1. Vastus Medialis Oblique/Vastus Lateralis Muscle
Activity Ratios for Selected Exercises in Persons
With and Without Patellofemoral Pain Syndrome
--
Background and Purpose. The purpose of this study was to determine which Kay Cemy
of selected exercises with and without the feet free to move would enhance
vastus medialis oblique muscle (VMO) activity over that of the vastus lateralis
muscle ( W ) and whether the use of taping would increase VMO activity.
Subjects. Twenty-one subjects without patellofemoral pain (PFP) syndrome and
10 subjects with PFP syndrome, aged 19 to 43 years @=26, SD= 71, partici-
pated. Metbods. Subjects were studied for the normalized, integrated electro-
myographic (IEMG) activity of their M O , W , and adductor magnus muscle
(subjects without PFP syndrome) and the V M O m ratio using wire electrodes.
Results. One exercise demonstrated greater activation of the VMO over the W
when compared with similar exercises in subjects without PFP syndrome. The
mean VMOhT activity ratio for terminal knee extension was 1.2 (SD= 0.5) with
the hip medially rotated and 1.0 (SD= 0.4) with the hip laterally rotated. Al-
though subjects reported that patellar taping decreased pain 94% during the
step-down exercise, the V M O m ratio was not changed. Conclusion and
Discussforr The results suggest that neither exercises purported to selectively
activate VMO activity nor patellar taping improve the V M O m ratio over simi-
lar exercises. lCerny K. Vastus medialis oblique/vastus lateralis muscle activity
ratios for selected exercises in persons with and without patellofemoral pain
syndrome. Phys Ther. 1995; 75672- 683.1
Key Words: Adductor magnus, Electromyography, Patellc$moral, Vastus lateralis,
Vastus medialis oblique.
Patellofemoral joint pain (PFP) is com- common site of knee pain in sports PFP syndrome.4-6-8As a result, both
mon in the general population, occur- medicine clinics.'-5 Lateral malalign- surgical and conservative treatments to
ring more often in women and in ment of the patella has been sug- correct this rnalalignrnent have been
athletes, with the joint being the most gested as one of the major causes of suggested.1~4-10
Many exercise treatments emphasize
the importance of the vastus medialis
K Cerny, PhD, PT,is Professor, Department of Physical Therapy, College of Health and Human oblique muscle (VM0)6,8,10 because of
Services, California State University, Long Beach, Long Beach, C 90840-5603 (USA)
A its medial pull on the patella.11-15
(KCERNY@CSULB.EDU).
Some researcherslb-19 suggest that
The study protocol was approved by the Human Subjects Committee, California State University, contraction of the hip adductor and
Long Beach. quadriceps femoris muscles simulta-
Results of this research were previously presented at the 1991 and 1992 Annual Conferences of neously would preferentially activate
the California Chapter of the American Physical Therapy Association and at the 1991 and 1922 the VMO. Other researchersl7.19 report
Annual Conferences of the Long Beach Veterans Administration Hospital-California State Univer- that the vastus medialis muscle (VM) is
sity, Long Beach-Memorial Medical Center of Long Beach.
activated preferentially in response to
m k article was submitted August 24, 1994, and was accepted April 3, 1995.
26 / 672 Physical Therapy / Volume 75, Number 8 / August 1995

2. Table 1, Subject Anthmpometric Data
Body Weight (Ibb)
NO. of -
Age 0 -
Subjects X SD Range X SD Range
Subjects without PFPB syndrome
Women 10
Men 11
Subjects with PFP syndrome
Women
Men
"PFP=patellofemoral pain.
b l lb=0.4536 kg.
valgus stress at the knee caused by The primary purpose of this study was fore beginning the study. The subjects
hip lateral rotation during knee exten- to determine whether any of the exer- rated their pain after stepdown exer-
sion exercises and that hip medial cises purported to increase the activity cise on a scale of 1 to 10, with 1 being
rotation, therefore, decreases the activ- of the VMO over the VL, the VMO/VL minimal pain and 10 being the worst
ity of the VM. Still others9'20921 have activity ratio, did so when compared pain that they could imagine, and they
reported greater VMO activity during with similar exercises in subjects with reported the percentage of change in
knee extension with the knee rela- and without PlT. A secondary pur- pain with step down after taping. The
tively flex.ed than in terminal knee pose of this investigation was to deter- subjects with PlT were required to
extension. Knee extension exercise mine whether therapeutic medial-glide have at least a 50% reduction in pain
with tibia'l medial rotation has been taping altered the activity of the VMO with patellar taping to participate in
proposed because the VMO is pur- or the V or the VMO/VL activity ratio.
L the study. All subjects provided in-
ported to prevent lateral rotation of Another purpose was to determine formed consent consistent with univer-
the tibial8.19 and therefore to decrease which of similar exercises increased sity policy.
