Effects of Contralateral Hip Adduction on

Muscle Thickness, Activity of Lumbar

Stabilizers and Pelvic Lateral Tilting

During Hip Abduction in Sidelying

Hyo uen Kim

The Graduate School

Yonsei University

Department of Rehabilitation Therapy

Effects of Contralateral Hip Adduction on

Muscle Thickness, Activity of Lumbar

Stabilizers and Pelvic Lateral Tilting

During Hip Abduction in Sidelying

Hyo uen Kim

The Graduate School

Yonsei University

Department of Rehabilitation Therapy

Effects of Contralateral Hip Adduction on

Muscle Thickness, Activity of Lumbar

Stabilizers and Pelvic Lateral Tilting

During Hip Abduction in Sidelying

A Masters Thesis

Submitted to the Department of Rehabilitation Therapy

and the Graduate School of Yonsei University

in partial fulfillment of the

requirements for the degree of

Master of Science

Hyo uen Kim

December 2011

This certifies that the masters thesis of Hyo uen Kim is approved.

Thesis Supervisor: Ohyun Kwon

Chunghwi Yi

Heonseock Cynn

The Graduate School

Yonsei University

December 2011

Acknowledgements

After the years of efforts, I am now able to complete graduate school. I would like

to take this opportunity to express my gratitude to everyone who has helped me to

graduate.

First, I sincerely appreciate Profs. Ohyun Kwon. He provided me with direction. I

could not have finished the course without his guidance. I deeply thank Profs.

Chunghwi Yi and Heonseock Cynn. I have written a better graduate thesis as a result

of your guide and advice. I also thank Profs. Sanghyun Cho, Hyeseon Jeon and

Seunghyun Yoo. I have expanded my knowledge and perspective from interactions

with you. I also give thanks to Mr. Byungkyu Lee, who always took care of

administrative issues.

I appreciate all my fellow students, especially Wonhwee Lee, Sujung Kim and

Boram Choi. You gave me lots of help with my thesis and with school life generally.

I also appreciate my co­workers. You always tried to cheer me up and were a great

comfort to me. Finally, I want to express my love for my parents, sister and Jinsu Lim.

You always prayed for me from your hearts. I was able to finish the course with your

support and encouragement.

Thanks to all of you. I hope to be able to repay your favors someday.

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Table of Contents

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

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

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

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

Method ············································································· 4

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

2. Experimental Equipment ·················································· 5

2.1 Sonography System ···················································· 5

2.2 Electromyography System ············································ 7

2.3 3­D Motion Analysis System ········································· 8

3. Experimental Procedure ··················································· 9

4. Statistical Analysis ························································· 12

Results ············································································ 13

1. Muscle Thickness ·························································· 13

2. Muscle Activity ···························································· 16

3. Pelvic Lateral Tilting ······················································ 17

Discussion ········································································ 18

Conclusion ········································································ 23

References ········································································ 24

- ii -

Abstract in Korean ······························································ 29

- iii -

List of Figures

Figure 1. Measurement of the muscle thickness ······························· 6

Figure 2. Test postures ···························································· 11

Figure 3. Comparison of muscle thickness ···································· 15

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List of Tables

Table 1. Characteristics of the subjects ········································ 4

Table 2. Means and standard deviations of muscle thickness ············· 14

Table 3. Comparison of muscle thicknesses ································· 14

Table 4. Comparison of the muscle activity ··································· 16

Table 5. Comparison of the angle pelvic lateral tilting ····················· 17

- v -

ABSTRACT

Effects of Contralateral Hip Adduction on

Muscle Thickness, Activity of Lumbar

Stabilizers and Pelvic Lateral Tilting

During Hip Abduction in Sidelying

Hyo uen Kim Dept. of Rehabilitation Therapy

The Graduate School

Yonsei University

The purpose of this study was to determine the effects of contralateral hip

adduction on muscle thickness, muscle activity of lumbar stabilizers, and the angle of

pelvic lateral tilting during hip abduction in side lying. Twenty healthy male subjects

with no medical history of lower extremity or lumbar spine disorders were recruited

for this study. Subjects performed 35° preferred hip abduction (PHA) and 35° hip

abduction with 10° contralateral hip adduction (CHA) during side lying. Thicknesses

