Motor Unit recruitment in Pause Squats

[Neal]

Hi, Coaches -

First of all, I have some understanding of the importance of the stretch reflex in the squat, and why it should be trained. This is not a veiled attempt to get permission to switch to an "easier" lift.

I'm doing HB Pause Squats as a light day squat on HLM. I haven't done Pause Squats in a few years, and have absorbed a lot more information in the interim. I was thinking about how "hard" it is to accelerate the bar out of the hole following the pause even in the earliest work reps/set, despite the relatively low intensity. That brief moment feels very similar to pushing through the sticking point under much higher intensity and in later sets/reps. I'd heard or read recently that as fatigue builds up across reps/sets under challenging loads, that forces the body to become more efficient and recruit more and more motor units. Does reducing the stretch reflex with the pause necessitate drastically more motor recruitment to initiate the concentric despite minimal fatigue and lower relative intensity?

[Steve Hill]

Drastically more? Probably not. More? Probably. The stretch shortening cycle (SSC) functions to (under some current thinking) return elastic energy from various structures in the muscle / tendon system, as well as coordinate the firing of muscle tissue that is under eccentric contraction; which, by nature, makes that firing more efficient than a volitional contraction, such as that necessary in a pause squat.

[Neal]

Thanks for the reply. Sorry if I'm being a bit dense. At the beginning of your response, it seems like you're saying the pause probably leads to more motor unit recruitment, but at the end it sounds like you're saying the SSC may "coordinate the firing of muscle tissue...[and]...makes that firing more efficient than...a pause squat." That sounds like you're saying the SSC actually leads to more motor unit recruitment than a pause. Would you mind clarifying a bit more for me?

[Mark Rippetoe]

The point of using the pause is to make the movement less efficient in terms of motor unit recruitment, i.e. harder. I believe this is in the book.

[Neal]

Found the section in the book. Pg. 237. It's in the index under either "Squat, Partial," or "Squat bounce," and that's how I overlooked it. Thank you for referring me back.