Effects of Lumbar Stabilization Using a

Pressure Biofeedback Unit on Muscle

Activity and Angle of Lateral Pelvic Tilt

During Hip Abduction in Sidelying

Heonseock Cynn

The Graduate School

Yonsei University

Department of Rehabilitation Therapy

Effects of Lumbar Stabilization Using a

Pressure Biofeedback Unit on Muscle

Activity and Angle of Lateral Pelvic Tilt

During Hip Abduction in Sidelying

A Dissertation

Submitted to the Department of Rehabilitation Therapy

and the Graduate School of Yonsei University

in partial fulfillment of the

requirements for the degree of

Doctor of Philosophy

Heonseock Cynn

June 2007

This certifies that the dissertation of Heonseock Cynn is approved.

____________________________________________

Thesis Supervisor : Chunghwi Yi

_________________________________ Sanghyun Cho

_________________________________

Hyeseon Jeon

_________________________________ Houngsik Choi

_________________________________

Hyukcheol Kwon

The Graduate School Yonsei University

June 2007

- i -

Table of Contents

List of Figures ····································································································· ii

List of Tables ····································································································· iii

Abstract ·············································································································· iv

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

Methods ··············································································································· 5

1. Participants ·································································································· 5

2. Surface Electromyographic Recording and Data Analysis ························· 7

3. Kinematic Study of Angle of Lateral Pelvic Tilt ········································ 9

4. Procedure ··································································································· 11

5. Statistical Analysis ···················································································· 15

Results ··············································································································· 16

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

Conclusion ········································································································· 24

References ········································································································· 25

Abstract in Korean ···························································································· 31

- ii -

List of Figures

Figure 1. A 3-dimensional ultrasound motion analysis system ························ 10

Figure 2. Pressure biofeedback unit ·································································· 13

Figure 3. Hip abduction in the stabilized-lumbar condition ····························· 14

- iii -

List of Tables

Table 1. Subect characteristics ············································································ 6

Table 2. Electromyographic activity in muscles and angle of lateral pelvic tilt

during preferred hip abduction and hip abduction with lumbar

stabilization ························································································· 17

- iv -

ABSTRACT

Effects of Lumbar Stabilization Using a Pressure

Biofeedback Unit on Muscle Activity and Angle of

Lateral Pelvic Tilt During Hip Abduction in Sidelying

Heonseock Cynn

Dept. of Rehabilitation Therapy

(Physical Therapy Major)

The Graduate School

Yonsei University

This study was conducted to assess the effect of lumbar spine stabilization

using a pressure biofeedback unit on the electromyographic activity and angle

of lateral pelvic tilt during hip abduction in a sidelying position. Eighteen able-

bodied volunteers (9 men, 9 women) with no history of pathology were

participated. Subjects were instructed to perform hip abduction in a sidelying

- v -

position in both the preferred hip abduction (PHA) and hip abduction with

lumbar stabilization (HALS). A pressure biofeedback unit was used for lumbar

stabilization. Surface electromyography was recorded from the quadratus

lumborum, gluteus medius, internal oblique, external oblique, rectus

abdominis, and multifidus muscles. Kinematic data for lateral pelvic tilt angle

were measured using a motion analysis system. Dependent variables were

examined with 2 (PHA vs HALS) × 2 (men vs. women) analysis of variance.

Significantly decreased electromyographic activity in the quadratus lumborum

(PHA, 60.39%±15.62% of maximum voluntary isometric contraction [MVIC];

HALS, 27.90%±13.03% of MVIC) and significantly increased

electromyographic activity in the gluteus medius (PHA, 25.03%±10.25% of

MVIC; HALS, 46.06%±21.20% of MVIC) and internal oblique (PHA,

24.25%±18.10% of MVIC; HALS, 44.22%±20.89% of MVIC) were found

when the lumbar spine was stabilized. Lateral pelvic tilt angle (PHA,

13.86°±4.66°; HALS, 5.55°±4.16°) was decreased significantly when the

lumbar spine was stabilized. In women the electromyographic activity

(percentage of MVIC) in gluteus medius, external oblique, and rectus

abdominis was significantly higher than that observed in men. With lumbar

stabilization, the gluteus medius and internal oblique activity was increased

significantly, and the quadratus lumborum activity was decreased significantly,

- vi -

causing reduced lateral pelvic tilt in a sidelying position. These results suggest

that hip abduction with lumbar stabilization is useful in excluding substitution

by the quadratus lumborum.

