Journal of Sport Rehabilitation, 2014, 23, 56-64
http://dx.doi.org/10.1123/JSR.2012-0070
© 2014 Human Kinetics, Inc.
www.JSR-Journal.com
ORIGINAL RESEARCH REPORT
Effects of Examiner Strength on Reliability
of Hip-Strength Testing Using a Handheld Dynamometer
David A. Krause, Mathew D. Neuger, Kimberly A. Lambert, Amanda E. Johnson,
Heather A. DeVinny, and John H. Hollman
Context: Hip-muscle impairments are associated with a variety of lower-extremity dysfunctions. Accurate
assessment in the clinical setting can be challenging due to the strength of hip muscles relative to examiner
strength. Objective: To examine the influence of examiner strength and technique on manual hip-strength testing
using a handheld dynamometer. Design: Repeated measures. Setting: Research laboratory. Participants: 30
active adults (age 24 ± 1.4 y). Interventions: Three examiners of different strength performed manual muscle
tests (MMT) in 2 different positions for hip extension, abduction, and external rotation using a MicroFet handheld dynamometer. Examiner strength was quantified via a 1-repetition-maximum leg press and chest press
with a Keiser A420 pneumatic resistance machine. Main Outcome Measures: Intrarater reliability (ICC3,1),
interrater reliability (ICC2,1), and measured torque values. Results: Intrarater reliability for all measurements
ranged from .82 to .97. Interrater reliability ranged from .81 to .98. Main effects for hip extension revealed
a significant difference in torque values between examiners and between techniques. For the short-lever hipabduction and seated hip-external-rotation tests, there was a significant difference between examiners. There
was no significant difference in measured torque values between examiners with the long-lever hip-abduction
or the prone hip-external-rotation tests. Conclusions: MMT of the hip may be performed with high reliability by examiners of different strength. To obtain valid MMT measurements of hip muscles, examiners must
consider their own strength and testing techniques employed. The authors recommend a long-lever technique
for hip abduction and a prone position for testing hip external rotation to minimize the influence of examiner
strength. Both positions appear to provide mechanical advantages to the examiner compared with the alternative techniques. The authors are unable to recommend a preferred hip-extension-testing technique to minimize
the influence of examiner strength.
Keywords: hip, muscle strength, physical examination
Accurate assessment of hip-muscle strength is
indicated for a variety of lower-extremity presentations. Hip-muscle weakness is proposed to contribute
to many-lower extremity conditions including patellofemoral pain, iliotibial band pain, and anterior cruciate
ligament injuries.1–9 Ireland et al5 reported that women
with patellofemoral pain were more likely to demonstrate
hip-abduction and -external-rotation weakness than agematched women without patellofemoral pain. Tyler et al6
tested the hip abductors and adductors in professional ice
hockey players to determine if preseason performance
correlated to the incidence of adductor strains. They found
that adduction strength was 95% of abduction strength
in uninjured players but only 78% of abduction strength
in injured players. Nadler et al10found, in general, that
Division I athletes with a history of lower-extremity or
low-back pain had a difference in hip strength compared
with athletes without previous injury. In a prospective
The authors are with the Program in Physical Therapy, Mayo
Clinic, Rochester, MN.
56
study of 98 high school running athletes, Finnoff et al1
found that athletes who developed patellofemoral pain
had a lower baseline hip external-to-internal strength
ratio than noninjured athletes, suggesting that a higher
external-to-internal-rotation strength ratio may protect
athletes from the development of patellofemoral pain.
The assessment of hip-muscle performance in athletes and active individuals may be accomplished through
a variety of ways ranging from sophisticated instrumented
testing equipment to simple manual techniques performed
in a clinical or training-room setting. Handheld dynamometry is a quick and simple clinical means to quantify
strength, with application to a variety of patient and client
populations.11,12 An advantage of handheld dynamometry
over traditional manual muscle testing using a grading
system is the ability to detect and quantify strength deficits that may otherwise go undetected.13,14 A limitation
of manual muscle testing with or without a handheld
dynamometer (HHD) is the examiner’s strength relative
to the strength of a tested muscle group. To perform a
valid manual muscle test, the examiner’s force must
be sufficient to match the force produced by the tested
Effects of Examiner Strength on Hip-Muscle Testing 57
muscle group.14–18 As handheld dynamometry is used as
a screening tool for hip-muscle performance in active
populations, the influence of examiner strength when
performing muscle tests requires further investigation.
