What you see in the photo are the wax-filled carbon nano-tubes woven and twisted into yarn fibers about twice the thickness of human hair. They are considered muscles because when electricity is sent through the material, the yarn contracts just like muscles do but in this case they are able to lift weights 50,000 times greater than their own weight. Compared to a normal human muscle fiber - at the same size - these yarns can lift 200 times what the muscle could do.
Not only can they lift these heavy weights, the contractions are ‘ultrafast’ meaning they could be used in robots as artificial muscles, micro-motors and used for surgery. Sadly though, these are not yet transplantable into humans so no super-strength just yet. But another cool property of this is that they can operate at temperatures well above the melting point of steel meaning they could replace industrial actuators in the future.
Here is a video of how it works when it is heated