Benjamin S. Boyd, • Linda Wanek, andreW T. Gray, MD, · PDF file · 2017-02-22journal of orthopaedic & A P

780 | november 2009 | volume 39 | number 11 | journal of orthopaedic & sports physical therapy

[ research report ]

1 Assistant Professor, Samuel Merritt University, Department of Physical Therapy, Oakland, CA; Visiting Assistant Professor, University of California, San Francisco, San Francisco, CA; Visiting Assistant Professor, San Francisco State University, Graduate Program in Physical Therapy, San Francisco, CA. 2 Professor and Director of Physical Therapy, San Francisco State University, Department of Physical Therapy, San Francisco, CA. 3 Associate Professor in residence at the University of California, San Francisco, Department of Anesthesia, San Francisco General Hospital, CA. 4 Professor and Director of Physical Therapy, University of California, San Francisco, Graduate Program in Physical Therapy, San Francisco, CA; Professor, Department of Anatomy, San Francisco, CA. This project was supported by NIH/NCRR UCSF-CTSI Grant Number UL1 RR024131. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH. Additional funding for this study was provided by a Graduate Student Research Award from the University of California, San Francisco awarded to Benjamin Boyd and a Mary McMillan Doctoral Scholarship from the Foundation of Physical Therapy awarded to Benjamin Boyd. The protocol of this study was approved by The Institutional Review Boards at University of California, San Francisco, San Francisco State University, and the Clinical Research Center Advisory Committee at University of California, San Francisco. Address correspondence to Dr Benjamin S. Boyd, Assistant Professor, Department of Physical Therapy, Samuel Merritt University, 450 30th Street, Oakland, CA 94609. E-mail: [email protected]

Benjamin S. Boyd, PT, DPTSc1 • Linda Wanek, PT, PhD2 andreW T. Gray, MD, PhD3 • kimberLy S. Topp, PT, PhD4

Mechanosensitivity of the Lower Extremity Nervous System During Straight-Leg Raise Neurodynamic

Testing in Healthy Individualsrespond to the mechanical stresses im-posed upon them during movement.27 Neurodynamic tests are used to assess the nervous system’s mechanosensitiv-ity through monitoring the response to movements that are known to alter the mechanical stresses acting on the ner-vous system. The most common lower quarter neurodynamic test is the passive straight-leg raise (SLR) test.13,31 The basic SLR test consists of the tester performing passive hip flexion, with the patient in a supine position and the knee held in full extension.9

A recent systematic review of SLR testing indicated a lack of standardiza-tion, including the use of various criteria for determining the test end point.31 The authors of this review reintroduced stan-dardized methodology proposed by Breig and Troup8 in 1979, including the use of the first onset of pain as the end point during the SLR test.31 Despite these rec-ommendations, alternative end points, such as maximally tolerated symptom, are still utilized.17 Because SLR testing is performed in both symptomatic and

Clinical neurological examinations are an integral part of clinical decision making for determining neural involvement in individuals with altered physical function and activity participation. One aspect of a standard neurological

examination involves assessing the sensitivity of peripheral nerves to limb movement, termed mechanosensitivity. Mechanosensitivity is thought to be a normal protective mechanism that allows the nerves to

t STudy deSiGn: Cross-sectional, observational study.

t objecTiveS: To explore how ankle position affects lower extremity neurodynamic testing.

t backGround: Upper extremity limb move-ments that increase neural loading create a protec-tive muscle action of the upper trapezius, resulting in shoulder girdle elevation during neurodynamic testing. A similar mechanism has been suggested in the lower extremities.

t meThodS: Twenty healthy subjects without low back pain participated in this study. Hip flexion angle and surface electromyographic measures were taken and compared at the onset of symp-toms (P1) and at the point of maximally tolerated symptoms (P2) during straight-leg raise tests performed with ankle dorsiflexion (DF-SLR) and plantar flexion (PF-SLR).

t reSuLTS: Hip flexion was reduced during DF-SLR by a mean SD of 5.5° 6.6° at P1 (P = .001) and 10.1° 9.7° at P2 (P.001), compared to PF-SLR. DF-SLR induced distal muscle activation and broader proximal muscle contractions at P1 compared to PF-SLR.

t concLuSion: These findings support the hypothesis that addition of ankle dorsiflexion dur-ing straight-leg raise testing induces earlier distal muscle activation and reduces hip flexion motion. The straight-leg test, performed to the onset of symptoms (P1) and with sensitizing maneuvers, allows for identification of meaningful differences in test outcomes and is an appropriate end point for lower extremity neurodynamic testing. J Orthop Sports Phys Ther 2009;39(11):780-790.doi:10.2519/jospt.2009.3002

t key WordS: neural provocation test, neural tension, sciatic nerve, sensitizing maneuvers

01 Boyd.indd 780 10/15/09 4:25:35 PM

journal of orthopaedic & sports physical therapy | volume 39 | number 11 | november 2009 | 781

predefined as the onset of symptoms (P1) and maximally tolerated symptoms (P2). Additionally, we analyzed the reliability of repeated SLR testing.

meThodS

This cross-sectional study in-cluded 20 healthy participants recruited from local medical and

academic communities. Exclusion crite-ria included low back or lower extremity pain lasting longer than 3 consecutive days in the past 6 months, peripheral neuropathy, diabetes mellitus, complex regional pain syndrome, lumbar spine surgeries, chemical dependence or alco-hol abuse, a history of lower extremity nerve trauma, or chemotherapy in the past year. Participants had to meet flex-ibility requirements of hip flexion of 90° or more with the knee flexed, full knee ex-tension, ankle dorsiflexion of 0° or more, and plantar flexion of at least 30°. The Institutional Review Boards at University of California, San Francisco, San Fran-cisco State University, and the Clinical Research Center’s Advisory Committee at University of California, San Francisco approved this study. Written, informed consent was obtained from the partici-pants prior to testing. All participants attended a single clinical assessment ses-sion. A subset of subjects (n = 5) returned within 1 to 2 weeks for an identical clini-cal assessment session for reliability test-ing. One examiner (B.B.) performed all physical examinations.

