effects of pectoralis minor stretching versus pectoralis ... · injury when pectoralis minor...

Effects of Pectoralis Minor StretchingVersus Pectoralis Minor Stretching with

Scapular Posterior Tilt Exercise onShoulder Kinematics in Stroke Patients

The Graduate School

Yonsei University

Department of Physical Therapy

Ilwoo Park

Effects of Pectoralis Minor StretchingVersus Pectoralis Minor Stretching with

Scapular Posterior Tilt Exercise onShoulder Kinematics in Stroke Patients

Ilwoo Park

A Master ThesisSubmitted to the Department of Physical Therapy

and the Graduate School of Yonsei Universityin partial fulfillment of the requirements

for the degree of Master of Science

June 2014

This certifies that the masters thesis of Ilwoo Park is approved.

Thesis Supervisor: Chunghwi Yi

Ohyun Kwon: Thesis Committee Member #1

Heonseok Cynn: Thesis Committee Member #2

The Graduate SchoolYonsei University

June 2014

Acknowledgements

It is my pleasant duty to acknowledge those people who have influenced my work

during my graduate studies. First of all, I would like to express my sincere apprecia-

tion to my advisor, Professor Chunghwi Yi for his professional guidance and inspira-

tion. He offered genuine support throughout the process. I am extremely thankful for

his help. This work would not have been possible without his continuous encourage-

ment. I would also like to convey my gratitude to Professor Ohyun Kwon. He shared

with me his clinical experience and gave me many ideas for my research. I have

gained familiarity with the musculoskeletal system as a result of his teaching. I also

sincerely appreciate Professor Heonseock Cynn who has always given me continued

attention with his smile and kindness. His detailed comments on my study made it

better. I also appreciate Professors Hyeseon Jeon, Seunghyun Yoo, and Sanghyun

Cho, who taught me in various academic fields.

I would like to express my deep gratefulness to all members in the Graduate School

Department of Physical Therapy. Above all, I am highly appreciative to Onebin Lim,

Wangjae Lee, and Jeongah Kim for providing continued support in many ways. I

wish to express gratitude to my graduate school classmate, Myungki Ji, Minsu Cho,

and Donghwi Son, who shared the happiest hours of our coursework in two years. I’m

very thankful to Kyuenam Park, and Sungdae Choung that such a wonderful under-

graduate classmate was in the graduate school. My thanks also go to Physical Thera-

pist Bongkyun Jeon, Boram Kim, and Hoseung Lee for helping me with laboratory

work and providing precious time.

More than anybody, I would like to share my honor with my family and wife’s

family. Without their great faith in me and endless love, I could not finish my gradu-

ate study. Finally, I wish to express my deepest gratitude to my wife for her love,

support, and encouragement. I would like to dedicate this dissertation to my wife,

Sowook Kim and our dear fetus, Chilbok. Thank you.

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Table of Contents

List of Figures ···································································· iii

List of Tables ····································································· iv

Abstract ············································································ v

Introduction ······································································· 1

Methods ············································································ 4

1. Subjects ······································································ 4

2. Experimental Equipment ··················································· 6

2.1 Three–Dimensional Electromagnetic Motion Tracking System · 6

2.2 Pectoralis Minor Muscle Length Test ······························· 7

3. Experimental Procedure ···················································· 8

4. Interventions ································································ 10

5. Statistical Analysis ························································· 13

Results ············································································ 14

1. General Characteristics of Subjects ······································ 14

2. Comparison of the Pre–Intervention Parameters Between the Two

Groups ····································································· 15

3. Scapular Posterior Tilt Angle ············································· 16

4. Humeral Forward Flexion Range ········································ 18

5. Pectoralis Minor Length ·················································· 20

Discussion ········································································ 22

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Conclusion ······································································· 27

References ········································································ 28

Abstract in Korean ······························································· 39

- iii -

List of Figures

Figure 1. The pectoralis minor muscle length test ····························· 7

Figure 2. The humeral forward flexion ········································· 9

Figure 3. The pectoralis minor muscle stretching ····························· 12

Figure 4. The scapular posterior tilt exercise ·································· 12

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List of Tables

Table 1. General characteristics of subjects ···································· 14

Table 2. Comparison of the parameters between the two groups at pre–intervention

············································································ 15

Table 3. Comparison of the two groups’ scapular posterior tilt angle pre– and post–

intervention ····························································· 17

Table 4. Comparison of the two groups’ scapular posterior tilt angle following the

