Eccentrics use less motor units?

[xi xia]

You have to realize that during a negative you're only using about half the motor units you normally activate during a concentric contraction. That means you are actually training fewer muscle fibers, which is why a literal plethora of studies have shown negative-focused strength programs do not provide significant gains compared to using both concentric and eccentric.

I am starting training for an OAC and saw this post on another recent OAC negative thread. This statement about negatives using half the motor units did not intuitively mesh with what I have learned and observation.

Being a pessimist, I searched scholarly journals online and found a few articles dealing with EMG activity of concentric vs eccentric action. Some of the articles did report less EMG activity during eccentric. One in particular cited other research showing same or MORE EMG activity during eccentric.

In the articles that report lower EMG activity, the research method for eccentric action does not seem to be anything like what happens in the training environment. Many of the examples had the person strapped into mechanized device that controls rate of movement. Others were done on the leg muscles and reported EMG activity during plyometric activity.

I did not do an exhaustive review of the literature.

Slizzard or anyone else, can you provide links or direction to the plethora of articles you are referring to? Thank you!!

Xi Xia