back pain is a common problem with annual prevalence of activity limiting low back pain at 
 38%1 . of individuals with chronic low 
 back pain ,
rehabilitation programs that include stabilization exercises reduce pain and disability in 
 individuals with chronic low back pain3 . 

both lumbar iliocostalis ( li ) and lumbar multifidus ( lm ) have a role in stabilization of the 
 spine .
the li provides stabilization globally at a multi - segmental region whereas lm is 
 viewed to provide stability at a local segmental level4 . both li and lm electromyographic ( emg )
activity have been described 
 for stabilization exercises performed in prone5,6,7 , and 
 quadruped8 . in standing ,
the emg output 
 of lm but not li was reported during maximum effort shoulder and trunk motions9 .
seated position stabilization exercise 
 studies are limited to reports of emg activity for erector spinae7 and lm6 
 during shoulder flexion .
while standard stabilization exercises are performed in prone and 
 quadruped , medical or musculoskeletal conditions10 may limit an individual s ability to assume these positions .
seated 
 dynamic exercise programs are comfortable and safe for individuals ( e.g. , those with 
 osteoarthritis ) who can not exercise in upright11 .
investigation of emg activity of li and lm during performance of 
 seated stabilization exercise using multiple shoulder motions has not been performed .
the 
 purpose of this study was to compare the emg activity of lm and li during full range and 
 stabilization exercises performed in prone , quadruped , and sitting to identify an exercise 
 hierarchy of percent ( % ) maximum voluntary contraction ( mvc ) as well as optimal recruitment 
 exercises for both li as a global multi - segmental stabilizer and lm as a segmental 
 stabilizer .
twelve healthy volunteers ( six male and six female ) aged 24 to 45 participated in the 
 study .
the average age of subjects was 31.4  7.48  years . mean height and weight were 171.08 
  8.22  cm and 66.67  13.10  kg , respectively .
participants who demonstrated full active 
 shoulder flexion motion , at least 50% active trunk extension motion , no spinal deformities , 
 and absence of pregnancy , neuromuscular disease , past spine surgery , or back pain within the 
 past three months were included in the study .
all subjects correctly performed the exercises 
 at a training session after instruction by a physical therapist .
the study was conducted at the gait laboratory at helen hayes hospital , west haverstraw , 
 ny , usa . the emg data were recorded with surface electrodes ( iomed inc . , salt lake city , ut , 
 usa ) .
the electrodes have a differential preamplifier with three stainless steel sensing 
 elements ( 13  mm in diameter spaced 5  mm apart with the center acting as a ground plate ) with 
 a gain of 300 , common mode rejection ratio of > 100 db , input impedance of 100,000 
 megohms , and a bandwidth of 8  hz to 27 khz .
data were collected with a vax 3200 
 computer work station and stored for further analysis .
placement for lm was consistent with methods described by 
 others12,13,14,15 at 1 to 2  cm lateral to the midline to the spine and adjacent to 
 the fourth and fifth lumbar vertebral bodies .
electrode placement for li was similar to ng 
 and colleagues16 at just proximal to the 
 posterior superior iliac spine , parallel to the line of the lateral  most bulk  of the 
 erector spinae .
prone active trunk hyperextension was used to visualize and mark the outline 
 of this muscle bulk .
additionally , prone resisted isometric shoulder extension confirmed no 
 activity at this electrode during latissimus dorsi muscle contraction .
we predicted that all participants could achieve full extension 
 with 7.3  kg as the resistance .
therefore , active prone hyperextension against a 7.3  kg 
 weight positioned mid scapula was defined as a maximum voluntary contraction ( mvc ) .
all 
 exercises lasted six seconds , using a metronome and verbal cues for three equal phases : a 
 two second build up , 2 second hold , and 2 second release .
after the preamplifier gain of 300 , the emg signals were sampled at 1,200  hz and 
 band pass filtered from 40 to 500  hz .
the data were full - waved rectified and the three 
 repetitions averaged for the three phases of the exercises .
these exercise data were normalized to a percentage of the average of the 
 mvc .
subjects were 
 instructed as follows : ( a ) in prone , move through full active prone trunk extension ( pte ) 
 range of motion without extremity motion , full active trunk extension with left arm / right 
 leg lift and with right arm / left leg lift , ( b ) maintain quadruped with isometric fixed 
 neutral pelvis for quadruped opposite arm / leg lift ( qoall ) both combinations , and ( c ) sit 
 and hold erect posture with isometric fixed neutral pelvis with right arm outstretched at 90 
 degrees shoulder flexion for isometric arm exercises . sitting arm exercise was performed 
 using the right arm with a 1.8  kg force applied at the wrist using a strain gauge held 
 perpendicular to the arm in the sagittal plane to produce flexion / extension , and transverse 
 plane for horizontal abduction / adduction isometric shoulder muscle contractions .
the 
 sequence of categories was chosen randomly by slips of paper drawn from a box .
each exercise 
 was repeated three times . a two - way anova ( exercise x side ) with repeated measures
was performed for each muscle to 
 assess differences in emg activity level among exercises and across sides .