The purpose of this study was to examine the effects
of examiner strength on hip-extension, -abduction, and
-external-rotation-strength testing techniques using an
HHD in active male and female adults. We hypothesized
that torque values would be influenced by both the
examiner and the testing technique used. Specifically, we
hypothesized that weaker examiner strength would result
in less recorded force compared with stronger examiners
with short-lever hip-extension and hip-abduction tests and
seated hip external rotation and that torque values with
long-lever hip-extension and -abduction tests and the
prone hip-external-rotation test would not be influenced
by examiner strength. Second, we hypothesized that all
testing techniques would be reliable both between and
within examiners. The goal of this study was to recommend testing procedures that can be effectively conducted
in the clinical setting by examiners of different strength.
We used a repeated-measures reliability study design.
Independent variables were examiner and testing technique. The dependent variable was torque.
test procedures and positioning of the HHD and were
aware of and monitored for potential compensations
by subjects during test performance. The supervising physical therapist was not present during subject
testing. Maximal voluntary strength of the examiners’
lower extremities and upper extremities was quantified
by measuring a 1-repetition-maximal effort (1-RM) for
a leg press and chest press with Keiser A420 pneumatic
resistance machines and integrated software (Keiser
Sport, Fresno, CA). LeBrasseur et al19 investigated the
reliability of muscle-strength testing using the Keiser
A420 and found that a 1-RM chest press and leg press
demonstrated excellent test–retest reliability (ICC .95–
.99) in younger and older men. For the recumbent leg
press, examiners started in a position of approximately
90° of knee flexion and 90° of hip flexion, and then
extended to 0° of knee flexion. A standardized protocol
consisted of warm-up repetitions, followed by a sequence
of progressively increased resistances approaching the
examiner’s 1-RM. The resistance was adjusted, and
1-RM attempts were performed, separated by 30-second
rest periods, until the 1-RM was determined. For the
seated chest press, examiners were positioned so the
machine’s handles were aligned with the midline of the
sternum in the horizontal plane and the anterior aspect
of the chest in the frontal plane. The examiners’ knees
were positioned at 90° of flexion with feet on the floor.
The same process as with the leg press was used to
determine the examiners’ chest-press 1-RM.
Subjects
Procedures
Participants were recruited over a 3-month period via
flyers and word of mouth in an academic setting. Thirty
subjects (11 men and 19 women) ranging from 18 to 30
years old participated (mean age 24 ± 1.4 y, mean height
173.1 ± 9.1 cm, mean weight 70.9 ± 13.9 kg). Subjects
with a history of hip or knee injury requiring medical
treatment within the past 2 years were excluded from the
study. All subjects reported they were free of any hip or
knee condition that would affect the ability to perform the
hip-muscle tests. An a priori power analysis concluded
that testing 25 participants would provide over 80% power
to detect a 20-point difference in test–retest reliability
between examiners. Before participation, all subjects provided written informed consent. This study was approved
by the institutional review board of Mayo Clinic.
Before testing, leg length was measured by the examiner
who served the role of recorder. These measurements were
used to torque values. Measurements were taken from the
anterosuperior iliac spine (ASIS) to the apex of the medial
malleolus and from the ASIS to the medial joint line of the
knee.1 The intertester reliability for this measurement is
reported as high as r = .98.20 Marks were then placed on
the skin 5 cm to the medial malleolus for consistent placement of the HHD. Estimated torque was calculated with
the equation Torque = force × moment arm. Moment-arm
length for torque calculation was based on placement of the
HHD. For long-lever tests, the moment arm was the ASIS to
the medial malleolus minus 5 cm.1 For short-lever tests, the
distance from the ASIS to the medial joint line was used.1 For
Examiners
Table 1 Examiner Demographics
Methods
Design
Three examiners performed the strength tests. We
specifically selected examiners of varied physical
characteristics and strength (Table 1). Examiners were
second-year doctor-of-physical-therapy students who
had completed a course in manual muscle testing. Before
formal testing, a physical therapist with over 25 years
clinical experience and board certified as an orthopedic
specialist reviewed manual muscle tests and had examiners practice and demonstrate proper technique to ensure
that all examiners were consistent and comfortable with
Examiner
1
2
3
female
female
male
Height (ft, in)
5, 3
5, 8
6, 0
Weight (lb)
123
155
170
Chest press (N)
470
675
1062
Leg press (N)
1828
2274
2787
Gender
58 Krause et al
hip external rotation, the value used was the distance from
the medial joint line to the medial malleolus minus 5 cm.1
Hip-strength values were obtained with use of a
MicroFet 2 HHD (Hoggan Health Industries, Inc, West
Jordan, UT) with a custom-curved, foam transducer pad
for patient comfort. Hip muscles assessed included the hip
extensors, abductors, and external rotators. All tests with
the exception of prone hip external rotation were consistent
with those described by Hislop and Montgomery.21 A prone
hip external rotation was a modification of the seated test.