the quadriceps femoris muscle angle the activity of the VMO, VL, and ad-
(Q angle) and lateral patellar track- ductor magnus muscle (AM). Finally, I
ing.22 Pronation of the subtalar joint wanted to determine whether gender
and medial rotation of the tibia, how- influenced the muscle activity studied. Myoelectric activity was measured by
ever, have also been claimed to in- use of indwelling wire electrodes of
crease lateral tracki11g.~,~3 Method 50-pm nickel alloy. The electrodes,
insulated except for 2 rnrn at the ends,
McConnel16J6trains patients with PFP Subjects were inserted into the muscle with a
syndrome in unilateral and bilateral 25-gauge needle. The needle was
limb flexion exercises in weight bear- Twenty-one subjects who had no withdrawn, leaving the barbed ends of
ing (walk stance and wall slide) and known lower-limb musculoskeletal the wire electrodes in place. The wire
stepdown exercises because these impairments and who exhibited no electrodes were inserted into the VMO
patients have increased pain with signs of neurological impairment and and V of all subjects. In addition, a
L
these activities. Although soft bracing 10 subjects with PlT participated in wire electrode was placed in the A M
has previously been suggested to this study. The subjects' average age, of the subjects without PlT syndrome
negate the valgus force of the quadri- average body weight, and gender are to ensure that they were contracting
ceps femoris muscles on the patella,l,5 shown in Table 1. Subjects with syrnp- the muscle during exercises. The wire
McConnel16J6suggests improving toms had a physician's diagnosis of for the VMO was placed in the middle
patellar tracking, decreasing pain, and PFP within 6 years of the testing date of the muscle belly. The wire for the
increasing the vastus medialis oblique/ and reported retropatellar pain during V was placed in the muscle approxi-
L
vastus lateralis muscle (VMO/VL) at least two of the following activities: mately one t i d of the distance from
hr
activity ratio in persons with PlT by (1) squatting, (2) ascending and de- the patella to the anterior superior iliac
taping the patella or tensor fascia lata scending stairs, and (3) prolonged spine. The wire for the A was in-
M
muscle medially. Little evidence exists All
sitting.1-3s4 subjects with PlT per- serted into the muscle just anterior to
to support the use of the exercises formed a step-down exercise from a the gracilis muscle, approximately one
and procedures reviewed. 22.9-cm (9-in) stool with and without t i d of the distance from the medial
hr
medial-glide taping of the patella be- femoral epicondyle to the syrnphysis
Physical 'Therapy / Volume 75, Number 8 / August 1995 673 / 27

3. pubis. The locations of the VL and AM corded during rest and during maxi- Exercises for Subjects Without
inseltions were chosen because they mal manual resistance tests. All PFP Syndrome: Open Chain
proved to be the most distal locations, recordings during the resistance tests
consistently affording a full electro- were obtained with the subjects posi- Three groups of open-chain activities
myographic (EMG) interference pat- tioned supine and supported on their were used for interexercise compari-
tern upon muscle activation during elbows. For the VMO and VL tests, the son: quadriceps femoris muscle setting
pilot testing. The distal VL insertion subjects' knee extension was resisted ("quad sets"), knee extension, and
was used to sample the oblique por- while the hip and knee were flexed isometric holds. All exercises were
tion of the VL, which is purported to approximately 30 degrees. For the AM performed against the resistance of an
best oppose the action of the VM0.12 test, the subjects were resisted for hip ankle cuff weight equal to 5% of each
The distal AM insertion was used to adduction with the knee extended. subject's body weight to the nearest
sample its activity near the origin of pound.
the VMO.'3 The leg each subject said Exercise Pmcedures
was the dominant leg was tested in all Quad sets (QS). Quad sets were
except one of the subjects without Exercises included what Lehmkuhl isometric exercises performed in full
PFP syndrome. The nondorninant limb and Smith24 and Soderberg25 have knee extension with the subjects posi-
was tested in one subject without PFP described as "open-chain and tioned long sitting and supported on
syndrome because he had a previous "closed-chain" activities of the lower their hands with their heels lifted off of
knee surgery on the dominant side. limb, performed in random order for 5 the table to decrease the possibility of
The most severely involved leg of the seconds each. Lower-limb open-chain substitution by hip extensor activity.
subjects with PFP was tested. exercises were performed with the The six quad set exercises were done
sole of the foot free to move, whereas with (1) the hip and ankle positioned
In order to decrease the chance of closed-chain exercises had the sole of in neutral (QS), (2) the hip maximally
wire electrode migration during test- the foot planted on the floor. The medially rotated and the ankle posi-
ing, subjects contracted the inserted terms "open chain and "closed chain" tioned in neutral (QSMR), (3) the hip
muscle maximally several times after are used here to denote whether the maximally laterally rotated and the
needle insertion to pull the wire into distal limb segment was free to move ankle positioned in neutral (QSLR), (4)
the muscle. In addition, the investiga- when the quadriceps femoris muscles the hip maximally adducted against a
tor moved the limb into full knee contracted. Open-chain exercises were pillow bolster with the ankle posi-
flexion and extension and full hip randomly chosen to be performed tioned in neutral (QSA), (5) the hip
abduction and adduction to allow the prior to or after closed-chain exercises. positioned in neutral and the ankle
wire to slip further into the tissues Subjects practiced dynamic exercises maximally dorsiflexed (QSDF), and (6)
before taping the external wire to the until the investigators were satisfied the hip positioned in neutral and the
limb with a stress-relief loop. that movements were smoothly timed ankle maximally plantar flexed
with a metronome at 1 beat per sec- (QSPF).
Surface ground plates and the teleme- ond. Starting positions of the knee
try system were attached to the sub- were monitored with a standard goni- Knee extension (KE). The knee
ject, and the electrode wires were ometer. Subjects moved and their extension exercises were performed
connected to attachment posts on the EMG activity was recorded during with the subjects in a sitting position
ground plates. Myoelectric signals exercises, beginning on the beat of a with the knee flexed from 30 to 0
were differentially amplified, band- metronome. Movement began with a degrees and the ankle positioned in
pass filtered (50-850 Hz), and trans- "go" command from the investigator neutral. The movement was timed
mitted by FM-FM telemetry to a re- immediately following a "ready" com- with a metronome for 3 seconds,
ceiver interfaced to a B&L computer mand at the previous metronome followed by a 2-second hold at full
(model 286): Placement of electrodes beat. Electromyographic recording extension. The three exercises were
in the vastus muscles rather than rec- during isometric exercises began after performed with (1) the hip positioned
tus femoris muscle was confirmed by the raw EMG level stabilized in a full in neutral (ICE), (2) the hip maximally
noting activity during isometric knee interference pattern. In consideration laterally rotated (KELR), and (3) the
extension and silence during com- of the tolerance of the subjects with hip maximally medially rotated
bined isometric hip and knee flexion. PFP syndrome, fewer exercises were (KEMR).