Key Words: Electromyography, Lumbar stabilization, Muscle activity.

- 1 -

Introduction

During the past decade in the field of physical therapy, the concept of

lumbar stabilization has emerged to prevent musculoskeletal injuries, to

rehabilitate, and to improve performance. Lumbar stabilization refers to

internal stabilization achieved by the isometric contraction of abdominal and

lumbar muscles to maintain stability (Kisner, and Colby 2002). It has also been

referred to in the literature as core strengthening, motor control training, and

dynamic stabilization (Akuthota, and Nadler 2004). Panjabi theorized that

spine stability is dependent on three subsystems: passive (spinal column),

active (spinal muscles), and control (neural control) subsystems (Panjabi

1992a). Panjabi also defined a neutral zone as being a midrange position with

minimal resistance to displacement owing to minimal tension in the passive

subsystem (Panjabi 1992b). In this midrange position, deep intersegmental

muscle contraction should be provided to control excessive motion and to

compensate for instability because passive restraints cannot control the spinal

movement. Two deep muscles, the transversus abdominis and lumbar

multifidus, are important for this spinal segment stabilization. It was also

suggested that cocontraction of these deep muscles must be performed without

involvement of the rectus abdominis or external oblique muscles, which are

- 2 -

overactive in patients with low back pain (Richardson et al. 1999).

A pressure biofeedback unit (Chattanooga Group, Hixson, TN), originally

developed for assessing the ability of abdominal muscles to actively stabilize

the lumbar spine, has been used to examine lumbar stabilization in various

studies (Herrington, and Davies 2005; Jull et al. 1993; Mills, Taunton, and

Mills 2005; Richardson et al. 1992; Wohlfart, Jull, and Richardson 1993). It is

a reliable and valid clinical instrument for assessing deep abdominal muscle

function, and has been used to develop a method for the careful monitoring of

lumbar stabilization (Cairns, Harrison, and Wright 2000; Richardson, and Jull

1995). The pressure biofeedback unit consists of an inflatable cushion

connected to a pressure gauge and an inflation device. When the pressure

biofeedback unit is placed and inflated, the subject is required to maintain the

desired pressure and a constant lumbar position during lower-extremity

movement under external loads. Changes in the pressure during hip movement

reflect an inability to maintain isometric contraction of the abdominal muscles,

resulting in uncontrolled movement and instability of the lumbar spine.

According to Janda (1996), hip abduction has failed if hip flexion, hip

external rotation, or lateral pelvic tilt is observed before a 40° of abduction is

achieved. Lateral pelvic tilt can occur when the quadratus lumborum

substitutes for a weakened gluteus medius (Chaitow 1996). The lateral portion

- 3 -

of the quadratus lumborum originates on the lateral ilium and inserts into the

twelfth rib without attachment to any vertebrae and produces primarily a

lateral bending moment, whereas the medial portion of the muscle provides

segmental stability through its segmental attachments (Richardson et al. 1999).

Substitution by the lateral portion of the quadratus lumborum leads to pelvic

obliquity (lateral pelvic tilt), and the lumbar spine undergoes lateral flexion

resulting in lateral instability and impaired movement (Sahrmann 2002).

Although many studies assessing lumbar stabilization have been conducted

with subjects in the supine position (Jull et al. 1993; Wohlfart, Jull, and

Richardson 1993), no studies on lumbar stabilization with subjects in the

sidelying position were found in the literature. In addition, we know of no

study confirming the effect of lumbar stabilization on the selective recruitment

of the gluteus medius and the inhibition of the quadratus lumborum in the

sidelying position. Given that hip abduction in the sidelying position is the

appropriate movement for testing the range of motion and strength of the

gluteus medius and is commonly prescribed as an exercise, investigating the

role of lumbar stabilization during sidelying will provide the clinician with

useful information for designing and implementing exercise protocols.