Two techniques of each muscle group were performed. Test
sequence and examiner order were randomized. The leg
tested was determined by asking subjects which leg they
would use to kick a ball. Make tests were performed for all
manual tests.9,22 A make test is one in which the examiner
maintains a static resistance while the subject exerts maximal effort into the resistance. The examiner who performed
the first sequence of tests provided testing instructions.
After the examiner explained each test procedure, subjects
were allowed a practice trial for familiarization before
each individual test. Subjects were instructed to increase
their force over a 5-second time interval. A standard cue
of “ready, set, go” was used by all examiners to start the
testing process. Verbal encouragement via the examiner
saying the word push repeatedly in a loud voice was provided during the muscle contraction. Subjects performed
2 maximal contractions for each tested motion.9,23 The
greatest value on the HHD of the 2 tests was recorded.
Examiners were blinded to results. A fourth examiner
who served the role of recorder viewed the display on the
HHD, recorded the result, and then reset the display to
zero. Tests for each individual position were performed
by 3 examiners (a total of 6 tests per test position). Each
examiner completed all tests before testing by the next
examiner. Once finished with testing, the examiner left the
room and the next examiner per randomization completed
all tests in the same order. Testing was performed in a
single session. Between tests, a period of 30 seconds for
rest was allowed. Between examiners, subjects rested for
3 to 5 minutes. To minimize effects of examiner fatigue,
no more than 3 subjects were tested per day. Tests were
repeated 1 week later to establish reliability.
The specific tests are illustrated in Figure 1. Shortlever hip extension was performed with the subject prone
Figure 1 — (A) Hip extension—short lever, (B) hip extension—long lever, (C) hip abduction—short lever, (D) hip abduction—long
lever, (E) hip external rotation—seated, and (F) hip external rotation—prone.
Effects of Examiner Strength on Hip-Muscle Testing 59
with test knee flexed to 90°. For additional stability,
the subject grasped the examination table. The hip was
extended enough to raise the knee off the table. The
HHD was positioned on the distal posterior thigh. Static
resistance was applied after attainment of the test position. For long-lever hip extension the subject was prone
with knees extended. The subject maintained an extended
knee and extended the extremity to clear the knee off the
table. Once the test position was established, resistance
was applied on the posterior leg 5 cm proximal to the
level of the medial malleolus of the test leg. All subjects
in our pool were able to extend their hip to the test position without the need for modification to accommodate
for hip-flexor tightness.
Short-lever hip abduction was performed with the
subject side-lying. The nontest limb was positioned
in 30° to 45° of hip flexion and 90° of knee flexion to
provide stability. The test limb was abducted so the leg
was approximately parallel to the table. Resistance with
the dynamometer was provided just proximal to the
lateral joint line of the tested knee. For long-lever hip
abduction the subject was in the same side-lying position. The examiner provided resistance proximal to the
lateral malleolus.
Seated external rotation was performed with the
subject positioned on the edge of the treatment table with
a rolled towel placed under the distal thigh. Resistance
with the HHD was provided 5 cm proximal to the medial
malleolus. For prone external rotation, the subject was
positioned on the treatment table with the test knee flexed
to 90°. Resistance was provided 5 cm proximal to the
medial malleolus.
Statistical Analysis
Intrarater reliability was examined using model 3 form
k intraclass correlation coefficient (ICC3,1) as described
by Shrout and Fleiss.24 Interrater reliability was examined using ICC2,1.24 We used t tests to assess differences
between tests (α = .05).
