Use of shaker exercise to improve strength of suprahyoid muscles in dysphagia

1. Dysphagia 20:133–138 (2005)
DOI: 10.1007/s00455-005-0004-2
Attaining and Maintaining Isometric and Isokinetic Goals
of the Shaker Exercise
Caryn Easterling, PhD, Barbara Grande, MA, Mark Kern, MS, Karri Sears, BSW, and Reza Shaker, MD
MCW Dysphagia Institute, Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
Abstract. Previous studies have shown that the Sha-ker
Exercise is effective in restoring oral intake in
patients with deglutitive failure due to upper esoph-ageal
sphincter (UES) dysfunction. Our aim was to
determine (1) exerciser compliance among healthy
older adults, (2) number of days required to attain the
isometric (IM) and isokinetic (IK) exercise goals, (3)
rate and reason for dropout of exercisers, and (4)
complaints associated with performance of the exer-cise.
Twenty-six nondysphagic older adults were en-rolled
from an independent-living community (66–93
yr) to perform the Shaker Exercise. Each participant
completed a questionnaire on exercise performance
and its associated difficulties three times a day for six
weeks. Four randomly chosen nondysphagic partici-pants
underwent pre- and postexercise videofluoro-scopic
swallow studies for biomechanical measure-ments.
Maximum anterior hyoid and laryngeal
excursions, as well as maximum anteroposterior UES
opening increased (p < 0.05) following exercise.
Duration to attain Shaker Exercise performance goals
varied among participants. IK was more easily at-tained
than IM. Only 50% and 70% of those enrolled
initially were able to complete the exercise duration
and attain its IK and IM goals, respectively. However,
those who stayed in the program attained the IK and
IM goals (100% and 74%, respectively). Most drop-outs
occurred in the first two weeks of exercise. Per-formance
of the exercise was associated with mild
muscle discomfort that resolved spontaneously after a
couple of weeks. We concluded that although the
Shaker Exercise can be performed independently, a
structured and gradually progressive program is nee-ded
to attain the exercise goals completely.
Key words: Shaker Exercise — Swallowing — UES
opening — Aspiration — Deglutition — Deglutition
disorders.
Introduction
Previous studies have shown that the Shaker Exer-cise,
an isometric and isokinetic exercise designed to
improve the strength of the suprahyoid muscles, in-creases
the upper esophageal sphincter opening in
healthy older adults and is effective in restoring oral
intake in patients with deglutitive failure due to upper
esophageal sphincter (UES) dysfunction [1,2].
Research has demonstrated that strength-training
exercises for limb muscles alter the effects of
muscle weakness that accompanies aging. The pre-ventable
and reversible muscle weakness that accom-panies
aging is referred to as sarcopenia. Sarcopenia is
a result of decreased physical activity and can be
accelerated by disuse and chronic illness [3–7]. Iso-metric
and isokinetic exercise has been shown to be
beneficial in reversing the sarcopenic changes in stri-ated
muscles of the limbs in people over 60 years of
age. Specifically, these types of exercise increased the
muscle contractile velocity and muscle hypertrophy,
vital components of improved power and improved
strength [8,9]. From several studies of limb muscle
strength training, muscle strength increases as a result
of physiological adaptations to stress placed on the
muscle tissue. Hypertrophy of the muscle occurs with
the increase in the number and size of the myofibrils
within the muscle fibers, an increase in the amount of
myosin contractile protein, an increase in capillary
Supported in part by a grant from Retirement Research Founda-tion.
Correspondence to: Reza Shaker, MD, Division of Gastroenterol-ogy
and Hepatology, Medical College of Wisconsin, 9200 W.