tukey hsd confidence intervals =0.05 were 
 used to determine which exercises resulted in significant left / right asymmetry .
statistical 
 analysis was performed using ibm statistical package for the social sciences ( spss ) version 
 23 .
identical hierarchies were identified for normalized data and are shown in table 1table 1.mean percentage mvc with standard deviation of iliocostalis and multifidus 
 musclesmusclepepoallr ue liftpoalll ue liftqoallr ue liftqoalll ue liftsflexr uesextr uesabdr uesaddr ueiliocostalis r0.93  0.23 * 1.06  0.48*0.80  0.33 * 0.36  0.180.27  0.200.13  0.080.08  0.50.20  0.070.09  0.05iliocostalis l0.95  0.28 * 0.85  0.28 * 1.02  0.31*0.25  0.110.38  0.260.24  0.080.07  0.050.08 
0.030.23  0.06multidifus r0.88  0.28 * 0.90  0.29 * 0.83  0.24 * 0.26  0.220.46  0.170.20  0.130.08  0.030.14  0.060.17  0.09multifidus l0.90  0.16 * 0.90  0.24 * 0.87  0.19 * 0.43  0.090.23  0.100.25  0.130.09  0.070.17
 0.090.16  0.08r : right ; l : left ; ue : upper extremity ; pe : prone extension ; poall : prone opposite 
 arm leg lift ; qoall : quadruped opposite arm leg lift ; sflex : sitting flexion ; sext : 
 sitting extension ; sabd : sitting horizontal abduction ; sadd : sitting horizontal 
 adduction ; * statistically significant difference from quadruped and sitting position 
 exercises ;  statistically significant difference from sitting position exercises ; 
 statistically significant difference for noted exercise and muscle left and right 
 comparison ; p<0.05 .
two - way anova analysis showed that significant main effect of % of emg 
 activity for li and lm muscles was observed , suggesting that % of emg activities varies with 
 exercise position ( ( f1,11)=106 , ( f1,11)=150 , p<0.05 ) .
post hoc 
 tests revealed that prone extension , prone right ue / left le , and prone left ue / right le 
 produces a statistically significant difference with greater li and lm emg activity compared 
 to quadruped and sitting positions exercises ( p<0.05 ) ( table 1 ) . additionally , quadruped arm lifting exercise generated a 
 statistically significant difference in lm emg activity that was greater than that produced 
 in sitting exercises ( p<0.05 ) .
r : right ; l : left ; ue : upper extremity ; pe : prone extension ; poall : prone opposite 
 arm leg lift ; qoall : quadruped opposite arm leg lift ; sflex : sitting flexion ; sext : 
 sitting extension ; sabd : sitting horizontal abduction ; sadd : sitting horizontal 
 adduction ; * statistically significant difference from quadruped and sitting position 
 exercises ;  statistically significant difference from sitting position exercises ; 
 statistically significant difference for noted exercise and muscle left and right 
 comparison ; p<0.05 a statistically significant interaction between exercise and side was found for li and lm 
 muscles activities ( ( f1,11)=106 , p<0.05 ) .
muscle activity was greatest 
 ipsilateral to side of arm activity for li for prone and quadruped .
in contrast , lm activity 
 was higher on side opposite to arm lift ( side of leg lift ) during qoall .
sitting exercises 
 did not show consistency in favoring either left or right side muscle activity for either 
 muscle ( table 1 ) .
the purpose of this study was to compare full range and stabilization exercises performed 
 in prone , quadruped , and sitting and establish a hierarchy of % mvc of emg activity of li 
 and lm , as well as to identify optimal recruitment exercises for both li as a global 
 multi - segmental stabilizer and lm as a segmental stabilizer .
all core muscles are important 
 for providing trunk stability18 , with 
 stabilization of the lumbar spine accomplished by the interaction of local and 
 multi - segmental muscle contraction4 .
the 
 long multi - segmental global muscles function as guy wires during trunk motion while the deep 
 segmental back muscles provide neuromuscular control at a vertebral level , with the lm 
 viewed as a primary segmental stabilizer of the lumbar spine19 .
a high resistance generates the need for a large force , produced 
 by the stronger global muscles ( e.g. , li)18 .
smaller muscles ( e.g. , lm ) are more efficient in generating a 
 segmental stabilization force and may be sufficient for resisting lighter loads18 .
trunk extensor muscle weakness can be 
 addressed via strengthening by using prone extension exercises through full range against 
 resistance19 . in this study
pte 
 recruited both li and lm maximally and symmetrically , which is consistent with their primary 
 action in extension of the lumbar spine and consistent with the results of emg studies by 
 others20,21,22 .
the high muscle 
 recruitment of 80 to 106% mvc produced during the bilateral recruitment of li and lm during 
 this exercise indicate it is an optimal exercise for strengthening .
high compressive forces on the spine may be hazardous to individuals with low back 
 pain23 .
decreased compressive forces 
 can be accomplished using quadruped exercises with a neutral spine position19 .
asymmetry during qoall was observed for 
 both li and lm , with greater activity occurring ipsilateral and contralateral to arm lift 
 respectively .
