That is an interesting article but I will have to disagree in part in that unidirectional movement patterns do cause the muscles that are overused to become stronger, shorter and tighter in comparison to their counterpart. Any movement is exercise. And excessive exercise with any form of resistance will cause the muscles to become stronger in relationship to the amount and duration of the applied resistance. This is basic biomechanics and happens in every occupation. Of course computer users are not alone with more prevalence of carpal tunnel syndrome found in the meat packing industry, assembly workers and others. It is also seen more often in women than men, but you will find out more why this occurs in my comments below.

I also know from research that it is possible to find statistics to support any argument. We must remember that there are so many variables in studies, that omitting one piece of information will change the outcome and outcome is often based on agenda. The Harvard study claims that
Carpal tunnel syndrome is certainly more prevalent is those who are obese or have other medical conditions, usually those with diabetes and thyroid conditions but of course these people are usually overweight, have fluid retention (edema), etc. Excessive fluids in the tissues cause increase in the size of the tissues, which in turn increase pressure on the median nerve as it functions within a restricted amount of space. It is proven that the carpal tunnel in many patients is decreased in size, the reason for all of the latest conservative treatments that attempt to length the transverse carpal ligament and increase the size of the carpal tunnel.

The first question is, why is the carpal tunnel smaller? Again, lets go back to the fact that excessive motion or exercise of a group of muscles causes them to become stronger. In the case of those typing all day, it is shown that if someone types 40 words a minute, they press 12,000 keys per hour or 96,000 keys per 8-hour day. Approximately 8 ounces of force is necessary to depress one key, resulting in almost 16 tons of force being used by the finger and wrist flexor muscles in one day. It is quite clear that this is a lot of exercise and will cause the finger and wrist flexor muscles to become stronger than their antagonist, the extensor muscles, that are only being used as a stabilizer as they are not being subjected to any direct resistance.

The carpal tunnel is also smaller in women than it is in men as their wrists are smaller. When a task is performed, it is not gender-specific as to the amount of resistance that is needed to perform the specified task. Whether a man or woman performs the task, that task requires a certain amount of resistance. If it is lifting a box that weights five pounds, then five pounds of resistance is applied. If it takes eight ounces of pressure to depress a key on a computer keyboard, then eight ounces of pressure is applied. Because the amount of resistance required to perform the task is equal between both men and women, when the tendons and muscles grow, they will grow more in a woman than in a man as men are stronger so the mount of resistance applied, although equal, is less to a man than to a woman. (Confused? Men are naturally stronger than women, making it easier for the to lift five pounds repeatedly than it is for women, therefore the muscle imbalance will occur faster in women than men as technically, the weight is much greater to the woman than to the man.)

Muscles and tendons grow in relation to the amount of resistance they are subjected to. Because men are naturally stronger than women it is easier for men to perform a required task, and will automatically cause the woman’s muscles and tendons to grow larger in comparison, therefore increasing the muscle imbalance even faster, resulting in compression of the median nerve and the onset of carpal tunnel syndrome.

The second question is, what happens when one muscle group becomes more powerful than its antagonist? A muscle imbalance occurs, with one muscle group pulling harder on one side of the joint than the opposing muscle group.

Third, what happens when a muscle imbalance occurs? A muscle imbalance causes unequal pressure to be exerted to opposing sides of the joint, causing it to move improperly or in the case of carpal tunnel syndrome, collapse inwardly. Note that the carpal tunnel cannot increase in size or expand in an outward manner due to the carpal ligament, but it can collapse inward, causing the eight carpal bones to be pulled inward due the over development of the flexor muscles and lack of development of the finger and wrist extensor muscles which act as the stabilizing force in maintaining the size of the carpal tunnel.

And last, how can carpal tunnel syndrome be prevented? Simple - Through basic hand exercises that create equality of strength between agonist and antagonist, with each muscle group having strength no less that 75% of its counterpart.
For some reason, this concept has been so difficult for physicians and therapists to comprehend although muscle imbalances have been recognized in baseball players and golfers for years with the same approach to treatment. If an athlete overdevelops the spinal rotators from constantly swinging a golf club or baseball bat from right to left over and over, causing a muscle imbalance to occur and resulting in nerve impingement, the treatment is to use increased resistance and mimic the athlete’s swing in the opposing direction, from left to right in order to develop the opposing spinal rotators, creating equality of muscle length and strength and reducing nerve impingement.

Although individuals that are obese and / or have some form of disease such as diabetes, these issues generally compound an imbalance that is already present due to overuse, such as excessive typing on a computer keyboard. The directive is to maintain muscle balance throughout the entire body and utilize proper form and appropriate tools that allow the body to function as it was designed, thus defeating repetitive strain injuries like carpal tunnel syndrome without invasive means of treatment.

Regards and Happy New Year!

Jeff Anliker, LMT`