Wisconsin Ave., Milwaukee, WI, 53226, USA; E-mail: rshaker@
mcw.edu

2. 134 C. Easterling et al.: Shaker Exercise Compliance
density per muscle fiber, and an increase in connective
tissue. Biochemically the muscle fibers increase the
concentrations of creatine, adenosine triphosphate,
glycogen, and the glycolytic enzyme activity. The
cumulative functional effect of these vascular, neuro-muscular,
and biomechanical changes is an increase in
muscular power or strength [10]. These studies show
the benefit of isometric and isokinetic exercise done
primarily using exercises for the limbs. However, the
same transformations should occur in other striated
muscles, such as the suprahyoid muscles, when they
undergo isometric and isokinetic exercise.
To review, the isometric strengthening portion
of the Shaker Exercise consists of three head lifts held
for 60 s with a 60-s rest period between each of the
three held head lifts. Isometric exercise is defined as
resistance without movement. Tension develops in
the muscle, however, the muscle does not shorten or
lengthen. Effective isometric contractions should be
performed until the exerciser experiences muscle fa-tigue
and then the exercise should be repeated several
times for maximum benefit [11]. The isokinetic por-tion
of the Shaker Exercise consists of 30 consecutive
head lifts performed without ‘‘holding’’ the head lift,
as described in the isometric portion. The velocity of
the repetitive head lifts is kept relatively constant.
Isokinetic exercise benefit is achieved when the mus-cle
shortens against an accommodating resistance.
The resistance matches the shortening force and is
produced by the muscle throughout the full range of
motion. The slower the velocity of the isokinetic
motion, the greater the strength gains will be [12].
Performing regular exercises has been shown
to improve daily functioning and decrease health care
costs and yet two thirds of persons over age 65 do not
exercise regularly. Furthermore, approximately 50%
of sedentary adults who start an exercise program
stop them within the first six months of involvement
[13,14]. Because the Shaker Exercise has been per-formed
independently, the aims of this study were to
determine (1) exerciser compliance among healthy
older adults, (2) number of days required to attain the
isometric (IM) exercise goal (60-s sustained head raise
3·) and isokinetic (IK) exercise goal (30 repetitive
head raises), (3) rate and reason for drop out of
exercisers, and (4) complaints associated with per-formance
of the exercise.
Methods
Subjects
We recruited healthy older adults from a senior independent-living
community. Letters were sent inviting residents to an informational
meeting regarding a paid six-week exercise research study. We
enrolled 26 nondysphagic older adult residents from this indepen-dent-
living community (7M, 19F; age range- 66–93 yr). Inclusion/
exclusion criteria were as follows: Each enrolled participant had a
negative past medical history for the following diseases: myositis,
neurologic disorders, cervical spine surgery, dystrophy, myasthenia
gravis, dysphagia, history of smoking, head/neck surgery, and a
condition that prohibited daily exercise. Each participant was able
to perform the exercise three times per day for six weeks. Each
participant was required to be able to exercise independently.
Exercise Protocol
Prior to beginning the Shaker Exercise, each enrollee viewed an
instructional videotape of the Shaker Exercise and demonstrated
accurate performance. Participants were also given the following
written directions: ‘‘The Shaker Exercise is to be performed three
times per day for six weeks. Part I: Lay flat on your back on the
floor or bed. Hold your head off the floor or bed looking at your
feet for one minute. Don!t raise your shoulders off the bed or floor
when lifting your head. Relax for one minute and repeat two more
times. Part II: Raise your head up and forward and look at your
feet thirty times. Do not sustain these head lifts or raise your
shoulders. Remember to breath while performing both steps of the
Shaker Exercise.’’ Volunteers were asked to keep their mouth
closed during the exercise. In addition to the written exercise
instruction sheet, each participant received an Exercise Log on
which to record the number of seconds for each sustained head lift
and number of repetitions performed for the nonsustained head
lifts. Each participant recorded this data three times per day for six
weeks. One of two speech pathologists visited each participant
weekly to check for accuracy of exercise performance, inspect re-cords
of exercise performance, and record comments or complaints
regarding the exercise.
