You’ve just started strength-training and you’re wondering when the results are going to appear. Recent research advises patience: While you’re waiting for your bulging biceps, what’s really bulking up is a primitive part of your nervous system.
Researchers at England’s Newcastle University suggest that weightlifting builds muscle mass by first strengthening one of the two major neural highways that travels via the spinal cord to the muscles. It’s only after those neural signals become stronger that your muscles experience the salutary effects of pumping iron.
Working with monkeys, Isabel Glover, PhD, and Stuart Baker, PhD, measured arm strength by stimulating the motor cortex and the two spinal pathways — the corticospinal tract (CST) and reticulospinal tract (RST).
The CST had been considered the dominant neural highway, with the RST mostly associated with posture, but they found that the CST remained unchanged during resistance training.
Stimulating the RST, though, triggered a greater response in the part of the spinal cord connected to the arm, suggesting that strengthening a specific neural signal is a precursor to building muscles.
“We showed that the more indirect pathway seemed to be responsible,” Baker notes. “This is important, since we’ve shown in the past that this pathway also helps people recover after a stroke. Improving the function of a hand rendered weak by a stroke might be using the same mechanisms as strength training in a healthy young bodybuilder.”