A 2-way mixed-model analysis of variance (ANOVA)
was conducted to test the null hypotheses that there would
be no difference between hip-strength-testing techniques
and no difference in torque recorded by examiners of
different strengths. An α level of .05 was used for all
statistical comparisons to minimize probability of type
I error. Simple-effects tests were used to analyze techniques by examiner interactions, and all post hoc tests
were conducted with Bonferroni corrections for multiple
comparisons.
Results
Thirty subjects completed testing. Examiner gender,
height, weight, and strength values established on the
Keiser A420 bench- and leg-press strength tests are presented in Table 1. All muscle tests were reliable. Intrarater
reliability (ICC3,1) ranged from .82 to .97 (Table 2). Interrater reliability (ICC2,1) ranged from .81 to .98 (Table 3).
Table 2 Intrarater Reliability, ICC3,1
Short lever,
seated (ER)
Long lever,
prone (ER)
examiner 1
.92
.94
examiner 2
.93
.93
examiner 3
.91
.94
examiner 1
.91
.82
examiner 2
.86
.94
examiner 3
.92
.92
examiner 1
.96
.96
examiner 2
.95
.93
examiner 3
.96
.97
Hip motion
Hip extension
Hip abduction
Hip ER
Abbreviations: ER, external rotation.
Table 3 Interrater Reliability, ICC2,1
Short lever,
seated (ER)
Long lever,
prone (ER)
Extension
.88
.90
Abduction
.81
.98
ER
.95
.97
Hip motion
Abbreviations: ER, external rotation.
The averages of all 30 torque values recorded by
each examiner for each hip-muscle test performed are
presented graphically in Figures 2 to 4.
Main effects for the examiner performing hipextension testing revealed that measured torque values
for examiner 1 were significantly less than those measured by examiner 2 (P < .001) and examiner 3 (P <
.001). Torque values measured by examiner 2 were not
significantly different than those measured by examiner
3 (P = 1.00). Torque values recorded with the short-lever
hip-extension test were significantly less than longlever-technique torque values (P < .001) (Figure 2). An
examiner-by-technique interaction was not found with
hip-extension tests.
Short-lever hip-abduction torque values were significantly greater than long-lever values (P < .001). Shortlever hip-abduction torque values for examiner 1 were not
significantly different from those measured by examiner
2 (P = .052). Values for examiner 1 were significantly
less than those of examiner 3 (P < .001). Torque values
of examiner 2 were not significantly different from values
measured by examiner 3 (P = .070). For long-lever hip
60 Krause et al
Figure 2 — Hip-extension torque values (main effects). Torque values for short-lever hip extension were significantly less than
long-lever torque values (P < .001). Torque values for examiner 1 were significantly less than those measured by examiner 2 (P <
.001) and examiner 3 (P < .001). Torque values for examiners 2 and 3 were not significantly different.
Figure 3 — Hip-abduction torque values. Short-lever torque values were significantly greater than long-lever torque values (P <
.001). For the short-lever test, torque values for examiner 1 were significantly less than those measured by examiner 3 (P = .001).
Values for examiner 1 were not significantly different than examiner 2 (P = .052). Torque values for examiners 2 and 3 were not
significantly different. Torque values for the long-lever test were not significantly different between examiners.
abduction, there was no significant difference in torque
values measured by the 3 examiners (Figure 3).
For hip external rotation, torque values with the
seated test were significantly greater than prone values
(P < .001). With the seated tests, values measured by
examiner 1 were significantly less than values measured
by examiner 2 (P < .001). Examiner 1’s measurements
were not different from those recorded by examiner 3
(P = 1.00). Values measured by examiner 2 were significantly greater than those of examiner 3 (P = .035).
There was no significant difference in torque values
among the 3 examiners for prone hip external rotation
(Figure 4).
Discussion
Our results support our initial hypothesis that torque
values would be influenced by examiner strength and
testing technique and that all testing techniques would
be reliable both between and within examiners. We
analyzed our reliability based on a reliability scale that
defined excellent reliability as .75 and greater, fair to good
reliability as .40 to .75, and poor reliability as less than
.40.13 Based on these reference values, our calculated
values for both intrarater reliability (range.82–.97) and
interrater reliability (range.81–.98) for all techniques
were excellent.
Effects of Examiner Strength on Hip-Muscle Testing 61
Figure 4 — Hip-abduction torque values. Short-lever torque values were significantly greater than long-lever torque values (P <
.001). For the short-lever test, torque values for examiner 1 were significantly less than those measured by examiner 3 (P = .001).