Videofluoroscopic Data Collection
To measure and verify previously reported changes in hyoid, lar-yngeal
excursions, and UES opening following six weeks of exer-cise,
four participants were randomly chosen from the 26
participants to undergo pre- and post-Shaker Exercise videofluo-roscopic
swallow studies. Maximum anterior hyoid and laryngeal
excursion, maximum superior hyoid and laryngeal excursion, and
maximum anteroposterior deglutitive UES opening diameter were
compared using pre- and postexercise videofluoroscopic images.
For videofluoroscopic recordings, the participants were instructed
to hold their head in a neutral position. Videofluoroscopic
recordings were obtained at 90 keV, using a 9-in. image-intensifier
mode and appropriate collimation so that an image was obtained
of the posterior mouth, pharynx, and pharyngoesophageal region.
Fluoroscopic images were recorded on a super- VHS videocassette
recorder (AG-1960 Proline; Panasonic, Tokyo, Japan), which re-corded
30 frames/60 fields/s. Fluoroscopic recordings were timed
using a specially designed timer. The output of the timer provided a
video-displayed time signal in hundredths of a second superim-posed
on the videofluoroscopic images. The videofluoroscopic
recordings were subsequently digitized and analyzed in a blinded
fashion with respect to participant identity and pre- or postexercise
study recording. The computer analysis system used for analyzing
the videofluoroscopic data consisted of a 486 IBM compatible
computer operating a 33 MHz. The computer system drives an
analog-to-digital conversion board and program specifically de-signed
for image capture and analysis. The image-analysis and

3. C. Easterling et al.: Shaker Exercise Compliance 135
capture software (JAVA, Jandel Scientific, San Mateo, CA) allows
capture of standard raster scan video images and morphological
analysis of digitized image data. The digitized images are stored as
computer files for any subsequent recall or analysis.
Results
Comparison of pre- and postexercise biomechanical
deglutitive events revealed maximum anterior hyoid
(AH) excursion (measured in millimeters) increased
15 ± 3%, maximum anterior laryngeal excursion
(AL) excursion (measured in millimeters) increased
33 ± 2%, and maximum anteroposterior UES de-glutitive
opening (measured in millimeters) increased
27 ± 3%. (Table 1 Figs. 1 and 2).
Comments and Complaints Reported by Participants
During the first week of the Shaker Exercise five fe-male
and two male participants experienced neck
muscle soreness and one (F) experienced dizziness
while performing the Shaker Exercise. Four exercisers
(3F, 1M) thought it was difficult to perform the
exercise with their busy schedules. Eight of 26 par-ticipants
required repeat instruction, cueing, and
encouragement to accurately perform the exercise.
Likewise, during the second week of exercising two
female participants reported neck muscle soreness, 1
male explained that he did not like to exercise without
his wife and 5 of 26 required repeat instruction,
cueing, and encouragement to continue. Three par-ticipants
(IF, 2M) in week 3 said that it was difficult
to fit the exercise in three times per day. Only one
exerciser registered a comment or complaint in week
4, as one female reported neck muscle soreness. No
comments or complaints were reported by any of the
participants in week 5 or 6. During the final week of
exercising 12 exercisers (9F, 3M) requested to con-tinue
doing the exercise as part of their daily routine.
Retention and dropout rate for participants is re-ported
in Table 2. Each week we determined how
many exercisers attained the isometric goal (IM)
(Table 3) and how many attained the isokinetic goal
(IK) (Table 4).
After six weeks of exercise, 12 of the 19
remaining participants, who completed the exercise,
were invited to continue exercising one time per day
for six months. During the first month of continuing
the exercise one time per day, 4 of 12 participants
dropped out, three for not having time and the fourth
passed away unexpectedly of unrelated preexisting
conditions. The remaining eight participants (8F)
completed the once-per-day exercise for six months
and did not record any complaint or discomfort.