Clinical assessment SessionParticipants completed a medical history questionnaire. In addition, the subjects were instructed in the use of a visual symptom-reporting card, which included a body chart, an 11-point pain scale, and a list of qualitative descriptors adapted from the McGill Pain Questionnaire.25 The 11-point numeric pain rating scale had the anchors of 0 (“no pain”) and 10 (“worst pain possible”). This type of scale has good reliability and validity across multiple ages and races.20,38

shown at the maximum hip flexion range (determined by the tester) in contrast to relative electrical silence through the rest of the range in healthy individuals.24 This mean SD increased activation was only 3% 1% of maximal voluntary contrac-tion and was not a statistically significant increase. Prepositioning in ankle dorsi-flexion induces hamstring muscle activa-tion earlier in hip flexion range during SLR testing in healthy individuals.18 This study also did not include statistical anal-ysis. Muscle activity provoked during the sensitized SLR test is thought to provide a protective mechanism to restrict further movement and to help prevent overstretch nerve injuries.18 This is consistent with findings in the upper limb, where passive neurodynamic testing has been shown to induce muscle activity from adjacent musculature.2,11,14,36

No study to date has simultaneously explored the differences in range of mo-tion, symptoms, and muscle responses for SLR neurodynamic testing at both the onset and maximally tolerated symp-toms in healthy individuals. In addition, no study has provided statistical analy-sis of both proximal/distal and flexor/extensor muscle activity during SLR neurodynamic testing. It is important to understand the specific effects of sensi-tizing maneuvers at each of these testing end points in normal asymptomatic indi-viduals to guide clinical decision making and to help establish standardized test-ing methodology in symptomatic popu-lations. The same test end point should be utilized in the uninvolved and involved limbs in people with nerve injuries, which necessitates understanding the normal response of the nervous system on the uninvolved limb.

In this study we attempted to elucidate the specific effects of the ankle dorsiflex-ion sensitizing maneuvers on the mecha-nosensitivity of lower extremity posterior neural structures in healthy individuals. The aims were to determine the amount of hip motion and muscle activity during 2 versions of the SLR (including ankle dorsiflexion sensitization) at 2 end-points

asymptomatic limbs, it is important to know the normal healthy response of the nervous system at both end points to sup-port this recommendation.

Interpretations of neurodynamic ex-amination findings are based primarily on expert consensus.27 The proposed in-terpretations of a “positive” test include considerations for whether the test (1) reproduces the patient’s symptoms, (2) identifies asymmetry between limbs or significant deviation from norm, and (3) induces changes in symptoms by distant joint movement, also called “sensitizing movements.”27 The third consideration is critical to identify the nervous system as the source of limitations to move-ment and is termed “structural differen-tiation.”32 Sensitizing movements involve adding a limb movement distant to the location of symptoms that would affect the neural structures in the limb without affecting the nonneural tissue local to the area of symptoms.12

Ankle dorsiflexion is a common sen-sitizing maneuver for SLR testing.5,12,18 Studies in rats and dogs have demon-strated increased strain (elongation) in the sciatic nerve at the proximal thigh when ankle dorsiflexion was added to SLR testing.1,7 Further support for the use of ankle dorsiflexion as a sensitizing maneuver is provided by findings from a cadaveric study,12 in which prepositioning the ankle in dorsiflexion created distal movement in the tibial nerve at the knee and ankle. Clinically, prepositioning the ankle in dorsiflexion leads to a reduction of hip range of motion during SLR test-ing, when taken to maximal resistance to hip flexion in people with low back pain and healthy individuals.5

Neurodynamic testing can also produce increases in local muscle tone. SLR testing without ankle dorsiflexion has been shown to induce hamstring and gluteal muscle activity when the hip flexion is held at the maximally tolerated position.17 How-ever, this study was performed on a small number of subjects and statistical analysis was not performed. In another study, an increase in hamstring muscle activity was

01 Boyd.indd 781 10/15/09 4:25:36 PM


[ research report ]

SLr TestingThe subject was positioned in supine, with a 2.5-cm-thick foam head support as the standardized position for neurody-namic SLR testing (FiGure 1). Additional pillows were provided if requested. A blood pressure cuff bladder was centered under the subject’s low back and was inflated to 40 mmHg, just prior to SLR testing. Changes in cuff pressure were documented at end of movement, dur-ing SLR testing, as a gross assessment of change in lumbar spine lordosis. Com-parisons were made between the SLR tests performed with the ankle in either dorsiflexion or plantar flexion. The sub-ject’s right ankle was placed in an APU PRAFO ankle brace, with outrigger bar and extra straps (Anatomical Concepts,

Inc, Poland, OH) to maintain a fixed an-kle position in either plantar flexion (30°) or in neutral (0°) dorsiflexion. The SLR performed with the ankle in 30° of plan-tar flexion (PF-SLR) was considered the base or reference test, and the SLR per-formed with the ankle in neutral position (DF-SLR) was considered the sensitized SLR test (FiGure 1a).

electromyography (emG) SetupStandard 1-cm circular bipolar Ag/AgCl surface EMG electrodes (Noraxon USA, Inc, Scottsdale, AZ), with an interelec-trode distance of 2 cm, were placed over the gluteus maximus, semitendinosus, bi-ceps femoris, medial gastrocnemius, so-leus, rectus femoris, vastus medialis, and tibialis anterior muscles of the right lower extremity (FiGure 1b). Electrode placement was in accordance with surface EMG for noninvasive assessment of muscles (SE-NIAM) guidelines.19 A single reference electrode was placed over the right patella. Skin preparation included cleaning and vigorous rubbing with an alcohol-soaked gauze pad. Three repetitions of 5-second maximal voluntary isometric muscle con-tractions (MVC) were performed against manually provided resistance, with the subject in supine, for purposes of EMG signal normalization.33,39 During MVC testing, the limb was supported on pil-lows, if appropriate, and stabilized man-ually immediately proximal to the joint being tested. Similar to other studies, the calf musculature was tested in a neutral ankle position, the quadriceps and ham-strings were tested with the knee in ap-proximately 30° flexion, and the gluteal musculature was tested in approximately neutral hip flexion.33,39 MVC procedures included instructions to either push or pull against the examiner’s resistance and to not let the examiner move the limb. EMG signals were amplified (2000) and acquired with a bandwidth frequency of 50 to 500 Hz, and a sampling rate of 2000 Hz, using a TeleMyo 900 System, NorBNC and A/D USB converter using MRXP Master Package software, Version 1.06.21 (Noraxon USA, Inc).

Goniometer SetupTwin-axis electrogoniometers (Noraxon USA, Inc) were placed laterally across the hip and knee joints to measure sag-ittal and coronal plane motion (FiGure

1B).13,15,24,29 Coronal plane motions were used to evaluate that neutral hip abduc-tion and adduction were maintained during testing. The hip goniometer was placed with the proximal end parallel to the subject’s torso adjacent to the iliac crest and the distal end on the lateral thigh, in line with the lateral femoral condyle. The knee goniometer was placed with the proximal end aligned with the greater trochanter of the femur and the distal end aligned with the lateral mal-leolus. Care was taken to ensure that the middle of the goniometer coil was cen-tered over the axis of rotation for each joint. Goniometers were held in place with double-sided tape and custom-made neoprene straps (FiGure 1b). A wall placard provided the tester with visual input of 10° increments and was placed so that the origin was aligned with the subject’s right greater trochanter. The participants were given a custom-built handheld electronic button (trigger), which was held in the dominant hand with both hands resting on the abdomen (FiGure 1b). Goniometer and trigger data were acquired at 2000 Hz and synchro-nized with the EMG data, using the Nor-BNC and A/D USB converter (Noraxon USA, Inc).

