Column: Muscles have memory, but can also forget

We’ve all heard of muscle memory, but muscles can also suffer amnesia when they are not used


By Kerry Senchyna

You’ve probably heard of muscle memory – the way in which the nervous system remembers how to contract a muscle with repeated training.

Muscles can also ‘forget’ how to function if we don’t use them. And the resulting effects of this can have implications beyond the muscle in question.

One example is in the gluteal muscle group in the hip, which contains numerous muscles surrounding the joint as befits the wide range of movement and tasks it has to perform. There are numerous muscles deep within the joint that are smaller and fan out and control the stability and finer movements of the hip, including flexion, extension, abduction, adduction and rotation. On top of these muscles are layered the larger power muscles of the gluteal group: gluteus minimus, medius and maximus.

When we spend an inordinately large part of our day sitting, and we don’t do much exercising, a few things happen to the hip and low back. First, the hip is put in a constant position of flexion, being bent at roughly 90 degrees. Over long periods of time this will shorten the muscles on the front of the hip (the hip flexor group) and lengthen the muscles on the back of the hip (the gluteal group).

This chronic imbalance of shortened muscles on one side and lengthened on the other can set up postural problems, and the lack of using the gluteal muscles will weaken them and tend to turn off the nervous system from firing them. This inhibition of firing will promote a kind of amnesia where the muscles don’t get enough neural stimulation and in essence – forget to fire.

If the firing patterns (called ‘recruitment’) are poor, this can cause other muscles to be used instead, potentially initiating a cascade of substitutions of improper muscle activation. The substitution muscles will often fill in for the affected muscles and become over-worked since they are doing two or more jobs at once. This can cause an injury.

The other problem that arises is that the hip muscles are normally used to fire in synchronization with the muscles of the back in order to stabilize and strengthen the low back. These muscles cross-over from the right side of the hip to the left lower back and vice versa in a criss-cross pattern through a connective tissue. If the gluteal muscles are weak and habitually turned off, this reduces the strength and stability of the low back.

Exercises that will strengthen the gluteal group are many and varied. There are numerous varieties of squats and lunges that are common in the gym but don’t necessarily require using weights. You can also lie on your back and lift your pelvis and back in the air in an exercise called a bridge. The medius and minimus can be strengthened by lying on your side and lifting your top leg in the air using varying leg configurations.

Once the target muscle starts firing properly again, repetition will ensure that it stays healthy.

Kerry Senchyna holds a bachelor of science degree in kinesiology.

Maple Ridge News