Based on published reports and clinical experience, we hypothesized that

increased gluteus medius activity and reduced quadratus lumborum activity

- 4 -

would result in decreased ipsilateral lateral tilt during hip abduction in the

sidelying position while the lumbar spine is stabilized with a pressure

biofeedback unit. The aims of this study were to assess the effect of lumbar

stabilization using a pressure biofeedback unit on the electromyographic

activity and angle of lateral pelvic tilt and to investigate the difference of

muscle activation between men and women during hip abduction in the

sidelying position.

- 5 -

Method

1. Participants

We recruited 18 able-bodied young subjects (9 men, 9 women) from

university students who volunteered to participate in this study. Subjects’

characteristics are shown in table 1. The exclusion criteria were past or present

neurologic, musculoskeletal, or cardiopulmonary diseases that could interfere

with hip abduction. Each subject signed informed consent approved by the

university institutional review board before entering the study.

- 6 -

Table 1. Subject characteristics (N=18)

Parameters Subjects (mean± SD) Age (y) 23.5±3.5 Weight (㎏) 59.3±5.1

Height (㎝) 167.7±4.3

Body mass index (㎏/㎡) 22.5±7.2

- 7 -

2. Surface Electromyographic Recording and Data Analysis

Electromyographic data were collected using a data acquisition system

(Biopac MP100WSW, Biopac Systems Inc, Goleta, CA) and a Bagnoli

electromyography system (Delsys Inc, Boston, MA). The skin was cleansed

with rubbing alcohol, and disposable Ag-AgCl surface electrodes were

positioned at an interelectrode distance of 2 ㎝. The reference electrode was

attached to the styloid process of the ulna on the dominant upper extremity.

Electromyographic data were collected for the following muscles on the same

side as the dominant lower extremity: quadratus lumborum (approximately 4

㎝ lateral from the vertebral ridge or belly of the erector spinae muscle, and at

a slightly oblique angle at half the distance between the 12th rib and the iliac

crest), gluteus medius (parallel to the muscle fibers, over the proximal one-

third distance between the iliac crest and the greater trochanter), external

oblique (on the inferior edge of the 8th rib, superolateral to the costal margin),

internal oblique (in the horizontal plane, 2 ㎝ medial to the anterior superior

iliac spine), rectus abdominis (2㎝ lateral to the umbilicus) (Cram, Kasman,

and Holtz 1998; Vera-Garcia, Grenier, and McGill 2000), and multifidus

(parallel to the muscle fibers, 2 ㎝ lateral to the midline running through the

L5 spinal process) (Arokoski et al. 2004).

- 8 -

The electromyographic signals were amplified and digitized with

AcqKnowledge software (version 3.7.2) (Biopac MP100WSW, Biopac

Systems Inc, Goleta, CA). The sampling rate was 1024 ㎐. Bandpass (20−450

㎐) and bandstop filters (60 ㎐) were used. The raw data were processed into

the root mean square (RMS) and were converted to ASCII files for analysis.

For normalization, the mean RMS of 3 trials of maximal voluntary isometric

contraction (MVIC) was calculated for each muscle. The manual muscle

testing position was used, as described by Kendall (Kendal, McCreary, and

Provance 2005). The electromyographic signals collected during hip abduction

were expressed as a percentage of the calculated mean RMS of the MVIC (%

MVIC).

- 9 -

3. Kinematic Study of Angle of Lateral Pelvic Tilt

A 3-dimensional ultrasonic motion analysis system (CMS-HS, Zebris

Medizintechnik GmbH, Isny im Allgäu, Germany) was used to measure the

angle of lateral pelvic tilt during hip abduction in sidelying (Figure 1). One

triplet bearing 3 active markers that emit an ultrasonic signal was secured to

the pelvis on the side of the lower extremity to be lifted. One triplet marker

was positioned to face the measuring sensor by a fastening belt passing around

at the level of anterior superior iliac spines. The measuring sensor consisting

of 3 microphones was positioned in front of the subject to record the ultrasonic

signal from the markers. The measuring plane was set and aligned according

the markers. The angle of the lateral pelvic tilt measured before hip abduction

was calibrated to 0° as a reference position, and the relative angle of the lateral

pelvic tilt during hip abduction was calculated from this reference position

(Knoll et al. 2004; Vogt, and Banzer 1999). The sampling rate was 20 ㎐.

