Mohamad Parnianpour

1988 Volvo award in biomechanics. The triaxial coupling of torque generation of trunk muscles during isometric exertions and the effect of fatiguing isoinertial movements on the motor output and movement patterns.

Previous studies have shown that reduction of precise motor control accompanies local muscular fatigue. The effects of isodynamic fatiguing of flexion and extension trunk movements on the movement patterns and the motor output of the trunk were investigated. Twenty male subjects with no history of low-back pain for the past 6 months volunteered for the study. A triaxial dynamometer was used that simultaneously provided measurement of torque, angular position and velocity of each axis. Resistances were set independently for each axis by an interfaced computer. The subjects performed trunk flexion and extension movement against a sagittal plane resistance equal to 70% of their maximum isometric extension strength in the upright position. The minimum resistances in the coronal and transverse planes were set up at 7 Newton meters. The subjects were asked to perform trunk movement as quickly and as accurately as possible while exerting the maximum efforts until exhaustion. Analysis of variance, the MANOVA procedure with a repeated measure design, was performed among the selected parameters of the first, middle and last three repetition cycles. The selected parameters are the trunk motor output and movement patterns; the total angular excursion, range of motion, maximum and average torque and angular velocity of the trunk. All the selected parameters were significantly reduced in the sagittal plane. Subjects displayed significantly less motor control and greater range of motion in the coronal and transverse planes in performing the primary task of flexion and extension. The reduction in the functional capacity of the primary muscles performing the required task is compensated by secondary muscle groups and the spinal structure is loaded in a more injury prone pattern, as identified by finite element models. In addition it is suggested that the fatigued muscles would be less able to compensate any peturbation in the load or position of the trunk. The repetitive loading results in a weakening of the viscoelastlc passive elements of the spineless structure. The loss of ability to protect these weakened passive elements makes the spine susceptible to industrial and recreational injuries.

The Oswestry Disability Index, the Roland-Morris Disability Questionnaire, and the Quebec Back Pain Disability Scale: translation and validation studies of the Iranian versions.

Study Design. Cross-cultural translation and psychometric testing were performed. Objectives. To cross-culturally translate the Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RDQ), and Quebec Back Pain Disability Scale (QDS) into Persian, and then investigate the psychometric properties of the Persian versions produced. Summary of Background Data. To the authors’ knowledge, there is no validated instrument to measure functional status in Persian-speaking patients with low back pain (LBP) in Iran. To our knowledge, the widely used back-specific measures, the ODI, RDQ, and QDS, have not been translated and validated for Persian-speaking patients with LBP. Methods. The translation and cross-cultural adaptation of the original questionnaires were performed in accordance with published guidelines. A total of 100 patients with chronic LBP were asked to complete a questionnaire booklet (the Persian versions of the ODI, RDQ, QDS, Short Form Health Survey (SF-36), and visual analog scale measure of pain). There were 31 randomly select patients with chronic LBP asked to complete the second questionnaire booklet 24 hours later. Results. The Cronbach-α for the ODI, RDQ, and QDS was 0.75, 0.83, and 0.92, respectively. The ODI, RDQ, and QDS showed excellent test-retest reliability (intraclass correlation coefficient = 0.91, 0.86, and 0.86, respectively) (P < 0.01). The correlation among the ODI, RDQ, QDS and physical functioning scales of the SF-36 was −0.66, −0.62, and −0.69, respectively (P < 0.001). The correlation among the ODI, RDQ, and QDS and visual analog scale was 0.54, 0.36, and 0.46, respectively (P < 0.001). Conclusions. The Persian versions of the ODI, RDQ, and QDS are reliable and valid instruments to measure functional status in Persian-speaking patients with LBP.They are simple and fast scales, and the use of them can be recommended in a clinical setting and future outcome studies in Iran.

The classification of anatomic- and symptom-based low back disorders using motion measure models

Study Design This study observed the trunk angular motion features of healthy subjects and those experiencing chronic low back disorders as they flexed and extanded their trunks in five symmetric and asymmetric planes of motion. Trunk angular positon, velocity, and acceleration were evaluated during several cycles of motion. Objective The trunk angular motion features of the low back disorder group were normalized relative to the healthy subjects and used to 1) evaluate the repeat-ability and reilability of trunk motion as a measure of trunk musculoskeletal status, 2) quantify the extent of the disorder, 3) determine the extent to which trunk motion measures might be used as quantifiable means to help classify low back disorders. Summary of Background Data Given the magnitude of the low back disorder problem, it is problematic that there are few quantitative methods for objectively documenting the extent of a disorder Impairment ratings of low back disorders can very by as much as 70% using current systems. Diagnoses and classification schemes are rarely based upon quantitative indicators and we are unable to easily assess and diagnose low back disorders so that proper treatment can be administered and the risk of exacerbating the problem can be minimized. Methods Three-hundred-thirty-nine men and women between 20 and 70 years old who had not experienced significant back pain were recruited as the healthy subjects in this study. One hundred-seventy one patients with various chronic low back disorders also were recruited and compared with the healthy group of subjects. All subjects wore a triaxial goniometar on their trunks that documented the angular position velocity, and acceleration of the trunk as the subjects flexed and extended their trunks in each of five planes of motion. Trunk motion features first were normalized for subject gender and age. Several two-stage eight-variable models that account for trunk motion interactions were developed to classify the 510 healthy and low back-injured subjects into one of 10 anatomic and sympton-based low back disorder classification categories. Results Using conservative cross-validation measures, it was found that the stage one eigth-variable model could correctly classify more than 94% of the subjects as either healthy or having a low back disorder. One of the stage two eight-variable models was able to reasonably classify the patients with low back disorders into one of 10 low back disorder classification groups. Conclusion The motion-related parameters may relate to biomechanical or learned sensitivities to spinal loading. This study suggests that higher-order trunk motion characteristics hold great promise as a quantitative indicator of the trunks musculoskeletal status and may be used as a measure of the extent of a disorder and as a measure of rehabilitative progress. Further more, once the interactive nature of these trunk motion characteristics is considered, the model could help diagnose low back disorders. However, independent data sets are needed to validate these findigs.

