My interview with Dr. Greg Carter brought me in touch with his good friend and buddy, Dr. David Kilmer, Associate Professor of Physical Medicine and Rehabilitation at UC Davis Medical Center in Sacramento, CA. Dr. Kilmer is the author of a journal article on exercise and neuromuscular disorders, The Role of Exercise in Neuromuscular Disease by David D. Kilmer, M.D., published in Rehabilitation of Neuromuscular Disease Vol. 9, No.1 Feb. 1998.

If you've read the CMT Newsletter for any length of time, you'll know that when I find someone who has an interest in any facet of our disease I latch on, and Dr. Kilmer has agreed not only to let me interview him for this article but will be on our medical advisory board from now on. Dr. Kilmer would like make it clear that he does not advocate an exercise program for everyone, regardless of the severity of their CMT, but suggests everyone be assessed independently and an exercise program be designed specifically for you, if it is deemed that it will help and is safe.

Linda: Thank you for agreeing to talk to us now and to be on our medical advisory board. Having someone with your interests and in your specialty on board is going to help a lot of us who want to know more about CMT and how we can exercise to keep fit and not do any harm to our body. Please tell us how you first got involved in the study of exercise and neuromuscular disorders. What is your background?

Dr. Kilmer: During my residency in Physical Medicine and Rehabilitation at UC Davis in the 1980s, I attended a Neuromuscular Disease Clinic. One of the most frequent questions from patients was, "Does exercise help me or hurt me?" I tried to find the answer in the scientific literature and was surprised to find very few studies examining this question. I had a background in Exercise Physiology from undergraduate and graduate work at UCLA, so when I embarked on my academic career this was a natural area to investigate. Plus, it's easy to become an expert in an area that is so poorly understood! I was lucky that UC Davis was already a center of neuromuscular disease research under Dr. Bill Fowler and, similar to Dr. Greg Carter, Dr. Fowler was a great help in getting me started with this area of research.

Linda: You mention in your journal article on exercise that children with neuromuscular diseases don't always learn to participate in sports like other children do and sometimes they become couch potatoes (my word) as adults. We know from experience that several things can happen with children who have CMT. Either they never develop the dexterity to be any good at any sport and take to other pursuits that they can excel in or they get very good at something because they love it and their parents approve and then, when they push themselves to become extremely good at it or set their sights on sport at a professional level, they find their atrophy is progressing because they are pushing themselves and they must abandon their dreams.

How can you tell a child to get good at a sport but not too good because he or she will never likely be able to reach the point where they are ribbon winners. Aren't we setting these kids up for heartbreak and the emotional stress of feeling that it is their fault they can't do better? Could this not be avoided if they were told they had a disability which could get worse with time and not to pin their hopes on a career in athletics.
I can't tell you how many mothers have asked me that question to gather ammunition against a CMT father pushing his CMT affected son to do well in a sport that he himself couldn't excel in.

Dr. Kilmer: You raise some difficult questions that really come down to a philosophy of why a person chooses to participate in athletics. I try to encourage physical activity as a means of socialization and self-esteem, understanding that the person is not likely to be a "ribbon winner."

Surprisingly, if we encourage kids rather than forcing our own competitive desires on them, it is often OK for them just to do their best. In addition, habits of physical activity as youngsters often carry over into adulthood, even if modifications need to be made to continue the sport. I haven't heard my patients express the "heartbreak and emotional stress" you speak of. Perhaps, because CMT is slowly progressive, they have time to adapt to the idea that professional athletics are really not possible. But we certainly can define "success" in many ways when it comes to athletics!

Linda: People with CMT can often do something well once, let's say lift 15 pounds on their wrist, and maybe twice, but asked to do it three or four times, they simply cannot. The muscle starts to go into tremor, the person feels they are weakening and repeats are impossible for hours, perhaps days. Can you tell us why this happens?

This same thing also occurs when a child is trying to hold a pencil to write with in school. Many of them simply lose the ability to grasp the pencil after 15 or 20 minutes or less. When they cannot hold a pencil, they cannot do well and some eventually lose interest in their studies altogether. I sometimes recommend a laptop computer to parents of children whose hands are so weak they cannot grasp writing utensils so they can keep up. Would you comment on that concern, please.

Dr. Kilmer: You are describing the phenomenon of fatigue, where a person can perform a certain task briefly but quickly becomes exhausted. There are no studies directly addressing this in CMT, but the general thought is that muscles which are weak and then forced to work at a higher percentage of their maximal capacity will rapidly lose their ability to sustain force.

For example, say an able-bodied person uses 20% of their strength to lift the wrist weight in the scenario you described above, while the person with CMT is using 80% of their maximal strength. The muscle affected with CMT will quickly run out of energy, while the normal muscle can go on for a long period. It comes down to the amount of reserve strength that we have. The rationale of gentle exercise is that it will increase the reserve strength that we have available, thus reducing muscle fatigue.

Linda: I've read your paper on exercise several times and each time I come away with the thought that a great deal more has to be learned about exercise and CMT before we really know anything. You talk about overuse weakness. I lost my ability to walk slowly over ten years or so. Finally, I had to use a cane, then canes, then a walker and now a walker in the house and a scooter and wheelchair outside. I am 56. I'm always telling people with CMT that walking is one of the best exercises they can do, yet I lost my ability to walk as I walked. Sometimes things don't make sense. Can you address this a little?