Testing procedureOne instructional trial was performed on the left lower extremity prior to for-mal testing of the right lower extremity. For the right limb, a total of 4 SLR tests were performed, with 2 trials assigned in a random order for each ankle position. The order was randomized to minimize the effects of test order on the SLR out-comes. A metronome and wall placard were used to facilitate consistent SLR testing speed of approximately 5°/s (FiG-

ure 1b). The tester placed the subject’s knee in full extension (defined as end range resistance) without lifting the

FiGure 1. Neurodynamic testing set-up for the straight-leg raise. (A) The subject's ankle was placed in the adjustable ankle brace. (B) Electrogoniometers were placed on the hip joint (EG1) and knee joint (EG2). Surface electromyographic electrodes (SEMGs) were placed over 8 right lower-extremity muscles, including the biceps femoris, gluteus maximus, medial gastrocnemius, rectus femoris, semitendinosus, soleus, tibialis anterior, and vastus medialis. A blood pressure cuff (BP cuff) was placed under the lumbar spine. The subject was given a custom-made joystick with a thumb switch that was held with the subject's hands resting on the stomach. The wall placard provided the tester with visual input and was aligned with the axis in line with the subject's right greater trochanter.

01 Boyd.indd 782 10/15/09 4:25:37 PM


Goniometer reliability TestingThe goniometers were attached to a rigid, wood-hinged model to test the reliability and validity of measurements compared to fixed metal angles of 0°, 30°, 45°, 60°, and 90°. Further reliability testing was performed on a subset of 5 participants, by performing 10 repeated SLR tests to arbitrarily, but consistently, predeter-mined hip flexion positions. Specifically, the beam from a laser level, placed on a fixed wooden surface, was aimed hori-zontally across the room at an angle per-pendicular to the subject’s limb and at

thigh off of the mat, and the subject was instructed to indicate this start position (“start”) by pressing the trigger 3 times. While holding the knee in full extension, the subject’s hip was moved passively into hip flexion, while manually avoid-ing rotation, abduction, or adduction of the femur. The subject indicated the on-set of symptoms (P1) and the symptom limit (P2) during the SLR by pressing the handheld trigger. Specifically, the subject was instructed to indicate “the moment you feel the first onset of any symptoms” (P1) and when “your symptoms become too intense to continue and feel you can-not tolerate any further movement” (P2). The motion was stopped at P2, and this position was held for 5 seconds, before the limb was returned to a resting position on the plinth. Two-minute rests were given between each SLR trial. Subjects were asked to report symptom location, inten-sity, and quality at the start position, at P1 (delayed reporting until immediately after P2 because motion was not stopped at this position), at P2, and then after a 2-minute rest.

data processingSurface EMG signals were converted using a root-mean-squared (RMS) for-mula, with a 50-millisecond interval. Mean voltage for EMG and degrees for hip range of motion were obtained for a 100-millisecond window centered on each of the following 3 time points: start, P1, and P2. For each muscle, MVC mea-surements were averaged from the center 3-second window of each of 3 repeated MVC tests.33 SLR testing surface EMG values were converted into percent MVC for each muscle. A “triggered muscle response” was defined as an increase in EMG activity (expressed as percent MVC) of at least a 1.5-fold above the supine-lying, resting levels (taken lying supine prior to establishing the start position). For example, if there was 3.0% MVC activity of the hamstring muscle in rest-ing, the muscle was considered activated (triggered muscle response) at 4.5% MVC during SLR testing.

an arbitrary height within the subject’s symptom-free hip flexion range of mo-tion. A second tester pressed the trigger when the subject’s limb blocked the laser beam, and the hip flexion angle was then measured.

Statistical analysisAll statistical analyses were performed using SPSS software, Version 14.0 (SPSS Inc, Chicago, IL). Descriptive statistics were used to describe the mean SD for all variables except frequency descriptive statistics for symptom quality and loca-

0.3 � 0.9

3.2 � 1.9

*2.5 �

1.6*

7.0 �

1.8*

6.6

� 2

.1*

0.5 � 1.3

0.7 � 0.9*

0.1 � 0.3

0.4 � 0.9

10.1 � 9.7*

34.1 � 15

.0*39.6

� 13

.7*57.5

� 24

.6*

67.6

� 2

2.1*

5.5 � 6.6*

P2

P1

P2

P1

Start

Start

A

B

Symptom Intensity

Range of Motion

FiGure 2. Straight-leg raise neurodynamic test results are presented for (A) symptom intensity (0-to-10 scale) and (B) hip flexion range of motion in degrees. Orange-lined body diagrams represent PF-SLR test and blue-lined body diagrams represent DF-SLR test. Significance between tests is indicated by an asterisk (*) and was set at P.05. Start represents the start position, P1 represents the first onset of symptoms, and P2 represents the maximally tolerated symptoms. Data are mean SD.

01 Boyd.indd 783 10/15/09 4:25:39 PM


[ research report ]

medialis (r = 0.71, P = .001), and dur-ing DF-SLR for the semitendinosus (r = 0.49, P = .032). At P1 muscle activity was significantly correlated with symptoms during PF-SLR for the gluteus maximus (r = 0.48, P = .039). There were no other significant correlations between muscle activity and symptom intensity at either predefined point in either SLR test.

Goniometric validity and reliability TestingRepeated goniometric measures on the wooden hinged model were a mean SD of 0.3° 0.2° for the known 0°

tion, which are reported as percentages. Repeated-measures, general linear mod-els were used for within-condition differ-ences between the rest, start, P1, and P2 positions for EMG, range-of-motion, and symptom intensity data. Between-test comparisons (DF-SLR to PF-SLR) were made using paired t tests. The general linear model calculations were adjusted due to nonsphericity using a Greenhouse-Geisser correction. Pearson correlation coefficients were calculated to assess the relationship between the lumbar pres-sure cuff measure and hip flexion range of motion at P2. An intraclass correlation coefficient (ICC3,1) was used for repeated-measures reliability analysis and reported with the 95% confidence interval (CI). The minimal detectable change for hip flexion range of motion was calculated using the standard error of the measure-ment.23 Alpha was set at .05. Significance was set at P.05.

reSuLTS

The average SD age of the 20 participants was 50.4 12.0 years (range, 25-63 years) and included

14 women and 6 men. Height was 1.7 0.1 m, body mass was 71.2 24.8 kg, and body mass index (BMI) was 25.9 8.8 kg/m2.

SLr neurodynamic TestingThe average SD for angular velocity of the PF-SLR was 3.0°/s 1.0°/s and of the DF-SLR was 2.8°/s 0.9°/s (P =.045).

