The 3 Rules of Muscles

The 3 Rules of Muscles

The three rules of muscles,
you ready? If you remember these three rules, you can figure out anything.
You can figure out what any muscle does and all you need is a picture. If you can
figure out these three rules, our functional anatomy class is over.
That’s it. And you can tell me the most complicated thing a muscle does, you just
have to be able to visualize the muscle and take it through these three steps.
Rule number one: Three rules of muscles: muscles only contract and relax. They don’t twist, they don’t bend, they
don’t shape, they don’t tone, they also don’t burn the fat that’s
laying directly above them. All they do is contract and relax. They’re little
machines that shorten and then they relax and they don’t shorten anymore. That’s it. Ready for number two? As you can
tell, these you getting terribly complicated. Muscles only work on joints they cross. Now, we’re taking it up a notch. My deltoid crosses what joint? Shoulder so we’d expected to move my
shoulder. That makes sense. Would you expect your deltoid to move your elbow? No, you’d have to have some pretty weird deltoids. They’d have to attach over here. That’s all fine and good and then we start talking about abs. Does your rectus abdominus
cross your hip? Then why does everybody do this to work their abs? Ever thought
about that? It drives me nuts. “I’m working my lower abs.” Your lower abs don’t cross your hips either,
not that they don’t exist or anything, but they don’t cross your hips either. “Well, that still works my abs.” Maybe it does, but are my abs the primary mover of my hip and why did I start moving my hip to do that? What is the prime mover of my hip? Your psoas. Where’s your psoas located? Goes from spine to hip, which makes sense, it crosses my hip, so it would move it. Do you know where it’s located in relation
to here? Just underneath your lower abs. So people think they’re feeling their
abs and they’re just feeling there psoas getting jacked up. Great! Now from a more technical perspective, so now I’m just busting myths and fooling around, which is cool, but biceps we all know the biceps cross what joint? Elbow and everybody goes, “elbow.” Good
they cross in front of the elbow, which means if they cross in front of the
elbow they’re probably going to pull my arm which way? This way. This is called elbow flexion but my biceps also crossed my shoulder. Muscles will act on joins they cross, so
if it crosses my shoulder by connecting to my coracoid process and my super
glenoid tubercle, that’s something in my glenoid fossa. Glenoid fossa- the
shoulder cup. So if it crosses in front of my shoulder this way, what do you
think it’s going to do to my arm? It’s going to go this way, which is called shoulder flexion. Not too bad so far. You ready for the
third and final rule? Muscles work best in the direction of their fibers. Those are the three rules. Going over this- muscles work best in
the direction of their fibers- we kind of mentioned it earlier already when we
were talking about planes. We said muscles that are going to take us
through the sagittal plane are probably going to be oriented how? Up and down in the front and back of our body. Muscles that are going to move us in the
transverse plan are probably going to be oriented how? Across. Parallel with the
transverse plane. We could also go obliquely. That might help us with rotation. That’s kind of a mixture of across and up and down. We do have muscles like that, that’s okay. Frontal
plane muscles we said are probably going to be oriented how? Up and down. Where on our body? On the sides. So let’s take a muscle, let’s take a muscle that we all know and take it through these three rules: the
pecs. All right, we all know where our pecs are
right? The pectoralis major, just going over it real quick. Origins and
insertions. You ready? Sternum, clavicle, costal cartilage and my
first seven of ribs, so this area. Insertion – lateral lip of my bicipital groove, medial lip of my greater tubercle, however you want to say that. So it’s over here. Now my pec only contracts, we’re cool with that. It crosses what joint? Shoulder. So
it’s going to move shoulder. Everything we’re talking about is going
to be joint actions of the shoulder. Good. That was a huge huge step. That’s all we
had to do. Now we have to think about the direction of these
fibers and how it’s going to pull this bone. If I start here, like this and my
chest shortens, where is it going to pull my arm? It’s going to pull it out that way? Maybe.
Maybe, it’s kind of right on top. It might pull this way. Just pull this way. Put one hand over your pec and then the other hand, put it right on top
of where you would imagine that bicipital groove to be and then shorten yourself. There you go. Internal rotation. Everybody got the three rules of
muscles? I’m kind of a few pages ahead here
on the pectoralis major but don’t worry about it. It’s still a real good example
for what we’re doing. We got shoulder internal rotation. Let’s talk
about some other stuf. If I put my arm like this, this hands my pec, now where is it going to pull my arm? This way. What is this? What is this joint action? Horizontal adduction. Those are the
two biggies. Now we can get a little, you can get a little more crazy. Can I go
back to what we were talking about before? My clavicular head, this is my
glenoid fossa, this is my humerus, some of the fibers of clavicular head are very
up-and-down oriented like this. With my arm down by my side, what do you think my clavicular head could help with? It doesn’t have a perfect angle for it,
but it could help with a little bit. A little bit of shoulder flexion. Cool. So we could say clavicular head helps with shoulder flexion. Some of the sternal fibers, there’s my sternum, come off like this. Pulling at a downward angle there. What do you think
they’re going to be able to help with? It’s my favorite example of that joint
action ever. How did Hulk Hogan show off his pecs? You could do cable crossovers or we could just go with the silliest example ever which is how –
yeah the Hulk Hogan. How did he show off his pecs? You can’t go, “Well, I
do horizontal adduction.” Because then your hands are in the way. Got to think about
this. He showed off his pecs how? This way right, so you could see his
pecs and his arm weren’t in the way. Of course, he had much bigger arms to get in the way than I do but you know what I’m saying. There’s a little bit of adduction
that your pecs can do. We could say that the sternal head assists, that would probably be the better word, with adduction. We didn’t need a kinesiology book, we
didn’t need a bunch of crazy research studies, we didn’t need an anatomy and
physiology text. We can just figure this all out. I have people come up to me and they go, “How do you memorize all of that stuff?” “I don’t.” Really, I don’t. If you get this concept, it doesn’t
matter what the muscle is. You just kind of have to be able to determine what the
joint is, kind of know how that joint moves. Today we’re going to be dealing
with a lot of ball and socket and hinge joints, the big joints that we deal with as trainers. But as long as you kind of know how the joint moves
you can visualize how that muscle pulls, all I have to be able to do is
name that joint action and I know everything that this muscle does. You with me? And I can be as creative as I want to be. I could put the head in any
position I want to or the shoulder in any position I want to or the hip or the knee in any position I want to and it doesn’t matter as long as I can
visualize it and go, “Okay, it crosses that joint, this is how it crosses, when it shortens, it’s going to pull the bone and x-direction. All right I got a good
picture of what that looks like, what joint action is that? That’s it. Cool with that?