Placement in the AM rather than the performed by the subjects with PFP
VM was confirmed by noting activity syndrome than by the subjects without Isometric holds in flexion (IS). Iso-
during isometric hip adduction and PFP syndrome. Abbreviations and metric hold exercises were isometric
silence during isometric knee exten- definitions of the exercises used in this knee extension exercises performed
sion. The EMG activity was then re- study are presented in Table 2. with the subjects in a sitting position
with their hip and ankle positioned in
neutral. The five exercises were done
with (1) the knee flexed 15 degrees
'B&L Engineering, 12309 E Florence Ave, Santa Fe Springs, C 90670
A and the tibia in neutral rotation (IS15),
Physical Therapy / Volume 75, Number 8 / August 1995

4. Table 2. Exercise Abbreviations and Dejinitions
Abbreviation Definition
Exercises for subjects without patellofemoral joint pain syndrome
Open chain
Quadriceps femoris muscle set (QS) lsornetric at full knee extension
QS Hip and ankle neutral
QSML Hip maximally medially rotated, ankle neutral
QSLR Hip maximally laterally rotated, ankle neutral
QSA Hip adducting against a bolster, ankle neutral
QSDF Hip neutral, ankle maximalty dorsiflexed
QSPF Hip neutral, ankle maximally plantar flexed
Knee extension (KE) 30" to 0" extension, ankle neutral
KE Hip neutral
KEMR Hip maximally medially rotated
KELH Hip maximally laterally rotated
Isometric hold (IS) Hip and ankle neutral
IS15 Knee at 15" flexion, tibia in neutral rotation
IS45 Knee at 45" flexion, tibia in neutral rotation
IS60 Knee at 60" flexion, tibia in neutral rotation
IS45MR Knee at 45" flexion, tibia maximally medially rotated
IS45LR Knee at 45" flexion, tibia maximally laterally rotated
Closed chain
Walk stance-stepdown (WS-SD)
Unilateral knee flexion to 45", hip in neutral rotation and subtalar
joint unconstrained
WSS WS with subtalar joint in maximal supination
WSP WS with subtalar joint in maximal pronation
WSPT WS after patellar medial-glide taping
WSTT WS after medial-glidetaping of the tensor fascia lata muscle
Step down from a 22.9-cm (9-in)stool leading with contralateral
SD limb, hip in neutral rotation and subtalar joint unconstrained
Wall slide (WSI)
WSI Bilateral knee flexion to 45", hip in neutral rotation
WSIA WSI while hip adducting against bolster
Exercises for subjects with patellofemoral joint pain syndrome
Open chain
QS, 1515, IS601, KE As described above
Closed chain
WS, WSI, WSIA, SD As described above
Isometric knee extension and hip adduction against a bolster sitting
with sole of foot on floor
(2) the knee flexed 60 degrees and the Exercises for Subjects Without seconds, followed by a 2-second hold
tibia in neutral rotation (IS60), (3) the PFP Syndmme: Closed Chain at the end position.
knee flexed 45 degrees and the tibia
in neutral rotation (IS45), (4) the knee Two groups of closed-chain exercises Walk stance-step down (WS-SO).
flexed 45 degrees and the tibia maxi- were used for interexercise compari- Walk-stance exercises were unilateral
rnally laterally rotated (IS45LR), and son: (1) walk-stance and step-down exercises performed to 45 degrees of
(5) the knee flexed 45 degrees and the exercises and (2) wall-slide exercises. knee flexion with the hip in neutral
tibia maximally medially rotated Movements were performed for 3 rotation and the subject's weight sup-
(IS45MR)
Physical Therapy /Volume 75, Number 8 /August 1995

5. ported on the forward, tested limb. exercises with and without patellar correlation coefficients (ICC[3,1D for
The opposite toe was permitted to taping. two repeated measures of QS, QSA,
remain on the floor for balance only. IS60, IS15, WS, WSl, WSlA, SD, and
Balance was also provided by touch- Open-chain exercises were QS, IS15, knee extension from 30 to 0 degrees
ing the hands of an investigator. The IS60, and KE. Closed-chain exercises of flexion using the same EMG pro-
five exercises were performed with (1) were done both before and after the cessing as in this study. Two insertion
the subtalar joint unconstrained (WS); patella was taped medially with a sites in locations bordering within 1.27
(2) the subtalar joint maximally supi- medial frontal-plane tilt and rotation to cm (0.5 in) of those used in thls study
nated (WSS); (3) subtalar joint maxi- position the inferior pole of the patella were sampled for each muscle. Eighty
mally pronated (WSP); (4) the subtalar inferiorly. The closed-chain exercises percent of all ICCs were above .30.
joint unconstrained after the patella were WS, WSl, WSlA, SD, and isomet- Reliability averaged .81 for the VMO,
was taped medially with a media ric knee extension and hip adduction ranging from .37 to .98, and averaged
frontal-plane tilt and rotation to posi- in a sitting position with hips and .91 for the VL, ranging from .77 to .98.
tion the inferior pole of the patella knees flexed to 90 degrees (ISQA). The VMO/VL ratio averaged .93, rang-
inferiorly (WSPT); and (5) the subtalar This exercise was considered closed ing from .88 to .%, with the exception
joint unconstrained after tensor fascia chain because subjects were instructed of .55 for walk stance using the lower
lata muscle medial-glide taping to contract the vastus muscles by insertion sites. The walk-stance ratio
(WSrr3. pushing the foot against the floor and for the upper insertion sites was .97.
to squeeze the bolster maximally.
