Friday was my first day of the ASHA Convention. For reasons I can’t remember, getting to ASHAcon on Friday rather than Thursday seemed work better for scheduling. I was wrong and missed out on a lot of great courses. I also missed out on a few meet-ups of those in the SLP blogosphere and Twitterverse. A learned lesson and a tip for future ASHAcon newbies: if you’re going to make the most of your ASHAcon experience (and the hard earned money you spend to get here!), get here on here on the opening day. The regret, it burns!
At any rate, I’m digressing from what I wanted to share with all of you good SLP folks. If you’ve ever thought about going to a short course, but have wavered because the cost (or the three hour, no break commitment), I’m telling you to reconsider. Short courses, if you’re not familiar, are ticketed courses on specific topics, many of which are put together by ASHA’s Special Interest Groups. The courses are presented by an array of panelists, usually those who have gained celebrity status among the ranks of their professional colleagues and humble followers. The partnership between such presenters and researchers provides an enormous wealth of knowledge to attendees in a way that is easy to follow along and digest. Among the seminars that I attended, the short course was a highlight of mine.
The short course I attended was Exercise Principles: How Much, How Often, How Intense? I believe that because there is a relatively small amount of course work on dysphagia in our professional training, many clinicians feel that there are gaps in our translational knowledge, that is the link between the science and our clinical practice. This sentiment may not be true for everybody, but I certainly feel this way at times. For example, what happens to our muscles when they are worked during exercise? How, on biological level, do muscles become stronger (or weaker)? What type of muscle do we use during swallowing, and will that influence that type of exercise we tell our patients to do? These are the types of questions that any of need to answer once we are already practicing and it exactly these types of questions that were answered by some of the biggest names in swallowing research: Dr. Lori Burkhead, Dr. Cathy Lazarus, Dr. Heather Clark and Dr. Michelle Troche. All of these presenters spoke at ease with the audience, with an authority gained by their years of experience and research, and it couldn’t have been a more informative and humbling presentation.
Because I’m a dork and believe in open-source knowledge in science, I want to share with you some of what I learned. First, some basic info on muscle anatomy. The basic unit of a muscle is a myofibril, which are essentially strands of proteins. Myofibrils are made up of repeating pieces of sarcomeres, which are also strands of protein. When the motor neuron releases acetylcholine and it binds to the muscle cell receptors, the sarcomere contracts, which causes the myofibrils to contract and in turn the muscle at large also contracts.
(Source. 1. Motor neuron. 2. Neuromuscular junction. 3. Muscle fiber. 4. Myofibril)
To strengthen a muscle, additional myofibrils must be built. In addition to this, there are two types of muscle:
- Type I; these are fatigue resistant and are good for endurance
- Type II; these are used for power and strength. This can be broke down into Type IIa and Type IIb, for moderate activity/efficiency and for high power/less efficient activity, respectively.
So why is this important to know for dysphagia rehab? Because form follows function. In large, the tongue is made up of Type II muscle fibers, with the base of the tongue predominantly made of Type II and the tongue tip having more Type I than any other part of the tongue. When a muscle deconditions, neural activation, motor neurons and efficiency are reduced, which translates to atrophy and easily fatigued muscles. Another important factor of deconditioning is the phenomena of sarcophenia, age related decline of muscle fibers. As it is, this largely affects Type II fibers, which we know is predominant in the tongue. Swallowing, we have a problem.
It can be argued, they said, that when a person becomes npo, this deconditioning occurs because swallowing frequency declines, which in turn exacerbates dysphagia. I think this is a valid working theory. Then the question becomes ‘how do we reverse this trend? The answer: by conditioning muscles. This almost exactly the opposite of deconditioning, by increasing neural activation and the number of motor neurons. And do this, exercise must be a component of treatment, and exercise must have some distinct characteristics.
First, exercise must be specific, meaning it should mimic what actually happens during the swallowing. Citing some examples from exercise physiology as an analogy, people who want to improve in cycling will bike as exercise, and these people will not see any improvement in other sports, like running or swimming. Intensity also matters, in fact, there are some rather specific guidelines for this. To build those myofibrils, ate muscle needs to be overloaded during an exercise, at at least 60% of the maximum output of that muscle. To prevent plateau, it’s important to recognize gains and new maximum output after exercise to maintain that 60% mark.
They also cited numerous studies highlighting specific exercise effects for the tongue with some novel findings. Exercising the tongue against resistance in a variety of directions (protrusion, elevation and lateralization) yielded stronger forces, no surprise there. But they also found that exercising the tongue in a single direction improved strength for tongue movements in all directions. To me, this seemed to deviate slightly from the specificity principle. However, in studying exercise conditions, they found specific effects for targeting strength, power and endurance of the tongue, all of which were mutually exclusive (i.e., targeting strength did not improve power).
A little more murky was the research regarding duration of exercise. Should exercise be done two times a week? Seven days a week? There seemed to be positive effects from anywhere between 2 and 7 days a week for at least 4 weeks or more. Though, no clear picture was really made on this point, other than exercising more often than not is important.
This was essentially the meat of the course. There was a lot more than this, of course, and I could write a much longer post than this if I wanted. The panel also discussed changes to tissues and muscles following radiation therapy for head and neck cancer, the importance of pre- and post-dypsphagia exercise and the time frame of when to expect improved muscle and swallow function. There was also talk on the use of expiratory muscle strength training (EMST) and its application to swallowing function. I was only vaguely aware of EMST in general, which is the use of a device into one blows against resistance to improve muscle respiratory muscle strength. As it happens, use of EMST also promotes soft palate and laryngeal elevation and base of tongue retraction-all things that happen during swallowing. Needless to say, I’ll be following research on this a little more closely in the future.
This short course was exactly what I look for when attending a seminar. It had knowledgable presenters who engaged the audience, it covered basic scientific concepts and in turn used that science to garner translational knowledge to bridge that gap between the lab and the clinic. Did anyone else attend this course? Please add anything you thought I didn’t cover, or something that I didn’t make more clear. Did you attend another short course, or another seminar that blew your mind? Let us know here. Drop the name of seminar, the presenter and what you took away presentation.
(Adam is one of the official ASHA Convention bloggers! Stay tuned for more insights from him and the other bloggers before, during and after convention.)
Adam Slota M.A., CCC-SLP is a speech pathologist working in long term care and long term acute care settings, primarily with tracheostomy and ventilator dependent patients. He is also the author of the blog slowdog where he writes about various topics in speech pathology and beer, among other frisky and/or mundane missives.