42 Replies to “The 3 Rules of Muscles”

  1. Thanks Jak,
    Engagement is an important piece of a presenters skill set. We work hard to ensure that we create a sophisticated lesson plan and then deliver our content in a fun and entertaining way.

  2. I'm currently studying for my NASM cert (taking eTeach as well). I have no formal education beyond HS, so it's a bit intimidating, esp. the physio. You're vids definitely help. I'll keep watching and studying. Thanx much!

  3. Hey CJ Barna,
    I was in the same position when I first got certified through NASM. It is a tough certification, but most people pass the exam, and you are doing the right things by studying hard and looking for education opportunities in the e-teach programs and educators like myself and Eric Beard. I am sure you will crush your certification exam. Hope to see you at a live workshop in the future.

  4. Thanks Gary Miller,
    I really appreciate the support. I'm hoping I will get the chance to create some of the educational programming around your new product – "The ProUnit Performance Trainer." I am definitely enjoying it.

  5. You are welcome Harry Pineda,
    More to come I promise… I had some unfortunate technical difficulties with the last snippets from lectures, but we are planning to make some of our 8 workshops available online. There would be a price involved, but as live workshops may be tough to attend for some individuals (depending on your location) I want to do my best to make things more available no matter where you are.

  6. As an LMT and soon-to-be NASM CES, I really enjoyed how you presented this – the most clear, simple, fun, gets your brain thinking instead of memorizing, explanation of kinesiology – you would be a great resource for any student! I'm going to see what else you have to offer – love youtube as a resource for studying and reviewing. Thank you!

  7. great job! been watching and studying your videos for hours:) this is a great resource for fitness students. I look forward to many more videos =)

  8. New comments on the video: The 3 Rules of Muscles

    #BrookbushInstitute   #Brookbush   #BrentBrookbush   #DrBrookbush   #DrBrentBrookbush   #FunctionalAnatomy   #Anatomy   #anatomycafe   #Kinesiology   #Anatomylesson   #AnatomyStudy   #muscles   #Function   #jointactions   #AnatomyGeek   #Healthscience   #ExerciseScience   #ExercisePhysiology  

  9. When your doing leg hanging leg raises like you showed, isn`t the rectus abdominis atleast doing a isometrical contraction?

  10. If you did any video on rotator cuff and its strengthening, could you please share it?
    I shall be highly thankful to you for that. Awaiting your reply.

  11. nice video!. I'm from venezuela but studying for take de CPT from NASM and this was very helpful, would u tag the right order of each video?. I get a little bit confuse after this video, like which one should I watch after… thank you!

  12. hi Brent, I am in zimbabwe africa currently doing my online GFI certification with ACE. A zumba instructor wanting to extend my knowledge and qualifications, without any previous experience in the fitness industry and not having studied for anything in a long time…. your videos are really helping me to understand a great deal. Thank you so much 😆

  13. and what about isometric exercises that I take as a PT in Poland to my patients? that exercises mean something?

  14. Thank you for this video! I don’t know how I came across your channel but I’m so glad I did. You really break it down

  15. Hi.. I m gbs patient and i have bilateral foot drop and i have 1+ power for dorsiflexion i m physical therapist .. Which exercises will help me for dorsi flexors activations ? Its humble request for your guide lines ..have nice day 😇

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