- vi -

of the transverses abdominis (TrA), internal oblique (IO), and quadratus lumborum

(QL) were measured in the rest position (RP) and during PHA and CHA using a

sonography system. Muscle activities of the dominant­side rectus abdominis (RA),

external oblique (EO), IO, QL, gluteus medius (GM), and non­dominant-side hip

adductor longus (Add) were measured during PHA and CHA using a surface

electromyography system (EMG). Kinematic data for pelvic lateral tilting were

collected during PHA and CHA using a three­dimensional (3­D) motion­analysis

system. One­way repeated analysis of variance was used to compare the thickness of

the muscles, and a paired t­test was used to compare EMG activity and the angle of

pelvic lateral tilting between the two exercises. Thicknesses of the TrA and IO were

significantly increased in CHA versus PHA, but there was no significant difference

between RP and PHA. Thickness of QL (anterio­posterior, A­P) was increased in

CHA more than PHA, but QL (medio­lateral, M­L) was not significantly different

between PHA and CHA. EMG activities of all muscles were increased significantly

more in CHA versus PHA. Pelvic lateral tilting was decreased significantly more in

CHA versus PHA. These results suggest that CHA could be recommended as a hip

abduction exercise for activating lumbar stabilizers and decreasing compensatory

pelvic tilting motion.

Key Words: Electromyography, Hip abduction, Lumbar stabilizer, Sonography,

Pelvic tilting.

- 1 -

Introduction

Lumbar stabilization has been actively studied over the past decade (Cynn et al.

2006). The concept of lumbar stabilization involves maintaining lumbar stability

through isometric contraction of lumbar and abdominal muscles during limb

movement. Increasing lumbar stability is considered an effective method of

preventing lumbar musculoskeletal disease and improving lumbar function (Kisner

and Colby 2002). Increasing lumbar stabilization is also effective for patients with

low back pain regardless of the cause or status (Luoto et al. 1998; O’Sullivan et al.

1997).

Previous studies have demonstrated that the activity of the lumbar stabilizers is

decreased and delayed during limb movement in patients with low back pain

compared with subjects without low back pain (Hodge and Richardson 1997;

Sahrmann 2002). Decreased lumbar stability during limb movement causes

compensatory movements. Excessive compensatory movement can causes

micro­trauma, and repeated micro­trauma can lead to lumbar dysfunction (Sahrmann

1993).

Hip abduction in side lying is commonly used clinically to evaluate movement

patterns (Libenson 1996; Sahrmann 1993) and to improve gait and balance ability

(Judge et al. 1993; Sashika et al. 1996). Many studies have investigated lumbar

stabilization in the standing and supine lying position, whereas few have examined

- 2 -

the side­lying position (Hodges and Richardson 1999; Jull et al. 1993). Cynn et al.

(2006) reported that an abdominal drawing­in maneuver and using a pressure

biofeedback unit increased lumbar stability and decreased pelvic lateral tilting during

hip abduction in side lying.

When a hip abduction exercise is performed in side lying, unwanted compensatory

pelvic lateral tilting can appear (Norris 1995). The normal pattern of hip abduction

has been described as about 40° abduction, with no hip flexion, external or internal

rotation, hip elevation, or pelvic rotation. When the hip abduction is initiated by

contraction of the quadratus lumborum before 20°, hip abduction induces pelvic

lateral tilt or hip hike. This altered movement pattern can cause excessive stress to

lumbosacral segments during a hip abduction exercise (Libenson 2007).

The function of TrA and IO in lumbar stability was investigated in previous studies

(Hodges and Richardson 1997; Hodges and Richardson 1999; O’Sullivan et al. 2002).

QL can stabilize the lumbar region during isometric contraction (Cholewicki and

Vanvliet 2002; McGill 1996). Page et al. (2010) stated that the role of the QL

changed from pelvic stabilizer to the prime mover in hip abduction, resulting in a

pelvic lateral tilt during hip abduction in side lying.