6–week intervention ···················································· 17

Table 5. Comparison of the two groups’ humeral forward flexion range pre– and

post–intervention ······················································ 19

Table 6. Comparison of the two groups’ humeral forward flexion range following

the 6–week intervention ················································ 19

Table 7. Comparison of the two groups’ pectoralis minor length pre– and post–

intervention ····························································· 21

Table 8. Comparison of the two groups’ pectoralis minor length following the 6–

week intervention ······················································· 21

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ABSTRACT

Effects of Pectoralis Minor Stretching

Versus Pectoralis Minor Stretching with

Scapular Posterior Tilt Exercise on

Shoulder Kinematics in Stroke Patients

Ilwoo Park

Dept. of Physical Therapy

The Graduate School

Yonsei University

The purpose of this study was to compare the effects of a 6–week period of

pectoralis minor stretching (PMS) and PMS with scapular posterior tilt exercise

(SPTE) on the scapular posterior tilt angle, humeral forward flexion range during

active humeral forward flexion, and relative pectoralis minor length in stroke

patients. Twenty patients (13 males and 7 females) who had undergone a stroke

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participated in this study. The subjects were randomly divided into two 10–patient

groups: PMS and PMS plus SPTE. Three–dimensional electromagnetic motion

tracking system was used to measure the paretic scapular posterior tilt angle and

humeral forward flexion range during active humeral forward flexion in a sitting

position, and the relative pectoralis minor length was measured using a pectoralis

minor length test. The results showed that the scapular posterior tilt angle and

humeral forward flexion range were significantly increased during active humeral

forward flexion in both groups. The pectoralis minor length was found by a pectoralis

minor length test to be significantly increasing in both groups. In a comparison of the

PMS and PMS plus SPTE groups, the scapular posterior tilt angle and humeral

forward flexion were increased more in the PMS plus SPTE group than the PMS

group. However, the results of our study were not statistically significant. The relative

pectoralis minor length increased more in the PMS group than the PMS plus SPTE

group, but also not significant. The 6–week PMS makes the paretic arm lift higher

through increasing scapular posterior tilt. In conclusion, PMS is an effective

intervention for the paretic upper limb function in stroke patients, but PMS plus SPTE

is not superior to PMS only.

Key Words: Pectoralis minor stretching, Scapular posterior tilt exercise, Shoulder

kinematics, Stroke.

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Introduction

A stroke is a quickly occurring disease of vascular origin, hemorrhagic or ischemic,

with noticeable symptoms and indications of the focal loss of cerebral function

(Peurala et al. 2007). One of the most ordinary results of stroke is hemiparesis on the

opposite side of a brain lesion (Messier et al. 2006). Usually, the paretic upper

extremity exhibits greater motor function loss than the lower extremity (Desrosiers et

al. 2003). After a stroke, shoulder problems are common and may lead to physical

disability in function (Mngoma, Culham, and Bagg 1999). Alignment changes in the

musculoskeletal components of the shoulder complex have been depicted in both the

flaccid and spastic stages of paralysis after a stroke and are believed to contribute to

the development of shoulder disorders in hemiplegic patients (Culham, Noce, and

Bagg 1995).

Ideal shoulder function is closely connected to proper scapular orientation and

motion (Kibler 2006; Kibler, and McMullen 2003; McClure et al. 2001; Meyer et al.

2008). It is generally recognized that the capability to keep position of the scapula at

rest and during movements/tasks (scapular positioning) is critical for optimal upper

extremity function (Hébert et al. 2002; Mottram 1997). One specific cause of

dyskinetic scapular movement may be an abnormally shortened pectoralis minor

muscle (Ludewig, and Cook 2000; McClure, Greenberg, and Kareha 2012). At the

shoulder girdle, long–term exposure to positions of increased scapular anterior tilting

and protraction is suggested to result in a shortening or tightening of the pectoralis

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minor muscle (Kendall et al. 2005; Sahrmann 2002). Decreased flexibility of the

pectoralis minor prohibits proper scapular kinematics, particularly in upward rotation,

external rotation, and posterior tilting (Borstad, and Ludewig 2005; Muraki et al.

2009). Due to the possible occurrence of scapular dyskinesis and upper extremity

injury when pectoralis minor tightness is present, stretching of the pectoralis minor

muscle is believed to be critical in the prevention and treatment of shoulder

dysfunction (Williams, Laudner, and McLoda 2013). Stretching exercise has been

considered a basic modality of treatment in the rehabilitation field for a long time

(Gracies 2001; Stokes 2004), is freely accessible, has few or no side effects, and is

inexpensive (Jo, Song, and Jang 2013).