Symptom intensityAs expected, the mean SD symptom intensity at P1 and P2 was increased above resting levels for both versions of the SLR (P.001) (FiGure 2a). There was also an increased symptom intensi-ty from P1 to P2 for both versions of the SLR (P.001). During PF-SLR the mean SD symptom intensity went from 0.1 0.3 at the start position to 2.5 1.6 at P1 and to 6.6 2.1 at P2. In contrast, during DF-SLR, the mean intensity went from 0.4 0.9 at the start position to

3.2 1.9 at P1 and to 7.0 1.8 at P2. The mean intensity at P1 was signifi-cantly higher by 0.7 0.9 points during the DF-SLR compared to PF-SLR (P = .002). There was no difference in mean intensity between PF-SLR and DF-SLR at the start position or at P2. In general, symptom intensity was not correlated with muscle activity (percent MVC), ex-cept at the start position. Muscle activity (percent MVC) and symptom intensity were significantly correlated at the start position during the PF-SLR for the semi-tendinosus (r = 0.56, P = .013), anterior tibialis (r = 0.53, P = .021), and vastus

FiGure 3. Sample surface electromyographic (EMG) recordings are presented. (A) Representative EMG activity during DF-SLR for semitendinosis (SemT). Line represents the EMG signal normalized to the maximal voluntary isometric contraction (MVC) and is reported as percent of maximal voluntary isometric muscle contractions (percent MVC). Vertical lines demarcate the start position, the onset of symptoms (P1), and the maximally tolerated position (P2). (B) Raw EMG signals for 1 subject comparing PF-SLR and DF-SLR with biceps femoris (BicF), gluteus maximus (GluM), medial gastrocnemius (MedG), rectus femoris (RecF), semitendinosus (SemT), soleus (Sol), tibialis anterior (TibA), and vastus medialis (VasM) muscles (top 8 lines) and hip flexion range of motion (bottom line). Vertical lines demarcate the start position, the onset of symptoms (P1), and the maximally tolerated position (P2).

01 Boyd.indd 784 10/15/09 4:25:40 PM


vated (P = .025), while additional muscle activation was seen in gluteus maximus (P = .045), vastus medialis (P = .010), soleus (P = .013), medial gastrocnemius (P = .018), biceps femoris (P = .049), and tibialis anterior (P = .037).

The addition of ankle dorsiflexion created a different pattern of muscle ac-tivation (TabLe). During DF-SLR, muscle activation criteria was met for the soleus (P = .015), semitendinosus (P = .005), tibialis anterior (P = .003), and vastus medialis (P = .027) at P1. When taken to P2 during DF-SLR, these 4 muscles re-mained activated (P = .010, P = .021, P = .001, P = .014), and the medial gastrocne-mius (P = .003) and rectus femoris (P = .024) were triggered.

Between-test comparisons identified a significantly greater soleus and tibialis anterior muscle activation at P1 during DF-SLR compared to PF-SLR (P = .042 and P = .008). At P2, there was a sig-nificantly higher activation of the tibialis anterior and the vastus medialis during DF-SLR compared to PF-SLR (P = .008 and P = .028).

Symptom LocationEighty-five percent of the subjects had no symptoms at the start position in PF-SLR and 75% in DF-SLR (FiGure 4). For those subjects who reported symptoms in

less hip flexion ROM at P1 during DF-SLR compared to PF-SLR, with a 95% CI from 2.4° to 8.6° (P = .001) (FiGure 2b). At P2 there was 14.9% less hip flexion ROM in DF-SLR compared to PF-SLR, with a 95% CI from 5.6° to 14.6° (P.001). There was no difference in hip abduction/adduction between PF-SLR and DF-SLR at P1 (P = .318) or at P2 (P = .572). There was no difference in knee flexion/exten-sion between PF-SLR and DF-SLR at P1 (P = .124) or at P2 (P = .260). There was no difference in knee coronal plane posi-tioning between PF-SLR and DF-SLR at P1 (P = .648) or at P2 (P = .498). Repeated testing between multiple testing sessions (mean SD interval of 10.4 4.3 days) performed on a subset of 5 subjects had an ICC of 0.87 (95% CI: 0.68, 0.95) for hip flexion ROM measurement.

muscle activationThe coefficient of variation for repeated MVC trials was 14.23%, which supported use of averaging of the 3 trials. There was relative EMG silence of the muscles un-til muscle activation was triggered late in the hip range of motion (FiGure 3). During PF-SLR, rectus femoris became activated at P1 (P = .021) (TabLe). When the PF-SLR was taken to P2, a slightly different pattern of muscle activation was seen. The rectus femoris remained acti-

angle, 31.3° 0.5° for the known 30° angle, 47.8° 0.7° for the known 45° angle, 64.1° 0.8° for the known 60° angle, and 95.9° 1.3° for the known 90° angle. Reliability (ICC) of repeat-ed goniometric measures in the sagit-tal and coronal plane on the wooden hinged model was 1.00 (95% CI: 1.00, 1.00). Using a subset of 5 participants, the range of variability with repeated goniometric testing of hip flexion to ar-bitrary but consistent positions in the symptom-free range (up to a maximum of 40°) was from 1.0° 0.3° to 2.4° 0.7°, with an ICC of 1.00 (95% CI: 0.99, 1.00). The minimal detectable change for hip flexion range of motion was 0.4° using this methodology.

range of motionICC3,1 for hip flexion range of motion between trials were 0.87 (95% CI: 0.69, 0.95) for PF-SLR at P1, 0.96 (95% CI: 0.91, 0.99) for PF-SLR at P2, 0.78 (95% CI: 0.50, 0.91) for DF-SLR at P1, and 0.88 (95% CI: 0.73, 0.95) for DF-SLR at P2. The hip range of motion to P1 and to P2 during the SLR test was greater than the start position for both DF-SLR and PF-SLR (P.001) (FiGure 2b). In addi-tion, hip range of motion was significant-ly greater at P2 than P1 for both PF-SLR and DF-SLR (P.001). There was 13.9%

TabLe Muscle Activation Pattern*

Abbreviations: DF, dorsiflexion; MVC, maximal voluntary isometric muscle contraction; P1, onset of symptoms; P2, point of maximally tolerated symptoms; PF, plantar flexion; SLR, straight-leg raise.* Values are mean SD percent MVC.† Statistically significant increase (P.05) above resting levels for general linear model of repeated measures for within-test differences.‡ Statistically significant difference (P.05) between PF-SLR and DF-SLR tests, using paired t test comparison for start and P1 and P2.

muscle resting Start p1 p2 Start p1 p2

Soleus 6.8 2.8 9.0 6.0† 9.5 6.7†‡ 11.8 9.6† 9.6 6.7† 11.1 9.1†‡ 12.7 10.6†

Medial gastrocnemius 5.2 1.5 6.4 3.0† 7.0 3.8† 8.2 5.7† 6.2 2.9† 7.4 4.1 † 8.7 5.5†

Tibialis anterior 2.7 1.1 3.1 1.4†‡ 3.6 1.8†‡ 4.1 3.4†‡ 5.6 5.6†‡ 5.6 4.4†‡ 6.1 4.4†‡

Vastus medialis 7.2 4.1 9.1 7.3‡ 12.0 13.7 17.0 16.7†‡ 5.6 2.8†‡ 12.3 13.7† 13.8 12.3†‡

Rectus femoris 6.8 3.6 7.0 3.9 10.4 7.5† 10.9 8.2† 7.3 3.8 9.7 6.7† 10.7 6.9†

Semitendinosus 3.8 1.3 3.7 1.2 4.9 2.8 8.3 11.9 3.8 1.1 6.1 4.1† 10.0 11.4†

Biceps femoris 4.5 1.5 5.4 2.3† 6.3 3.9† 10.6 12.6† 5.3 2.6† 6.1 2.9† 9.6 11.5

Gluteus maximus 12.1 4.5 15.4 10.5 16.3 10.1† 24.6 27.4† 15.4 10.4 16.9 12.0† 22.5 23.4

pF-SLr dF-SLr

01 Boyd.indd 785 10/15/09 4:25:41 PM


[ research report ](70% at P1 and 65% at P2), followed by tight/tension (50% at P1 and 40% at P2), and third most common was ache (10% at P1 and 15% at P2). Pain and numbness were reported infrequently during SLR, and no subjects reported tingling or pins/needles. After 2 minutes of rest following the SLR test, 90% of the subjects report-ed no symptoms following PF-SLR and 70% reported no symptoms following DF-SLR. The symptoms that remained after PF-SLR were most commonly ache (15%) and dull (10%), and after DF-SLR were most commonly ache (15%) and stretch (10%).

Lumbar Spine pressure cuff measureRepeated-measures reliability (ICC) of the lumbar pressure cuff measurements taken at P2 was 0.87 (95% CI: 0.69, 0.95) for PF-SLR and 0.91 (95% CI: 0.78, 0.96) for DF-SLR. Lumbar pressure cuff mea-surements increased from 40 mmHg at start position to a mean SD of 67.6 11.5 mmHg at P2 during PF-SLR and 66.5 12.6 mmHg at P2 during DF-SLR. The pressure in the cuff at P2 was not sig-nificantly different between PF-SLR and DF-SLR (P = .298). Pearson correlations between the lumbar pressure cuff mea-surement and hip flexion range of motion at P2 were 0.77 (P.001) for the PF-SLR and 0.79 (P.001) for the DF-SLR.

diScuSSion

This study further supports the concept that ankle positions may be used as sensitizing maneuvers to the

base SLR test. The quality and location of symptoms were altered and a broader muscular response was triggered with the addition of the sensitizing maneuver of ankle dorsiflexion. The higher symptom intensity that we observed in healthy sub-jects at P1 during DF-SLR compared to PF-SLR was statistically significant but did not meet the 2-point threshold for clinical significance and is therefore not a meaningful difference.10 Hip flexion range of motion was reduced during the dorsi-flexion version of the SLR test at both the

frequent at P1 and distal symptoms in the right posterior leg and plantar foot were more frequent at P2.

Symptom QualityThe frequencies of descriptors used by the subjects to report symptom qual-ity during both versions of the SLR are presented in FiGure 4. During PF-SLR, the most common descriptor used was stretch (75% at P1 and P2) and the next most frequent was tight/tension (25% at P1 and 35% at P2), followed by ache (15% at P1 and P2). During DF-SLR, the most frequent descriptor was also stretch

the start position, the locations were the right anterior leg, posterior hip, posterior thigh, and posterior leg.

The frequencies of symptom locations reported at P1 and P2 during SLR are presented in FiGure 5. During PF-SLR, the most frequent symptom location for P1 was in the right posterior thigh, followed by the right posterior leg. When this test was taken to P2, the right posterior thigh remained the most frequent symptom lo-cation, while the frequency of symptoms in the right posterior leg increased. In contrast, during DF-SLR, distal symp-toms in the right posterior leg were more

Ache

Stretch

Tightness/tension

Burning

Pain

Numbness

Tingling

No symptoms

0 10 20 30 40 50 60 70 80 90 100

Percent (%)

Ache

Stretch

Tightness/tension

Burning

Pain

Numbness

Tingling

No symptoms

0 10 20 30 40 50 60 70 80 90 100

Percent (%)

Ache

Stretch

Tightness/tension

Burning

Pain

Numbness

Tingling

No symptoms

0 10 20 30 40 50 60 70 80 90 100

Percent (%)

Ache

Stretch

Tightness/tension

Burning

Pain

Numbness

Tingling

No symptoms

0 10 20 30 40 50 60 70 80 90 100

Percent (%)

Ache

Stretch

Tightness/tension

Burning

Pain

Numbness

Tingling

No symptoms

0 10 20 30 40 50 60 70 80 90 100

Percent (%)

Ache

Stretch

Tightness/tension

Burning

Pain

Numbness

Tingling

No symptoms

0 10 20 30 40 50 60 70 80 90 100

Percent (%)

Start

P1

P2

PF-SLR DF-SLR

10%

85%

15%

75%

25%

15%

75%

35%

15%

65%

40%

10%

70%

50%

15%

10%

75%

FiGure 4. Frequency of quality descriptors used to report symptoms during the PF-SLR and DF-SLR tests. Histograms are presented for symptoms reported in at least 10% of the subjects at the start, onset of symptoms (P1), and maximally tolerated position (P2), respectively.

01 Boyd.indd 786 10/15/09 4:25:43 PM


onset and maximally tolerated symptoms. The lower bound of the CI exceeded the minimal detectable change, indicating that this difference was a real difference in range.28 Our results are consistent with a previous study that identified a signifi-cant 9° reduction in hip range of motion by the addition of ankle dorsiflexion.5 We hypothesize that the SLR with ankle plantar flexion does not preload the sciat-ic, tibial, and plantar nerves, thus allow-ing the hip greater range of flexion before the nerve complex undergoes sufficient mechanical stress to trigger a symptom-atic or motor response. Furthermore, we hypothesize that the SLR with ankle dor-siflexion triggers an earlier restriction to

movement during SLR testing through preloading of these neural structures. This is supported by previous findings of increased mechanical stress and strain on the sciatic, tibial, and plantar nerves dur-ing ankle dorsiflexion.12

Changes in muscle tone were expect-ed to be small during SLR testing, and an appropriate threshold was necessary to determine meaningful differences. A previous study of an upper limb neu-ral provocation test had documented a statistically significant increase of ap-proximately 1.5 times the muscle activity compared to resting levels in upper trape-zius muscle.2 We used this 50% increase in muscle electrical activity over resting

muscle tone as a conservative threshold to define “muscle activation.” This crite-rion was more stringent than previously utilized thresholds of greater than 1, 2, or 3 standard deviations above the rest-ing mean electrical activity.22,33,34,36 In fact, the criterion used in our study led to a higher threshold for activation by an average of 1.5% MVC compared to the previously utilized methodology. It was expected that stretch-induced increases in muscle tone would be no greater than 25% MVC.2 This was indeed the case dur-ing the passive SLR test for all muscles measured in this study.

