Some muscles are “movers” while others act to stabilize that movement. When you do an exercise, the primary muscle that’s doing the work is referred to as the target muscle. The “prime mover” or target muscles are assisted by secondary muscles called synergists.
To make matters more complicated, working behind the scenes are muscles that don’t actually move. Instead, they contract isometrically when a target muscle is moving to help stabilize and support that movement. Appropriately, these muscles are referred to as stabilizer muscles. Even though they don’t actively move muscles, stabilizers aren’t slackers. When they’re strong, they help you perform better when you weight train.
What Stabilizers Do
Each time you move a muscle, certain muscles act as “movers,” the target muscle and its synergists, while others act to stabilize the movement. Interestingly, some muscle groups have the ability to do both. For example, the rotator cuff muscles in your shoulders participate in internal and external shoulder rotation, but they also stabilize by holding the head of the humerus more securely in the glenoid fossa when the shoulder moves. In this capacity, the rotator cuff muscles reduce motion when the shoulder internally or externally rotates.
We tend to think of all muscles as being “mobilizers,” but any movement that you make requires stationary muscles to serve as stabilizers. The two types of muscles work together as a team to execute a movement safely and with a minimum amount of wasted movement or energy. For example, the biceps muscle attaches to the radius, a bone in your forearm, and your scapula. When you flex your elbow to curl, the biceps muscle pulls on your scapula, a bone with some freedom to move. To keep the scapula from moving and the joint from experiencing stress, the trapezius muscle, and rhomboids function as scapula stabilizers to minimize movement of the scapula and make the movement safer. Stabilizers that prevent unwanted movement of a particular bone or joint are called fixators.
Another type of stabilizer that reduces unwanted movements is called a neutralizer. Some muscles are capable of performing more than one type of movement. For example, when your biceps contract during a biceps curl, your elbows flex and your arms move towards your chest, but your biceps also can supinate (palms rotate upward).
Neutralizers offset joint movement in the alternative direction, so movement occurs through only one plane. The neutralizer, in this case, is the pronator teres, a muscle that keeps the target muscle, the biceps, from supinating. The pronator teres essentially holds the bone in place so supination doesn’t occur when you do a biceps curl. Fixators and neutralizers have something in common – they both block unwanted movements when you’re contracting a muscle. They also reduce wear and tear on joints by preventing the joint from being pulled in more than one direction at a time.
Why Strong Stabilizers Are Important
Stabilizers offer support when you lift weights or do any kind of movement. When stabilizers are weak, your risk for muscle imbalances and injury increase. Plus, stabilizing muscles provide the firm foundation your body needs for postural support. For example, the gluteus medius muscle stabilizes the hip joint when you walk or run. If these muscles are weak, it throws off the alignment of the pelvis and places excessive stress on larger muscles that have to compensate for the weak hip stabilizers. People with weak hip stabilizers are also prone to knee injuries.
Stabilizers are usually small muscles that contract isometrically. When they’re weak and can’t do their job properly, larger muscles have to work harder and are more likely to become strained or injured. One cause of lower back pain is weak trunk stabilizers. The transverse abdominis and multifidus are muscles that help stabilize the lower spine. When these stabilizing muscles are weak and deconditioned the lower spine experiences greater stress. People who have chronic lower back pain often have poor activation of stabilizer muscles in their core and trunk.
In addition, when stabilizing muscles are weak and don’t offer enough support, you’re limited in how much resistance you can successfully lift when you train. The primary stabilizing muscles are in your shoulders, hips, and trunk. Weak stabilizers in your hips will reduce the amount of weight you can use when squatting and, possibly, impact your form, while weak shoulder stabilizers impact upper body movements like bench press and overhead press.
Strengthening Stabilizer Muscles
To strengthen your stabilizer muscles, focus on compound movements that work multiple muscle groups – squats, deadlifts, and push-ups are good choices. Planks are another exercise that target the stabilizing muscles in your trunk and core.
Another way to give your stabilizers a workout is to add a balance component to your training. For example, do squats or curls while standing on a Bosu ball or do unilaterals. For example, squatting on one leg forces the stabilizers in that leg to work harder to maintain balance.
One thing you definitely want to avoid when trying to strengthen stabilizing muscles are weight machines. Free weights call stabilizer muscles into play to help balance the weights. You don’t get that when you work out at a gym using weight machines. Grab a pair of dumbbells to give your stabilizers the strength they need.
The Bottom Line
Strong stabilizers maximize the amount of weight you can lift without experiencing injury. They also help maintain proper posture and lower your risk for muscle strains and imbalances. To keep these muscles strong, force the stabilizing muscles to work harder by doing unilaterals and exercises on unstable surfaces. Skip the machines and grab a pair of dumbbells to make your stabilizers work harder.
Chances are you don’t think a lot about stabilizing muscles, but focus more on working the big muscles you can see – but giving your stabilizers some attention can help you more safely and effectively work larger muscle groups.
SteadyHealth.com. “Understanding So-Called Stabilizer Muscles”
Princeton University Athletic Medicine. “Pelvic Stabilization, Lateral Hip
, and Gluteal Strengthening Program”
Basic Biomechanics of the Musculoskeletal System. Margareta Nordin, Victor Hirsch Frankel. Third edition.
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