Is Full Motor Unit Recruitment Required For Growth?

D

Daniel1995

New Member
Can a muscle fiber grow if it is not actively recruited during a set? Is full recruitment something we should be pursuing in our training? Would love to hear a detailed reply from Bryan on this
 
Welcome Daniel, good to see another Aussie on board!

I don't believe full recruitment is necessary, but I guess it depends on what is meant by that exactly (whether it means just having a muscle switch 'on'/contract in general against a load, or full activation which is training closer to failure)...

I'd also love to hear Bryans thoughts on this too (and particularly regarding myoreps, as myoreps is based on making more reps effective by getting more volume at the full recruitment end)
 
I think I can say pretty confidentially, that muscle 'fibers' can grow, which means the muscle they reside in, would in effect 'grow'. think of endurance people who have type 1 hypertrophy and very little type 2 hypertrophy. I'm sure they aren't fully recruiting those muscles very often so the motor units doing less, would get less to zero stimulation.
If you look at how recruitment works, you can see that many motor units are as 'activated' as possible very early in the set, as the set progress, more and more 'activate' more (higher rate coding), so as you approach failure, the larger last recruited motor units are finally active enough to experience fatigue.
 
I supppse the question I want more directly answered is whether sub max loads can be just as effective than maximal loads at achieving a growth response despite the fact that full motor unit recruitment isnt occurring.

I often hear people say that full motor unit activation is required for maximum muscle growth. Which would suggest that high intensity protocols (whether its lifting at >%85rm or training to failure) will achieve more recruitment and therefore more growth. However, this goes against hst and the use of sub max loads as you wont be achieving full activation until the end of every two week block. So, is full motor unit recruitment required for maximum musclw growth? Is it something we should be pursuing in our training by implementing such loading strategies such as myo reps?
 
Daniel1995 said:
I supppse the question I want more directly answered is whether sub max loads can be just as effective than maximal loads at achieving a growth response despite the fact that full motor unit recruitment isnt occurring.
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Submax still can not only fully recruit, but fully activate, IF neural output is maximized (full effort).

I often hear people say that full motor unit activation is required for maximum muscle growth. Which would suggest that high intensity protocols (whether its lifting at >%85rm or training to failure) will achieve more recruitment and therefore more growth. However, this goes against hst and the use of sub max loads as you wont be achieving full activation until the end of every two week block. So, is full motor unit recruitment required for maximum musclw growth? Is it something we should be pursuing in our training by implementing such loading strategies such as myo reps?
Click to expand...

I think you might be mixing up full recruitment with full activation.
For example, the biceps usually have full 'recruitment' at 65% volitional effort, or you could think of it as first rep with 65% of 1Rm has full 'recruitment'. But, as the set progresses, rate coding and synchronization increase with each rep, so even though all MU's have been recruited the whole time, their firing more often , more 'at once', with each rep as fatigue occurs.

With HST, you would get quite a few training days where for sure, all motor units are not only recruited, but highly activated and maximally activated on the last couple days of that RM section.

I don't think a person could do a set with even a 1/2 way decent load, and 'not' get at least full recruitment by the end of the set. You'd have to use a really light load and stop way before failure.
 
Ah, okay I understand the difference now. So, can a muscle still sufficently grow without full motor unit activation? As when training with submax weights in hst you wont achieve 'full' activation, so im wondering how significant it is and whether 'fatigue' is something we should 'chase' in order to achieve this.
 
Daniel1995 said:
Ah, okay I understand the difference now. So, can a muscle still sufficently grow without full motor unit activation? As when training with submax weights in hst you wont achieve 'full' activation, so im wondering how significant it is and whether 'fatigue' is something we should 'chase' in order to achieve this.
Click to expand...

Yes, for sure. Most of my training has been sub-failure, I rarely train to failure and I have grown doing that.
Also, just for clarification. Many motor units will still hit 'maximum' activation, even with less than full effort.
Think of the motor units like this,
Imagine you have 10 car engines, each representing a motor unit
If the engine is running, that's recruitment
How hard it's revving, that's 'activation/rate coding'
OK, first engine starts up, it's recruited
as it revs up, when it hits 3000 RPM, the next engine 'starts
The first one keeps revving up now it's redlined, the 2nd one is now at 3000RPM so the 3rd engine starts
The first one stays at redline, second revs up to redline, 3rd one now at 3000RPM so the 4th engine starts
etc.
You could get to a point where the first 6 are redlined and the next two are running but not quite redlined and thet last two are just running.
So all are recruited but only 6 are really working, 2 are working pretty hard and 2 are working but just not maxed.
 
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