As expected, progression of the end point of the SLR from P1 to P2 triggered EMG activity in more muscles than had been activated at P1. In the PF-SLR, moving to P2 triggered activity in gluteus maximus, vastus medialis, biceps femo-ris, tibialis anterior, soleus, and gastroc-nemius, in addition to the rectus femoris, which was active at P1. Progression of the SLR from P1 to P2 triggered cocontrac-tions of antagonist muscle groups, as has been documented in an upper limb neu-rodynamic test.36 Additionally, although the intensity of symptoms increased from P1 to P2, we did not observe a correlation between the increase in symptom inten-sity and the increase in muscle activation. This is in agreement with the work of Balster and Jull2 in an upper limb neuro-dynamic test of healthy subjects. In con-trast, van der Heide et al36 documented a correlation between the onset of pain and muscle activity in an upper limb neuro-dynamic test in healthy subjects. In this latter study, however, the correlation was determined using only the subjects who experienced pain consistently. It is pos-sible that progression of the SLR from the first onset of symptoms to maximally tolerated symptoms results in a global at-tempt to stop the movement by stabilizing the joints with cocontractions, as hypoth-esized by van der Heide and colleagues36 in their study of the response of biceps brachii, triceps brachii, and trapezius in an upper limb neurodynamic test.

The addition of dorsiflexion to the

5%

5%

10%

5%

80%

35%

5%

15%

5%

75%

60%

5%

15%

20%

10%

85%

55%

10%

5%

15%

25%

80%

80%

PF-SLR at P1

DF-SLR at P1 DF-SLR at P2

PF-SLR at P2

91–100%81–90%

71–80%

61–70%

51–60%

41–50%

31–40%

21–30%

11–20%

1–10%

0%

FiGure 5. Body chart representations for frequencies of symptom location reported during the PF-SLR and DF-SLR at the onset of symptoms (P1) and the maximally tolerated position (P2). Frequencies are reported in 10% intervals from a white color of 0% frequency to 90% to 100% as dark red. There were more frequent distal symptoms in the DF-SLR test when compared to the PF-SLR for both the P1 and the P2 time points.

01 Boyd.indd 787 10/15/09 4:25:49 PM


[ research report ]base SLR induced muscle activation in both the soleus and the tibialis ante-rior at P1. The distal muscle activation was not seen at P1 in the PF-SLR. This muscle response was not likely due to volitional changes in muscle activation, as the subjects were instructed to remain relaxed throughout the SLR testing and were masked from viewing the EMG recordings. Distal muscle activity at the first onset of symptoms in the DF-SLR leads us to hypothesize that this is a pro-tective reflexive mechanism of the local muscle to stop further stress and strain of the nerves by limiting further motion. Such a local protective response has been demonstrated in the upper limb, where-in neurodynamic tests that elongate the brachial plexus result in increased sur-face EMG activity of the upper trapezius muscle and increased contractile force of muscles that elevate the shoulder.2,36 Our study demonstrated that the mass muscle activation pattern presents earlier in the SLR if the limb is in ankle dorsiflexion.

As expected, during the SLR, symptoms reported by healthy subjects differed from those reported previously by people with lower limb radicular pain.6 In our study, a few subjects described minimal dull, ache, sore, or tenderness in the posterior hip, thigh, or leg at the start position, in which the knee was moved into full exten-sion. It is likely that elongation of the soft tissue in the posterior limb provoked the symptoms. During the SLR testing, the most frequent symptoms reported were stretch or tension in the posterior thigh or leg. The addition of ankle dorsiflexion to the base SLR provoked more tension, tightness, and burning, and more distal location of symptoms. In these healthy subjects, pain and numbness were report-ed infrequently (10%). In contrast, SLR testing in people with lower limb radicular pain has been found to provoke reports of “pain” in 83% of the symptomatic limbs at a mean of only 58° of hip flexion.6 This study also identified the frequent report of deep symptoms that may follow a myoto-mal or sclerotomal pattern.6

Some researchers have proposed the

first onset of pelvic movement as an end point for SLR testing when used as a low-er extremity flexibility assessment,16,21,30,37 but it is unclear if this is an appropriate end point for SLR neurodynamic test-ing. One research study indicated that pelvic movement occurred simultane-ously with hip flexion during the SLR test even when the pelvis was strapped to the table.4 Another study found that pel-vic motion began after the first 10° and that lumbar lordosis began to decrease after 30° of hip flexion motion during the SLR.17 Our study suggests that, as hip range of motion increases during SLR, the pressure under the lumbar spine also increases. We found excellent reliability of this measurement during SLR testing and a strong relationship between hip range of motion and the amount of pres-sure measured under the low back at P2 (Pearson r = 0.77-0.79). Further research is necessary to determine whether the increase in pressure in the SLR is due to movement of the lumbar spine and pel-vis, or to changes in the muscle activity of the erector spinae in the region of the blood pressure cuff. Regardless of the mechanism, it appears that movement of the pelvis or lumbar spine would not be an appropriate end point for the SLR test when used as a neurodynamic test.

What end point should be used for stop-ping neurodynamic tests of asymptom-atic limbs that allows for both sufficient information gathering and protection of the person being tested? Our study has shown excellent reliability of hip flexion measurements at the onset of symptoms (P1) on the same day (ICC = 0.78-0.96) and repeated testing in subsequent weeks in subjects with healthy nervous systems (ICC = 0.87). We found that the altered ankle position of only 30° between the PF-SLR and DF-SLR created differenc-es in hip ROM, symptom intensity, and muscle activation that were measurable at P1. In our study, taking the test to the maximally tolerated position (P2) did not provide additional clinically relevant information. For example, the muscle re-sponse was widespread and not specific to

ankle position, symptom intensity was not discriminatory for ankle position, and P1 had already allowed for identifying reduc-tions in range of hip flexion motion with ankle dorsiflexion. Although testing to P2 had excellent repeatability, it carries with it risks, such as overstretch and further ir-ritation of the nervous system, particular-ly when used with people in pain or with suspected nerve injuries.

One of the limitations to our study is extrapolating this information to people who have pain. Our findings are from people with healthy nervous systems and provide guidelines for expectations in the asymptomatic limb of those patients with pain down 1 lower extremity. The pres-ence of pain or injury in the injured limb may induce a different response in the asymptomatic limb. Therefore, care should be taken in extrapolating the out-comes from this study to individuals who have pain, even when testing their as-ymptomatic limb. Future research should consider the influence of neuropathic and nonneuropathic pain on the outcome of the SLR in the asymptomatic limb.