Values for examiner 1 were not significantly different than examiner 2 (P = .052). Torque values for examiners 2 and 3 were not
significantly different. Torque values for the long-lever test were not significantly different between examiners.
Based on examiner-by-technique interactions identified, we recommend preferred positions for performing
hip-abduction and hip-external-rotation testing. We are
unable to suggest a preferred position for hip extension
as there was no examiner-by-technique interaction. We
recommend using a long lever for hip abduction and a
prone position for testing hip external rotation to minimize the potential influence of examiner strength. Both
positions appear to provide mechanical advantages to
the examiner compared with the alternative techniques.
For hip abduction, resistance at the distal leg provides a
long-lever advantage for the examiner, possibly making
the test less demanding to perform. For hip external rotation, the prone position may provide an opportunity for
the examiner to assume a better position to perform the
test as compared with the seated test.
The leg and chest press provided a basis to compare
the relative strength of the 3 examiners and its influence
on performing hip-muscle tests. Based on the 1-RM chest
press and leg press, examiner 1 had the lowest strength
of the 3 examiners, with examiner 2 having less strength
than examiner 3. Strength differences appear to be a
factor contributing to differences in torque results of both
hip-extension tests examined, short-lever hip abduction,
and seated hip external rotation. Examiner 1 obtained
the lowest torque values of the 3 examiners for tests of
hip extension, short-lever hip abduction, and seated hip
external rotation. This suggests that these specific tests
are physically challenging to perform. Other possible
influencing factors include the examiner’s height and
weight. In addition to lesser strength, examiner 1 was the
shortest and lightest of the 3 examiners. The influence of
height was likely minimal, as the examination table was
adjustable, allowing the examiner to be positioned for
mechanical advantage. Increased weight could be used to
the advantage of the examiner for better stabilization as
compared with an examiner of lesser weight. Examiner
strength differences did not influence the long-lever hipabduction test or the prone hip-external-rotation test, as
evidenced by no significant differences in torque values
recorded between examiners with these tests.
Our finding of excellent ICCs while also noting
significant differences in torque values between examiners with some tests can be explained by the nature
of the mathematical analysis. The general equation for
calculating an ICC is a ratio of between-subjects variance minus within-subject variance divided by betweensubjects variance. If between-subjects variance is large
and within-subject variance is relatively small, then the
magnitude of the ICC will approach 1.00. In our data,
within-subject variance was represented by examiner-toexaminer differences in the hip-torque values measured
on individual subjects. In some of the tests that were
conducted, the examiner-to-examiner differences were
statistically significant (P < .05). Nevertheless, the variance between examiners on individual subjects was considerably smaller than the variance between subjects, so
the ICC values approached 1.00. Our data illustrate how
measurements may be relatively reliable but not necessarily valid. Measurements taken by stronger and weaker
testers can have a relatively high magnitude of reliability
as assessed with the ICC—as our data show—but that
does not necessarily mean that strength measurements
taken by stronger and weaker testers will be equivalent.
The torque results were consistent, but given that
there was a significant difference with some tests, the
results did not always accurately reflect the measurement
of interest, which was the force-producing capacity of the
tested muscle group. Instead, some values may represent
the maximum amount of force the examiner could resist
for a specific muscle test. Findings of examiner strength’s
influence on manual muscle testing are reported by others.
62 Krause et al
Mulroy et al17 reported that a female examiner with a
lower maximal vertical push force than a male counterpart
could not detect quad weakness as accurately as the male
examiner. Similarly, Thorborg et al18 investigated the influence of gender and upper extremity strength on manualmuscle-test values. They found that a female examiner
obtained lower strength-test values for movements in all
planes of the hip than those obtained by a male examiner.
Our findings do not consistently support these findings.
With the long-lever hip-abduction test and the supine
hip-external-rotation tests, we did not find a significant
difference between examiners. While other hip tests in this
study found a significant difference between examiners,
the torque measured by 1 of the female examiners was not
significantly less than the torque measured by the male
examiner, and thus we did not find a consistent gender
effect among our examiners. An examiner’s strength and
the specific testing technique appear to have more influence on measured torque than gender does.
