Intrasession reliability of force platform parameters in community-dwelling older adults

Bauer C, Gröger I, Rupprecht R, Gaßmann KG. Intrasession reliability of force platform parameters in community-dwelling older adults.

Objective

To investigate the intrasession reliability of center of pressure (COP) parameters calculated from force platform measurements.

Design

A cross-sectional study.

Setting

Gait and balance laboratory.

Participants

Community-dwelling healthy older adults (N=63) above the age of 62 years (mean age, 78.74y).

Interventions

Not applicable.

Main Outcome Measures

COP was estimated from a force platform, and the following parameters were calculated: (1) the total length of the COP displacement, (2) area of sway, (3) length of the COP displacement in the sagittal plane, and (4) length of the COP displacement in the frontal plane. Intraclass correlation coefficients (ICCs) were calculated by using 3 successive trials with 4 different test conditions. The test conditions were (1) normative standing with eyes open, (2) normative standing with eyes closed, (3) narrow stance with eyes open, and (4) narrow stance with eyes closed.

Results

The ICCs for the tests with eyes closed (.710-.946) were higher than those for tests with eyes open (.841-.945). The highest value was obtained for the vector sum of the COP during anteroposterior movement in narrow stance with eyes closed (.946). The value .710 was the lowest of all parameters and was an outlier for the narrow stance with eyes closed test, which was otherwise very reliable.

Conclusions

Eight of 16 calculated ICCs showed excellent reliability (>.90). They can be recommended for further use in clinical trials. Tests with closed eyes were more reliable than tests with eyes open. We recommend using eyes closed test conditions when assessing static balance control. For these tests, all the calculated ICCs were over .90, except for measurements of sway area.     

Reliability of traditional and fractal dimension measures of quiet stance center of pressure in young, healthy people

OBJECTIVES: To assess reliability of traditional and fractal dimension measures of quiet stance center of pressure (COP). DESIGN: Cross-sectional study. SETTING: University laboratory. PARTICIPANTS: Thirty young healthy men (n=20) and women (n=10) (mean age, 23 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: COP was recorded for 3 trials across 4 conditions: eyes open and eyes closed standing on firm and foam surfaces. Traditional COP variables--peak sway velocity and range of sway, both in the anteroposterior (AP) and mediolateral (ML) directions, and total excursion area, and fractal dimension of the COP in the AP and ML directions--were calculated. Reliability statistics were calculated. RESULTS: Range of sway (AP) was the most reliable traditional variable (intraclass correlation coefficient model 2,1 [ICC(2,1)] range -.28 to .72.). Peak sway velocity (AP) had poorest reliability (ICC(2,1) range, .05-.29). Only 1 of the traditional variables had excellent reliability; total excursion area (firm, eyes closed) (ICC(2,1)=.95). All bar 1 fractal dimension measures had excellent ICCs. Relative technical error of measurement ranged from 4% to 7% for the fractal dimension measures. Coefficients of variation were also very good, ranging from 1.8% to 6.7%. CONCLUSIONS: Fractal dimension measures were more reliable than traditional measures of COP. Although traditional measures are used extensively to assess COP, their reliability is questionable. Fractal dimension measures show promise to reliably quantify COP and warrant further investigation.     

Intrasession reliability of the "center of pressure minus center of mass" variable of postural control in the healthy elderly

OBJECTIVES: To estimate the intrasession reliability of a single measure of the biomechanical variable "center of pressure minus center of mass" (COP-COM) to determine, first, how many trials must be averaged to obtain a reliable measure of postural stability, and second, the minimal metrically detectable change of the COP-COM. PARTICIPANTS: Community-living, healthy, elderly people over 60 years of age (n = 7). DESIGN: Measurements were made in double leg stance, eyes-open condition. Nine successive trials, with rests between, were carried out for each subject. DATA ANALYSIS: Intraclass correlation coefficients (ICCs). MAIN OUTCOME MEASURE: The biomechanical variable COP-COM, which represents the distance between the center of pressure and the center of mass, was measured from two force platforms and three position sensors. RESULTS: The ICCs obtained for one measure of the COP-COM were .79 in the anterior-posterior (AP) direction and .69 in mediolateral (ML) direction. With four trials, the COP-COM variable is reliable at .94 in the AP direction and .90 in the ML direction. Minimal metrically detectable changes were .10 mm (AP) and .16 mm (ML). CONCLUSION: Using four repetitions of the COP-COM variable provides a reliable measurement of postural stability.     

