How Massage Works - Part One - Muscles

As a massage therapist, I think and talk about muscles a lot. Learning anatomy was a huge part of my massage education. When a client comes in with pain in a certain area or not able to move as well as they would like, I’m instantly thinking about what muscles may be involved and what might be going on in there.

Here’s where I make my first confession: I don’t know everything about the body. I’ll give you a minute to recover from that stunning news…


Truthfully, there are muscle names I’ve forgotten, facts I never learned, and a lot of information that’s just sort of foggy. When a client would ask a more detailed question, I could stumble my way through an answer but always felt there was more I could know and convey. So my first deep dive topic this year is the good ol’ muscles.

Muscles - How Are They Formed?

A muscle is a collection of long muscle cells, or fibers, grouped together with blood vessels and packaged with connective tissue in a specific way. Muscle cells have the ability to contract, or shorten, and relax. There are three different types of muscle cells, but for now we are going to focus on just the skeletal type which are attached via connective tissue to bones and are responsible for the movement of the body and keeping you upright against gravity. These are what you most likely think of when you think of a muscle!

(The Other Stuff)

There’s other stuff in your body other than muscles and bones (and organs), of course. The stuff holding it all together is appropriately named connective tissue. That’s your tendons, ligaments and fascia which deserves its own whole month down the road.

How They Function

When skeletal muscle fibers get the message from our nervous system to contract, the muscle shortens and the cells get closer together. I say this like it’s a simple thing - it’s actually complicated process involving neurotransmitters, protein filaments, and calcium. Let’s just simplify it into the brain saying “yo, muscle, get shorter!” and the muscle being all like, “k.” A muscle spasm or cramp is when the muscle involuntarily contracts without the message from the brain to do so. Those are often caused by muscle fatigue or dehydration.

When in a contracted position, the blood vessels in the muscle are constricted and it can’t get nutrients in or cellular waste out effectively. When a healthy muscle returns to its normal resting length, the exchange of oxygen, nutrients, and wastes also goes back to normal.

There are two types of muscle contraction - static and dynamic. With static or isometric contractions, the muscle contracts but the attachment points do not move. Close your mouth then clench your jaw - that clenching is an isometric contraction. Another example of static contraction is muscle tone which is the constant contraction that holds your posture and keeps you upright against gravity. The nervous system is constantly sending a message to about 10% of the muscle’s cells to remain contracted. Without this constant static contraction you’d be a pile of mush on the floor. Thanks, muscles! Dynamic or isotonic contractions are those in which the muscle attachments get closer together and create movement.


The muscles coordinate, often in pairs, to create movements. A muscle can be a prime mover (or agonist), synergist, or antagonist.  Prime movers are responsible for the majority of the intended movement, synergists or accessory muscles help out by also contracting to assist the movement or stabilize, and the antagonist moves in opposition and relaxes as the prime mover contracts.  The clearest example of this is the movement of the arm at the elbow. As your arm bends and your hand moves closer to your shoulder, the biceps brachii muscle is contracting and it’s buddy the triceps brachii is relaxing. On the way back down, the muscles swap jobs. Good ol’ triceps is contracting as biceps takes a breather.

How They (Dis)Function

So now you know the basics of what makes up a muscle and how it’s supposed to work. Of course, there’s always room for disfunction. Sometimes, like that weird guy with a crush on you, the brain will not stop texting certain muscles telling them to contract. This can happen for a few reasons - repetitive motion, posture, illness or injury, or stress. This nagging creates hypertonic or tense skeletal muscles that don’t go back to their resting state which can lead to discomfort or pain because of the chronic lack of oxygen also known as ischemia. After a while this tight, contracted state is the muscle’s new “normal”, the nervous system is confirming that this is exactly as long as the muscle needs to be.

Another way that muscles can go a little screwy is by being imbalanced. When one muscle in an agonist/antagonist pair is hypertonic, it pulls the joint into an unnatural resting position. The other muscle in the pair is stretched and overworked to the point of fatigue, resulting in a less than ideal state and limited functionality.


