October 1, 2013 Features

Muscle Isolations

When it comes to the orofacial musculature, exercises benefit only certain clients and must be highly targeted to be effective. Here are questions and research findings to weigh when considering exercise in speech and swallowing treatment.

I recently participated in a 10-week high-intensity fitness boot camp, which assessed participants' pre- and post-training speed and endurance, among other fitness metrics. Before training, our metrics varied considerably: Some of us could run a nine-minute mile. Some couldn't run for even one minute. Some could do 20 pushups. Some could do only five. Some could throw the 14-pound medicine ball against the wall. Some of us could throw only a 6-pound ball. After 10 weeks of training, most of us could run faster and longer than we could before boot camp. We could do more pushups and throw a heavier medicine ball.

What struck me during this experience is that the term "fitness" seems to warrant some level of qualification. That is, almost everyone is "fit enough" to do some things. Moreover, one could argue that getting "fitter" might not make someone any better able to do some things. For example, being able to do 35 instead of 20 pushups has not made my crocheting any faster or accurate.

To be effective, fitness-building must be targeted to specific goals, and this is true across all areas, including the one I study: "fitness" of the orofacial musculature. In the muscle groups relevant to speech and swallowing, fitness encompasses strength, endurance, speed and coordination. Though not necessarily the most important of these physiologic variables, strength is the most widely studied, arguably the easiest to assess, and presumably most frequently targeted in speech and swallowing intervention. But before targeting it, the clinician needs to think through how to make the treatment effective for clients—how to move them to the orofacial equivalent of a higher pushup count.

Key questions

What follows are questions that I recommend clinicians raise when targeting strength, but they also generalize to any aspect of fitness targeted for intervention.

1. Before initiating a strength training program, ask, "What does the client have to be strong enough to do?" Asking this question helps avoid the pitfall of focusing on underlying physiologic function (as in, "The knee muscles are weak—strengthen the knees!") without adequately considering why the physiology is being targeted (as in, "The knees are too weak to provide stability going down stairs—strengthen the knees!") In the case of speech, the client must be strong enough to create tension to shape and constrict the vocal tract. For swallowing, strength must be sufficient to contain, manipulate and propel a bolus, and to protect the airway.

2. "What evidence do I have that weakness is the only or main factor preventing him or her from doing that?" This question builds on the previous question by reminding the clinician to assess different aspects of muscle strength. A helpful distinction here is maximum performance versus minimum competence. Maximum performance refers to what the client can achieve with maximal effort, usually under atypical conditions (for example, with a tongue blade positioned in front of the tongue). Assessment of maximum performance ("Push/squeeze as hard as you can!") tells us something about the fundamental integrity of the system: Neuromuscular or movement disorders often result in reductions in maximal performance. However, this level of assessment may not provide clear insight into whether the client possesses minimum competence, which refers to the strength needed to constrict the vocal tract for frication or to propel a bolus to the oropharynx.

Studies of tongue strength have not identified a reliable level of maximum performance that predicts minimum competence. The clinician must instead observe performance during the target or related tasks to judge minimum competence. For example, a client who can produce a perceptually accurate /t/ and "sh" likely has enough strength to produce /s/.

This question also encourages the clinician to consider whether factors beyond strength are limiting the client's abilities. For example, a client with a left hemisphere stroke may show detectable weakness of the tongue. However, conditions such as aphasia or apraxia of speech could be the main cause of a client's communication problems. In such situations, tongue-strengthening to improve articulation would not aid communication.

3. If weakness appears to be the client's main limitation, the next question is, "Will exercise make him/her stronger?" Consider whether the client has the capability to benefit from exercise. For example, such neuromuscular conditions as myasthenia gravis can impair the physiologic mechanisms that allow the muscles to benefit from exercise. Also consider whether the exercise incorporates the necessary features to increase strength. Relevant features include the appropriate amount of resistance and the progression of the exercise program. Another component is exercise frequency, so that sufficient time is allowed for recovery. In addition, exercise duration should allow for adaptions of both the nervous system—increased efficiency of motor unit recruitment, which happens relatively quickly—and the muscles—increased diameter of muscle fibers, which can take many weeks.