Test-retest reliability of hand-held dynamometric strength testing in young people with cerebral palsy

OBJECTIVE: To evaluate the test-retest reliability of measuring lower-limb strength with a hand-held dynamometer in young people with cerebral palsy (CP). DESIGN: One rater measured the isometric strength of the lower limbs in 10 participants with CP on 2 occasions separated by 6 weeks. SETTING: University movement rehabilitation laboratory in Australia. PARTICIPANTS: Ten young people (mean age +/- standard deviation, 13.5+/-3.4 y) with spastic diplegic CP. Eight of the participants walked independently and 2 walked with assistive devices. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Retest reliability of lower-limb strength, expressed in the units of measurement for the interpretation of group mean and individual scores and as intraclass correlation coefficients (ICC(2,1)). RESULTS: For groups, mean lower-limb strength increases of 7 kg (30%) could be interpreted as real change using 95% confidence intervals (CIs). For individuals, for strength gains to be interpreted as real change using 95% CIs, strength increases would need to be greater than 16.8 kg (70%) for the measurement of knee extension and to be greater than 4.3 kg (25%) for ankle plantarflexion. Measurement of hip extension strength was not reliable for group mean or individual scores. All reliability coefficients were greater than.80. CONCLUSION: A hand-held dynamometer can reliably measure changes in lower-limb strength for groups of young people with CP. It is uncertain whether this method is useful for evaluating change in individuals. Relying only on a coefficient of reliability to decide the usefulness of a measurement can be misleading.     

Interrater reliability of clinical examination measures for identification of lumbar segmental instability

OBJECTIVE: To determine the interrater reliability of common clinical examination procedures proposed to identify patients with lumbar segmental instability. DESIGN: Single group repeated-measures interrater reliability study. SETTING: Outpatient physical therapy (PT) clinic and university PT department. PARTICIPANTS: A consecutive sample of 63 subjects (38 women, 25 men; 81% with previous episodes of low back pain [LBP]) with current LBP was examined by 3 pairs of raters. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Repeat measurements of clinical signs and tests proposed to identify lumbar segmental instability. RESULTS: Kappa values for the trunk range of motion (ROM) findings varied (range,.00-.69). The prone instability test (kappa=.87) showed greater reliability than the posterior shear test (kappa=.22). The Beighton Ligamentous Laxity Scale (LLS) for generalized ligamentous laxity showed high reliability (intraclass correlation coefficient=.79). Judgments of pain provocation (kappa range,.25-.55) were generally more reliable than judgments of segmental mobility (kappa range, -.02 to.26) during passive intervertebral motion testing. CONCLUSIONS: The results agree with previous studies suggesting that segmental mobility testing is not reliable. The prone instability test, generalized LLS, and aberrant motion with trunk ROM demonstrated higher levels of reliability.     

The effects of scale display of visual feedback on postural control during quiet standing in healthy elderly subjects

Pinsault N, Vuillerme N. The effects of scale display of visual feedback on postural control during quiet standing in healthy elderly subjects.

Objective

To assess the effects of scale display of visual feedback (VFB) on postural control during quiet standing in healthy elderly subjects.

Design

Before and after intervention trials.

Setting

Medical university bioengineering laboratory.

Participants

Twelve healthy elderly subjects (mean age, 70.2±2.8y; mean body weight, 65.5±4.1kg; mean height, 163.4±6.5cm).

Intervention

Participants were asked to stand upright as immobile as possible in an eyes-open condition and 3 VFB conditions involving increasing scale displays: 2 to 1 (VFB₂), 5 to 1 (VFB₅), and 10 to 1 (VFB₁₀). These latter conditions correspond to the ratio between the real displacements of the center of pressure (COP), as measured by the force platform, and their visualization on the monitor screen.

Main Outcome Measure

COP displacements were recorded using a force platform.

Results

VFB had different effects on the COP displacements depending on the scale display; no significant difference was observed between the VFB₂ and the eyes-open conditions, whereas the VFB₅ and VFB₁₀ conditions yielded decreased COP displacements relative to the eyes-open condition.