The final exercise was a step down The average EMG value was calcu-
from a 22.9-cm stool, with the subject At the end of testing, wire electrodes lated for each muscle of each subject
leading with the contralateral limb were slipped out of the muscle, and for each exercise, and a VMO/VL ratio
while the tested limb was in neutral the skin was cleaned with alcohol. was calculated from these values.
hip rotation. The hold was with the Total testing time was 1 2 to 2 hours
Y Mean values for VMO, VL, and AM
contralateral foot just off of the floor per subject. myoelectric activity and the VMO/VL
(SD). ratio were calculated for each exercise.
Data Anahsis Exercises in each of the five groups of
Wall slide (WSO. The wall-slide exer- exercises for subjects without PFP
cises were bilateral exercises that the The EMG activity was digitized at syndrome (QS, KE, IS, WS-SD, WSl)
subjects performed from an upright 2,000 samples per second through an were compared across exercises for
standing position to 45 degrees of AID convertert run by the B&L soft- muscle activity and VMO/VL ratio by a
knee flexion while the trunk main- ware (version 4.19).*The software two-way repeated-measures multivari-
tained contact with the wall. This was then rectified the signals and set noise ate analysis of variance (MANOVA),
done to prevent decreasing the quad- thresholds from the first 2 seconds of with gender as the grouping factor.
riceps femoris muscle demand by activity of the resting EMG record. The Exercises for openchain activities for
shlftig the center of gravity of the threshold was the lowest level of patients with PFP syndrome were
trunk anteriorly. The subjects' feet activity recorded below which 95% of compared across exercises for muscle
were parallel, shoulder width apart, the resting EMG signal was found. activity and VMOm ratio by a one-
and just far enough from the wall to Only EMG activity greater than thresh- way repeated-measures MANOVA.
allow knee flexion to 45 degrees. The old was then quantified by integration. Exercises for closed-chain activities for
hips were in neutral rotation. The two Signals were integrated each 1/50 sec- subjects with PFP were compared
wall-slide exercises were performed as ond for each 5-second exercise. The across exercises for muscle activity
(1) a straight wall slide (WSl) and (2) a EMG values for each exercise were and VMONL ratio by a two-way
wall slide while squeezing a pillow normalized by the software by division repeated-measures MANOVA, with
bolster between the knees (WSlA). by the EMG value from the maximal taping as the grouping factor. When
exercise tests. All EMG values reported MANOVA results were sigdicant, a
Exercises for Subjects With PFP are therefore expressed as a percent- subsequent univariate analysis of vari-
Syndmme age of maximal activity. ance (ANOVA) was done for each
muscle tested. A level of significance
Procedures were identical to those for Within-day reliability of the integrated, of .05 was accepted, and a Bonferroni
subjects without PFP syndrome, unless normalized EMG values for the VMO, adjustment was used for post hoc
otherwise noted. Groups of exercises the VL, and the VMOnZ ratio was t tests. The BMDP statistical
for interexercise comparison were previously established in 12 subjects was used for all analyses.
open-chain exercises and closed-chain without PFP syndrome by intraclass
AU reported significant results refer to
tModel DT2801-A, Data Translation, 100 Locke Dr, Marlborough, MA 01752-1192.
post hoc sigmlicance. For these results,
QMDP Statistical Software Inc, Los Angeles, CA 90086
30 / 676 Physical Therapy / Volume 75, Number 8 / August 1995

6. Table 3. Integrated Electromyograpbic Activity (Percentage ofMaximum) During Quadriceps Femoris Musclea Set of Exercises
for Subjects Without Patellofemoral Pain Syndrome (N=20)
VMO VL AM VMONL
X SD Minimum Maximum X SD Minimum Maximum x SD Minimum Maximum X SD Minimum Maximum
Neutral 53 26 13 97 50 23 6 80 12 22b 0 68 1.2 0.5 0.6 3.0
Hip medial rotation 53 28 10 111 46 22 7 79 16 25 0 78 1.2 0.5 0.4 2.9
Hip latetal rotation 48 27 9 91 48 24 3 87 7 10 0 31 1.1 0.6 0.2 3.5
Hip adduction 56 23 2 94 52 19 20 86 32 206 1 75 1.1 0.4 0.0 2.1
Ankle dorsiflexion 58 24 7 92 52 21 10 92 14 25 0 78 1.2 0.4 0.2 2.0
Ankle plantar flexion 52 24 7 84 50 27 5 105 5 11 0 45 1.2 0.5 0.6 2.8
"Muscle ahbreviations: vastus medialis oblique (VMO), vastus lateralis (VL),adductor magnus (AM)
b~ignificant
post hoc difference for two-way analysis of variance (F= 11.7; df= 1,8; P=.0031).
the MANOVA and ANOVA results position for the VMO, VL, or V M O M (34%+ 18% and 35%+ 15%, respec-
were also significant. ratio (Tab. 3). The EMG activity tively) than in either rotated position
ranged from 48% to 58% of maximum of the hlp. The VMO activity was
Subjects Without PFP Syndrome for the VMO and from 46% to 52% of 28%+6% for KEMR and 22%+12% for
maximum for the VL. The VMO/VL KELR, whereas VL activity was
Due to rc:cording difficulties, one male ratio ranged from 1.1 to 1.2. Although 28%2 13% for KEMR and 26%+ 12%
subject's data were lost for the quad AM activity was higher for QSA for KELR (Tab. 4). No difference, how-
set and closed-chain exercises. (32%2200/0) than for QS (12%222%), ever, was seen in the VMO/VL ratio
the increased AM activity did not affect between KE and either KEMR or
Open-chain exemises. Means and the VMO, VL, or VMO/VL ratio activity KELR. Comparison between KEMR
standard deviations of data and com- (Tab. 3). and KELR showed higher VMO activ-
parisons that yielded statistically signif- ity and VMO/VL activity ratio in KEMR
icant results are reported in Tables 3 Knee extension exercises were com- than in KELR (Tab. 4). The VMO/VL
-
through 5. No differences in myoelec- pared post hoc between KE and both ratio was 1.220.5 for KEMR and
tric activity due to gender were seen. KEMR and KELR and between KEMR 1.020.4 for KELR.