After data collection angular displacements for lateral pelvic tilt were low-pass

filtered with a cutoff frequency of 8 ㎐. The kinematic data were analyzed by

the Windata software (version 2.19, Zebris Medizintechnik GmbH, Isny im

Allgäu, Germany). The mean angle of 3 trials was determined for comparison.

- 10 -

Figure 1. A 3-dimensional ultrasonic motion analysis system.

- 11 -

4. Procedure

Each subject was required to assume 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. The

nondominant lower extremity could be flexed at both the hip and knee joints

for comfort and stability. While sidelying, the subject was asked to perform

hip abduction with the dominant lower extremity in both the preferred

condition and the stabilized-lumbar condition, in random order. An

inclinometer was used to determine when the hip was in 35° of abduction. A

bar was placed at this level and provided feedback to the subject as they were

instructed to abduct their hip until the side of their knee touched the bar and to

hold the position for 5 seconds. The electromyographic signal was recorded

during this 5 seconds period. In the stabilized-lumbar condition, the pressure

biofeedback unit (Figure 2) was placed between the firm mattress and the

subject’s lumbar spine in the sidelying position. The elastic bag was inflated

until the lumbar curve was straight, at which point the target pressure was

determined. The spinous processes in lumbar region were palpated and a rigid

ruler was used to visually establish that curve was straight. The head of subject

was supported with semi-rigid pillow under the head and both arms were

- 12 -

crossed comfortably on the chest. Subjects were instructed to use the visual

feedback provided by the analog gauge of the pressure biofeedback unit in

order to maintain the determined target pressure during hip abduction (Figure

3). A researcher monitored the pressure fluctuations. Pressure changes of ±5

㎜ Hg from the target pressure were allowed to accommodate changes induced

by breathing.

Prior to testing all subjects were familiarized with the standard position and

movement and with the use of the pressure biofeedback unit and felt

comfortable at the time of data collection.

- 13 -

Figure 2. Pressure biofeedback unit.

- 14 -

Figure 3. Hip abduction in the stabilized-lumbar condition.

Pressure biofeedback unit with analog gauge

Triplet marker

- 15 -

5. Statistical Analysis

The data are expressed as the mean ± standard deviation (SD). A 2×2

analysis of variance with 1 within-subject factor (condition) and 1 between-

factor (sex) was used to determine the main effects and their interaction in

each muscle with the significance level set at P equal to or less than 0.05.

- 16 -

Results

The electromyographic activity and the angle of lateral pelvic tilt during preferred

hip abduction (PHA) and hip abduction with lumbar stabilization (HALS) is shown

in table 2. There were significant main effects for condition (PHA vs HALS) in

quadratus lumborum (F1,16=54.51, P=.000), gluteus medius (F1,16=46.29, P=.000),

internal oblique (F1,16=23.92, P=.000), and for angle of the lateral pelvic tilt

(F1,16=73.79, P=.000). There were significant main effects for gender in gluteus

medius (F1,16=4.98, P=.040), external oblique (F1,16=20.10, P=.000), and rectus

abdominis (F1,16=14.25, P=.002). There were also significant condition by gender

interactions in gluteus medius (F1,16=7.30, P=.016), external oblique (F1,16=11.55,

P=.004), and multifidus (F1,16=10.37, P=.005). With lumbar spine stabilization, the

electromyographic activity was decreased significantly in the quadratus lumborum

and increased significantly in the gluteus medius and internal oblique. The angle of

lateral pelvic tilt was decreased significantly with lumbar spine stabilization. In

women the electromyographic activity in gluteus medius, external oblique, and rectus

abdominis was higher than that observed in men.