The abnormal kinematics caused by relative muscular imbalance in the force

couples around the scapula arises from weakness in one or more scapular rotators

(Glousman et al. 1988; Johnson et al. 1994; Kibler 1998; Mottram 1997). The

inferomedial–directed fibers of the lower trapezius may also have a strong influence

on the posterior tilt and external rotation of the scapula during arm elevation

(Ludewig, Cook, and Nawoczenski 1996), which reduces the subacromial

impingement hazard (Graichen et al. 1999; Ludewig, and Cook 2000), and makes the

lower trapezius a principle site of focus in rehabilitation. The poor scapular

positioning and asymmetric muscles observed in stroke patients is the result of

muscle imbalance between the upper and lower trapezius, with lower trapezius

weakness (Reinold, Escamilla, and Wilk 2009). The lower trapezius is a particularly

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important muscle in shoulder function because of its role in scapular upward rotation,

external rotation, and posterior tilt (Andrews, Harrelson, and Wilk 2012).

Previous studies have investigated the effects of pectoralis minor stretching (PMS)

in healthy subjects (Borstad, and Ludewig 2005; Lewis, and Valentine 2007),

cadavers (Muraki et al. 2009), and collegiate swimmers (Williams, Laudner, and

McLoda 2013). There are no studies on the effects of PMS in stroke subjects. In

addition, to our knowledge, it has never been reported whether the additional

strengthening exercise of lower trapezius can facilitate changes in the scapular

posterior tilt angle and humeral forward flexion range during active humeral forward

flexion.

The purpose of this study was to compare the effect of a 6–week intervention

consisting of PMS or PMS plus scapular posterior tilt exercise (SPTE) on the paretic

scapular posterior tilt angle, humeral forward flexion range during active humeral

forward flexion, and relative pectoralis minor length in stroke patients.

The hypothesis was that PMS would increase the paretic scapular posterior tilt

angle, humeral forward flexion range during active humeral forward flexion, and

relative pectoralis minor length caused by decreasing the distance in pectoralis minor

length test. Additionally, it would be more effective to combine SPTE with PMS.

- 4 -

Methods

1. Subjects

Initially, this study began with 29 subjects who have suffered from a stroke (19

males and 10 females) in Oliver Memorial Hospital. All subjects were randomly

distributed into one of two intervention groups: the PMS group; or the PMS plus

SPTE group. However, 9 subjects (6 males and 3 females) discharged from the

hospital during the 6–week intervention. Thus, the remaining 20 subjects (13 males

and 7 females) were finally included in this study. The PMS group was comprised of

10 subjects (6 males and 4 females), and the PMS plus SPTE group included 10

subjects as well (7 males and 3 females).

The inclusion criteria were unilateral stroke subjects who, 6 months after a stroke,

had no pain in the affected arm (Price et al. 2001), scored above 24 points on the

Mini–Mental Status Examination–Korea, had sufficient cognitive ability to

comprehend the instructions (Park, and Kwon 1989), two grades or less on the

Modified Ashworth Scale (Baek et al. 2009). The exclusion criteria were as follows:

had orthopedic disorders in the affected upper limb, apparent glenohumeral joint

subluxation (more than 1.5 ㎝ between the acromion process and the humeral head)

on the affected side (Boyd, and Torrance 1992), and a cerebellar or vestibular lesion.

The present study was permitted by the director of Oliver Memorial Hospital, and

then was approved by the Yonsei University Wonju Institutional Review Board; the

- 5 -

subjects were provided with a detailed explanation of the study and gave written

informed consent prior to their participation.

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2. Experimental Equipment

2.1 Three–Dimensional Electromagnetic Motion Tracking System

The real–time three–dimensional positions of the humerus and scapula were de-

tected using the electromagnetic motion tracking system (Polhemus Liberty 240/8

system, Polhemus Incorporated, Colchester, USA). This system was used to measure

the humeral forward flexion range and scapular posterior tilt angle in the paretic limb.

Kinematic data were collected at a sampling rate of 120 ㎐ using a two–channel de-

vice in company with the Liberty host software (version 3.0). The source (58 × 52 ×

53 ㎜), located on the subject’s right side, was placed on top of a rigid wooden struc-

ture to minimize metal interference. It produced a low–frequency electromagnetic

field that was demodulated by several sensors. To record the kinematics of the hu-

merus and scapula, the two electromagnetic sensors (28 × 22 × 14 ㎜) were attached

on the distal, flat, broad surface of the acromion and the midportion of the humerus,

just below the deltoid insertion (Roren et al. 2013).