Conclusions

The effectiveness of the VFB system in improving postural control during quiet standing in elderly subjects depends on the scale display. These findings could have implications in clinical and rehabilitative areas.     

Evaluation of postural stability in the elderly with stroke

OBJECTIVE: To compare clinical and biomechanical measures of balance in elderly stroke patients with those of healthy elderly people. DESIGN: Two-group comparison design. SETTING: Laboratory environment. PARTICIPANTS: Fifteen poststroke patients and 15 healthy age-matched older adults (N=30). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The biomechanical variable COP-COM, which represents the distance between the center of pressure (COP) and the center of mass (COM) in terms of root mean square. The mean of 4 trials of the COP-COM variable for each test condition was used for statistical analysis. Furthermore, the different systems (sensory, motor, central processor) related to postural stability were evaluated. RESULTS: Statistical significance of the COP-COM variable was larger in the stroke group than in healthy subjects, in both the anteroposterior (AP) and mediolateral (ML) directions. Furthermore, statistically, stroke subjects showed amplitudes of the COP-COM variable that were significantly larger in the eyes-closed condition. The significant negative correlation demonstrated between COP-COM amplitude and the balance scales (Berg, Tinetti) indicated that the patients with larger COP-COM amplitudes had lower clinical balance score. Furthermore, correlation coefficient scores between COP-COM variables in both AP and ML directions and motor performance using Fugl-Meyer Assessment (rho=-.53, rho=-.51, respectively) and reaction time (rho=-.53, rho=-.44, respectively) were significant. Vibration (rho=.41) and touch-pressure (rho=.42) perception thresholds correlated significantly only in the AP direction. CONCLUSIONS: Evaluating postural stability with COP-COM variable provided an accurate measure of postural stability in poststroke elderly people. Furthermore, postural stability in quiet stance, as measured by COP-COM amplitude, was related to functional measures of balance as well as physiologic factors relating to balance, such as visual conditions, lower-extremity peripheral sensibility, motor recovery, and simple reaction time.     

Between-days reliability of H-reflexes in human flexor carpi radialis

OBJECTIVES: To assess between-day reliability of the latency and peak-to-peak amplitude of a technique to elicit the H-reflex and M response of the flexor carpi radialis (FCR) and the ratio of maximum H-reflex and M-response amplitude (Hmax/Mmax). DESIGN: Test-retest reliability study. SETTING: Electrophysiology laboratory at a university. PARTICIPANTS: Fifteen consecutively recruited healthy volunteers (8 men, 7 women; age range, 22-65y). INTERVENTION: Volunteers were tested on 2 separate days at the same time of day for H-reflex and M response by stimulating the median nerve in the cubital fossa in the presence of a standardized voluntary contraction of the FCR muscle. MAIN OUTCOME MEASURES: Onset latencies, peak-to-peak amplitudes, and Hmax/Mmax. RESULTS: Latency measurements of H-reflex and M response showed excellent reliability between days, as did the maximum amplitude of the M response. The maximum amplitudes of the H-reflex and Hmax/Mmax ratio were less reliable but still within acceptable limits. CONCLUSIONS: The H-reflex and M response can be reliably elicited in the FCR. This technique provides a useful clinical tool for diagnostic purposes during the course of neurologic disorders and in preclinical and postclinical intervention studies.     

Measuring muscle strength for people with chronic obstructive pulmonary disease: retest reliability of hand-held dynamometry

OBJECTIVE: To evaluate the retest reliability and quantify the degree of measurement error when measuring isometric muscle strength with a hand-held dynamometer for people with chronic obstructive pulmonary disease (COPD). DESIGN: Retest reliability of hand-held dynamometry for 4 muscle groups was assessed on 2 occasions separated by a 2-week interval. SETTING: Community rehabilitation center. PARTICIPANTS: Eight men and 4 women (mean age +/- standard deviation, 71.4+/-10.3y) with moderately severe COPD (percentage of predicted forced expiratory volume in 1 second, 41.5%+/-17.7%). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Muscle strength (in kilograms). Statistical analysis was conducted by calculating intraclass correlation coefficients and 95% confidence intervals for both group and individual scores. RESULTS: All reliability coefficients were greater than .79. Muscle strength would need to increase by between 4% and 18% in groups of people with COPD and between 34% and 58% in a person with COPD to be 95% confident of detecting real changes. CONCLUSIONS: Hand-held dynamometry is suitable for monitoring change in muscle strength and testing hypotheses for groups of people with COPD. However, hand-held dynamometry is not likely to detect changes in muscle strength for a person with COPD.     

