How do we assess the function of the transverse abdominis?
○Masaki Yokomori PT3）

Shintarou Kudo PhD1）2）, PT.

1）Department of physical therapy, Morinomiya University of Medical Sciences2）Graduate school of health sciences, Morinomiya University of Medical Sciences3）Department of rehabilitation, Seijinkai medical corporation, Minase Hospital

The transverse abdominis muscle(TrA) is one of the dynamic stabilize system of the trunk, and it shows to increase the thickness of TrA from supine tosingle leg stance without regarding trunk movements(Yokomori M, et al. 2019).
Several researchers reported the function of the TrA can be assessed using drawing-in maneuver (DI) with ultrasonography(US) (Kiesel KB, et al. 2007,
Koppenhaver SL, et al. 2009), however, it is unclear that these assessment reflects to both the performance and TrA activity during lower limb reach taskwith single leg standing.
The aim of this study is to investigate for the validation of the assessment of the TrA using DI with US.

48 healthy-male subjects
Aplio300/B mode；
12M㎐ transducer
Navel height

Y-Balance Test (YBT)

Exclusion
The Manual Muscle
Testing of trunk andhip joint abductor
muscle was assumed
to be less than 4

Drawing-in（DI）

Anterior
axillary line

Anterior①Muscle thickness change ratio (%)=(maximum muscle thickness during YBT - muscle thickness
at supine position )/ - muscle thickness at supine position *100（Kiesel,et al.2007）

Less than 100％

 US: Aplio 300, B mode, 7 MHz micro curvilinear transducer
 Used the custom made ultrasound transducer holder
Th6(Thorax)

TrA

TrA

TrARestDI

TrA normal group
30 subjects

VSS2(Pelvic)

DI=(Reach distance/height)*100
 Reach distance was measured using tape measure Measurement of Anterior, Posteromedial, Posterolateral reach The median of the reach of three times in each direction was used as a representative for analysis(①, ②, ③).
 ①,②,and ③ were compared between the TrA normal group and the TrA dysfunction group.
 The independent samples t-test and the non-parametric Mann-Whitney test.
 Significance was set at p<0.05.
 Statistical analysis was performed using SPSS (version 25).

Posteromedial reach

20.0
10.0
0.0
-10.0Flex
TrA normal③Reach distance (%)

Side-bendRot
TrA Dysfunction

TrA normal0.45(Reach distance /height)* 100 (%)(Reach distance /height) * 100 (%)-50.0
TrA normal

Side-bend

0.4
0.35
0.3
TrA Dysfunction

Rot

30.0
20.0
10.00.0-10.0
Flex
TrA normal

TrA Dysfunction

0.6
0.4
0.20
TrA normal

TrA Dysfunction

Posterolateral reach

Posteromedial reachAnterior reach

TrA normal

0.0

TrA Dysfunction

20.0
10.00.0-10.0
-20.0
Flex

＊<0.0550.0

Posteromedial reachAnterior reach＊100.0Side-bend

Rot

TrA Dysfunction

Posterolateral reach(Reach distance /height) * 100 (%)

30.0

TrA normalTrunk motion(°)

Trunk motion(°)②Trunk motion (°)

＊

80.0
60.0
40.0
20.0
0.0
-20.0
-40.0

TrA Dysfunction

Posterolateral reach
Muscle thickness
change rate (%)

＊

80.0
60.0
40.0
20.0
0.0-20.0

Muscle thickness
change rate (%)

Muscle thickness
change rate (%)

Anterior reach

TrA normal

S2(Pelvic)

X: flex-ext
Y: side bend
Z: rot A 3-dimensional motion analysis device : VICON MX
 Trunk movement : movement of the thorax with respect to the pelvic
 Measurement of flexion / extension, side bending, rotation③Reach distance (%)

TrA dysfunction group18 subjects

 This study was reviewed and approved by the Ethical Committee at the University ofMorinomiya Medical University（2018-063）, and carried out in accordance with theDeclaration of Helsinki.

Th6(Thorax)=(maximum movement during YBT -start standing position)（20.6±1.1years,170.2±4.6㎝,61.4±7.2 ㎏）（20.2±1.1years,172.5±5.5㎝,63.8±7.6㎏）①Muscle thickness
change ratio (%)②Trunk motion (°)

Trunk motion(°)

Over 100％

Rest

Posterolateral

Measurement was performed during YBTMuscle thickness change ratio (%)＝（DI-Rest）/Rest×100

TrA

Posteromedial

0.6
0.55
0.50.45
0.4

TrA Dysfunction

TrA normal

TrA Dysfunction① The muscle thickness change rate was significantly lower in all three directions in the TrA dysfunction group (p <0.05).
② Each trunk movement were no significant differences between the two groups.
③ Each reach distance were no significant differences between the two groups.

Muscle thickness of TrA in YBT increased more than supine position.
However, muscle thickness change ratio was significantly lower in TrA dysfunction group, and it became clear that DI reflects muscle activity during YBT.
On the other hand, TrA muscle function did not affect the trunk motion and the reach distance.
TrA functions as dynamic stability of the spine and is anatomically poor for causing spine motion (Urquhart DM, et al. 2005).
In addition, it is reported that the reach distance is affected by the function of the lower limbs (Jatin P, et al. 2014, Gordon A, et al 2013, Rasool J, et ai. 2007).
Therefore we could not be assessed the function of the TrA using trunk motion observation and performance test.
It was clarified that DI reflected the TrA activity during YBT.
DI can be estimated function of the TrA during YBT.

We find that the dysfunction of the TrA assessed using DI decrease thickness of TrA during the YBT.
Both trunk motion and reach distance during YBT cannot predict the function of TrA.