Comparison of the quad set exercise and KELR. Comparisons of KE with
with all its variants showed no differ- KEMR and KELR showed higher VMO Isometric hold exercises were com-
ences due to ankle or hip rotation and VL activity in the KE exercise pared post hoc between IS60 and both
Table 4. Integrated Electromyograpbic Activity (Percentage of Maximum) During Knee Extension Exercises From 30 to 0 Degrees
for Subjects Without Patellofemoral Pain Syndrome (N= 21)"
VMO VL AM VMONL
2 SD Minimum Maximum X SD Minimum Maximum X SD Minimum Maximum X SD Minimum Maximum
- -
HIP neutral 34 18b.c 3 81 35 15d,e 14 64 4 8 0 36 1.1 0.4 0.6 2.0
HIP medial rotation 28 16b 8 84 28 13d 7 54 3 8 0 37 1.2 0.5' 0.5 2.4
Hip lateral rotat~on 22 12' 4 64 26 12e 10 51 8 26 0 116 1.O 0.4' 0.3 2.2
-- --
"Muscle abbreviations: vastus medialis oblique (VMO), vastus lateralis (VL),adductor magnus (AM).
b~ignificanr
post hoc difference for two-way analysis of variance (ANOVA) (F= 10.2; df= 1,19; P=.0049.)
'Significanl. post hoc difference for two-way ANOVA (F=21.1; df= 1,19; F . 0 0 0 2 ) .
d~ignilicant
post hoc difference for two-way ANOVA ( F 1 7 . 3 ; df= 1,19; F ,0005).
eSignilicanf post hoc difference for two-way ANOVA (F=13.4; d p 1 , 1 9 ; P=.0017).
'Significant past hoc daerence for two-way ANOVA (F=10.0; df=1,19; F . 0 0 4 9 ) .
Physical Therapy / Volume 75, Number 8 /August 1995

7. -
Table 6. Integrated Electromyographic Activfty (Percentage of Mam'mum) During Zsometrlc Exercise for Subjects Without
Patellofemoral Pain Syndrome (N=21,P
VMO
2 SD Minimum Maximum
VL
X SD Minimum Maximum
AM
X SD Minimum Maximum
VMONL
x SD Minimum Maximum
Knee flexion posture
60" 5 3b 1 14 5 3C 1 12 1 2 0 6 1.3 1.2 0.1 5.0
45" 5 4 0 17 7 6 0 18 1 3 0 12 1.3 1.3 0.2 4.4
Tibial medial
rotation 6 4 0 15 8 5 2 17 1 2 0 10 1.2 1.4 0.2 4.8
Tibial lateral
rotation 5 4 0 17 8 6 1 20 1 2 0 10 1.0 1.0 0.1 3.6
15" 18 1 2 ~0 61 22 10C 8 42 3 4 0 15 1.0 0.5 0.3 2.5
"Muscle abbreviations:vastus medialis oblique (VMO), vastus lateralis (VL), adductor magnus (AM).
*significantpost hoc difference for two-way analysis of variance (ANOVA) (F=34.9; df--1,19; P=.0000).
'Significant post hoc di5erence for two-way ANOVA (F=84.7; dp1,19; P=.0000)
IS15 and IS45 and between IS45 and Separate analysis by gender for the cally sigmlicant results for open- and
both IS45MR and IS45LR. Less myo- VMO and V comparing WS with
L closed-chain exercises are given in
electric activity of the VMO and V L WSS, WSP, WSFT, WS'IT, and SD Tables 8 and 9, respectively. The
was seen in IS60 (5%+3% for both) tended to show greater activity for VMOM. ratio did not d&er in com-
than in IS15 (18%+12% and both the VMO and V during the SD
L parisons of QS with IS60, IS15, and KE
22%+ I@?,respectively) without a exercise than during the WS exercise and of IS60 with IS15 (Tab. 8). Higher
change in the VMO/VL ratio (Tab. 5). (Tab. 6). Both muscle values for VMO and V activity, however, oc-
L
Tibial rotation did not affect the VMO women but only VL values for men curred during the QS activity than in
or V activity or the VMO/VL ratio for
L were different between SD and WS. any other open-chain activity. The QS
the 45-degree position. When data from men and women activity was 101%+30% for the VMO
were combined, the difference in and 90?!+36% for the VL. The highest
Closed-chain exemises. Data were VMO activity between SD and W wasS activity in other open-chain exercises
lost while recording the activity during sigmlicant (P=.0000). No influence of was 49/02 17% for the VMO and
the WSFT in 1 male subject. Analysis gender or exercise was seen for either 48%+ 17% for the V during KE. In
L
was therefore performed on 19 sub- AM activity or VMO/VL ratio for the addition, IS15 demanded more vastus
jects for all six exercises in the WS-SD WS-SD exercise comparisons, although muscle activity than did IS60 (Tab. 8).
group and also for al 20 subjects for
l a trend toward increased AM activity The VMO activity increased from
the remaining five exercises. No differ- from W to SD was found.
S 6%+ 5% for IS60 to 40%+ 25% for IS15,
ences resulted between these analyses. whereas V activity increased from
L
No differences in EMG activity due to 7%+6% to 37%+21%, respectively.
Means and standard deviations of data gender were seen in WSl exercises.
and comparisons that yielded statisti- Likewise, no difference in VMO/VL Patellar taping did not affect closed-
cally significant results are reported in ratio was seen between WSl and chain muscle activity, even though the
Tables 6 and 7. Gender/exercise inter- WSh, but greater activity was seen in decrease in pain after patellar taping
actions were seen for the VMO and the AM, VMO, and V during WSlA
L for the SD exercise averaged 94%.
