Researchers at the University of Texas have created artificial muscles that are 100 times more powerful that human muscles. The two different types of muscles both consume Oxygen and release the energy in hydrogen and alcohol to do work. One version converts the chemical energy into heat which contracts at shape-memory allow. The other version converts chemical energy into electrical energy which contracts a series of carbon nanotubes.
"The muscle consumes oxygen and fuel that can be transported via a circulation system; the muscle itself supports the chemical reaction that leads to mechanical work; electrochemical circuits can act as nerves, controlling actuation; some energy is stored locally in the muscle itself; and, like natural muscle, the materials studied contract linearly."
Next up is a circulation system to let the muscles "breath."
Jack LaLanne would be impressed.