- 17 -

Table 2. Electromyographic activity in muscles and angle of lateral pelvic tilt during preferred hip abduction and hip abduction with lumbar stabilization

PHA (mean ± SD) HALS (mean ± SD) Muscle activity (% MVIC) Quadratus lumborum

Men 56.08±21.46 32.23±15.34 Women 64.70±9.78 23.57±10.72 All 60.39±15.62 27.90±13.03 Gluteus medius

Men 22.37±10.67 36.98±18.05 Women 27.73±9.83 55.14±24.35 All 25.03±10.25 46.06±21.20

Internal oblique

Men 20.26±17.34 31.15±25.70 women 28.24±18.86 57.29±16.08 All 24.25±18.10 44.22±20.89 External oblique Men 19.93±8.24 16.94±12.54 Women 39.67±19.74 50.08±34.04 All 29.80±13.99 33.51±23.29 Rectus abdominis Men 14.53±7.60 12.57±9.18 Women 30.97±22.82 32.93±26.96 All 22.75±15.21 22.75±18.07 Multifidus Men 41.19±16.51 25.42±15.20 Women 43.29±23.97 40.82±24.75 All 42.24±20.74 33.12±19.99

Angle of lateral pelvic tilt (deg) Men 11.99±4.15 4.36±3.14 Women 15.73±4.58 6.73±4.87 All 13.86±4.66 5.55±4.16

- 18 -

Discussion

Lumbar stabilization can be achieved by the co-contraction of the

transversus abdominis and lumbar multifidus. When the transversus abdominis

contracts, the intra-abdominal pressure (IAP) increases, and the tension of the

thoracolumbar fascia increases. Consequently, stabilization of the spine is

maintained by the IAP in the abdominal cavity and the stiffness of the lumbar

spine (Ebenbichler et al. 2001). Furthermore, the activation of the transversus

abdominis is independent of the direction of limb movement and is continuous

throughout lower limb movement (Cresswell, Grundstrom, and Thorstensson

1992; Hodges, and Richardson 1997), suggesting a stabilizing function of the

abdominal pressure. Panjabi determined that the lumbar multifidus acts as a

stabilizer in the lumbar spine because it is a deep, segmentally attached muscle.

The role of the multifidus as a segmental stabilizer has been also demonstrated

previously (Kaigle et al. 1995; McGill 1991; Wilke et al. 1995).

We found significantly increased internal oblique activities with lumbar

stabilization. The internal oblique was thought to enhance the stability of the

spine in previous studies (Cresswell, Grundstrom, and Thorstensson 1992;

Tesh, ShawDunn, and Evans 1987; Macintosh, Bogduk, and Gracovetsky

1987), and this is consistent with our results, suggesting that increased internal

- 19 -

oblique muscle activity contributed to lumbar stabilization. In this study,

however, the activity of the external oblique, rectus abdominis, and multifidus

did not show significant changes with the use of a pressure biofeedback unit.

Lumbar stabilization during hip abduction in sidelying does not seem to affect

the activity of these muscles. Unlike the internal oblique muscle, the external

oblique and rectus abdominis do not blend at the lateral raphe of the

thoracolumbar fascia (Kisner, and Colby 2002), so that the external oblique

does not contribute to lumbar stabilization. The rectus abdominis run

longitudinally from pubic crest and symphysis to costal cartilages and sternum.

Thus, this muscle could have led to sagittal plane stabilization with the

multifidus that runs relatively longitudinally. Our findings are consistent with

those of Arokoski and colleagues who reported that it was difficult to contract

the paraspinal muscles independently from the external oblique during

stabilization exercise in the sidelying position (Arokoski et al. 2004). In

addition, Jull et al. (1993) found no RMS amplitude difference in rectus

abdominis and the lumbar erector spinae with abdominal setting action during

leg lifting in supine position.