VL for the WS-SD exercise group. than in WS1 (Tab. 7). The AM activity Analyses comparing W with WSl, SD,
S
Athough muscle activity was similar increased from 2%+ 3% to 30%+ 53% and ISQA and WSl with WSlA were
between men and women for all WS when adduction was added to the WS1 not sigdicant for the VMOM ratio
exercises, ranging from 11% to 15% exercise. The VMO increased from (Tab. 9). Both the VMO and VL were
for women and from 11% to 16% for 9 ? + 6 %to 17%+7%, whereas the V L less active in the W (31%+ 23 for
S
men, women required approximately increased from 9?+5% to 17%+8% VMO and 38%+36% for VL.) than in
twice the activity as men for SD (Tab. with the addition of adduction to WSl. the SD (65%?22% for VMO and
6). Average VMO activity was 77%+36% for VL) or ISQA (63%+31%
24%211% for men and 45%+60/0 for Subjects With PFP Syndrome for VMO and 69/0+36% for VL). The
women, whereas VL activity averaged VMO increased its activity when ad-
19??7% for men and 41%+3% for Means and standard deviations of data duction was added to the wall slide
women. and comparisons that yielded statisti- from 13%+7% to 30%+ 18%. The
32 / 678 Physical Therapy /Volume 75, Number 8 /August 1995

8. Table 6. Integrated Electromyographic Activity (Percentage ofMaximum) During Walk-Stanceand Step-Down Exercbes for
Subjects Without Patellofemoral Pain Syndrome (N= 2 0 7
VMO VL AM VMOM
-
X SD Minimum Maximum X
SD Minimum Maximum X
SD Minimum Maximum SD Minimum Maximum X
Walk-stance neutral 11 24b 0 105 1.3 0.2 0.4 4.9
Women 12 8' 2 27 11 5d 2 20
Men 13 6e 5 22 13 9' 3 30
Walk-stance supinated 9 10 0 55 1.1 0.4 0.5 2.6
Women 15 9 6 29 14 6 7 23
Men 14 6 5 28 15 7 5 32
Walk-stance pronated 5 7 0 26 1.0 0.4 0.4 2.1
Women 14 9 3 37 15 8 4 32
Men 15 6 8 26 16 6 5 23
Walk-stance TFLg tape 7 13 0 56 1.1 0.5 0.5 2.3
Women 14 7 8 26 13 4 7 20
Men 13 6 3 23 13 8 4 28
Walk-stance patellar
tape (n= 19) 9 15 0 59 1.3 0.9 0.5 4.1
Women(n=lO) 12 6 2 21 11 6 3 22
Men (n=9) 13 6 4 25 11 8 5 31
Step down 21 2d) 0 71 1.2 0.6 0.5 3.4
Women 45 6' 35 54 41 13d 23 69
Men 2411 7 40e 19 7' 10 32
aMuscle abbreviations: vastus medialis oblique (VMO), vastus lateralis (VL), adductor rnagnus (AM).
rend for past hoc difference for two-way analysis of variance (ANOVA) not significant ( P 3 . 9 ; df-1,18; P=.0630).
"Significantpost hoc difference for one-way ANOVA (F=154.4; df-1,9; P=.0000).
d~ignificantpost hoc dierence for one-way ANOVA (F=61.6; df-1,9; P=.0000).
'Trend for post hoc difference for one-way ANOVA not significant (F=10.3;df-1,9; P=.0106), Note: P=.0000 when men and women combined
(F=102.9; df-1,181.
/Significant post hoc differencefor one-way ANOVA ( F11.8; d f - 1,9; F ,0074).
Tensor fascia lata muscle.
Table 7. Integrated Electtomyographic Activity (Percentage of Mm'mum) During Wall-Slide Exercbes With and Without H p
i
Adduction for Subjects Without Patellofemoral Pain Syndrome (N=207
VMO VL AM VMONL
-
X SD Minimum Maximum % SD Minimum Maximum X SD Minimum Maximum x SD Minimum Maximum
Without adduction 9 6b 1 18 9 5' 1 18 2 3d 0 12 1.3 1.2 0.3 5.3
With adduction 17 7b 6 32 17 8' 5 31 30 53d 1 240 1.2 0.7 0.4 3.1
aMuscle abbreviations: vastus medialis oblique WMO),vastus lateralis (VL), adductor magnus (AM)
b~ignificant
difference for two-way analysis of variance (ANOVA) (F=28.3; df-1,18; P=.0000).
'Significant difference for two-way ANOVA (F=35.5; df-1,18; P=.0000).
d~ignificant
difference for two-way ANOVA (F=6.0; df-1,18; e . 0 2 5 3 )
Physical Therapy / Volume 75, Number 8 /August 1995

9. increase in the VL activity from Discussion effectively compare the EMG signal
-
16%? 10%for WSI to 36%?32% with between muscles, each of which may
WSlA did not reach the rigor of post Technique be a different distance from the re-
ha: significance. cording electrode, and between sub-
The amount of EMG signal recorded is jects, each of whom may have
dependent on the location and size of different-sized muscles and different
the recording electrodes. In order to distances from active muscle to elec-
Table 8. Integrated Electromyographic Activity (Percentage of Maximum1 During Open-Chain Exercises for Subjects With
Patellofemoral Pain Syndrome (N= 10)"
VMO VL VMONL
- -
X SD Minimum Maximum X SD Minimum Maximum X SD Minimum Maximum
Quadriceps femoris
muscle set 101 3Pd 54 149 90 36e-g 42 149 1.2 0.5 0.8 2.3
Isometric at 60' 6 5b*h 1 14 7 6e,i 2 22 1.0 1.0 0.0 3.3
Isometric at 15" 40 25C,h 12 81 37 21f,j 6 73 1.2 0.6 0.3 2.4
Extension 30"-0" 49 17d 31 79 48 17g 27 67 1.1 0.4 0.5 2.2
"Muscle abbreviations: vastus medialis oblique (VMO), vastus lateralis (VL). Note: extension was not compared with isometric exercises.
post hoc difference for analysis of variance (ANOVA) (F= 103.4; df= 1 9 ; P= ,0000).
b~ignificant
'Significant post hoc difference for ANOVA (F=60.1; df= 1,9; F . 0 0 0 0 ) .
post hoc difference for ANOVA (F=41.4; df= 1,9; P= ,0001).
d~ignificant
-
'Significant post hoc difference for ANOVA (F= 52.2; df= 1,9; P= .0000).
