Charcot-Marie-Tooth Disease and Exercise
by Eric P. Rugo, Student, The Ohio State University (1987)

Physicians generally advise people who have Charcot-Marie-Tooth (CMT) disease against weight training since it would be detrimental to their condition. This advice holds true with the implementation of normal therapeutic exercises. However, a method of weight training, presented here, can improve a CMT patient's condition and at the same time provide a measure of performance accurate enough to rule out or minimize the chance of a detrimental effect. CMT or Peroneal Muscular Atrophy is an illness in which there is a chronic degeneration (breakdown) of the nerves that supply the hands. This disease affects the motor neurons of the distal extremities resulting in a decreased action potential to the nerves and muscles in the diseased area. (Motor neurons are efferent, meaning neural impulses go from the central nervous system to somewhere on the peripheral). This leads to muscular atrophy and a decrease in blood flow to that region.Symptoms of weakness and a lack of sensation as well as a decrease of muscle response to manual results.

Training Methods

When a load is applied to a contracting muscle, the muscle "breaks down" causing a directly proportional stimulus for muscle growth, called muscular hypertrophy. This explains how weight training increases muscular strength and endurance.

People having CMT lack ability for 100 per cent muscular hypertrophy. When their muscles break down, regeneration is not at maximum efficiency. Only a certain percentage of their muscle will undergo hypertrophy. The amount of hypertrophy is variable for individual muscle groups. For example, a person with CMT may have maximal hypertrophy in their triceps and only 50 per cent hypertrophy in their biceps. Acute muscular atrophy can occur quickly a well as over a long period of time. The percentage of muscular hypertrophy can be determined by conducting a muscle biopsy. This method is not practical for our purposes, but there is another way to determine the amount of muscular hypertrophy.

When training someone with CMT, graph the subject's performance related to the muscle, or muscle group in the following manner.

A pair of graphs are plotted using a common horizontal time axis. These graphs are repetitions vs. time and weight vs. time. The values for weight and repetitions used are the average value for each week's effort. Therefore each time element is a one week interval. The method used to evaluate the graph should employ the least square regression line determination. If there is an increase in performance, as indicated by a positive slope of the regression line (see Fig. 1), the training is effective.

There is an adequate amount of hypertrophy occurring in that muscle. If there is a decrease in performance (a negative sloped line as in Fig. 2) the percentage of hypertrophy going on in that muscle is insufficient. If the latter case is true, there should be a two to three week rest for that muscle. At the end of the rest period the muscle in question should be re-evaluated through the graphing technique. If there are still no signs of increased hypertrophical capacity, then the training of that muscle should be terminated.

When graphing someone's performance, especially with weight training, proficiency in exercise technique should be noted. An improvement in technique could result in a decrease in graphed performance. This decrease should not be deemed as of a negative nature. It is the natural result of a change in mechanical advantage caused by the implementation of proper exercise technique. Proper exercise technique is vital to any kind of training for safety and effectiveness.

One last note about training CMT patients. Many of them have had tendon transfers to increase their strength and range of motion. There is no reason to avoid these areas. The surgically altered tendons are as strong, if not stronger, than the normal ones.

CMT is a very unpredictable disease. It is important to remember muscular atrophy is not always manifested over a long period of time It can occur in a matter of days. The proposed graphing technique allows a detailed and quantitative measure of performance. Detrimental effects in performance can be observed in a reasonable time period which will minimize the chances of further atrophy due to exercise.

The author would like to acknowledge the information provided by Dr. Robert N. Clark, chief orthopedic surgeon, Children's Hospital, Columbus, Ohio. His seminar on Charcot-Marie-Tooth disease (November 10, 1986) provided the basis for this investigation.