Tip of the Week: Understanding Muscle Groups

Today's tip is understanding the relationships between muscle groups to get the most out of your practice. For almost every major movement in the body, there is an agonist and antagonist muscle involved.

The agonist muscle is the primary mover involved. Usually this means a contraction or shortening of the agonist muscle in order to create movement.

The antagonist muscle has several functions. It can relax (lengthen) in order to allow the agonist muscle to function to its fullest. It can also slow down the movement of the agonist muscle to prevent tearing or overuse.

An example is the biceps and triceps muscle group. When you do a biceps curl (see image above), the agonist muscle is the biceps, and the antagonist muscle is the triceps.
Now this is where it can get tricky. When you create the opposite movement—when you bring your hand AWAY from your shoulder (see image below)—the agonist muscle is the triceps and the antagonist muscle is the biceps.

This is because in order to create the movement of bringing the hand away, the triceps has to contract or shorten and the biceps has to lengthen or relax.

Why is this important in yoga? Because if you understand the relationships between muscle groups, you can work smarter to get the most out of your practice! 

When you contract (or shorten) your quads (agonist), you will help your hamstrings (antagonist) lengthen more effectively and more safely.

When you suck your stomach in, thus contracting your abs during a forward bend (agonist), you will help to more efficiently stretch the muscles in your back (antagonist).

Think about all the muscle pairs that work together in the movement of the body. Different movements will engage different muscle groups in the wrist, arm, shoulder, spine, hips, knees and ankles. Think about what muscles you contract in order to get other muscles to relax.

*Some examples of agonist/antagonist muscle pairs that essentially counteract each other’s activity about a joint:

• Pectorals/latissimus dorsi—pecs and lats
• Anterior deltoids/posterior deltoids—front and back shoulder
• Trapezius/deltoids—traps and delts
• Abdominals/spinal erectors—abs and lower back
• Left and right external obliques
• Quadriceps/hamstrings—quads and hams
• Shins/calves
• Biceps/triceps
• Forearm flexors/extensors

Here’s another element to consider: as mentioned above, another job of the antagonist muscle is to slow down the movement to ensure a safe bend. In our muscles, there are these things called “stretch receptors.” They are there to prevent you from overstretching and tearing muscle.
When you first start to stretch, you might find resistance in the muscle. But if you hold the stretch, in a few moments, you might find some relaxation and give in the muscle, thus allowing you to stretch deeper. That’s the stretch receptor saying to the muscle, “Okay, I can see this is a safe stretch, you’re not going to tear anything—go ahead.”

This is why, for example, in Standing Separate Leg Stretching, it’s so important to both contract the quads (agonist) to release the hamstrings (antagonist) and also hold the pose for probably longer than you’d like to get the best stretch possible. Bouncing is not so good; a long, slow, firm and constant pull will get best results.