We chose to use the make test for performing muscle
tests. A break test, in contrast, is one in which the examiner provides a level of force sufficient to overcome the
force produced by the subject. Stratford and Balsor25
found higher reliability for the make test (.95) than for
the break test (.87) when examining elbow flexors. They
theorized that the lower reliability with the break test was
due to additional skill required on the part of the examiner
to administer the test. The examiner must overcome the
force produced by the subject and record the force at the
specific point when movement is detected. Bohannon22
found similar reliability between the 2 tests, again testing
elbow flexors, and concluded that one test is not superior
to the other. Both studies report that the break test results
in greater force than the make test.22,25 This may be due to
the eccentric activation of the muscle with the break test.
This suggests that an examiner may need greater strength
to perform a valid break test than for the make test.
Kramer et al26 tested the reliability of hip manual
muscle testing for abduction in young and elderly women
using handheld dynamometry and belt-resisted manual
muscle testing, which would essentially be a make test.
Although both methods were found to be reliable, beltresisted testing demonstrated higher reliability. In addition,
higher torque values were obtained using belt resistance.
Therefore, examiners of lesser strength might consider
using belt fixation to ensure maximal torque production in
manual muscle testing and thus a more valid test.
The difference in the degree of hip flexion between
the 2 techniques of hip external-rotation testing likely
influences the demands on specific hip muscles. Calculating moment arms using anatomical specimens in various
hip-flexion angles, Delp et al27 reported that hip position
changes the moment arm of the various components of the
gluteus maximus, piriformis, quadratus femoris, obturator
internus, and obturator externus. While they reported a
greater moment arm for the gluteus maximus in the prone
position, we recorded greater force in the seated position.
Other factors may have contributed to differences we
found. While we monitored for substitution patterns, the
seated position may allow more opportunity for subjects
to position their trunk or pelvis to generate more force.
Other potential influencing factors include differences
in patient stabilization and the ability of the subject to
visually observe the seated test.
Torque values for long-lever hip abduction were different than we expected. We expected calculated torque
values to be as great as or greater than those with the
short lever. We attempted to keep the position of the hip
consistent and thus do not think that a difference in the
amount of hip abduction explains this difference. Possible
explanations include the long-lever test’s being an inherently more challenging test for the subject, thus requiring
greater demands to the hip musculature for stabilization.
Further investigation with electromyography is needed
to confirm this hypothesis.
Clinicians should consider their own strength and the
strength of the patient when performing manual muscle
tests of the hip. This is particularly relevant when therapists
of different strengths are cotreating a patient and manual
muscle testing is performed throughout the patient’s
episode of care. Differing dynamometry values may be
obtained from different therapists that do not correlate to
actual differences in patient strength. This compromises
the ability to show the strength gains or strength deficits of
a patient. While we found all manual-muscle-testing techniques in this study to be reliable both within and between
examiners, significant differences in torque values were
found between techniques. As torque values depend on
the specific test used, therapists should remain consistent
with tests used throughout an episode of care.
A limitation of this study could be the influence of
the patients’ perceptions of the examiners’ strength on
their efforts in the manual muscle test. Because examiners were visibly different in height, weight, and strength,
subjects may have given different efforts for different
examiners. Another limitation of this study was the
homogeneity of the subject pool. All subjects were active
and overall healthy young adults. This would represent an
athletic, active population but may not represent results in
other patient populations. Finally, our torque calculations
are estimates of actual torque, as we used the ASIS as
a reference for our leg-length measurements. While the
ASIS does not represent the actual axis of rotation at the
hip, as the limb measurement was consistent for a specific
individual across the 3 examiners, we do not believe that
our methods change our suggestions for preferred testing
positions and the relative influence of examiner strength.
This study examined the intrarater and interrater
reliability of torque production of the hip muscles among
examiners of different strengths under different testing
techniques. Future research should examine the validity of different techniques between multiple examiners
of different strengths on a single subject. In addition,
comparing manual-muscle-testing techniques against
a gold-standard strength test, such as a Biodex, could
further investigate technique validity.
Effects of Examiner Strength on Hip-Muscle Testing 63
Conclusion
Hip manual muscle testing may be performed with excellent reliability by examiners of different strength. The
validity of some tests is influenced by examiner strength.
To obtain valid manual-muscle-testing measurements
of hip-muscle groups using an HHD, examiners must
consider their own strength and the testing techniques
employed. We recommend using tests that provide a
mechanical advantage to the examiner. We recommend
using a long lever for hip abduction and a prone position
for testing hip external rotation to minimize the potential
influence of examiner strength.
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