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Comment by pmcarlton | Hacker News Reader

It takes a few clicks to get to the supplemental data movie:

https://rs.figshare.com/articles/media/a_participant_running...

You'd probably want to switch directions often!

The ankle flex when the right foot lands makes me wince every single time. I wonder how much that's to do with the direction of gravity, the angle of their body looking not quite horizontal (and therefore 'weirding' the angle that feet hit the ground), and how much is to do with the individual's physiology.

You could build it with a slight angle. Or gradually steeper like a high speed race track.

The ‘bowls’/balls used for motorcycle stunt riding might be good examples for this (and could be fun).

In actual lunar gravity the forces should balance out. At a particular speed, tied to the wall angle, the forces should align with the floor to let the foot land as if running on a horizontal surface. Imaging a motorcycle in a turn. Then tilt the road to match the bike's lean angle. The tire/foot then falls flat against the road.

due to the angles, it would be like running in a circle on earth. It is mostly a question of what the equivalent earth track diameter is. It can be quite painful and damaging to run in small circles.

Why? The bungee cord is only needed for earth gravity.

Because the moon still has gravity, and there would be some asymmetrical force on your legs either which would be reversed if you went the other direction. So switch directions all the time to be less lopsided.

The moon has a sixth of earth gravity. The force you would feel would be very small and the whole point of this is to increase the resistance against the wall you’re running on.

If you’ve ever been on a spinning wheel at a carnival where they move the whole thing 90 degrees it would be a bit like that.

The track would actually be straight, so you wouldn’t have to compensate for turning even.

I’m not saying you wouldn’t want to switch directions, but there shouldn’t be some imperative to do so often.

The runner will feel a pull to the left, as if the track had a slope in that direction. I wonder if that could give motion sickness to somebody. Probably people sent to the Moon will be selected against that because of the journey to and from the Moon but I really have no idea about that.

Another problem, as pointed out by someone else in the comments, is that the floor is not flat but points upward and the feet and ankles might feel that. Furthermore it's another possible source of motion sickess (flat but not flat.)

It's not a symmetric exercise, look at the feet. You'd probably want to keep the overall workout balanced by alternating periodically?

I.e. “don’t skip the left day!”

It's because walls are a bit too steep. If you made them into paraboloid, a per would naturally climb as high as they need to, to be able to run symmetrically.

But one leg will still be running a shorter distance then the other.

This is steaming my brain a bit. Is it not the case (assuming an "optimal" tilt of the track) that the inner leg would travel more radii each step, meaning you would travel a larger segment of the circle on every inner step than outer step, ending up with an equal gait? This is my intuition without any formulated proof.

Person running would need to constantly turn a bit to one side to not climb further up the wall. So it shouldn't be much different from running in circles on flat surface.

Not sure if runners that train by running in small circles are concerned about evenness and try to run the same amount clockwise and counter clockwise to even things out.

Ex collegiate track and XC athlete, yes, we'd alternate directions once in a while when doing long workouts on the track. It's a 36.5m radius, and it does get to you eventually. You feel it in your knees long before your ankles. I ran distance events (1500, 3200, 5k), so I think I had it easier than the 200m and 400m guys (and especially the 400m/300m hurdle guys) whose spikes were desperately clawing at the track to hold the turn, but I did have some workouts with a lot of laps. We didn't bother to make it exactly even, but if we were doing ladder workouts we'd switch directions somewhere near the middle.

Indoor meets often had 200m tracks with tighter (frequently nonstandard!) radii. The good ones were banked, though it never seemed to be at the right angle, always too steep or too shallow.

Every race still goes counterclockwise, though.

Maybe it's my XC side talking, but I'd love to see a track in a figure 8 with an underpass. Left turn, over the bridge, right turn , under the bridge, and repeat! It would break up those monotonous 8 and 12 lap races nicely, and you could fit a longer track in a shorter rectangular building by using the hypotenuse. I'm sure people would hate the hilly incline, though...

That would be extremely interesting, but the fact that you have an incline would change the ideal body type and tactics so much it would be a different sport at that point.

But I would love to see it for medium distances, just to see what crazy stuff would happen!

I did HS sprinting as cross training for fencing. Fencing is extremely asymmetric, to the point where my right (front) leg could lift twice the weight of my back (left) leg. It was freakish, and probably not healthy lol. It made my sprinting coach really uncomfortable, because my stride looked weird on the straights.

The curves felt great for me though, I really liked the 200m better than the 100m. Can't imagine how shitty it'd have been for a left handed fencer to run track, because the big muscles would be on the inside leg.

Yes for sure. Track running can result in injuries on the left side usually in the foot/ankle area.

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