Limitations of application of our findings to the clinical setting also in-clude the precise measurement tools and standardized protocols required to determine small range-of-motion dif-ferences between PF-SLR and DF-SLR. The equipment used in this study is not readily available to the clinician, and the procedures are too time consuming to be feasible in patient care. It is possible that clinicians can detect this 5° difference in hip flexion range of motion between PF-SLR and DF-SLR, as this is slightly greater than the intraobserver variability for standard hip goniometery of 3° and inclinometry of 2.7°.3 It is possible that hip rotation occurred during this SLR testing, which could have influenced our outcomes (we did not measure this axis of motion in this study). Nevertheless, standardized procedures and precision measurements can be used clinically to minimize the risks of confounding variables such as poorly controlled limb movement, different patient instructions,

01 Boyd.indd 788 10/15/09 4:25:50 PM


and different range-of-motion measure-ment tools. Clinically, full ankle dorsiflex-ion range of motion can be used during SLR (compared to dorsiflexion to 0° used in our study) to increase the impact of sensitizing maneuvers by, theoretically, increasing the stress to the posterior el-ements of the lower extremity nervous system. In addition, a conceptual un-derstanding of the impacts of sensitizing maneuvers on symptoms, nerve mobility, and muscle activity will assist with inter-pretation of SLR outcome measures.35

There is a limitation in making defini-tive conclusions based on the variability in the EMG data found in our study. Pos-sible cross talk between muscles could have influenced the EMG findings. Be-cause not all subjects respond with the same muscle activation pattern, extrapo-lation of our findings to clinical settings could be unwarranted at this phase. A better understanding of all of the possible response patterns and why individuals respond differently is necessary to ensure that the assessment of muscle response is not misinterpreted in a clinical setting. Further exploration of muscle responses in the lower extremity in various popu-lations of people with pain during neu-rodynamic testing is warranted. Finally, it is quite possible that structures other than nerves and their associated connec-tive tissue, such as blood vessels and fas-cia that span multiple joints in the limbs, could be contributing to the alteration in range of motion, muscle activity, and symptoms that were found in this study.

concLuSion

mechanosensitivity of the ner-vous system is a normal protec-tive mechanism that includes

symptom production, increases in muscle tone, and subsequent reductions in range of motion in the lower limb during neu-rodynamic testing. Performing the SLR to the first onset of symptoms is an as-sessment tool that is highly reliable in as-ymptomatic limbs of healthy individuals, allowing for identification of meaningful

differences in test outcomes through the use of sensitizing maneuvers, and may be of use in patients with irritable condi-tions. Normal protective muscle guarding induced by the nervous system to avoid overstretch in healthy individuals should be considered when assessing resistance felt during SLR testing and considered when prescribing muscle and soft tissue stretches. t

key poinTSFindinGS: Ankle dorsiflexion, when used as a sensitizing maneuver for SLR neurodynamic testing, increases the frequency of distal symptoms, triggers a broader muscular response, and subse-quently reduces the amount of hip flex-ion range of motion when tested to the first onset of symptoms.impLicaTionS: The use of ankle dorsiflex-ion is an appropriate sensitizing maneu-ver for SLR neurodynamic testing, and performing the test to the first onset of symptoms provides sufficient informa-tion to assist structural differentiation.cauTion: This study was limited to indi-viduals with no history of nerve injury and the use of precise instrumentation for assessing range of motion and mus-cle activity. Caution should be exercised in extrapolating these findings to clini-cal measurement tools and to popula-tions with nerve injury.

Acknowledgements: The authors would like to thank Isabel Belkind, Stephanie Boyd, Ryan Broms, Nancy Byl, Sean Darling, Romy Ha-vard, Adriane Kauffman, Alyssa Keeney-Roe, Stephanie Klitgord, Andrew Moon, Michael Ng, Steve Paul, Sandra Radtka, and Zheng Xu for their assistance with data collection and processing, and manuscript editing.

2. Balster SM, Jull GA. Upper trapezius muscle activity during the brachial plexus tension test in asymptomatic subjects. Man Ther. 1997;2:144-149. http://dx.doi.org/10.1054/math.1997.0294

3. Bierma-Zeinstra SM, Bohnen AM, Ramlal R, Ridderikhoff J, Verhaar JA, Prins A. Comparison between two devices for measuring hip joint mo-tions. Clin Rehabil. 1998;12:497-505.

4. Bohannon RW. Cinematographic analysis of the passive straight-leg-raising test for hamstring muscle length. Phys Ther. 1982;62:1269-1274.

5. Boland RA, Adams RD. Effects of ankle dorsi-flexion on range and reliability of straight leg raising. Aust J Physiother. 2000;46:191-200.

6. Bove GM, Zaheen A, Bajwa ZH. Subjective nature of lower limb radicular pain. J Manipula-tive Physiol Ther. 2005;28:12-14. http://dx.doi.org/10.1016/j.jmpt.2004.12.011

7. Boyd BS, Puttlitz C, Gan J, Topp KS. Strain and excursion in the rat sciatic nerve during a modi-fied straight leg raise are altered after traumatic nerve injury. J Orthop Res. 2005;23:764-770. http://dx.doi.org/10.1016/j.orthres.2004.11.008

8. Breig A, Troup JD. Biomechanical considerations in the straight-leg-raising test. Cadaveric and clinical studies of the effects of medial hip rota-tion. Spine. 1979;4:242-250.

9. Butler DS. The Sensitive Nervous System. Unley, Australia: NoiGroup Publications; 2000.

10. Childs JD, Piva SR, Fritz JM. Responsiveness of the numeric pain rating scale in patients with low back pain. Spine. 2005;30:1331-1334.

11. Coppieters M, Stappaerts K, Janssens K, Jull G. Reliability of detecting 'onset of pain' and 'submaximal pain' during neural provocation testing of the upper quadrant. Physiother Res Int. 2002;7:146-156.

12. Coppieters MW, Alshami AM, Babri AS, Souvlis T, Kippers V, Hodges PW. Strain and excursion of the sciatic, tibial, and plantar nerves during a modified straight leg raising test. J Orthop Res. 2006;24:1883-1889. http://dx.doi.org/10.1002/jor.20210

13. Coppieters MW, Kurz K, Mortensen TE, et al. The impact of neurodynamic testing on the percep-tion of experimentally induced muscle pain. Man Ther. 2005;10:52-60. http://dx.doi.org/10.1016/j.math.2004.07.007

14. Coppieters MW, Stappaerts KH, Wouters LL, Janssens K. Aberrant protective force genera-tion during neural provocation testing and the effect of treatment in patients with neurogenic cervicobrachial pain. J Manipulative Physiol Ther. 2003;26:99-106.

