Muscles, where do they get their power from?

Doctors have a new way of thinking about how to treat heart and skeletal muscle diseases. Body builders have a new way of thinking about how they maximize their power. Both owe their new insight to high-energy X-rays, a moth and cloud computing.

The understanding of how muscles get their power has been greatly expanded with new results published online July 10 in the Royal Society journal Proceedings of the Royal Society B. The Royal Society is the U.K.'s national academy of sciences.

The basics of how a muscle generates power remain the same: Filaments of myosin tugging on filaments of actin shorten, or contract, the muscle — but the power doesn't just come from what's happening straight up and down the length of the muscle, as has been assumed for 50 years.

Instead, University of Washington-led research shows that as muscles bulge, the filaments are drawn apart from each other, the myosin tugs at sharper angles over greater distances, and it's that action that deserves credit for half the change in muscle force scientists have been measuring.

Researchers made this discovery when using computer modeling to test the geometry and physics of the 50-year-old understanding of how muscles work. The computer results of the force trends were validated through X-ray diffraction experiments on moth flight muscle, which is very similar to human cardiac muscle. The X-ray work was led by co-author Thomas Irving, an Illinois Institute of Technology professor and director of the Biophysics Collaborative Access Team (Bio-CAT) beamline at the Advanced Photon Source, which is housed at the U.S. Department of Energy's Argonne National Laboratory.

Source: Science Daily