/significant post hoc difference for ANOVA (F=29.0; d p 1,9; P=.0004).
RSignificantpost hoc difference for ANOVA (F=21.1; d p 1 , 9 ; P= ,0013).
'significant post hoc difference for ANOVA (F=25.6;df= 1,9; e . 0 0 0 7 ) .
'Significant post hoc ditference for ANOVA (F=24.4; df-1,9; F . 0 0 0 8 ) .
Table 9. Integrated Electromyographic Activity (Percentage of Mmammum)
During Closed-Chain Exercises for Subjects With
Patellofernoral Pain Syndrome (N= 101"
VMO VL VMONL
-
X SD Minimum Maximum X SD Minimum Maximum x SD Minimum Maximum
Walk stance 31 23beC 6 89 38 36d,e 8 137 1.O 0.6 0.3 2.6
Wall slide 13 7' 2 28 16 109 5 45 0.9 0.5 0.3 2.0
Wall slide with adduction 30 18' 8 74 36 32g 11 131 1.0 0.5 0.3 2.0
Step down 65 22b 31 98 77 36d 40 171 0.9 0.3 0.5 1.4
Isometric sitting at 90'
with adduction 63 31" 13 148 69 36e 27 173 1.0 0.4 0.4 1.9
"Muscle abbreviations:vastus medialis oblique (VMO), vastus lateralis 0 2 .
. ) Data averaged for patellar taped and untaped exercises
post hoc difference for two-way analysis of variance (ANOVA) (F=50.9; df= 1,9; P=.0001).
b~ignificant
'Significant post hoc ditference for two-way ANOVA (F=18.5; df=1,9;P=.0020).
post hoc diference for two-way ANOVA (F=218.3; d p 1 , 9 ; P=0000).
d~ignificant
'Significant post hoc difference for two-way ANOVA (F=56.3; df=1,9;P=0000).
&&cant post hoc d8erence for two-way ANOVA (F=11.1; df= 1,9; P= ,0088).
8Trend for past hoc difference for two-way ANOVA (F=6.3; df=1,9; e . 0 3 3 6 ) .
Physical Therapy / Volume 75, Number 8 / August 1995

10. trodes, a method of expressing the known, as both muscles may be in- cally compare their data and their
EMG activity of a spechc muscle as a creasing their activity the same results could be in error due to vol-
ratio of activity to some reference amounts. Normalized EMG data are ume conduction of adductor muscle
value eliminates the influence of loca- ratio data. A true absence of activity activity to their widely spaced (22.54
tion and size of recording electrodes. can exist, and ratios are used in nor- c [rli surface electrodes over
m a
Use of the maximum isometric EMG malization of the data. the VM. Hanten and Sculthies' adduc-
activity as the normalizing factor al- tion exercise, although not requiring
lows expression of activity in an easily Knee flexor activity may have oc- quadriceps femoris muscle activity, still
understandable ratio and has been curred in some of the openchain elicited high levels of activity in both
shown to provide better reliability exercises and most likely occurred in the VMO and VL.18 Perhaps conscious
(ICC) than using either dynamic maxi- the closed-chain exercises. The pur- activation of the vastus muscles with
mal or submaximal EMG activity in the pose of this study was to compare adduction negates any benefit of ad-
gastrocnemius muscle.26 results across similar exercises, regard- duction exercise to preferentially aai-
less of whether other activity was vate the VMO. Wheatley and Jahnkel9
The software used for data collection present. Rather than examine vastus also reported greater V activity dur-
M
prevented collection of data for less muscle activity when no other activity ing QS with leg lateral rotation. In
than 5 seconds per trial. Because was present, this study was designed addition, the findings of my study are
movement during dynamic exercise to study exercises widely used in not consistent with the theories that
would be much slower than custom- physical therapy. the VMO is selectively activated in a
ary in clinical practice if movement flexed position of the knee, during
was prolonged for 5 seconds, only 3 VMOIVL Ratio tibial medial or lateral rotation, or
seconds of movement was used, with during subtalar joint pronation.6.9.18-23
a 2-second hold at the end position. This study did not support the claims
As a result, two fifths of each dynamic that certain commonly used exercises Results of taping the patella and the
exercise was actually isometric. Be- or patellar or tensor fascia lata muscle tensor fascia lata muscle in my study
cause no differences were found in medial-ghde taping enhance VMO are in contrast to McConnell's finding
VMO/VL ratios at different isometric activity over VL activity. The only of an increased VMO/VL activity ratio
positions, this practice of collecting 2 exercise to show a higher VMO/VL in symptomatic subjects with such
seconds of isometric data in each ratio in comparison with similar exer- taping, even though subjects with PFP
dynamic exercise probably had no cises was KEMR in comparison with in my study reported greatly reduced
effect on the overall ratio. Further- KELR. This finding is in contrast to the pain during the SD exercise after
more, exercises with movement were commonly held hypothesis that hip medial-glide taping.16 McConnell did
compared only with other exercises lateral rotation, by creating a knee not report her EMG recording proce-
with movement, except that K was E abduction torque, enhances the activ- dures. Whether her VMO data may
compared with ISs and ISQA was ity of the VM'9 but is consistent with have been contaminated by volume
compared with exercises with move- the reported lack of preferential activa- conduction of activity of nearby mus-
ment in subjects with PFP syndrome. tion of the VMO during knee exten- cles to the VMO electrode, therefore,
sion with a knee abduction torque.27~2~ cannot be judged.