The static accuracy of this system is 0.03 inches in root mean square (RMS) for the

X, Y, or Z position and 0.15° RMS for the sensor orientation, and the latency is 3.5

㎳ (Polhemus Specifications, 2012). The real–time streaming data were exported to

an ASCII file and analyzed using Microsoft Excel by an independent researcher.

- 7 -

2.2 Pectoralis Minor Muscle Length Test

For postural analysis, pectoralis minor shortness is examined as an unduly

anteriorly translated or protracted humeral position (Page, Frank, and Lardner 2009).

Because of its origin (the superior margins of the third, fourth, and fifth ribs) and

insertion (the medial and upper surface of the coracoid process of scapula), the

pectoralis minor muscle tilts the scapula anteriorly (Kendall et al. 2005).

Each subject was asked to lie with his/her knees flexed and arms resting by his/her

sides. The researcher marked a dot on the posterior border of the acromion. The linear

distance between this dot and the table was measured using a rigid plastic triangular

rule (Set Square, Tonglu Hengmei Stationery Co., Hangzhou, China) without exerting

any downward pressure onto the table (Lewis, and Valentine 2007). The normal

distance between the acromion and the table is 1 inch or 2.54 ㎝ (Sahrmann 2002).

The measuring technique is detailed in Figure 1. Lewis, and Valentine (2007)

reported excellent intra–rater reliability in subjects with [intraclass correlation

coefficients (ICC) 0.90 to 0.97] and without (ICC 0.92 to 0.96) shoulder symptoms.

Figure 1. The pectoralis minor muscle length test.

- 8 -

3. Experimental Procedure

Before the intervention, all subjects’ scapular posterior tilt angle and humeral

forward flexion range on the paretic side were measured while the subjects lifted both

arms forward, and their pectoralis minor length was measured in a supine position.

The subjects were instructed to lift both arms to prevent trunk lateral flexion, and the

pelvis was stabilized by a therapist to prevent trunk extension (Figure 2). The subjects

performed humeral forward flexion for 15 seconds, including a 5–second waiting in

pre–lift, 5–second maximal elevation, and 5–second hold in the their peak range. At

this moment, a metronome application for smartphones, the Metronome Beats 2.2

(Stonekick, Australia) was used for movement speed and time (Kim et al. 2012b). In

order to obtain the value of change, we subtracted the average of the resting phase

from that of the holding phase. The resting and holding phase averages were

calculated, except for the first and the last second, that is, the average data of 3–

second periods were calculated. After the initial measurement, the subjects were

remeasured after the 6–week intervention period.

Subjects who participated in this study received rehabilitation treatment as

inpatients in the daytime. This may have been a confounding variable, so we made a

request for gait training in physical therapy and hand function training in occupational

therapy. For our study, the subjects participated in additional interventions after

dinner and rest, according to their feasibility. The interventions were offered 5 days

per week for 6–weeks. It is impossible for one researcher to perform interventions to

- 9 -

many subjects in the evening, so three therapists dispensed interventions to the

subjects at the same time. Prior to the interventions, the principal investigator taught

methods for PMS and SPTE to two therapists. After sufficient practice, two therapists

offered interventions like the principal investigator.

Figure 2. The humeral forward flexion.

- 10 -

4. Interventions

The interventions were PMS and PMS plus SPTE on the paretic upper limb. The

subjects in the PMS group executed gross–stretching exercise in the supine position

with the paretic arm abducted and externally rotated to 90° and the elbow flexed to

90° (Williams, Laudner, and McLoda 2013). The therapist stabilized the subject’s

trunk by placing therapist’s hand on his/her contralateral coracoids, and then gently,

passively, horizontally abducting the subject’s paretic shoulder (Figure 3). In this

study, the subjects received a gross passive stretching intervention for 10 repetitions,

holding the stretches for 30 seconds, with a 30–second resting period between each

stretch (Bandy, Irion, and Briggler 1997; Taylor et al. 1990; Williams, Laudner, and

McLoda 2013).