previous studies report mixed results for li with no asymmetry24 , asymmetry of muscle activity with li 
 greater ipsilateral to arm lift8 , 25 , and contralateral to arm lift23 .
prior studies of quadruped exercise for 
 lm activity have also reported varied asymmetry with greater ipsilateral to arm 
 lift and contralateral to arm lift23 , 
 25 , 26 . in this study , during qoall the li and lm produced 24 to 38% and 
 23 to 46% mvc , respectively .
this is less than the recommended 60 to 70% of a 1 repetition 
 maximum ( and similar % mvc ) advocated to achieve a strengthening effect for novice 
 exercisers27 .
consistent with its proposed role 
 as a postural muscle4 , the lm is composed 
 of mostly type 1 fibers28 . in this role , 
 the lm will perform tonic contractions4 . 
 low load exercise of 30 to 40% mvc is recommended for targeted endurance training of type 1 
 muscle fibers4 . additionally , success has 
 been achieved using an exercise program for patients with clinical instability , which 
 included targeted recruitment of lm , resulting in decreased pain and improved function29 .
these results indicate that qoall will 
 produce low levels of spinal compression and optimally train lm to support its role as a 
 postural muscle .
some individuals can not assume a prone or quadruped position to perform spine strengthening 
 exercise .
the exercises performed in sitting demonstrated that recruitment of li was 
 dependent on direction of force .
motions of sitting flexion and adduction produced higher li 
 emg values contralateral , while abduction demonstrated a greater ipsilateral li force .
behm 
 and colleagues7 reported a similar pattern 
 of greater contralateral lumbosacral es emg activity when performing a unilateral shoulder 
 press using a dumbbell while seated .
they proposed that unilateral resisted exercise creates 
 a disruptive torque moment thereby creating an unstable condition with a response by the 
 contralateral es .
however , their use of a swiss ball as an unstable base did not increase 
 recruitment of contralateral es when compared to a stable sitting environment during 
 unilateral shoulder press with a dumbbell .
our results demonstrated that recruitment of lm 
 in sitting was symmetrical , with greatest % mvc during shoulder flexion .
aronski and 
 coauthors6 also reported lm produced 
 symmetrical contraction during alternating flexion with dumbbells in high sitting .
this 
 study is the first to describe the emg production of back stabilizing muscles while 
 performing multiple unilateral resisted shoulder exercises in a seated position .
our results 
 indicate that seated arm exercises as performed in this study are insufficient to produce a 
 strengthening or endurance training effect on the trunk stabilizers .
the superficial and deep fibers of lm may exhibit differing 
 emg recruitment patterns which are not observable with surface electrodes .
results may vary 
 in persons with back pain , older adults , when using different extremity positions or 
 different amounts of resistance . whereas a standardized mvc of prone extension against 
 7.3  kg was utilized
, an isometric resistance in trunk extension may produce a higher emg 
 reading . in conclusion
, our study indicates that full range prone exercises generate sufficient emg 
 output to provide a strengthening stimulus for both li and lm . for the healthy individual , 

pte generates the greatest emg production , thus providing the best exercise for 
 strengthening the trunk extensors .
the quadruped stabilization exercise best trains the lm 
 in its role as a segmental stabilizer .
the qoall exercise produces low spinal loading and 
 recommended % mvc activity for training lm in its role as a segmental stabilizer , thus 
 making this the optimal exercise for an individual with low back pain .
lastly , sitting 
 isometric arm exercises , at the loads used in this study , generate insufficient load for any 
 training effect for either li or lm .
further research is needed to determine optimal 
 exercise dosage for strengthening and endurance of both global and segmental muscles in a 
 sitting position .
 [ purpose ] the purposes of this study were : 1 ) describe a hierarchy of electromyographic 
 activity production , using percentage maximum voluntary contraction of lumbar iliocostalis 
 and lumbar multifidus muscles during prone , quadruped and sitting exercises ; and 2 ) 
 identify optimal recruitment exercises for both lumbar iliocostalis as a global 
 multi - segmental stabilizer and lumbar multifidus as a segmental stabilizer . 
 [ subjects ] 
 twelve healthy volunteers ( six male and six female ) aged 24 to 45 participated . [ methods ] 
 
 surface electromyographic activity data were collected bilaterally from lumbar 
 iliocostalis and lumbar multifidus muscles during exercises . 
 [ results ] two - way anova 
 showed that prone extension , and prone alternate arm and leg lifting exercises produce a 
 statistically significant difference in percent maximum voluntary contraction of lumbar 
 iliocostalis and lumbar multifidus bilaterally compared to other exercises . 
 quadruped 
 alternate arm and leg lifting exercises produce greater activity in lumbar multifidus 
 muscle than sitting exercises [ conclusion ] prone exercises generate the greatest 
 electromyographic activity and may be the most effective exercises for strengthening both 
 lumbar iliocostalis and lumbar multifidus muscles . 
 quadruped alternate arm and leg lifting 
 produces electromyographic activity at the recommended percent maximum voluntary 
 contraction for training the lumbar multifidus in its role as a segmental stabilizer and 
 is an effective training exercise for this goal . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION