T Nation

What's the Theory Behind Low Reps for BBing Purposes?


I don't mean like basic 5x5 or w/e I'm more talking about stuff on the "regular guy offseason training article" or Thibs new video all of their reps were short and CW talks about low reps for hypertrophy all the time. I find it interesting but I don't know much about it I'm hoping someone can give me the "science" about it.


Erm. Well, this is just based on past information I've gleaned from Thib's other articles, but I presume that the lower reps are to increase muscle fiber recruitment and stimulate more fibers, thus resulting in hypertrophy of more fibers leading to more growth. Or something like that. I might be completely missing the mark on your question.


heavy weight for a short duration espically when done esplosivly relies on fast twitch motor units to be recruited due to the fact that they are larger more powerful fibres, they are also the fibres responsible for the size and strength gains you will see, unfortunally they can only maintain and contract for roughly 15 seconds or less before they become fatigued and slow twitch fibres will than predominatly take over which are endurance fibres and relativly small and weak comparing the two.


Lifting heavier things means you have more muscle given your body weight is going up.


I'm sorry, this is pretty much totally incorrect.


Low rep training infers you are training at high relative intensities (%1RM over 80% for example).

As you require your muscles to generate more force, or tension, your nervous system drives the muscles harder which in turn tends to recruit your higher threshold motor units, which drive your large type II muscle fibers.

You tend to recruit more high threshold motor units with higher load, and if the load is progressively lifted for more repetitions (obviously the total amount of reps you can lift at a high intensity varies between individuals).

Your type II muscle fibers are very responsive to the intensity of your lift, the higher the relative intensity you lift at the more hypertrophy (increased fiber size) you will see in the type II fibers.

Type I fibers tend to hypertrophy to a similar level regardless of the intensity used.

The level of fatigue does not mean you will recruit different types of motor units. If you are lifting a heavy load, it is not possible to recruit more type I fibers as you fatigue to help the lift as they simply are not strong enough, and more importantly, they more than likely have already been maximally recruited (Henneman's size principle if you want to go read something else).

The mix of volume vs intensity, and other issues about how many reps per muscle group tend to work, are interesting discussions that have been raised in the T-cell.


Motherfucker knows his shit!


Good stuff, why do they tend to use a smaller range of motion?


Dude, I'm really glad you're around (after looking at your next post.)

There is a small light in the '09 chasm.


Great little write up. I actually printed that out to give to a couple of kids at my gym who keep asking me the same damn question at least once a week -lol



That is pretty cool of you to do for them. Shit I think it is pretty badass that you even thought of them.

And yeah GG is the man too.


Actually it's not totally incorrect except for the odd "15 seconds for slow twitch takeover" comment... they'll come in a lot faster than that. I guess he was basing that off the duration of the phosphate system. When you lift something "esplosivly", you recruit both fast and slow twitch motor neurons at once. Alpha motor neurons innervating type II fibers have the fastest rates so they end up contracted prior to type 1 fibers, and the size principal goes out the window in this situation.

The fact that you can sort of selectively recruit fast twitch muscle fibers is the main theory for low reps for BBing purposes.


this is how i understood it

doing the really low setts with really heavy weights primes ur cns system and recruits more motor units in ur muscle as welll as increasing ur max strength rather than making u bigger. How it works is that this makes u prime condition for bbing. Now when you do you higher sets forr hypertrophy, you can lift heavier for longer, and u muscle's will build more muscle more efficiently since there will b more motor units present during excercise.

so low reps prep u body so itcan gain later at twice the rate. thats how i understood it


So would it be "smart" to do a workout where on lift is like 5x5, say like bench press. Than one at 3x12-15 for that full hypertrophy zone, and a lift of like an 8x3 or 6x4 where the lifts are really explosive. Or am I confusing myself. Thx for the input guys.


i think you confused yourself son. i seem to notice that most strong people are stronger now than they were. so i would assume progression is the key factor. progression is the requirement, while methodology is subject to personal evaluation


It's not about low reps, it's about the amount of force required by a given muscle. You can lift something explosively with a moderate-low load and generate significant power, greater than that lifting with a higher load, but not elicit any increases in muscle size.


Confusing yourself...., follow the "big guy" principle. You don't see the big guys training all over the place like this, so stop worrying yourself. Keep it simple, train heavy (& frequently per muscle group per week, but I've made my thoughts on that clear elsewhere :-), eat lots of 'good' food, rest well, and that will be $1000.00 - I accept Paypal :wink:


Its all about the CNS !


But....but "big guys" are stupid. They say so here every day about how they don't know how to train and only got big by accident because of genetics and drugs. So why should we do what the big guys did?

What needs to be abolished is the idea that a specific number of reps produces a specific result in and of itself. I am not sure where that idea took hold, but it is as if some of them actually believe "12-15" reps somehow produces "hypertrophy" simply because you did 12-15 reps.

Somewhere along the lines, the idea that PROGRESSION is what produces growth fell by the wayside.

My guess is, the idea that big muscles are weak helped that thought process along.

I lifted with "low reps" for the majority of my training life because fast twitch muscle fibers are responsible for the most growth and while there seems to be documentation of fast twitch taking on characteristics of slow twitch muscle, I do not believe there is much showing change in the opposite direction....which means focusing on strength gains and power instead of endurance should over time produce the greatest growth response.

What constitutes how you should train is the range that you alone see the most growth as there are people who grow just fine from higher reps and those who grow phenomenally from much lower reps.

Your growth is NOT dependent on number of reps alone and never has been. It is and always will be based on progression and intensity when training....something most of these people are missing in favor of chasing poorly understood theory.


You might as well have written, "it is all about the human body!!!" because that makes just as much sense.