Mirror versus stationary cross feedback in controlling the center of foot pressure displacement in quiet standing in elderly subjects

OBJECTIVE: To investigate the effect of mirror feedback on postural control during quiet standing in elderly adults. DESIGN: Before and after intervention trials. SETTING: Pneumology center in France. PARTICIPANTS: Eleven elderly adults (mean age, 70.7+/-4.6 y; mean body weight, 64.5+/-15.0 kg; mean height, 161.4+/-12.0 cm). INTERVENTIONS: Participants were asked to stand upright, as immobile as possible, in 2 eyes-open and mirror-feedback conditions. The latter experimental condition consisted of supplying the subjects with their frontal reflection by positioning a mirror in front of them. MAIN OUTCOME MEASURES: Foot center of pressure (COP) displacements in the mediolateral (ML) and anteroposterior (AP) directions were recorded using a force platform. RESULTS: The mirror-feedback condition had different effects on postural sway, depending on the direction: range, variability, and maximal instantaneous speed of the COP displacements decreased in the ML direction, whereas these effects remained unchanged in the AP direction. CONCLUSIONS: This study provided evidence that mirror feedback may put elderly adults at lower risk of falling.     

Scapular positioning in patients with shoulder pain: a study examining the reliability and clinical importance of 3 clinical tests

Nijs J, Roussel N, Vermuelen K, Souvereyns G. Scapular positioning in patients with shoulder pain: a study examining the reliability and clinical importance of 3 clinical tests.

Objective

To examine the interobserver reliability, internal consistency, and clinical importance of 3 clinical tests for the assessment of scapular positioning in patients with shoulder pain.

Design

Prospective repeated-measures design.

Setting

Private practices for physical therapy and hospital outpatient physical therapy divisions.

Participants

Twenty-nine patients with shoulder pain who were diagnosed by a physician as having a shoulder disorder.

Interventions

Not applicable.

Main Outcome Measures

Study participants filled in a visual analog scale for pain and the Shoulder Disability Questionnaire. Next, 2 assessors performed the following tests: measurement of the distance between the posterior border of the acromion and the table, measurement of the distance from the medial scapular border to the fourth thoracic spinous processes, and the lateral scapular slide test.

Results

The interobserver reliability coefficients were greater than .88 (intraclass correlation coefficients) for the measurement of the distance between the posterior border of the acromion and the table, were greater than .50 for the measurement of the distance from the medial scapular border to the fourth thoracic spinous processes, and were greater than .70 for the lateral scapular slide test. The Cronbach α coefficient for internal consistency for all tests was .88. No associations between the outcome of the tests and self-reported pain severity or disability were found.

Conclusions

These data provide evidence favoring the interobserver reliability of 2 of 3 tests for the assessment of scapular positioning in patients with shoulder pain. The clinical importance of the tests’ outcomes, however, is questionable.     

The reliability and validity of the brief symptom inventory-18 in persons with traumatic brain injury

Meachen S-J, Hanks RA, Millis SR, Rapport LJ. The reliability and validity of the Brief Symptom Inventory−18 in persons with traumatic brain injury.

Objective

To investigate the psychometric properties of the Brief Symptom Inventory−18 (BSI-18) among persons with traumatic brain injury (TBI).

Design

Inception cohort design with cross-sectional follow-up of 6 months to 15 years.

Setting

Rehabilitation hospital.

Participants

Adults (N=257) with moderate to severe TBI (81 inpatients and 176 follow-up participants, analyzed separately).

Interventions

Not applicable.

Main Outcome Measures

The BSI-18 is a brief screen of psychologic distress with a Global Severity Index (GSI), and 3 clinical subscales: somatization, anxiety, and depression.

