Muscles contract thanks to two protein filaments: thin actin chains (carbon-based) and thick myosin motors. At rest, a safety protein blocks the docking sites on actin. A nerve signal releases calcium, which removes the safety and opens the way for motors. But activation isn’t solitary: the first attached motor pulls the filament and, like a flipped magnet, triggers neighboring regions to activate.
Physicists described this with a model of a chain of magnets: once one flips, neighbors follow suit, and this cascade is tied to changes in the system's entropy.
The drug Omecamtiv mecarbil disrupts this magnetic crosstalk: neighbors stop sensing each other, and contraction weakens. All this happens in the watery environment of the cell.
One gram of muscle tissue can generate up to 30 newtons of force — about the same as holding a 3-kilogram dumbbell with one finger. This results from the synchronized work of millions of molecular motors.
Sci-fi tales of artificial muscles made from carbon nanotubes become a bit closer to reality thanks to models like these.