The subjects in the PMS plus SPTE group were instructed to first stretch the

pectoralis minor and then do the SPTE. The optimal strengthening exercise of the

lower trapezius is performed in the prone position (Ekstrom, Donatelli, and Soderberg

2003). However, the subjects in this study are stroke patients, so they are hard to

move to a prone position and cannot stay this position long because of labored

respiration. For this reason, our SPTE was done in the sitting position, which was

proposed by Mottram (1997). First, the therapist put the subject’s less affected side

hand on the affected side coracoid process, and instructed the subject to move his/her

coracoid process away from his/her healthy hand. At this moment, the therapist

- 11 -

directed the subject to move the coracoid process by gently pushing back the subject’s

healthy hand. Additionally, the therapist’s other hand tapped the subject’s paretic

lower trapezius region to evoke muscle contraction (Figure 4). For the SPTE, the

isometric exercise was performed by means of holding a position for 10 seconds, and

this was repeated 10 times (Richardson, and Jull 1995).

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Figure 3. The pectoralis minor muscle stretching.

Figure 4. The scapular posterior tilt exercise.

- 13 -

5. Statistical Analysis

The data are represented as the mean ± standard deviation. An independent t–test

was done with the pre–intervention values to test for homogeneity of variance in the

two groups and the one–sample Kolmogorov–Smirnov test was examined to

determine whether there was normal distribution. The paired t–test was used to

determine the significance of changes within each group (pre– and post–

interventions), and the independent t–test was used to determine the significance of

differences between the PMS group and the PMS plus SPTE group. To compare each

outcome, Cohen’s d was utilized to calculate the effect size. To calculate Cohen’s d,

the mean of one group was subtracted from the other and divided by the standard

deviation (Cohen 1988). All statistical analyses were performed using the SPSS

version 12.0 software (SPSS Inc., Chicago, IL, USA). The level of statistical

significance was set at α = 0.05.

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Results

1. General Characteristics of Subjects

The general characteristics of the 20 subjects including age, gender, hemiplegic

side, modified Ashworth scale, time since stroke, diagnosis, and mini–mental status

examination–Korean are shown in Table 1.

Table 1. General characteristics of subjects (n=20)

PMS

a

group (n1=10)

PMS plus SPTEb

group (n2=10)

t p

Age (yrs) 63.4 ± 8.8c 55.1 ± 15.4 1.48 0.16

Gender (male/female) 6/4 7/3

Hemiplegic side (right/left)

4/6 3/7

MASd†

(G0/G1/G1+/G2) 2/4/2/2 2/3/3/2

Time since stroke (month)

15.6 ± 7.6 16.6 ± 6.6 –0.31 0.76

Diagnosis (infarction/hemorrhage)

6/4 7/3

MMSE–Ke 25.6 ± 1.8 26.1 ± 2.2 –0.55 0.59

aPMS: Pectoralis Minor Stretching.

bSPTE: Scapular Posterior Tilt Exercise.

cMean ± standard deviation.

dMAS: Modified Ashworth Scale.

† MAS was measured by elbow flexor at elbow joint (Bohannon, and Smith 1987). eMMSE–K: Mini–Mental Status Examination–Korean.

p value is the comparison of groups using an independent t–test.

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2. Comparison of the Pre–Intervention Parameters Between the

Two Groups

Prior to the intervention, there were no significant differences (p > 0.05) between

the two groups in the following measurements: scapular posterior tilt, humeral

forward flexion, and relative pectoralis minor length (Table 2).

Table 2. Comparison of the parameters between the two groups at pre–intervention

(n=20)

PMS

a

group (n1=10)

PMS plus SPTEb

group (n2=10)

t p

Scapular posterior tilt (°)

18.31 ± 5.84c 20.38 ± 7.99 –0.66 0.52

Humeral forward flexion (°)

102.52 ± 24.69 114.45 ± 41.33 –0.78 0.44

Relative pectoralis

minor length (㎝) 4.31 ± 1.14 4.54 ± 1.40 –0.40 0.69





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3. Scapular Posterior Tilt Angle

There was a statistically significant increase from pre– to post–intervention for the

scapular posterior tilt angle in both groups (Table 3). When comparing the two groups,

the scapular posterior tilt angle was greater in the PMS plus SPTE group than in the

PMS group; however, the difference was not statistically significant (Table 4).

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Table 3. Comparison of the two groups’ scapular posterior tilt angle pre– and post–

intervention (n=20)

Table 4. Comparison of the two groups’ scapular posterior tilt angle following the 6–

week intervention (n=20)

Pre–intervention

Post–intervention

t p d

PMSa group

(°) 18.31 ± 5.84

c 24.73 ± 6.27 –4.775 < 0.01 1.51

PMS plus SPTE

b group

(°) 20.38 ± 7.99 34.10 ± 17.30 –3.385 < 0.01 1.07




p value is the comparison of groups using a paired t–test.

