By Krista Scott-Dixon, PhD

In Part 1 of this series I emphasized that the body knows movements, not muscles. The body is designed to work together. Its parts are team players, not a collection of prima donnas who are constantly vying for their place on center stage. The body doesn't think, "Okay, I have to pick up those groceries from my car trunk, so I guess I'll let the forearm flexors grab the bags, and then I'll blast the biceps when I pull the bags out." It's thinking, "Must. Get. Bags." in a sort of Frankenstein voice. It finds the goal, then it figures out a way to accomplish the goal by having all the parts work together. If it can't do something one way, then it figures out another way. It's very adaptable, that body of yours.

Body Movement 102

Here are some more things to know about movements, which I touched on in Part 1. Although each movement is like a mini-symphony of muscles, all activities nevertheless have a few soloists and some backup players. Muscles have one-track minds: they contract. That's their only job, and they only do it one way. Different movements are possible because of a complicated coordination by the brain and nervous system, acting like the conductor.

3 Types of muscle roles

1.  The role of agonists muscles

Agonists, or prime movers, are the muscles that provide the main drive for that particular motion. In the theatrical production, the agonists are the heroes, if only for that moment. For instance, during a biceps curl, the biceps are the agonists.

2.   Antagonists muscles: their role

Antagonists, like their name, are muscles that do the opposite of what the agonists do. They’re like the super villains. Antagonists have to relax in order for the agonists to work. So, using our example above, the triceps are the antagonists during a biceps curl. If you can’t relax the triceps while curling the weight with the biceps, you’re going to do some damage.

3.   Stabilizer muscles - what do they do?

Stabilizers hold the body in the proper position and help stabilize the movement. They are the supporting cast of characters: the wacky best friend, the extras in the background, the walk-ons, and the Bob Hope cameos. You’ll often hear people say “This exercise works your stabilizer muscles,” as if “stabilizers” are a particular kind of muscle. While some muscles, such as the deep abdominal/spinal muscles, are more likely to get that job than others, the stabilizer role is assigned depending on what the movement actually does. In the case of the biceps curl, stabilizers might include the shoulders, forearms, midsection, and even the legs if you’re standing.

The role of connective tissues during movement

Along with muscles, connective tissues (such as tendons and ligaments) play a role, acting like stiff elastic bands to hold joints together, attach muscles to bone, and provide a little bit of bouncy elastic energy for movements. For instance, when you jump, you’re using your leg muscles but you’re also using the elastic energy stored in your tendons.

The point of telling you all this is to explain that because of the way this complicated symphony works, you will see the most results when you pick movements that get as many instruments playing at once.

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