Abnormal Muscle Function

Understanding the normal function of muscles can also give you a better idea of the abnormal. The most common abnormal muscle condition in athletes is muscle imbalance, which occurs when two or more muscles don’t contract and relax as they should. Using the example above when you contracted the biceps and the triceps got looser, imagine if the biceps remained tight and the triceps remained loose even after you released your grip on your thigh. This is very much like the condition of muscle imbalance—except both muscles are in an abnormal state.

A muscle that stays too relaxed is referred to as abnormal inhibition and sometimes called “weak” (although this is not true weakness, which refers to the lack of power). This muscle imbalance can be relatively minor causing minimal impairment, or in some cases extreme to the point of causing severe pain in a joint controlled by that muscle. More importantly, in most cases, this inhibition causes an opposite muscle to become too tight, a condition called abnormal facilitation. These abnormal muscles—muscle imbalance—can adversely affect the joint(s) they control, the tendons they’re attached to, and other muscles, ligaments, and body areas all over. Most physical injuries are caused by muscle imbalance, whether the pain or problem is felt in the joint, ligament, tendon, or muscle.

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The full spectrum of muscle function goes from extreme weakness to extreme tightness, with normal in the middle (see chart on page 374). The extremes are usually due to a brain or spinal cord injury; those with cerebral palsy, multiple sclerosis, or who’ve had a stroke typically have this type of muscle weakness.

Muscle imbalance, the combination of abnormal inhibition and facilitation, is a very common problem in endurance athletes. Here’s what happens:

The inhibited muscle is abnormally lengthened, and is often the starting point for many common physical injuries that are not induced by trauma such as falling off your bike or twisting an ankle on the trail. This muscle weakness itself is often silent. However, you might feel the lack of function produced by it, such as something not right in the knee joint or difficulty in maintaining a proper running gait. And, when the muscle doesn’t properly control the movement of a nearby joint, it causes that body part to become inflamed.

The other side of abnormal muscle inhibition is tightness (abnormal facilitation). This tight muscle is often noticeably uncomfortable and sometimes painful, and it can impair movement by restricting flexibility. Tight muscles are shortened, making them candidates for mild, slow stretching; however, in most cases this would be treating the secondary problem as the cause is usually the weak (inhibited) muscle. In addition, in attempting to loosen the tight muscles through stretching, you risk weakening the inhibited muscle more (because it’s already over-stretched).

It should be noted that muscles attach to bones through tendons. So when a muscle is not functioning properly, the tendons don’t either. Most tendon problems are secondary to muscles that don’t work well. Likewise, ligaments connect bones to other bones. And muscles have an important support relationship with both ligaments and bones, both directly and indirectly. So when a ligament or bone problem exists, there is usually an associated muscle imbalance as well.

The cause of muscle imbalance must be addressed if normal muscle balance is to be restored. Often, the body can accomplish this on its own, especially when it’s fit and healthy overall. In fact, the body is always self-correcting problems because normal wear and tear of endurance training can cause minor muscle imbalances. Even without knowing it, the body is always working to restore balance. During the process of correcting its own problems, the body may show relatively minor symptoms, and often none at all. When your body can’t fix a particular problem, that’s when symptoms appear and an injury develops.