In women the higher percentage of MVIC in gluteus medius, external

oblique, and rectus abdominis was observed. This higher percentage of MVIC

in women is thought to be caused for maintaining lumbopelvic stability

- 20 -

required during hip abduction in sidelying position. The sex-dependent

differences exist affecting the lumbopelvic stability between men and women,

even though we did not measure the differences. First, less skeletal muscle

mass, thickness of lateral abdominal muscles, and physiologic cross-sectional

area of abdominal region in women were reported from the previous studies

(Janssen et al. 2000; Marras et al. 2001; Springer et al. 2006). As muscle mass

increases, so does amount of titin. Passive muscle stiffness will increase as

amount of titin increases, because titin contribute to passive muscle stiffness

(Sahrmann 2002). Thus, passive muscle stiffness in women will be lower than

that in men. This lower passive stiffness can result in less lumbopelvic

stability while assuming hip abduction in sidelying position. Second, the

wider pelvic size in women (Marras et al. 2001), as an anthropometric

difference, may be one of the causes inducing the less lumbopelvic stability in

women. The center of gravity in sidelying position in women would be

positioned relatively higher than men secondary to the wider pelvis, possibly

threatening the lumbopelvic stability of maintaining hip abduction in sidelying

position. For these possible reasons, it is presumed that the higher percentage

of MVIC in gluteus medius, external oblique, and rectus abdominis was

required in women to overcome the less lumbopelvic stability during hip

abduction in sidelying position. Further studies should address the relationship

- 21 -

between the neuromuscular control in the lumbopelvic region during hip

abduction in sidelying position and the sex-specific differences.

Janda (1996) also identified an abnormal recruitment sequence for hip

abduction in symptomatic subjects compared with non-symptomatic subjects.

In patients with low back pain, gluteus medius activity was delayed, whereas

gluteus medius activity was observed before the ipsilateral quadratus

lumborum in normal subjects. The recruitment imbalance between the gluteus

medius and quadratus lumborum can induce movement impairment. For this

reason, the gluteus medius and quadratus lumborum should be closely

monitored for lumbar stability and joint support (Sahrmann 2002). Clinicians

often report overactivity and trigger points for the quadratus lumborum with

gluteus medius insufficiency in patients with back pain (Chaitow 1996). In

addition, increased tension in the quadratus lumborum was implicated in

pelvic upward movement and rotational malalignment (Schamberger 2002).

Care should be taken to prevent an overactive quadratus lumborum from

substituting for the gluteus medius.

Our results confirm the hypothesis that lumbar stabilization during hip

abduction in sidelying can reduce quadratus lumborum activity and ipsilateral

pelvic tilt and can recruit the gluteus medius and internal oblique. Previous

studies have recommended a treatment protocol that included relaxation to

- 22 -

decrease the activity of the quadratus lumborum and exercise to facilitate the

recruitment of the gluteus medius (Richardson et al. 1999; Chaitow 1996). The

lumbar stabilization method used here could stabilize the pelvis and recruit the

gluteus medius muscle without substitution by the quadratus lumborum.

Therefore, we suggest that lumbar stabilization during sidelying is useful in

treatment protocols designed to prevent motor control dysfunction by reducing

quadratus lumborum activity and strengthening the gluteus medius.

Our study showed that lumbar stabilization using a pressure biofeedback

unit significantly increased gluteus medius and internal oblique activity, while

decreasing quadratus lumborum activity and ipsilateral pelvic tilt in hip

abduction during sidelying. We used surface electromyography to investigate

muscle activity and assumed that the detected signal represented each muscle

in its entirety; however, there are potential signal alterations caused by muscle

movements below the surface electrode or cross-talk from adjacent muscles.

Although we established the predetermined hip abduction at 35° of vertically

to assure hip abduction in the frontal plane and to prevent possible hip or

pelvis movement in other planes that might affect the targeted muscle

activities, there were still some possibilities of forward and backward rolling

movement of pelvis. The mean body mass index (BMI) for subjects in our

study was 22.5. This mean BMI is within the normal range indicating that

- 23 -

subjects participated in the study are not overweight or obese. However, we

did not investigate abdominal obesity that can affect EMG measurement in

abdominal muscles leaving EMG signal alteration. Since adipose tissue

between the muscle and the recording electrodes can attenuate EMG signal

(Cram et al. 1998), further analysis of overweight or obese individual is

needed to determine whether the influence of lumbar stabilization may be

compromised when excessive fat tissues exist under abdomen. Our results

cannot be generalized in other populations because all the subjects

participating in the study were young and able-bodied. Therefore, the benefits

of lumbar stabilization used in this study should be confirmed in other

populations. The activities of the transversus abdominis was not measured in

our study. Therefore, further studies are warranted to assess deep muscle

activity during hip abduction training while sidelying with lumbar stabilization

and to determine the direct benefit and selective muscle facilitation associated

with lumbar stabilization.