4. Finally, perhaps the most relevant question is, "Will making him/her stronger improve the target function?" Consult the treatment outcome literature for specifics on the client groups, disorders and muscle groups most responsive to strength training, as well as for guidance on exercise dosage and potential benefits of combining multiple exercises. You can find evidence-based reviews on sites such as ASHA's Practice Portal and SpeechBITE. The literature from related fields, such as motor learning, can also aid decision-making.

Exercise benefits?

So what does the current evidence reveal about oral exercises? Strengthening exercise targeting the respiratory and phonatory musculature appears to benefit clients most. Exercise programs that are relatively high in specificity for speech movements (Lee Silverman Voice Treatment, for example) report positive results, as do those that are limited in specificity for speech (expiratory muscle training, for example). Exercises for velopharyngeal musculature that incorporate speech may also help, although generally only when weakness, rather than structural abnormality, is the main culprit. There is disappointingly little evidence to suggest that tongue strengthening consistently benefits speech, even in clients with dysarthria.

In contrast, tongue strengthening is a much more promising treatment for dysphagia. Many of the respiratory and laryngeal exercises shown to improve speech also show benefit for swallowing. Beyond these exercises is the plethora of strengthening exercises devised specifically for swallowing movements, such as the effortful swallow, the Masako maneuver and the Mendelssohn maneuver. In general, the evidence to support strengthening in dysphagia management is stronger than the evidence to support strengthening for improving speech.

Ultimately, muscular fitness is clearly not sufficient to ensure adequate skill in speech and swallowing. And even when muscle exercises could possibly help a client, treatment that incorporates functional speech and swallowing is essential. In keeping with the example above, knee exercises may facilitate the necessary fitness, but going down stairs with the stronger knee is the practice that will ultimately improve the target function.

Just as many people would not require fitness boot camp to improve their needlecraft skills, many clients will not require fitness training for the speech and swallowing musculature. Our roles as clinicians are to identify when fitness is—and is not—a limiting factor, develop appropriate treatment programs based on sound evidence-based practice, and critically gauge the benefit of our interventions. Who knows? As our evidence base continues to grow, we may find a place for speech or swallowing boot camp.

Heather Clark, PhD, CCC-SLP, is a senior associate consultant of speech pathology and associate professor of speech pathology in the Department of Neurology at the Mayo Clinic in Rochester, Minn. She is an affiliate of ASHA Special Interest Groups 2, Neurophysiology and Neurogenic Speech and Language Disorders; 3, Voice and Voice Disorders; 5, Speech Science and Orofacial Disorders; and 13, Swallowing and Swallowing Disorders. clark.heather1@mayo.edu

cite as: Clark, H. (2013, October 01). Muscle Isolations. The ASHA Leader.

SIG 5 Perspectives Explores the Case Against Blowing Exercises

In this month's issue of Perspectives from ASHA Special Interest Group 5, Speech Science and Orofacial Disorders, Gregory Lof and Dennis Ruscello take a hard look at the use of nonspeech oral motor exercises, particularly blowing, in treating children with cleft palate and velopharyngeal inadequacy.

The article traces the origins of this form of treatment and reviews research that finds it to be ineffective in clients with cleft palate and VPI. It also points to alternative treatments, such as biofeedback and continuous positive airway pressure, that—research indicates—can benefit clients with these disorders.



Sources

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Ashford, J., McCabe, D., Wheeler-Hegland, K., Frymark, T., Mullen, R., Musson, N., . . . Hammond, C. S. (2009). Evidence-based systematic review: Oropharyngeal dysphagia behavioral treatments: Part III. impact of dysphagia treatments on populations with neurological disorders. Journal of Rehabilitation Research & Development, 46(2), 195–204.

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