15. Dingwell JB, Cusumano JP, Sternad D, Cavanagh PR. Slower speeds in patients with diabetic neu-ropathy lead to improved local dynamic stability of continuous overground walking. J Biomech. 2000;33:1269-1277.

16. Girouard CK, Hurley BF. Does strength training inhibit gains in range of motion from flexibility training in older adults? Med Sci Sports Exerc. 1995;27:1444-1449.

17. Goeken LN, Hof AL. Instrumental straight-leg raising: a new approach to Lasegue's test. Arch

referenCeS

1. Babbage CS, Coppieters MW, McGowan CM. Strain and excursion of the sciatic nerve in the dog: biomechanical considerations in the de-velopment of a clinical test for increased neural mechanosensitivity. Vet J. 2007;174:330-336. http://dx.doi.org/10.1016/j.tvjl.2006.07.005

01 Boyd.indd 789 10/15/09 4:25:51 PM


[ research report ]Phys Med Rehabil. 1991;72:959-966.

18. Hall T, Zusman M, Elvey R. Adverse mechani-cal tension in the nervous system? Analysis of straight leg raise. Man Ther. 1998;3:140-146.

19. Hermens HJ, Freriks B, Disselhorst-Klug C, Rau G. Development of recommendations for SEMG sensors and sensor placement procedures. J Electromyogr Kinesiol. 2000;10:361-374.

20. Herr KA, Spratt K, Mobily PR, Richardson G. Pain intensity assessment in older adults: use of experimental pain to compare psychometric properties and usability of selected pain scales with younger adults. Clin J Pain. 2004;20:207-219.

21. Hsieh CY, Walker JM, Gillis K. Straight-leg-raising test. Comparison of three instruments. Phys Ther. 1983;63:1429-1433.

22. Kautz SA, Patten C, Neptune RR. Does unilateral pedaling activate a rhythmic locomotor pattern in the nonpedaling leg in post-stroke hemipare-sis? J Neurophysiol. 2006;95:3154-3163. http://dx.doi.org/10.1152/jn.00951.2005

23. Kovacs FM, Abraira V, Royuela A, et al. Minimum detectable and minimal clinically important changes for pain in patients with nonspe-cific neck pain. BMC Musculoskelet Disord. 2008;9:43. http://dx.doi.org/10.1186/1471-2474-9-43

24. McHugh MP, Kremenic IJ, Fox MB, Gleim GW. The role of mechanical and neural restraints to joint range of motion during passive stretch. Med Sci Sports Exerc. 1998;30:928-932.

25. Melzack R. The McGill pain questionnaire: from description to measurement. Anesthesiology. 2005;103:199-202.

26. Moseley GL, Nicholas MK, Hodges PW. A ran-

domized controlled trial of intensive neurophysi-ology education in chronic low back pain. Clin J Pain. 2004;20:324-330.

27. Nee RJ, Butler D. Management of peripheral neuropathic pain: integrating neurobiology, neu-rodynamics, and clinical evidence. Phys Ther Sport. 2006;7:36-49.

28. Noteboom JT, Allison SC, Cleland JA, Whitman JM. A primer on selected aspects of evidence-based practice to questions of treatment. Part 2: interpreting results, application to clinical practice, and self-evaluation. J Orthop Sports Phys Ther. 2008;38:485-501. http://dx.doi.org/10.2519/jospt.2008.2725

29. Pang MY, Yang JF. Sensory gating for the initiation of the swing phase in different direc-tions of human infant stepping. J Neurosci. 2002;22:5734-5740.

30. Raab DM, Agre JC, McAdam M, Smith EL. Light resistance and stretching exercise in elderly women: effect upon flexibility. Arch Phys Med Rehabil. 1988;69:268-272.

31. Rebain R, Baxter GD, McDonough S. A system-atic review of the passive straight leg raising test as a diagnostic aid for low back pain (1989 to 2000). Spine (Phila Pa 1976). 2002;27:E388-395.

32. Shacklock M. Improving application of neurody-namic (neural tension) testing and treatments: a message to researchers and clinicians. Man Ther. 2005;10:175-179. http://dx.doi.org/10.1016/j.math.2005.03.001

33. Shultz SJ, Carcia CR, Perrin DH. Knee joint laxity affects muscle activation patterns in the healthy knee. J Electromyogr Kinesiol. 2004;14:475-483. http://dx.doi.org/10.1016/j.jelekin.2003.11.001

34. Shultz SJ, Perrin DH, Adams JM, Arnold BL, Gansneder BM, Granata KP. Assessment of neuromuscular response characteristics at the knee following a functional perturbation. J Elec-tromyogr Kinesiol. 2000;10:159-170.

35. Topp KS, Boyd BS. Structure and biomechan-ics of peripheral nerves: nerve responses to physical stresses and implications for physical therapist practice. Phys Ther. 2006;86:92-109.

36. van der Heide B, Allison GT, Zusman M. Pain and muscular responses to a neural tissue provocation test in the upper limb. Man Ther. 2001;6:154-162. http://dx.doi.org/10.1054/math.2001.0406

37. Wang SS, Whitney SL, Burdett RG, Janosky JE. Lower extremity muscular flexibility in long distance runners. J Orthop Sports Phys Ther. 1993;17:102-107.

38. Ware LJ, Epps CD, Herr K, Packard A. Evalu-ation of the Revised Faces Pain Scale, Verbal Descriptor Scale, Numeric Rating Scale, and Iowa Pain Thermometer in older minority adults. Pain Manag Nurs. 2006;7:117-125. http://dx.doi.org/10.1016/j.pmn.2006.06.005

39. Worrell TW, Crisp E, Larosa C. Electromyo-graphic reliability and analysis of selected lower extremity muscles during lateral step-up condi-tions. J Athl Train. 1998;33:156-162.

@ more inFormaTionwww.jospt.org

PUBLISH Your Manuscript in a Journal With International Reach

JOSPT offers authors of accepted papers an international audience. The Journal is currently distributed to the members of APTA’s Orthopaedic and Sports Physical Therapy Sections and 14 orthopaedics, manual therapy, and sports groups in 13 countries who provide online access as a member benefit. As a result, the Journal is now distributed monthly to more than 30 000 individuals around the world who specialize in musculoskeletal and sports-related rehabilitation, health, and wellness. In addition, JOSPT reaches students and faculty, physical therapists and physicians at more than 1,400 institutions in 55 countries. Please review our Information for and Instructions to Authors at www.jospt.org and submit your manuscript for peer review at http://mc.manuscriptcentral.com/jospt.

01 Boyd.indd 790 10/15/09 4:25:52 PM

Documents

Benjamin S. Boyd, • Linda Wanek, andreW T. Gray, MD, · PDF file · 2017-02-22journal of orthopaedic & A P