Where I see this most commonly is in the chest and upper back or shoulders. Think about it - how often throughout the day are your arms doing something in front of you. Driving, typing, texting, etc? The muscles of your chest and front of your shoulders are doing that work and they’re really good at it. What’s the downside? Your upper back and shoulders are usually not strong enough to compete, resulting in weak muscles between your shoulder blades that feel tight and achey. Sound familiar?

What The Heck Is A Knot

Ah yes, those pesky things. I hear about them all the time - “my back is full of knots!” We all pretty much know what they feel like - ouch. But what exactly are they?

The truth is...we don’t really know.

Ask five different massage therapists and you’ll get five different answers. The thing is, muscle “knots” don’t show up on any medical imaging and there doesn’t seem to be a consensus about what they are. What we do know is that they aren’t literal knots - your muscles haven’t tied themselves up into an angry little bow. I actually don’t even use the word anymore!

In my experience areas that people think of as knots are usually either areas of hypertonic muscle fibers (remember that from earlier?) or just the normal bumpiness of your anatomy. Either way, they are completely normal and there’s nothing wrong with you. Whaaaat? I know! You’re welcome! If you’re not in pain but still have those knots you’re totally fine. Say hello to my left shoulder which basically feels like a rock most of the time but rarely gives me any trouble.

If you ARE in pain, the “knots” could be either the culprit or the after effect of whatever else is going on.

Whether you do or don’t have “knots” and whether you do or don’t have pain from those “knots”, you should get a massage. But you knew I was going to say that, didn’t you?


Massage And Muscles

For many, these hard working, booty shaking, “which way to the beach” pointing muscles are the main focus of massage. Learning the musculoskeletal system takes up a large amount of our training and most massage therapists will use fun words like gastrocnemius and levator scapula on the regular. So what does massage actually do for them?

Massage, at its core and no matter the modality, is the application of pressure to tissue. The hope is that by manually lengthening and mobilising hypertonic muscle tissue, it will become more compliant and less stiff. Knowing what you all now know (you’re welcome) about how muscles work, as they lengthen and relax they are flushed with blood carrying oxygen and nutrients and thus perhaps decreasing pain. We’re all lumps of dough in need of kneading. (I don’t bake.)

This is where my research for this post took a somewhat surprising turn for me. With so much attention being paid to muscles through my education I figured there would be clear answers to this question. But the truth is, we don’t actually know what is happening to muscles on a physiological level during a massage. I can “feel” changes occurring under my hands. I can sometimes feel what I perceive as a release or softening in the tissue. However, in my search around the internet for answers it became clear that what we think we’re doing - applying pressure which in turn changes the muscles - may not be quite right.

Massage ain’t just about the muscles. There’s this whole beautiful complicated nervous system that’s basically running the whole show and it plays a huge role in massage. Perhaps even the essential role. The role without which massage doesn’t actually work. Thing is, your muscles themselves may care very little that you’re pushing on them. What matters is the signals that touch sends to the nerves in the skin which are then relayed to the brain and how those signals are translated back to the muscles.

Muscles are obviously important, and it’s important to know how they work, but it’s not the whole story of massage. For now you’ve been reading enough and we’ll get back to the nervous system next month. If you’ve made it this far, let me use these muscles to give you a tip of the hat, a high five, or a hug.


Braun, Mary Beth, and Stephanie J. Simonson. Introduction to Massage Therapy. 2nd ed., Wolters Kluwer Health/Lippincott Williams & Wilkins, 2008.

Burgan, Beth. “How Does Massage Work?” Taking Charge of your Health & Wellbeing, University of Minesota, 2016,

Harvey, Ian. What are "muscle knots" (for massage therapists and clients). YouTube, 4 Apr. 2016,

Reynolds, Gretchen. “Ask Well: Muscle 'Knots'.” Well, The New York Times, 13 July 2015,

Taylor, Jason James, and Barbara Janson Cohen. Memmler’s Structure and Function of the Human Body. 9th ed., Wolters Kluwer Health/Lippincott Williams & Wilkins, 2009.

Yates, Kip. “What is a Knot and Why Do I Have Them?” Legit Massage, 2 Feb. 2012,

Molly Kerrigan