How would Superspeed be Explained?

Question

In the comics, superspeed,- being the ability to move (in particular, run) at speeds typically at least as fast as something like a racecar), whenever it is shown, seems to tend to have the explanations as to how it works being something along the lines of:

1. That it's a relative of the power of superstrength, or
2. That it works by having interdimensional lightning flow through one's body, letting him break the laws of space and time.

Trying to come at it from a less vague point of view, though, if we (all impossibilities aside) start with the assumption (for the sake of argument) that a character has the power of superspeed as defined above, what's a more detailed and plausible-sounding explanation for it? Would increasing muscle strength (albeit quite exponentially) be all it would take? Would he have to be a cyborg who has high RPM servos instead of regular joints? The less "magic" an explanation requires, the better.

P.S.: Bonus points for explanations as how the other side of superspeed so commonly portrayed in comics could work,- being the ability to think so fast that you perceive everything around you as moving in slow-motion.

Answer 1

It's about power.

Human runners are limited by how fast they can get oxygen and nutrients to their muscles (aerobic respiration/aerobic exercise). Sprinters tapping stored energy reserves can go faster than marathon runners.

There are other limits, of course. The speed at which the muscle contracts depends in part on how far a myosin head can pull the muscle given the energy from hydrolyzing one ATP molecule. The speed of nerve conduction depends on how far the voltage can be "felt" by a voltage-gated channel, which depends on how high that voltage is, which depends on how strong an ion gradient is maintained, which depends on the energy spent moving every last ion to one side. Above all, there is wind resistance - just as fast speed limits are being targeted by those seeking to reduce carbon emissions, fast runners will need a lot more energy to go the same distance.

Because all the limitations come down to power, you need two things above all:

1. more energy to the tissues faster. Perhaps there are electrical channels or batteries worked into the biology, rather than only circulation. Perhaps there are incredibly potent chemical or physical energy storage mechanisms in or near the muscles.

2. more heat dissipation. Humans (some humans, not me) are already great runners. To do that, humans developed eccrine sweat glands all over their now-hairless bodies to try to dump as much heat into the passing air as possible. In your case, you might tolerate greater heat levels (so now you lose more energy per second in a hotter breeze behind you). Maybe you can build in some "regenerative braking" to recover energy from fast-moving muscles rather than losing it as heat. Maybe you can catalyze neutrino pair production inside your body and they carry away huge amounts of thermal energy.

If you can get the power to the muscles and the heat away, the rest is just a matter of engineering. That isn't to say it would be easy! :)

Answer 2

The Plutonian, from the comic Irredeemable, has an interesting take on this. He's a Superman-type hero, which looks like he has very strong physical powers, while in fact the root of his might is psychokinesis.

He unconsciously micro-manages the space around him, making him look indestructible, or moving molecules very fast so they end up looking like some kind of laser beam.

One of the difficult thing to explain with super fast characters is how they deal with friction, and how they are able to actually move without causing explosions. E = MC² and stuff: the faster the movements, the more energy they need AND the more energy they release, hence magic lightning and narrative hand-waving.

By micromanaging the space around him instead of just being very strong, your character can actually, you know, not cause small nuclear explosions. Keep his clothing intact. Actually move stuff while being super fast without straight up destroying them through the sheer power needed to move at that speed.

And your character don't even need to know how he does it.