During hip abduction, contraction of contralateral hip in adduction can stabilize

the lumbar region (Lee 1999). Lee (1999) described four systems that contribute to

lumbo–pelvic stability: the anterior oblique, posterior oblique, longitudinal, and

lateral systems. Among them, the lateral system consists of the hip abductor and the

- 3 -

contralateral hip adductor. These muscles are related closely in the kinetic chain to

make forces and co­contract or release to optimize the function of the pelvis (Lee

1999). Root and Spero (1981) also demonstrated that enough force from the

contralateral hip adductor can act against the force of hip abductor, maintaining

pelvic stability. However, there has been no reported study on whether contralateral

hip adduction can increase lumbar stability in hip abduction in side lying.

The extent of lumbar stability had been measured through the activity of the

lumbar stabilizers (Cholewicki and McGill 1996; Reeve and Dilley 2009). The

quantity of muscle activity can be measured using electromyography. The increased

thickness of lumbar stabilizers could reflect their increased activity (Hodges et al.

2003; McMeeken 2004) and the thickness of lumbar stabilizers can be measured

using sonography (Ainscouph­Potts et al. 2006).

The purpose of this study was to investigate the effects of contralateral hip

adduction on the thickness and activity of the lumbar stabilizers and pelvic lateral

tilting during hip abduction in side lying. The hypothesis of the study was that

thickness and activity of lumbar stabilizers would be increased and pelvic lateral

tilting would be decreased in hip abduction with contralateral hip adduction (CHA)

compared with preferred hip abduction (PHA).

- 4 -

Method

1. Subjects

Twenty healthy male subjects were recruited from Yonsei University. Exclusion

criteria were past or present neurological, musculoskeletal, or cardiopulmonary

disease. Subjects with low back pain, knee pain, hip joint contracture, and gluteus

medius strength below a grade of good on manual muscle testing were also excluded.

All subjects were right­leg dominant.

Prior to the study, ethics approval was obtained from Yonsei University. All

subjects were informed about the purpose and procedures of the study, and written

informed consent was obtained. Characteristics of the subjects are presented in Table

1.

Table 1. Characteristics of the subjects (N=20)

Parameter Mean ± SD

Age (yr) 21.8 ± 2.8

Body mass (㎏) 71.9 ± 10.8

Height (㎝) 173.3 ± 4.1

- 5 -

2. Experimental Equipment

2.1 Sonography System

The SONOACE X8 (Medison, Inc., Seoul, South Korea) was used to measure

muscle thickness of the dominant­side TrA, IO, and QL. A linear transducer

(L5­12EC) 4.5㎝ in size and with a frequency of 10 MHz was used (Richardson,

Hodge and Hides 2004). TrA and IO were measured at a point 2.5㎝ antero­medial

to the midpoint between the ribs and ilium on the mid­axillary line (Critchley 2002;

Mcmeeken et al. 2004). The thickness of TrA and IO were measured (vertical

diameter) between the fascias at a point 1.5 cm from the aponeurotic attachment

(Reeve and Dilley 2009) (Fig. 1). To measure the QL, the transducer was moved

laterally from the transverses plane at the L3 level until an image was obtained

(Desmoulin and Millner 2007). The thickness of the QL was measured (medio­lateral

(M­L) diameter and anterio­posterior (A­P) diameter) at the widest point (Desmoulin

and Milner 2007) (Fig. 1). Measurements were conducted by one expert and

measured while the subject maintained end posture while holding his breath after

expiration. The transducer was maintained vertical to the skin and in the same

position during the measurements to reduce errors.

- 6 -

Figure 1. Measurement of muscle thickness

A: internal oblique, B: transverses abdominis, C: quadratus

lumborum anterio­posterior, D: quadratus lumborum

medio­lateral.

- 7 -

2.2 Electromyography System

The Noraxon Telemyo 2400T (Noraxon, Inc., Scottsdale, AZ, USA) was used to

measure muscle activity The skin was shaved with a razor, rubbed with sand paper,

and cleaned with alcohol. Pairs of surface electrodes and adhesive skin interfaces

were separated by 2㎝. The reference electrode was placed on the anterior superior

iliac spine (ASIS). EMG data were collected from the following muscles:

dominant­side rectus abdominis (RA; parallel and approximately 3㎝ lateral and

superior to the umbilicus, arranged along the longitudinal axis over the muscle belly);

dominant­side EO (half way between the ASIS of the pelvis and the inferior border

of the rib cage at a slightly oblique angle, running parallel to the underlying muscle

fibers); dominant­side IO (half way between the ASIS of the pelvis and the midline,

just superior to the inguinal ligament); dominant­side gluteus medius (GM; over the

proximal third of the distance between the iliac crest and the greater trochanter);

dominant-side QL (approximately 4 ㎝ lateral from the vertebra ridge and at a

slightly oblique angle at half the distance between the 12th rib and the iliac crest); and

non-dominant­side hip adductor longus (Add; medial aspect of the thigh in an

oblique direction, 4㎝ from the pubis).