Diff. t p d

PMSa group (°) 6.42 ± 4.25

c

–1.710 0.115 0.76 PMS plus SPTE

b group (°) 13.72 ±12.82





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4. Humeral Forward Flexion Range

There was a statistically significant increase pre– to post–intervention for the

humeral forward flexion range in both groups (Table 5). When comparing the two

groups, the humeral forward flexion range was greater in the PMS plus SPTE group

than in the PMS group; however, the difference was not statistically significant (Table

6).

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Table 5. Comparison of the two groups’ humeral forward flexion range pre– and post–

intervention (n=20)

Table 6. Comparison of the two groups’ humeral forward flexion range following the

6–week intervention (n=20)

Pre– intervention

Post–intervention

t p d

PMSa group

(°) 102.52 ± 24.69

c 112.88 ± 25.05 –5.746 < 0.01 1.82

PMS plus SPTE

b group

(°) 114.45 ± 41.33 128.61 ± 35.81 –4.654 < 0.01 1.47





Diff. t p d

PMSa group (°) 10.36 ± 5.70

c

–1.074 0.297 0.48 PMS plus SPTE

b group (°) 14.15 ± 9.62





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5. Pectoralis Minor Length

There was a statistically significant decrease in the measured values of pectoralis

minor length obtained from the pectoralis minor length test pre– and post–

intervention in both groups (Table 7). When comparing the two groups, the difference

between PMS and PMS plus SPTE was not statistically significant (Table 8).

- 21 -

Table 7. Comparison of the two groups’ pectoralis minor length pre– and post–

intervention (n=20)

Table 8. Comparison of the two groups’ pectoralis minor length following the 6–week

intervention (n=20)

Pre– intervention

Post–intervention

t p d

PMSa group

(㎝) 4.31 ± 1.14

c 3.36 ± 0.74 –4.814 < 0.01 1.52

PMS plus SPTE

b group

(㎝)

4.54 ± 1.40 3.64 ± 0.91 –5.031 < 0.01 1.59





Diff. t p d

PMSa group (°) 0.95 ± 0.62

c

0.188 0.853 0.08 PMS plus SPTE

b group (°) 0.90 ± 0.57





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Discussion

The purpose of the present study was to investigate the effect of a 6–week

intervention with PMS or PMS plus SPTE on the scapular posterior tilt angle,

humeral forward flexion range during active humeral forward flexion, and pectoralis

minor length in stroke patients. The results of the present study showed that the

scapular posterior tilt angle and humeral forward flexion range were significantly

increased during active humeral forward flexion in both groups. Pectoralis minor

length caused by decreasing distance from pectoralis minor length test was also

significantly increased in both groups. To the author’s knowledge, this is the first

study to examine the effects of 6–week interventions (PMS, and PMS plus SPTE) on

the scapular posterior tilt angle, humeral forward flexion range during active humeral

forward flexion, and pectoralis minor length in stroke patients.

Changes in muscle tone in a resting position, limited range of motion (ROM), and

pain are common problems that occur following a stroke (Mngoma, Culham, and

Bagg 1999). Stretching is one of the basic treatment modalities used in the

rehabilitation field (Gracies 2001; Stokes 2004). Muscles’ structural, viscoelastic, and

excitability properties can be changed by stretching (Nielsen, Crone, and Hultborn

2007), and subsequently the ROM can improve (Wilkinson 1992). Increased ROM

contributes to functional mobility (Kisner, and Colby 2002). In our study, the

pectoralis minor of the paretic side in stroke patients was targeted in a stretching

exercise. After a 6–week stretching intervention, relative pectoralis minor length was

- 23 -

lengthened in the PMS group. Although the measured change was relatively small

(0.95 ± 0.62), our result indicates that the pectoralis minor length increased

significantly following the stretching exercise (p < 0.05). Our results suggest that

stretching exercises have an effect on lengthening the shortened pectoralis minor

muscle in stroke patients, and therefore improve functional upper limb movements.

Our results are consistent with previous studies of PMS (Borstad, and Ludewig 2006;

Roddey, Olson, and Grant 2002; Williams, Laudner, and McLoda 2013).

