How could an animal run fast using blade-like feet that sink into spongy ground?

In my fictional planet, forests grow not on soil, but on vast spongy mats of fungi. Traditional Earth-like feet would struggle to get grip on the squishy ground, so most megafauna taxa have feet like blades that cut into the fungus.

A very rough drawing of a classic fauna example from this world

On this world, however, I want to have cursorial predators, like cheetahs, with high speed and agility. The thing is, I'm not sure if the "feet sinking into ground" idea would impair their speed.

So, what I'm asking is: How would such a (quadrupedal) predator run, and what anatomical/morphological adaptations would it have to do so?

I suppose you'll need more clarification on the "How would it run" part, so this is what I mean:

On the diagram below (Note: that is not what the creature actually looks like) I've labelled the respective feet 1, 2, 3 and 4.

When a leopard runs, it puts one foot forward at a time, so its running style would be like this, going by the diagram:

1 - 2 - 3 - 4

A running cheetah brings its two forelegs forward, then its hind legs, like this:

1,2 - 3,4

Which style would be more suited to running with blade-like feet in springy, spongy ground?

Then, the second part of the question was "What anatomical/morphological adaptations would it have?". By this, I basically mean stuff like the shapes of the blade, overall build, spikes on the blades for grip, etc.

So, if I was to sum up the ideal, but not necessarily required, qualities, it should be able to:

• Run at over 100 km/h
• Jump 10 metres horizontally
• Jump 4 metres vertically
• Accelerate at 9 m/s

Answering with A) Which running style, and B) Morphological adaptations, what is the closest the creature could get to those abilities?

EDIT: Just had another idea. What about a second, smaller blade, perpendicular to the big one, that helps pull the creature back out of the sponge? Here's another very rough drawing to help you visualize it:

posted over 6 years ago

SealBoi‭

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