Raw data were rectified and filtered using a Lancosh FIR digital filter. The

sampling rate was 1000 Hz. A band­pass filter (20­500 Hz) and a band stop (60 Hz)

were used. EMG data were converted to root mean square (RMS) values. To

- 8 -

normalize the EMG data, the mean RMS of three trials of 5­s maximal voluntary

isometric contractions (MVICs) was calculated for each muscle at a manual

muscle­testing position, according to Kendall et al. (2005). The data were expressed

as a percentage of the MVIC (%MVIC), and the mean value of three trials was used

for data analysis.

2.3 3­D Motion Analysis System

A three­dimensional ultrasonic motion analysis system (CMS­HS, Zebris,

Medizintechnik, Isny, Germany) was used to measure pelvic lateral tilting during hip

abduction in side lying. Three active markers were placed at the level of the dominant

ASIS by fastening a belt. The markers faced the measuring sensor, which consisted

of three microphones. The measuring sensor was placed in front of the subject and

recorded the ultrasonic signals from the markers. The angle of the pelvic lateral tilt

was calibrated to 0° at the rest position as a reference before the movement, and then

the relative angle of the pelvic lateral tilt during hip abduction was calculated from

this reference. The sampling rate was set at 20 Hz. A low­pass filter with a cutoff

frequency was set at 8­Hz. Kinematic data were analyzed using the Windata software

(ver. 2.19). The mean angle of three trials was used in data analysis.

- 9 -

3. Experimental Procedure

The rest position (RP) was a side­lying position with the non­dominant lower

extremity contacting a firm mattress. The upper trunk, pelvis, and dominant lower

extremity were aligned in a straight line. PHA is a 35° abduction of the dominant hip

during side lying (Cynn 2006). CHA is 10°adduction of the contralateral hip and then

a 35° dominant­hip abduction during side lying. The degree of contralateral hip

adduction was set at the proper angle according to a pilot study. During PHA and

CHA, subjects were required to maintain steady trunk alignment without hand

support. Bars were placed at 35° hip abduction and 10° hip adduction positions (Fig.

2).

Before testing, subjects were trained for approximately 15 min to familiarize them

with PHA and CHA. Subjects performed RP, PHA, and CHA randomly. The subject

was asked to maintain each posture for 5 s to allow image capture of TrA, IO, and

QL using the sonography system. The principal investigator placed the transducer at

a point 2.5㎝ antero­medial to the midpoint between the ribs and ilium on the

mid­axillary line for the TrA and IO muscles. After capturing TrA and IO images, the

transducer was moved laterally at the L3 level to capture the QL image. Between the

two conditions, a 5­min rest period was provided at the RP.

After a 30­min rest, electrodes and the three markers were attached for collecting

EMG and kinematic data. Subjects were asked to perform PHA and CHA in the same

- 10 -

way. During the each test, muscle activity and the angle of pelvic lateral tilting were

recorded using EMG and a 3­D motion analysis system. All examinations were

conducted by the same researcher.

- 11 -

Figure 2. Test postures

A: rest Position, B: preferred hip abduction,

C: hip abduction with contralateral hip adduction.

- 12 -

4. Statistical Analysis

Repeated­measures one­way analysis of variance (ANOVA) was used to

determine significant differences in muscle thicknesses of the TrA, IO, and QL

among RP, PHA, and CHA, and the least significant difference (LSD) was calculated

post hoc. The paired t­test was used to determine significant differences in muscle

activity of the RA, IO, EO, QL, GM, and Add muscles and pelvic lateral tilting

between PHA and CHA. The level of statistical significance was set at α = 0.05.

