Aqua Aerobics - PE 245 Muscle Balance Lecture Notes

Muscle balance is a vital component to injury prevention.  Whether you chose to lift weights or use water resistance or calisthenics to maintain muscle strength and endurance, you need to focus on muscle balance.  The major muscle groups work in pairs and those muscle pairs need to be balanced in terms of strength and flexibility.  For example, we bend our elbow by using the biceps muscle.  It's pair is the tricep muscle.  The tricep muscle must be willing to stretch for the bicep muscle to contract and bend the elbow fully.

Here is an over-simplification of the major muscle pairs and what they do:
 

If you are going to do bicep curls, for example, you also need to do tricep extensions in order to work both muscle pairs and keep them balanced.  When you maintain balanced muscles, you have better body symmetry and better posture.  Weight lifters who only work the chest muscles (pectorals) and neglect the upper back muscles (trapezius) will have forward stoop to their shoulders.  This is the appearance of unbalanced body symmetry which could later cause upper back pain.

Our daily routines can cause muscle imbalance.  We use more pectoral muscles than we do trapezius muscle because we do so much lifting of groceries, children, and other items.  We have more range of motion in front of us and so we do more things where we can easily see what we are doing.  We use more the iliopsoas more than we use the gluteals because we walk forward and upstairs more than we walk backwards.  We use our biceps more than our triceps due to lifting against gravity.  As a result of these naturally occurring muscle imbalances, we need to work the other half of the pair to maintain muscle balance.

Activities of daily living oftentimes cause pain due to muscle imbalances even though we are not aware of what is taking place.  One example is a pain that develops in one of the shoulder blades.  This could be caused by working a computer mouse that is on a desk that is at a level too high for the person seated and using it.  It could also be caused by turning the head to one side to watch TV, talk to someone, or work while the rest of the body is  facing forward.  When the muscles develop on only one side of the upper back, the muscle imbalance eventually results in pain.

When muscle imbalances result, you need to stretch the muscle that is too strong and too short and strengthen the muscle that is too weak.  In some cases this may involve more than one set of muscle pairs.  Low back pain is a classic example of muscle pair imbalance.  Not all low back pain is caused by muscle imbalance, but much of it is.  In this case the pain results from a forward tilt of the pelvis and involves two pairs of muscles.  In order to understand this example, imagine the pelvis with 4 strings attached.  The two strings are attached to the top of the pelvis and hold the front and back of the "bowl" up in correct position.  The two strings attached to the bottom hold it down in correct position.  If those four strings lose their balance, then the "bowl" can tip either forward or backward.  The abdominal muscles hold the pelvis up in front and usually become too weak and their partner, the erector spinae which holds the pelvis up in back usually becomes too strong.  The iliopsoas muscle which pulls the pelvis down in front usually becomes too strong, while the partner, the gluteals, which hold the pelvis down in back becomes too weak.  The result is a forward tilt which increases the curvature of the lower back and places too much pressure on the spine in that area, causing pain.

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