From a kinematic point of view, a strong relationship exists between the scapula tilt

and pectoralis minor length (Hébert et al. 2002; Ludewig, and Cook 2000). This is

because the origin of the pectoralis minor is the third, fourth, and fifth ribs and the

insertion is the coracoid process of the scapula. The pectoralis minor is thus elongated

during the scapular posterior tilting that occurs with arm elevation (McClure et al.

2001). The scapular posterior tilt angle was significantly increased after 6–weeks

stretching in the PMS group (6.42 ± 4.25). Our results suggest that PMS is a useful

intervention to improve the scapular posterior tilt angle. Our findings are consistent

with previous studies showing that the effect of pectoralis minor length on scapular

kinematics (Borstad, and Ludewig 2005; Roddey, Olson, and Grant 2002; Williams,

Laudner, and McLoda 2013).

As noted above, scapular movement is essential during humeral forward flexion.

The movement of scapular upward rotation, external rotation, and posterior tilt occurs

with humeral forward flexion (Ludewig, and Cook 2000; McClure et al. 2001).

McClure et al. (2001) reported a strong correlation between the scapular posterior tilt

- 24 -

angle and the humeral forward flexion range. Considering the mechanical relationship

between the pectoralis minor, scapular posterior tilt, and humeral forward flexion, the

range of humeral forward flexion is also affected by the pectoralis minor length. The

humeral forward flexion range observed in this study was significantly increased in

comparison with pre–stretching in the PMS group (10.36 ± 5.70). Our results are

consistent with previous studies showing a correlation between humeral forward

flexion and the pectoralis minor (Borstad, and Ludewig 2005; Wang et al. 1999). In

sum, the scapular posterior tilt angle increased as a result of PMS, and then the

humeral forward flexion range thereby increased. The current study suggests that

PMS is effective for improving upper limb function in stroke patients.

First, we formulated two hypotheses. One of the hypotheses already been proven.

The other hypothesis is that PMS plus SPTE would increase the scapular posterior tilt,

humeral forward flexion, and pectoralis minor length more than PMS alone. However,

the results of our study did not support that hypothesis. Even though the scapular

posterior tilt angle and humeral forward flexion increased more in the PMS plus

SPTE group (13.72 ± 12.82, 14.15 ± 9.62, respectively) than the PMS group (6.42 ±

4.25, 10.36 ± 5.70, respectively), the results of our study were not statistically

significant. The pectoralis minor length increased more in the PMS than the PMS plus

SPTE (0.95 ± 0.62, 0.90 ± 0.57, respectively), but this was also not statistically

significant.

Harris, and Eng (2010) concluded that strengthening exercises are effective for

improving upper limb strength and function in stroke patients by means of meta–

- 25 -

analysis. However, our results did not support their findings. This could be because

of the dependent variable. Previous researchers judged the effects by grip strength

(Bütefisch et al. 1995; Langhammer, Lindmark, and Stanghelle 2007; Pang, Harris,

and Eng 2006), upper limb strength (Bourbonnais et al. 2002), and upper limb

function (Gelber et al. 1995; Logigian et al. 1983; Platz et al. 2005). There was no

specific description about the pectoralis minor, scapular posterior tilt, and humeral

forward flexion. Even though the strengthening exercise in our study was effective,

it may not have had a strong influence on the three dependent variables. Another

possible reason is the intervention period. Previous studies reported that

strengthening exercise is effective for elderly stroke patients when they performed

such exercise for 12 weeks (Kim et al. 2012a; Studenski et al. 2005). The subjects of

our study were over 50 years old in both groups (63.4 ± 8.8, 55.1 ± 15.4,

respectively). Thus, 6 weeks may be too short for our subjects. Spasticity also may

affect the results. Spasticity is one of the most common conditions in strokes

(Esquenazi 2011) and significantly contributes to functional impairments and

limited activities of daily living (Hsu, Tang, and Jan 2003; Welmer et al. 2006).

Because of spasticity, it may be difficult to control the selective movement of the

shoulder. Lastly, our unique findings could also be due to the different position

used in the strengthening exercise. The general position used to strengthen

the lower trapezius is a prone position (Ballantyne et al. 1993;

Ekstrom, Donatelli, and Soderberg 2003). It is an effective position to

strengthen muscles using gravity as resistance (Kisner, and Colby 2002). In

- 26 -

this study, however, the exercise was not performed in a prone position

because of subjects were stroke patients; it would be dangerous for them to

breathe in this position. Alternatively, we performed SPTE in a sitting

position in accordance with a study done by Mottram (1997). However, this

may not be as effective to strengthen muscles as the prone position.