- 13 -

Results

1. Muscle thickness

The mean thickness of TrA and IO in each posture is presented in Table 2. The

thickness of TrA and IO increased significantly in CHA compared with PHA and RP

(F = 92.61, p = 0.000; F = 10.09, p = 0.000, respectively; Table 3; Fig. 3). The A­P

thickness of QL was increased significantly in CHA versus PHA (F = 86.63, p =

0.000; Table 3; Fig. 3). The M­L thickness of QL decreased significantly (F = 16.54,

p = 0.000; Table 3). The result from the post hoc analysis showed no significant

difference between PHA and CHA (Fig. 3).

- 14 -

Table 2. Means and standard deviations of muscle thickness

RPa: rest position; PHAb: preferred hip abduction; CHAc: hip abduction with contralateral hip adduction; TrAd: transverses abdominis; IOe: internal oblique; QL (M-L)f: quadratus lumborum (medio­lateral); QL (A-P)g: quadratus lumborum (anterio­posterior). hmean±SD.

Table 3. Comparison of muscle thicknesses

TrAa: transverses abdominis; IOb: internal oblique; QL (M-L)c: quadratus lumborum (medio­lateral); QL (A-P)d: quadratus lumborum (anterio­posterior).

Muscle (㎝) RPa PHAb CHAc

TrAd 0.61 ± 0.14h 0.73 ± 0.15 0.86 ± 0.18

IOe 0.65 ± 0.23 0.82 ± 0.26 0.99 ± 0.20

QL (M-L)f 1.74 ± 0.28 1.53 ± 0.30 1.52 ± 0.21

QL (A-P)g 0.40 ± 0.10 0.44 ± 0.11 0.48 ± 0.14

Muscle Type Ⅲ Sum of Squares df Mean Square F p

TrAa 0.59 2 0.29 92.61 0.000

IOb 0.99 2 0.48 10.09 0.000

QL (M-L)c 0.65 2 0.32 16.54 0.000

QL (A-P)d 0.07 2 0.03 86.63 0.000

- 15 -

Figure 3. Comparison of the muscle thicknesses

RP: rest position; PHA: preferred hip abduction; CHA: hip abduction

with contralateral hip adduction; TrA: transverses abdominis; IO:

internal oblique; QL (M­L): quadratus lumborum (medio­lateral); QL

(A­P): quadratus lumborum (anterio­posterior); *p < 0.05.

- 16 -

2. Muscle activity

Mean values and standard deviations of EMG amplitude for each muscle are

presented in Table 5. The activity of all muscles was statistically significantly

increased in CHA versus PHA (Table 4).

Table 4. Comparison of the muscle activity

PHAa: preferred hip abduction; CHAb: hip abduction with contralateral hip adduction; RAc: rectus abdominis; IOd: internal oblique; EOe: external oblique; QLf: quadratus lumborum; GMg: gluteus medius; Addh: hip adductor longus. imean±SD.

Muscle (%MVC) PHAa CHAb t p

RAc 1.63±0.86i 7.07±3.89 6.29 0.000

IOd 10.46±4.77 24.86±10.77 7.77 0.000

EOe 6.17±3.89 26.94±17.64 5.92 0.000

QLf 17.07±9.38 54.22±24.33 8.79 0.000

GMg 26.11±18.38 46.21±38.35 4.19 0.000

Addh 1.24±2.09 10.20±7.60 5.48 0.000

- 17 -

3. Pelvic lateral tilting

The angle of pelvic lateral tilting was significantly decreased in CHA versus PHA

(p = 0.000) (Table 5).

Table 5. Comparison of the angle of pelvic lateral tilting

PHAa: Preferred hip abduction; CHAb: Hip abduction with contralateral hip adduction

cmean±SD.

PHAa CHAb t p

Pelvic lateral tilting (°) 11.41±4.71c 7.78±3.19 6.33 0.000

- 18 -

Discussion

This study was performed to determine whether contralateral hip adduction could

improve lumbar stability, activate lumbar stabilizers and the gluteus medius muscle,

and decrease unwanted compensatory pelvic lateral tilting during hip abduction in

side lying. To compare changes in muscle thickness, real­time ultrasound was used.

The result of this study demonstrated that the thicknesses of TrA, IO, QL (A­P)

increased significantly in CHA versus PHA. Furthermore, activity in the

dominant­side RA, EO, IO, and QL increased significantly in CHA versus PHA.