Discussion
In this study we defined the common complaint that
may develop performing the Shaker Exercise and
determined the success rate in staying in the exercise
program and of the rate of attainment of the isotonic
and isokinetic components of the Shaker Exercise
among the residents of a senior citizen facility. Study
findings suggest that duration to attain Shaker
Exercise performance goals varies among healthy
older adults. The isokinetic exercise goal appears to
be easier to attain than the isometric goal. However,
only 50% and 70% of those who enrolled initially
were able to complete the exercise duration and attain
its isometric and isokinetic goals, respectively.
Surface submental electromyographic (sEMG)
studies of the sternocleidomastoid, infrahyoid, and
suprahyoid muscles during the isometric and isoki-netic
exercise aimed at strengthening the suprahyoid
muscles revealed that the sternocleidomastoid muscle
fatigued before the infrahyoid and suprahyoid mus-cles.
In this study, evidence of early muscle fatigue
indicated that the sternocleidomastoid muscle might
limit performance of the exercise and attainment of
the exercise goals. However, after six weeks of exer-cise,
the duration of the exercise could be increased in
the sEMG study group as the muscle fatigue in all the
monitored muscles was delayed. The delay in muscle
fatigue was attributed to improved muscle strength, a
result of performing the Shaker Exercise [15]. Fatigue
of the sternocleidomastoid muscle may delay attain-ment
of the IM goal in some of the study partici-pants.
Additionally, the pathophysiology of sarco-penia
is not well understood. What is known about
sarcopenia is that it is defined by muscle atrophy of
the fast twitch or type IIA and type IIX muscle fibers.
It is characterized by diminished innervation at the
level of the motor unit and presents as an overall
decrease in functional muscle fitness. The decrease in
functioning motor units causes irregularity of motor
unit firing and incoordination of muscle activity
[6,7,16]. Motor neurons of interest in an active exer-cise
program such as the Shaker Exercise are type I or
slow twitch and type IIA and type III fast twitch. The
smaller units are type I units. Type I units are re-cruited
first, depending on the movement, and de-velop
less tension than type II. Type I units are more
fatigue-resistant than type II units. Types IIA and
IIX develop more tension and fatigue faster than type
I. The order of recruitment of a specific type of unit
depends upon the type of movement performed. An
exercise such as the Shaker Exercise is performed to
the point of fatigue, has a low-intensity portion, in-

4. 136 C. Easterling et al.: Shaker Exercise Compliance
Table 1. Biomechanical measure pre- and post-Shaker Exercise (mean ± SE)
AH (mm) AL (mm) SH (mm) SL (mm) UES (mm)
Pre-Shaker Exercise 20 ± 2.9 18 ± 2.1 11 ± 2.5 20 ± 1.3 11 ± 0.4
Post-Shaker Exercise 23 ± 2.6* 24 ± 2.1* 11 ± 2.2 20 ± 1.4 14 ± 0.5*
cludes many repetitions, and a portion of high
intensity with few repetitions will recruit both type I
and type II motor units. If this occurs the Shaker
Exercise should improve both strength and endur-ance
[8,17]. Because of the decreased number of type
IIA and type IIX motor units in aging muscles, it is
possible that isometric exercise goals are more diffi-cult
to attain than the isokinetic exercise goals be-cause
of the amount of tension required to perform
the isometric goal.
The present study!s findings also indicate the
need for a more structured and gradually progressive
exercise plan in order to attain the exercise perfor-mance
goals. Adhering to a regular exercise program,
especially by the elderly, has generally been found to
be difficult. Resnick [14] developed a seven-step pro-gram
to help older adults initiate and adhere to a
regular exercise program. Using the seven-step pro-gram,
which included (1) education, (2) exercise
prescreening, (3) setting goals, (4) exposure to exer-cise,
(5) role models, (6) verbal encouragement, and
(7) verbal reinforcement/rewards, the researcher no-ted
19% of the exercisers adhered to the regular
exercise program. Findings of the present study sug-gest
that the majority of dropouts from the Shaker
Exercise occur in the first two weeks, while the
dropout rate after that is negligible. Study findings
also indicate that when the individuals continue to
stay in the program, the success rate for attaining the
isokinetic goal of the exercise is higher (100%) than
that of the isometric goal of the exercise (74%).