- 24 -

Conclusion

This study showed that the activity of the gluteus medius and internal

oblique increased significantly, the activities of the quadratus lumborum

decreased significantly, and the lateral pelvic tilt was reduced significantly

during sidelying with lumbar stabilization achieved using a pressure

biofeedback unit. Therefore, hip abduction with lumbar stabilization during

sidelying can be recommended as a more effective method for excluding

unwanted substitution by the quadratus lumborum and to facilitate gluteus

medius muscle activity.

- 25 -

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국문 요약

고관절고관절고관절고관절 외전시외전시외전시외전시 압력압력압력압력 생체되먹임생체되먹임생체되먹임생체되먹임 기구를기구를기구를기구를 이용한이용한이용한이용한

요부요부요부요부 안정화가안정화가안정화가안정화가 근근근근 활성도와활성도와활성도와활성도와 관상면관상면관상면관상면

골반골반골반골반 경사각도에경사각도에경사각도에경사각도에 미치는미치는미치는미치는 영향영향영향영향

연세대학교 대학원

재활학과(물리치료학 전공)

신 헌 석

본 연구는 압력 생체되먹임 기구(pressure biofeedback unit)를

이용한 요부 안정화(lumbar stabilization)가 옆으로 누운 자세에서 고관절

외전시 근 활성도와 관상면 골반 경사각도에 미치는 영향을 알아보았다.

건강한 9명의 남자와 9명의 여자가 연구대상자로 참여하였다. 연구대상자는

옆으로 누운 자세에서 압력 생체되먹임 기구를 이용하여 요부가 안정화된

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조건과 자연스러운 조건에서 각각 고관절 외전을 수행하였다.

표면근전도를 이용하여 허리네모근(quadratus lumborum: QL),

중간볼기근(gluteus medius: GM), 배속빗근(internal oblique: IO),

배바깥빗근(external oblique: EO), 배곧은근(rectus abdominis: RA),

뭇갈래근(multifidus, MF)에서 근 활성도가 측정되었으며, 관상면 골반

경사각도는 삼차원 동작분석기로 측정하였다. 요부가 안정화된 조건과

자연스러운 조건의 차이와 남녀차이를 비교하기 위하여 이요인

분산분석이 이용되었다.

요부가 안정화된 조건에서 고관절 외전시 허리네모근의 활성도는

유의하게 감소하였고(p=.000), 중간볼기근과 배속빗근의 활성도는

유의하게 증가하였다(p=.000, p=.000). 그리고 요부가 안정화된 조건에서

고관절 외전시 관상면 골반 경사각도는 유의하게 감소하였다(p=.000).

여자의 중간볼기근, 배바깥빗근, 배곧은근에서의 활성도가 남자 근육의 각

활성도보다 유의하게 높게 측정되었다(p=.040, p=.000, p=.002). 요부

안정화의 유무와 남녀차이의 상호작용은 중간볼기근, 배바깥근,

뭇갈래근에서 나타났다(p=.016, p=.004, p=.005). 그러므로 요부가

안정화된 조건에서 허리네모근 활성도의 유의한 감소와 중간볼기근과

배속빗근 활성도의 유의한 증가는 옆으로 누운 자세에서 관상면의 골반

경사각도를 유의하게 감소시키는데 기여하였다고 해석될 수 있다. 또한

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이러한 결과는 압력 생체되먹임 기구를 이용한 요부 안정화가 옆으로

누운 자세에서 허리네모근의 대치작용을 감소시키고, 중간볼기근과

배속빗근의 활성도를 증가시키는 목적으로 이용될 수 있다고 할 수 있다.

핵심되는 말: 근전도, 근 활성도, 요부 안정화.