently.

There's a shit ton of energy "wasted" when tires are slipping instead of gripping.

The same is true when you're out hiking, though it comes with a big safety issue as well. If you're on a surface, like mixed pebbles, soil, and it being fairly loose, your feet are going to have to dig in deeper, and will likely "waste" part of every step as the soil shifts and moves under you. The better the traction, the less effort each step up a hill takes. More of your energy is being directed into forward movement on a grippy surface than a loose one.

You don't even need to be slipping to feel the difference, just go try walking on a beach after walking on a sidewalk to get there. Every step takes more effort to move forward, and it's even detectable without paying much attention.

Treadmills are optimized for a stable surface out of the gate; for safety, and for the necessity of moving parts. Makes total sense that they're going to be more efficient to work on than a less controlled surface, even when all other factors are the same. You could do their experiment with a fan to mimic air resistance, and I guarantee you that it wouldn't account for more than a tiny fraction of the difference in power used.

There's more than one reason we pave roads and sidewalks