Study findings also show that performance of
the Shaker Exercise, similar to other muscle exercises,
can be associated with mild muscle discomfort that
resolves spontaneously after a couple of weeks of
exercise. In addition, the study findings suggest that
some elderly may desire to perform the Shaker
Exercise as part of a healthy exercise routine. The
effect of such a program on prevention of dysphagia
after intercurrent deconditioning merits further
investigation. However, further studies are needed to
determine the minimal duration and repetitions re-quired
to augment UES opening using the Shaker
Exercise.
The study!s finding of a significant increase in
anterior excursion of the larynx as well as the ante-rior–
posterior diameter of the UES following six
weeks of exercise is in agreement with previous
studies of larger numbers of healthy elderly [1] and
patients with UES dysphagia [2]. Documentation of
these changes was used to objectively determine the
performance of the exercise rather than to prove its
effect on the deglutitive biomechanical events. Dys-phagic
patient exercise compliance, attainment, and
maintenance of IM and IK goals could be expected to
be greater than that of normal older participants in
the current study if the seven-step program men-tioned
above is incorporated. The dropout rate
should be slower with clinician adherence to the
*p < 0.05.
Fig. 1. Effect of the Shaker Exercise on anterior laryngeal excursion.
The preexercise laryngeal excursion of 18 ± 2 mm increased to
24 ± 2 mm after six weeks of exercise (p<0.05). This trendwas seen
in all subjects.
Fig. 2. Effect of six weeks of exercise on anteroposterior (AP)
diameter of the UES. In all subjects the AP diameter of the UES
increased following six weeks of exercise. As a group the postexercise
value of 13.9 ± 0.5 mm was significantly higher than preexercise
values of 11.7 ± 0.5 mm (p < 0.05). This trend was seen in all
subjects.

5. C. Easterling et al.: Shaker Exercise Compliance 137
principles of the seven-step program for exercise
program compliance.
Conclusion
Although the Shaker Exercise can be performed
independently, a more structured and progressive
program is needed to attain the isometric and isoki-netic
exercise goals. Further studies are also needed
to determine the minimal duration and repetitions
required to augment UES opening using the Shaker
Exercise.
Acknowledgments. The authors wish to thank the staff and resi-dents
of Alexian Village of Milwaukee, Wisconsin, for their patient
and dedicated participation in this project.
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Table 2. Shaker Exercise dropout rate
Weeks
Variables 1 2 3 4 5 6
Dropout (DO) rate 3/26 (12 %) 3/26 (12 %) 0% 1/26 (4 %) 0% 0 %
Reasons for dropout 1F-dizziness
1F, 1M pending unrelated surgery
2F-arthritis
1M-wife DO so he DO
1F-arthritis
Table 3. Shaker Exercisers—Attainment of isometric goal
Week l Week 2 Week 3 Week 4 Week 5 Week 6
+++++!!!!!!! +++++++!!! +++++++++ +++++++++ +++++++++ +++++++++
!!!!!!!!!!! !!!!!!!!!! !!!!!!!!!! ++!!!!!!!! ++++!!!!!! +++++!!!!! flflfl flflfl fl
5/26 19% 7/23 30% 10/20 50% 11/20 55% 13/19 68% 14/19 74%
+ = attained, ! = not attained, fl = dropped out.
Table 4. Shaker Exercisers—Attainment of isometric goal
Week 1 Week 2 Week 3 Week 4 Week 5 Week 6
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+!!!!!!!!!!! ++!!!!!!!! +++!!!!!! ++!!!!!!! ++++!!!!!! +++++!!!!! flflfl flflfl fl
12/26 46% 12/23 52% 13/20 65% 17/20 85% 19/19 100% 19/19 100%
+ = attained, ! = not attained, fl = dropped out.

6. 138 C. Easterling et al.: Shaker Exercise Compliance
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