The observed increased muscle thickness in TrA, IO, and QL (A­P) and increased

muscle activity in RA, EO, IO, and QL under the CHA condition may have several

explanations.

First, the base of support (BOS) in CHA was less than that in PHA. In this study,

subjects were asked to maintain the alignment without hand support during the tests.

Under the CHA condition, the subject was asked to adduct his bottom leg. Thus, the

contact area of the body on the floor, BOS, was markedly decreased in the CHA

condition versus PHA. A previous study demonstrated that decreased BOS was more

challenging and led to coactive muscle contraction (Santos and Aruin 2009).

Ainscouph­Potts et al. (2006) showed that TrA and IO thickness increased

significantly in decreasing the stability and area of BOS in a sitting position and

- 19 -

lifting the foot off the floor on a gym ball compared with crooked lying and relaxed

sitting on a gym ball with both feet on the ground. Kim et al. (2011) reported that

single­leg raising in hook­laying position on a round foam roll, which provided a

small BOS, induced more abdominal muscle activity than lying on the floor. Thus,

TrA, IO, and QL (A-P) and the activity of RA, EO, IO, and QL are likely to contract

synergistically, especially under the CHA condition when there is less BOS than

under the PHA condition.

Second, the load to the lumbar vertebrae was increased significantly in CHA

versus PHA. Cholewicki et al. (2002) reported that 10 major trunk muscles (RA, EO,

IO, latissimus dorsi, iliocostalis lumborum, longissimus thoracis, lumbar erector

spinae, multifidus, psoas, QL) contributed to maintaining stability of the lumbar

spine rather than single muscles of the trunk, according to the increased load to the

lumbar vertebrae in a biomechanical model study. Cholewicki and McGill (1996)

demonstrated that the relative stability index and muscle effort increased with

increased moment demand or the joint compression force during the tasks in their

study. Cholewicki, Simons, and Radebold (2000) reported that vertical and horizontal

trunk load magnitude increased the activity of trunk muscles. In the present study, the

load on the trunk may have been increased in CHA due to lifting both legs. This

increased trunk load during CHA increased the demand for muscle contraction in the

trunk. Thus, RA, EO, IO, and QL activity was significantly increased in CHA.

In this study, activity in RA, EO, IO, and QL increased significantly in CHA

versus PHA. Some authors have suggested that the activity of local muscles,

- 20 -

including TrA and the multifidus for lumbar segmental stability, is needed for lumbar

stability (Hodge and Richardson 1997; Hodge and Richardson 1999). However,

others have insisted that the activities of all muscles of the trunk are important for

lumbar stability (Cholewicki and McGill 1996; Cholewicki and Vanvliet 2002). The

results of this study support the latter conclusion: not only local muscles but all

muscles of the trunk play an important role in lumbar stability. Although activity of

the TrA was not included in this study, it seems possible that TrA activity is

increased in CHA. EMG activities of TrA and IO have been shown to act together for

all directions of rapid shoulder movement (Marshall and Murphy 2003). Thus, CHA

would help to increase activity of the TrA.

The hip abduction test can be used to evaluate the quality of the lateral muscular

pelvic brace and lumbo­pelvic stabilization. The poorest pattern of hip abduction is

when the QL acts in pelvic tilting rather than pelvic stabilization (Libenson 1996).

Alteration in hip abduction patterns may cause excessive stress to lumbo­pelvic

segments. Cynn et al. (2006) demonstrated that lumbar stabilization during hip

abduction was useful to prevent excessive activation of the QL and excessive pelvic

lateral tilting. In the present study, the activity of GM increased significantly in CHA

compared with PHA. Kinematic data showed a significantly decreased angle of

pelvic lateral tilting in CHA compared with PHA. Contraction of the contralateral hip

adductor muscle during contraction of the hip abductor muscle may stabilize the

pelvis in CHA (Lee 1999). A stabilized pelvis may result in increased GM activity

- 21 -

and a decreased angle of pelvic lateral tilting in CHA. Thus, the CHA exercise can be

recommended to prevent unwanted compensatory pelvic lateral tilting during hip

abduction in side lying.