I had no method of quantifying my Whether the small magnitude of in-
ability to control the speed of move- crease in VMO/VL ratio (0.2) found Some caution must be taken in inter-
ment. Undoubtedly, some error ex- with medial over lateral rotation of the preting the findings of no effects of
isted in subjects' ability to move at a femur is clinically significant is not specific exercise or taping on the
constant speed with the metronome. known. Its significance most likely VMO/VL activity ratio because of the
Likewise, I had no better method of depends on the magnitude of the low number of subjects in this study.
controlling isometric knee flexion lateral tracking of the patella. Ratio differences of 0.7 for ISs, 0.3 for
positions than use of a standard goni- QSs, and 0.6 for KEs, WS-SD, and
ometer. The error introduced by these Likewise, preferential activation of the WSls in subjects without PFP syn-
shortcomings is unknown. These VMO over the VL is not consistent drome and of 0.7 for openchain exer-
techniques, however, approximate with this and other EMG studies of hip cises, 0.5 for closed-chain exercises,
clinical practice more than would a adduction27or tibial rotationl8.29 with and 0.4 for taping in subjects with PFP
more elaborate method used to con- knee extension. Two investigations of syndrome were necessary to satisfy a
trol speed or position. openchain adduction exercises that statistical power of .80.3O True differ-
did not require a simultaneous quadri- ences less than these ratios, therefore,
The VMONL ratio was used in this ceps femoris muscle contraction, how- could have been present without
study because it reflects the relative ever, did show preferential activation rejection of the null hypothesis. The
contributions of the VMO and VL. I of the V or VM0.18J9 Wheatley and
M magnitude of change in the VMO/VL
believe an increase of VMO activity Jahnke19 reported that V action po-
M ratio necessary for therapeutic effect is
with a specific exercise is meaningless tentials occurred during hip adduction, unknown. Certainly, the greater the
if the relative activity of the VL is un- but they did not quantlfy or statisti-
Physical 'Therapy / Volume 75, Number 8 / August 1995

11. increase in magnitude, the greater will flexed or moving for at least 3 seconds Conclusions
be the medial pull on the patella. of all other open-chain activities. As a
result, subjects had the opportunity to Whether in the subjects with PFP or in
Lack of preferential activation of the produce high levels of EMG activity in those without PFP, only one exercise
VMO over the V due to exercise
L the QS exercises while maintaining resulted in a higher VMONL activity
purported to produce such activation their test position. I suggest that they ratio over similar exercises. The KEMR
or due to patellar taping leads to the produced this high level of activity showed a higher VMONL ratio than
question of whether the VMO can be because they were well motivated. the KELR. Exercises more commonly
trained to selectively increase its activ- Attempts at increasing EMG activity prescribed to enhance VMO activity
ity. Studies of EMG biofeedback train- during the other openchain exercises over that of the VL, however, failed to
ing for the VMO are needed to answer would have either increased the speed selectively activate the VMO. Further-
this question. of movement (controlled with a met- more, the results of this study indicate
ronome) or moved the leg from the that medial-glide taping of the patella
Because no dfierence in the VMONL isometric test position. Either of these or tensor fascia lata muscle does not
ratio was found with patellar taping activities would have resulted in dis- alter the VMONL ratio.
although pain was decreased an aver- carding the data and repeating the
age of 94%, I question that taping exercise until the desired velocity or Acknowledgments
decreases pain due to appropriate posture was attained. As a result, the
realignment of the patella. The ability EMG activity was lower for these I thank the following California State
to reliably determine patellar align- exercises. Because 0thers27,3~ have University, Long Beach, physical ther-
ment is p0or.3~ Therefore, the ability found higher vastus muscle activity in apy students for their assistance in this
to appropriately realign the patella is QS than in straight leg raising, the QS project: Janet Froggatt, Anthony
questionable. Furthermore, I found no has consistently been shown to be an Granger, Cynthia Grauf, Kathy Harbert
evidence in the literature that patellar excellent exercise for recruiting vastus Greenwood, Michael Greenwood,
taping can maintain the position of the muscle activity. Gregory R Jue, Mark Klem, Sonja
patella during exercise. The effect on Maul, Nancy Rhoan, Susan Royce,
PFP of placebo taping of the patella or The increased activity in both the Stacy Sarnano, Ernie Sanchez, Milan
of taping the patella with randomly VMO and VL during IS15 over IS60 Steijn, David Swink, Carol Whitmire,
chosen direction has not been studied. in both the subjects with and with- and Laura Olsen. I thank Michael
The positive effect of taping may be out PFP syndrome is expected due Monahan for his question in class that
due to additional sensory input or the to the increased quadriceps femoris inspired this research, and I thank
placebo effect. The effect of patellar muscle demand at 15 degrees with- Charles Felder, PT, OCS, instructor for
taping, therefore, should be studied in out preferential demand for VMO McCOM~~~ seminars, who consulted
a large group of subjects with PFP. a ~ t i v i t y . ~ ~ ~ " ~ ~ This3 increased
~.3 -35 with me on this project and who
Two groups of subjects without mechanical demand at 15 degrees taught me the McComell taping
knowledge of taping theory randomly is due to the combined effects of technique.
assigned to receive medial or lateral increased gravitational lever arm
patellar taping can be studied using a and decreased muscle length and
blind research design. lever arm of the quadriceps femoris References
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i &
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~- - - -
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