Results

Internal consistency of the GSI was high in both follow-up participants (α=.91) and inpatients (α=.84), whereas estimates for the somatization, anxiety, and depression subscales were more variable (α range, .61-.84). As would be expected for a measure of affective state, retest reliability estimates were only moderate. The BSI-18 GSI correlated with multiple measures of psychosocial adjustment. After accounting for demographics, injury severity, inpatient functional status, years since injury, and various psychosocial factors, the BSI-18 showed incremental validity in predicting concurrent functional, psychosocial, and psychologic status.

Conclusions

The BSI-18 GSI had excellent reliability and validity among inpatients and follow-up participants. Modest reliability estimates may place an upper bound on the validity of the BSI-18 clinical subscales in inpatient TBI populations.     

The intra- and interrater reliability of hip muscle strength assessments using a handheld versus a portable dynamometer anchoring station

OBJECTIVE: To compare the inter- and intrarater reliability of a portable dynamometer anchoring station (DAS) to a handheld dynamometer (HHD). DESIGN: Repeated-measures design. SETTING: Human performance and movement analysis laboratory. PARTICIPANTS: Fifteen healthy participants, ages 23 to 44 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Three consecutive measures of peak bilateral isometric strength were obtained for hip abduction, extension, and flexion by 2 investigators by using the DAS and the HHD after a 1-hour rest period. This testing scenario was repeated 1 week later. Intraclass correlation coefficients (ICCs) were used to determine reliability. RESULTS: Interrater ICCs of average peak strength ranged from.84 to.92 (hip flexors),.69 to.88 (hip abductors), and.56 to.80 (hip extensors). Intrarater ICCs ranged from.59 to.89 for tester A and from.72 to.89 for tester B using the DAS, and from.67 to.81 for the HHD across muscle groups. CONCLUSIONS: The DAS showed good intrarater reliability for hip flexion and abduction, whereas the HHD demonstrated higher reliability for hip extension. The results support the use of dynamometers that are quick and reliable and that reduce tester bias during hip strength assessment.     

Reliability of the dynamic gait index in people with vestibular disorders

OBJECTIVE: To examine the interrater reliability of the Dynamic Gait Index (DGI) when used with patients with vestibular disorders and with previously published instructions. DESIGN: Correlational study. SETTING: Outpatient physical therapy clinic. PARTICIPANTS: Subjects included 30 patients (age range, 27-88y) with vestibular disorders, who were referred for vestibular rehabilitation. INTERVENTIONS: Subjects' performance on the DGI was concurrently rated by 2 physical therapists experienced in vestibular rehabilitation to determine interrater reliability. MAIN OUTCOME MEASURES: Percentage agreement, kappa statistics, and the ratio of subject variability to total variability were calculated for individual DGI items. Kappa statistics for individual items were averaged to yield a composite kappa score of the DGI. Total DGI scores were evaluated for interrater reliability by using the Spearman rank-order correlation coefficient. RESULTS: Interrater reliability of individual DGI items varied from poor to excellent based on kappa values (kappa range,.35-1.00). Composite kappa values showed good overall interrater reliability (kappa=.64) of total DGI scores. The Spearman rho demonstrated excellent correlation (r=.95) between total DGI scores given concurrently by the 2 raters. CONCLUSION: DGI total scores, administered by using the published instructions, showed moderate interrater reliability with subjects with vestibular disorders. The DGI should be used with caution in this population at this time, because of the lack of strong reliability.     

Intrarater test-retest reliability of hip range of motion and hip muscle strength measurements in persons with hip osteoarthritis

Pua YH, Wrigley TW, Cowan SM, Bennell KL. Intrarater test-retest reliability of hip range of motion and hip muscle strength measurements in persons with hip osteoarthritis.

Objective

To examine the relative and absolute intrarater test-retest reliability of muscle strength and range of motion (ROM) measurements of the hip performed in people with hip osteoarthritis.

Design

Repeated measures.

Setting

Human movement laboratory of a university.

Participants

Participants (N=22; 10 men, 12 women; age range, 50-84y) with hip osteoarthritis.

Interventions

On 2 separate occasions, at least 1 week apart, isometric torque measurements were obtained from the hip rotators, flexors, abductors, and extensors. Passive ROMs in hip rotation, flexion, abduction, and extension were also determined.

