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Thread: Motor Unit Recruitment in Resistance Exercises

  1. #1
    Junior Member
    Join Date
    Aug 2011

    Post Motor Unit Recruitment in Resistance Exercises

    Hi everyone,

    Charlie often mentions in his materials that certain exercises will have a higher MU recruitment than others (e.g. circa 65% for the Back Squat vs. 35% for the Bench).

    This notion makes a great deal of sense to me from a logical standpoint (i.e. more muscle mass worked/involved should in theory = more MU recruitment/contribution), but I wanted to see if there was any published research supporting this.

    I have not had much luck so wanted to ask if anyone knows of/can direct me to any research that specifically measures or comments on MU recruitment for different key resistance exercises in this context, or where Charlie received his information on this area from?

    The other thing I would like to add (and hear people's thoughts on) is that in my opinion MU recruitment is not necessarily the only item in the picture, as things like % of Maximal Voluntary Contraction will also influence the "effect" of a given exercise and/or summated output from a given amount of MU recruitment (and therefore total stress on the system + CNS).

    Thanks in advance for your time and look forward to hearing people's thoughts,


  2. #2
    Recrutment patterns vary greatly from person to person add the experience factor, brachiomorphs vs dolicomorphs etc.

    What I think Charlie was pointing Is the "estimation" of work for the overall muscle mass and how much It would cost the CNS to fire all that. When we know that, It makes us more concious about the whole volume/intensity gestion.

    For example: If the quadriceps is recruited at around 65% in a given exercice for two athlete. That may represent 20% of muscle activation total vs Full body muscle and only 15% in the other????

    If you look at %MU activation there are many research, Bompa provide a simple presentation in his book: "Periodization training for sports". T-mag have had some good article on this too.

    one of the series

  3. #3
    here is also very good information link:

    A sprint activates 234% more mean gluteus maximus muscle than a vertical jump.

    In order, the hip extension exercises with the highest glute activation are
    the kneeling squat (67%)
    deadlift (55%), sumo deadlift (52%)
    Zercher squat (45%).

    In order, the hip hyperextension exercises with the highest glute activation are the
    single leg bent leg reverse hyper (122%)
    hip thrust (119%)
    pendulum quadruped hip extension (112%)
    bent leg reverse hyper (111%).

    Since popularizing the hip thrust exercise, I've heard a lot of experts "chime in." Some say that they prefer pull-throughs since it's a similar motion. Listen, the hip thrust is to the pull through as the bench press is to the standing cable chest press; good to do every once in a while, but a stable base and a barbell maximizes activation.

    moderators let me know If anything Is done incorrectly "copyright"

  4. #4
    Junior Member
    Join Date
    Aug 2011
    Hi Adonail,

    Thanks very much for the reply, I agree that recruitment patterns will differ between many individuals which is why I mentioned the importance of MVC in addition to MU recruitment.

    I also appreciate the Bompa suggestion, will take a look in there but from memory he didn't seem to have much in the way of explanation where he got those figures from?

    Similarly, the T-Nation articles are interesting however in my opinion they don't exactly constitute real studies (for one there is no mention of methodological procedures) so I am wary of taking the information from there as conclusive. In this format I would say these articles mainly represent well-researched opinion rather than anything else.

    I know Bret well and asked him my original question this morning, and he said he didn't have an answer either but would be very interested to know the same thing.

    In a nutshell, I'm just curious to see where the specific numbers/estimates Charlie mentions originated from, and if there has been any more sound research done on this topic since he formulated them.


    Last edited by CedricU; 09-29-2011 at 05:17 PM.

  5. #5
    What Is your background? You seem to be very critic, that Is a good thing. But, If your purpose Is sprint performance, I am not sure you will find the holy grail If the real information exist at all.

  6. #6
    Junior Member
    Join Date
    Aug 2011
    My athletic background is professional Rugby, which is also the field I currently work in.

    You are very right, the information might not exist but I would never know if I didn't ask as I stated above I am just curious to know what this info (which makes sense to me) is based on.
    Last edited by CedricU; 09-30-2011 at 01:01 PM.

  7. #7
    manual therapist from what field?

    Stay here, we need more people like you to keep this site alive and informative as well.

    My take on the % are simply based on muscle recruited and size % of the total body muscle mass estimation.
    Last edited by adonail; 09-29-2011 at 04:21 PM. Reason: add question

  8. #8
    Junior Member
    Join Date
    Aug 2011
    Thanks Adonail, my initial therapy education was in myofascial + trigger point therapy.

  9. #9
    Charlie's Motor Unit diagram was intended to be a conceptual diagram that shows relative motor unit involvement for various activities/exercises. It was not based on any particular research or empirical evidence. If anything, it was based on Charlie's own experiences as an athlete and coach, and his intuitive knowledge. In many cases, I truly believe it was based on his own observations with regard to both fatigue and adaptation in athletes he coached.

    But there were no scientific studies done or rabbits sacrificed with muscle biopsies or needle EMG's for this diagram. In fact, I believe we were sitting in his dining room, passing different ideas back and forth on relative intensities of various activities. We started with sprinting on the left side of the diagram and a bicep curl on the right side of the diagram, and the rest was history. The diagram is meant to create more thought on the subject of exercise selection, nervous system involvement and resultant fatigue. It is not meant to be an absolute priority list of exercises for a training program.

    As someone mentioned earlier, everything will be individual specific. If an athlete does not have the coordination or aptitude to perform a clean and jerk, snatch or other variation, there's no point in selecting that exercise as a high intensity stimulus. They may be better served by combining other exercises (i.e. heavy squat and heavy bench + sprint - as was done with BJ). The exercises listed in the MU diagram have the potential to involve a high proportion of Motor Units, but many people do not have the ability to take advantage of that potential. So, they are forced to keep things simple... which isn't all that bad an approach.

  10. #10
    Junior Member
    Join Date
    Aug 2011
    All makes sense and completely agree, thanks for outlining that NumberTwo.

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