Dr. Kilmer: Unfortunately, CMT is a progressive disease, and despite your best efforts to remain active, the disease still progressed. You may wonder if the walking actually caused the weakness to progress faster. This phenomenon, called "overwork weakness," has been a concern of clinicians for years. I can tell you that no systematic scientific studies have ever shown evidence of overwork weakness. I believe that walking has many benefits to persons with CMT, and you should still encourage people to walk if possible. If it becomes difficult, as in your case, there are still options such as a therapeutic pool which can really help flexibility, strength and aerobic conditioning.

However, once muscle strength is severely weakened, research in other neuromuscular diseases shows that there is essentially no benefit to resistance exercise, and I am NOT advocating that everyone gets out there and lifts weights. It is so hard to make generalizations about this disease...of course many are severely affected, such as yourself, while others have few problems into their 60s.

Linda: What questions still need to be answered; what did you find that you don't know enough about from your work doing that research and article?

Dr. Kilmer: One question which needs to be addressed is the extent to which a sedentary lifestyle, so frequent in people with all neuromuscular diseases, contributes to the loss of function in CMT. For example, strengthening programs have shown fairly positive results in persons with CMT. It may be that parts of muscles which are less affected by the disease but weak on the basis of being in poor shape are showing the most improvement.

Another question we are now addressing is the actual functional differences which may occur in muscles which become stronger through exercise. What does this mean in terms of one's ability to perform daily functions such as carrying groceries, climbing stairs, cleaning the house, and so forth.

Linda: Your paper concludes by saying that "future studies should incorporate reliable measures of fatigue as another outcome variable along with measures of functional performance." You also say,"It is no longer sufficient to show strength improvements; we must quantify the changes in a patient's ability to work and enjoy physical activity." I agree. Too much of the research done today looks at us as things and doesn't take into consideration the fact that we must work to make a living, that we are often exhausted when we finish work or fall into bed after being mom to four or five children and running a household. Sometimes, exercise is what you do as you go about your day. There is nothing extra left for a "regime." Is there some way you can look at fatigue and daily activities as part of "exercise?"

Dr. Kilmer: This addresses my point above about areas of needed research . We now realize that many folks are not motivated or unable or
just don't have time for an exercise regimen. There is now some evidence that exercise sufficient to potentially reduce risk factors for heart disease may occur with routine activities if they are done with a little extra effort. We are currently writing a grant proposal to investigate the "minimal" amount of exercise which may be functionally beneficial to persons with diseases like CMT.

Linda: We know there are many, many people with CMT who would love to help you take a look at CMT and exercise. We have about 250 people in California and I know there are many more. Would you ever consider doing something on CMT and exercise? What do you have planned for your next piece of work on exercise and neuromuscu-
lar diseases?

Dr. Kilmer: In addition to the project I've already talked about, we are looking at the effect of ankle bracing in order to improve prescription and use of these devices so often helpful to persons with CMT but often not used due to pain, cosmetics, and poor fit. We don't have any exercise interventions planned in the immediate future, but since this is an area in which we have lots of experience, we'll be putting together a project soon to look at functional improvements which may occur with exercise programs, particularly those that can be done simply at home.

Linda: A reader, Robert Anderson, has asked me to ask you a question: Does walking while wearing AFOs up to the knees do anything to strengthen calf muscles?

Dr. Kilmer: A good but somewhat complex question. I don't know that anyone has actually studied that scientifically.

To understand my answer, one must know that the calf muscles (gastrocnemius-soleus) provide plantar flexion (push the foot down as in stepping on the gas pedal), while the anterior leg muscles (tibialis anterior, peroneals) provide dorsiflexion (bring the foot up). The anterior leg muscles are what is usually the weakest in CMT.

In CMT AFOs are designed to mainly provide a "dorsiflexion assist," because that is what is weak. They can also be designed and made to provide plantar flexion assist in other conditions though.

Thus, you still have to provide your own plantar flexion, decelerating at "heel strike," into "foot flat" and then actively pushing at the "toe off" part of gait (walking). So, theoretically, walking in AFOs with CMT should be good exercise for the calf muscles. Whether or not this actually "strengthens" these muscles is not clear but I would assume that a reasonable amount of walking would do that.
Note: I assume the reader is using the term "strengthen" to mean progressively improving the force that the muscle can generate, which is different than just maintaining strength and preventing disuse atrophy.

Linda: As a new advisor to CMT International, would you kindly tell us a little about yourself.

Dr. Kilmer: Yes, I'm married to Stephanie, an occupational therapist, who always reminds me that function is the name of the game when treating patients in addition to looking at more mundane measures of strength. We have an 11-year-old daughter, Taryn, who shares her Dad's love of sports and the piano. I only wish I could play like her! I love all kinds of sports and have completed quite a few triathlons, including several with another advisor of yours, Dr. Greg Carter. I won't tell you who dominates the competition. We just finished a great ski season here in California, another love of mine, and I think it was the only good thing to come out of El Nino.

Linda: We'd like to be able to ask you questions on exercise as readers ask them. May we? We know you don't know everything but we also know there is much to learn in hearing people's concerns. Are you game?

Dr. Kilmer: Sure, I'd be happy to help any way I can.