Main Outcome Measures

Relative reliability was estimated using the intraclass correlation coefficient, model 2,2 (ICC_2,2). Absolute reliability was estimated using the coefficient of variation (CV) and the standard error (SE) of measurement.

Results

For measurements of muscle strength, ICC_2,2 ranged from .84 to .97, and the CV ranged from 8% to 15.7%. Hip extensors and internal and external rotators showed high ICC_2,2 (>.96) and low CV (<9.8%); hip abductors showed the lowest ICC_2,2 (.84) and the highest CV (15.7%). For ROM measurements, ICC_2,2 ranged from .86 to .97 and SE ranged from 3.1° to 4.7°. Hip flexion ROM showed the highest ICC_2,2 (.97) and an SE of 3.5°; hip extension ROM showed the lowest ICC_2,2 (.86) and the highest SE (4.7°).

Conclusions

Strength and ROM testing of the hip in people with hip osteoarthritis can be performed with good to excellent reliability.     

Intrarater reliability of the KT1000 arthrometer in determining anterior translation of the glenohumeral joint

OBJECTIVES: To establish intrarater reliability of the KT1000 arthrometer in determining glenohumeral anterior translation and to determine if a difference existed between measurements of glenohumeral anterior translation in 2 testing positions. DESIGN: Intrarater reliability study. SETTING: Academic laboratory. PARTICIPANTS: Convenience sample of 15 unimpaired volunteers (mean age +/- standard deviation, 25+/-4 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects were positioned supine with the shoulder in 20 degrees of abduction and 0 degrees of external rotation (position 1) and 90 degrees of abduction and 90 degrees of external rotation (position 2). The KT1000 was placed on the shoulder with the tibia sensor pad near the joint line and the patella sensor pad over the coracoid process. Testing involved an anteriorly directed force of 67N. Testing procedures were repeated after 1 week. RESULTS: The intraclass correlation coefficients (ICCs) for intrarater reliability for position 1 (ICC=.93; 95% confidence interval [CI], .81-.98) and for position 2 (ICC=.93; 95% CI, .80-.97) were excellent. The degree of anterior translation measured in position 1 was significantly greater than in position 2 ( t =4.79, P <.01). CONCLUSIONS: Use of the KT1000 to measure glenohumeral anterior translation in the 2 testing positions appears to be a relatively simple, reliable method. Because testing position 1 allowed significantly greater anterior translation than testing position 2, the 2 positions should not be used interchangeably.     

Differences in isometric neck muscle strength between healthy controls and women with chronic neck pain: the use of a reliable measurement

Cagnie B, Cools A, De Loose V, Cambier D, Danneels L. Differences in isometric neck muscle strength between healthy controls and women with chronic neck pain: the use of a reliable measurement.

Objectives

To determine the intra- and interrater reliability of the Biodex isokinetic dynamometer to measure the maximal isometric strength of the cervical flexors and extensors, to develop an age- and sex-based normative database in a healthy population, and to evaluate the differences in neck strength between women with chronic neck pain and healthy controls.

Design

Cross-sectional.

Setting

Physical and rehabilitation medicine department.

Participants

Ninety-six healthy volunteers (4 age groups: 20-29, 30-39, 40-49, 50-59y; each consisting of 12 men and 12 women) and 30 women with chronic neck pain.

Interventions

Not applicable.

Main Outcome Measures

Peak isometric strength of the cervical muscles was tested for flexion and extension by using the Biodex isokinetic dynamometer. The intra- and interrater reliability of the protocol was evaluated in 12 volunteers.

Results

The reliability for strength was high for both flexion and extension (intraclass correlation coefficient, .92-.96). The mean peak torque for flexion and extension was significantly higher in men (24Nm, 36.4Nm, respectively) compared with women (16.6Nm, 26.5Nm, respectively) (P<.001). Peak torque production for extension was significantly lower in the patient group (22.3Nm) compared with the healthy female control group (26.5Nm) (P=.003). No significant differences in flexion strength between patient and female control group were found.

Conclusions

Results show a high degree of intra- and interrater reliability in measuring isometric neck muscle strength when using the Biodex isokinetic dynamometer. The use of normative data for neck strength when evaluating patients with neck disorders needs to take sex into account. The current study has shown that women with chronic neck pain have lower neck muscle strength in extension than the healthy female group.