In this study, the thickness of QL (A­P) increased significantly in CHA versus

PHA. The thickness of the QL has not yet been thoroughly investigated. However,

Desmoulin and Milner (2007) demonstrated that the thickness of the QL (A­P) was

significantly correlated with the isometric lateral flexion force of the trunk. McGill

(1996) demonstrated that the quadratus lumborum appeared to be an important

stabilizer of the lumbar column and acted primarily during isometric side­support

tasks. Consequently, QL functions as a stabilizer during the isometric side­flexion

force of the trunk. Although these studies did not use the same method as the present

study, maintaining hip abduction in side lying produced isometric lateral­flexion

force on the trunk. Thus, the increased thickness of QL (A­P) and activity of the QL

demonstrated that the QL contracts isometrically and acts as a stabilizer of the pelvis

during the CHA condition.

This study has some limitations. First, the results were obtained only in young

healthy male subjects. Older persons or those with injured spines may show different

results. Second, the standard references for the thickness of the QL by sonography

were insufficient. Although Desmoulin and Milner (2007) demonstrated that the A­P

thickness of the QL increased significantly during isometric lateral flexion of the

trunk, it is necessary that the thickness of the QL using a sonography system also be

- 22 -

investigated. Third, this study was a cross­sectional study that investigated the effects

of CHA on muscle thickness, activity of lumbar stabilizers, and pelvic lateral tilting

during CHA. The effects of long­term training using CHA should be examined in

further studies.

- 23 -

Conclusion

In this study, the effect of CHA on lumbar stabilizers and compensatory movement

was determined. The results demonstrate that the thickness and activity of lumbar

stabilizers were significantly increased in CHA compared with PHA. Furthermore,

the angle of pelvic lateral tilting was decreased significantly in CHA versus PHA.

Thus, a CHA exercise can be recommended to prevent unwanted compensatory

pelvic lateral tilting during hip abduction exercises in side lying.

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References

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국문 요약

옆으로 누운 자세에서 고관절 외전 시 반대측 고관절

내전이 요추 안정화 근육의 두께, 근활성도와 골반

외측경사에 미치는 영향

연세대학교 대학원

재활학과

김 효 언

본 연구는 옆으로 누운 자세에서 고관절 외전 시 반대측 고관절

내전이 요추 안정화 근육의 두께와 근활성도, 골반 외측경사에 미치는

영향을 알아보기 위해 시행되었다. 본 연구는 요추나 하지의 과거 병력이

없는 20명의 건강한 성인 남성을 대상으로 하였다. 대상자는 옆으로 누운

자세에서 임의로 고관절 35°외전 (preferred hip abduction; PHA)과

반대측 고관절 10°내전 후 고관절 35°외전 (hip abduction with

contralateral hip adduction; CHA)을 실시하였다. 대상자가 동작을 하는

동안 오른쪽 복횡근, 내복사근과 요방형근의 두께, 오른쪽 복직근,

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외복사근, 내복사근, 요방형근, 중둔근과 왼쪽 고관절 내전근의 근활성도,

골반의 외측경사를 측정하였다. 휴식자세 (rest position), PHA와 CHA

시 근육의 두께를 비교하기 위해 반복 측정된 일요인 분산분석 (repeated

one-way analysis of variance)을, PHA와 CHA 시 근활성도와 골반

외측경사를 비교하기 위해 짝비교 t-검정 (paired t-test)을 사용하였다.

내복사근과 복횡근의 두께는 PHA시 보다 CHA 시 유의하게 두꺼워졌다.

요방형근의 안-밖 두께는 CHA와 PHA사이 유의한 차이가 없었으며 앞-

뒤 두께는 CHA 시 PHA보다 유의하게 두꺼워졌다. 근활성도는 모든

근육에서 CHA시 PHA보다 유의하게 증가하였다. 골반의 외측경사는

CHA시 PHA보다 유의하게 감소하였다. 이러한 결과들은 옆으로 누운

자세에서 고관절 외전 시 반대측 고관절을 동시에 내전하는 것이 요추의

안정성을 증가시키고 골반의 보상작용을 줄일 수 있다고 제안할 수 있을

것이다.

핵심 되는 말: 고관절 외전, 골반경사, 근전도, 요부 안정화, 초음파.