Recent studies demonstrate that females with adolescent idiopathic scoliosis have measurable asymmetry in trunk rotation strength. Doctors have often prescribed trunk rotation exercises to address this concern and to potentially halt progression of spinal curvatures in children.
Some researchers have hypothesized that a muscle weakness may be involved with the etiology of scoliosis. Most studies have dismissed this hypothesis and have since found that strength differences in scoliosis patients are a result of the biomechanical and soft tissue adaptation that is secondary to curve formation. Muscle physiology is often misunderstood especially with scoliosis biomechanics.
There are two main divisions of muscle fiber in the human skeletal system. Type I tonic muscles and Type II phasic muscles. Type I muscles are slow twitch fatigue resistant muscle responsible for postural control. These muscles are controlled by the brain subconsciously and are responsible for the bone position that is viewed on an x-ray. If the tone of the Type I muscles changes it will alter the structure of the human frame via postural adaptation. Type II muscles on the other hand fatigue easily and are considered voluntary movers. When you consciously tell your hand to reach for a pencil and grasp it and pick it up you are activating Type II phasic muscles. Once the task is finished the muscle is essentially turned off again. Type I muscle are very deep and infiltrate the spine and pelvis. Muscles have both types of fibers but the amount of a certain type depends on how well that muscle can influence upright posture. The more it has the ability to aid in postural stability the more it is filled with Type I fatigue resistant fibers.
Since trunk rotation is an active voluntary activity the muscles responsible for the action will be primarily Type II. Since Type II muscles do not heavily influence the spines gravitational alignment it is therefore unlikely that this group of muscles will affect the actual structure of the spine. So trunk rotational scoliosis exercises which strengthen these muscles won’t be able to influence the stability of the scoliosis due to this physiological muscle type phenomenon. The following studies demonstrate the effects from trunk rotation exercises which conclusively show the short term nature of this type of scoliosis exercise program.Taking into consideration that scoliosis is a progressive condition any short term effect however promising that fails to alter the natural course of the condition must be reviewed and scientifically scrutinized.
As a clinician who works with scoliosis patients daily, it is my opinion that subconscious reactive exercises for scoliosis patients involving the Type I muscle fibers are certainly a more effective way to influence scoliosis progression and potentially reduce curve size from a long term perspective. Scoliosis is a neurologically driven condition and therefore needs a neurology based exercise program to influence its natural course.
So when we look at trunk rotation exercises we must understand their purpose and both the short and long term effects on scoliosis of the spine. These trunk rotation exercises should solely be used as an adjunct short term exercise program for children with scoliosis. Because this spinal condition is multifactorial it would be best to look at a very well structured scoliosis exercise program a program that is customized to the individual and not just a broad spectrum generalized approach. It is always better to seek the advice and support of an exercise specialist to aid in prescribing the appropriate exercises to properly address the unique biomechanics of a child’s scoliosis.