Peak muscle performance needs two separate forms of the nNOS protein, according to a new study.

Research at the University of Washington in Seattle, US, has shown that the nNOS-beta protein is crucial for skeletal muscles in mice and not just the nNOS-mu protein.

The scientists said in the Journal of Clinical Investigation that nNOS-beta is a “critical regulator of the structural and functional integrity of skeletal muscle”.

In essence, during exercise, nNOS-mu signaling maintains blood delivery to active muscle, while nNOS-beta regulates muscle fatigue resistance and post-exercise force output.

Muscles lacking both nNOS-mu and nNOS-beta exhibited profound muscle fatigue and post-exercise weakness.