Moreover, we were unable to confirm the effects of the strengthening

exercise objectively because we did not measure the muscle power before

and after SPTE.

The present study has several limitations. First, the lower trapezius muscle activity

or strength after strengthening was not measured. In order to determine whether the

strengthening exercise was effective, we should have measured the pre– and post–

intervention muscle strength. Further research is needed to measure muscle strength

pre– and post–intervention. Second, the electromagnetic sensors used in our study

were attached on the skin to detect bone movement. The artifact arising from skin

movement may have had a considerable impact on our results. Finally, the 6–week

intervention period was not sufficient time for elderly stroke patients, considering

their physiological condition. Further research needs to be done using more than a 6–

week intervention to determine the effects of SPTE on the scapular posterior tilt,

humeral forward flexion and pectoralis minor length of stroke patients.

- 27 -

Conclusion

The present study compared the effects of a 6–week intervention with PMS or PMS

plus SPTE on the paretic scapular posterior tilt angle, humeral forward flexion range

during active humeral forward flexion, and pectoralis minor length in stroke patients.

The results indicate that PMS and PMS plus SPTE had significant effects in terms of

increasing the kinematics of the shoulder function. The reported increase on the

scapular posterior tilt angle and humeral forward flexion was greater in the PMS plus

SPTE group than in the PMS group; however, the difference between the groups was

not statistically significant. The pectoralis minor length was increased more in the

PMS than the PMS plus SPTE group. In conclusion, PMS is an effective intervention

for paretic upper limb function in stroke patients, and PMS plus SPTE is no more

effective than PMS alone.

- 28 -

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국문 요약

뇌졸중 환자에게 견갑골 후방 경사 운동과 소흉근

신장운동을 병행 시 어깨 운동형상학에 미치는 효과

연세대학교 대학원

물리치료학과

박 일 우

본 연구의 목적은 뇌졸중 환자에게 적용한 견갑골 후방 경사 운동과

소흉근 신장운동이 견갑골 후방 경사 각도, 상완골 전방 굴곡 범위,

소흉근 길이에 미치는 영향을 비교하는 것이다. 본 연구를 위해 병원에

입원 중인 뇌졸중 환자 20명(남자 13명, 여자 7명)이 대상자로

참여하였다. 대상자들은 10명씩 두 집단으로 나뉘어 6주간, 한 집단은

소흉근 신장 운동을, 다른 한 집단은 소흉근 신장 운동과 견갑골 후방

경사 운동을 병행하였다. 3차원 전자기식 동작 측정 시스템을 이용하여

6주간의 치료적 중재 전후 각각 한 번씩, 앉은 상태에서 팔을 앞으로 들어

올리는 동안의 견갑골 후방 경사 각도와 상완골 전방 굴곡 범위를

- 40 -

측정하였고, 바로 누운 상태에서 대상자의 마비 측 견봉과 매트 사이의

직선 거리를 측정하여 소흉근 길이 변화를 측정하였다. 통계학적

유의수준은 α = 0.05로 하여 치료적 중재 전후의 집단 내 비교를 위해

짝비교 t–검정을, 집단 간 비교를 위해 독립적 t–검정을 실시하였다. 연구

결과 두 집단 내에서 모두 견갑골 후방 경사 각도와 상완골 전방 굴곡

범위가 유의하게 증가하였고, 소흉근도 유의하게 신장되었다. 두 집단 간

비교 시 신장 된 소흉근 길이 변화량은 두 집단간에 유의하지 않았다.

또한 두 집단 간 견갑골 후방 경사 각도와 상완골 전방 굴곡 범위를

비교하였을 때도, 통계학적으로 유의한 차이가 없었다. 따라서 뇌졸중

환자의 마비 측 상지 기능 개선을 위해서 소흉근 신장 운동은 효과적인

중재 방법이라고 할 수 있지만 견갑골 후방 경사운동과 소흉근 신장운동을

병행하였다고 해서 소흉근 신장운동만 시킨 것보다 상지 기능개선에 더

효과적이라고 할 수는 없겠다. 그러나 추후에 사례 수를 더 늘려서 연구해

볼 필요가 있겠다.

핵심 되는 말: 견갑골 후방 경사 운동, 뇌졸중, 소흉근 신장 운동, 어깨

운동형상학.

effects of pectoralis minor stretching versus pectoralis ... · injury when pectoralis minor...

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