Effects of Spinal Flexion and Extension Exercises on Low-back Pain and Spinal Mobility in Chronic Mechanical Low-back Pain Patients

It has been estimated that one fourth to one half of all patients treated in physical therapy clinics suffer from low-back pain. The purpose of this study was to compare the effects of spinal flexion (Group I) and extension (Group II) exercises on low-back pain severity and thoracolumbar spinal mobility in chronic mechanical low-back pain patients. Both groups had significantly less low-back pain after treatment (P < .10). There was no significant difference, however, between the spinal flexion and extension exercises in reduction of low-back pain severity. The results indicated a significant difference between the groups in increasing the sagittal mobility (P < .10). The results did not indicate any significant difference between and within groups in increasing the coronal and transverse mobility of the thoracolumbar spine. Either the spinal flexion or extension exercises could be used to reduce chronic mechanical low-back pain severity, but the flexion exercises had an advantage in increasing the sagittal mobility within a short period of time.

EMG activity of trunk muscles and torque output during isometric axial rotation exertion: a comparison between back pain patients and matched controls

Abnormal patterns of trunk muscle activity could affect the biomechanics of spinal movements and result in back pain. The present study aimed to examine electromyographic (EMG) activity of abdominal and back muscles as well as triaxial torque output during isometric axial rotation at different exertion levels in back pain patients and matched controls. Twelve back pain patients and 12 matched controls performed isometric right and left axial rotation at 100%, 70%, 50% and 30% maximum voluntary contractions in a standing position. Surface EMG activity of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus were recorded bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured. Results showed that there was a trend (P = 0.08) of higher flexion coupling torque during left axial rotation exertion in back pain patients. Higher activity for external oblique and lower activity for multifidus was shown during left axial rotation exertion in back pain group when compared to the control group. In right axial rotation, back pain patients exhibited lesser activity of rectus abdominis at higher levels of exertion when compared with matched controls. These findings demonstrated that decreased activation of one muscle may be compensated by overactivity in other muscles. The reduced levels of activity of the multifidus muscle during axial rotation exertion in back pain patients may indicate that spinal stability could be compromised. Future studies should consider these alternations in recruitment patterns in terms of spinal stability and internal loading. The findings also indicate the importance of training for coordination besides the strengthening of trunk muscles during rehabilitation process.

The quantification of low back disorder using motion measures : Methodology and validation

STUDY DESIGN Trunk angular motion features were used as a means to quantify the extent of a low back disorder in healthy people and patients with chronic low back disorders. OBJECTIVE To refine and validate a previously reported means of quantifying the extent of a low back disorder. SUMMARY AND BACKGROUND Many assessment tools of low back disorder are subjective. A quantitative assessment tool would facilitate the tracking of the recovery and help document the appropriateness of treatments. METHODS The trunk motion characteristics of 374 healthy people and 335 patients with chronic low back disorders of varying severity were documented as they flexed and extended their trunks in five different planes of motion. The trunk motion features were normalized as a function of age and gender. Four classification techniques were used to assess the ability of the quantitative motion measure to identify those with and without low back disorders. In addition, 31 patients were observed longitudinally to determine whether the motion measures agreed with observed changes in back pain symptoms. RESULTS The quantitative trunk motion measure distinguished between people with low back disorders and healthy people between 88% and 94% of the time, depending on which classification system was used. Sensitivity and specificity varied between 83% and 97%. The quantitative measure also showed promise as a means to distinguish between muscle-based and structure-based low back disorders. Prospective findings indicated that the quantification system agreed well with clinical observations of progress. CONCLUSIONS The quantification of trunk motion can serve as a measure of the extent of a low back disorder. When considered along with other clinical information, the ability to assess and treat low back disorders is enhanced.

The effect of fatigue on multijoint kinematics and load sharing during a repetitive lifting test

Study Design. A repetitive lifting test in the sagittal plane was performed with a submaximal load at a maximal lifting rate to understand the effects of fatigue on kinematic and kinetic measures of performance. Objectives. To quantify the effect of fatigue during a highly repetitive lifting task, in terms of lifting force transmitted to the load, joint motion patterns, and internal joint load sharing. Summary of Background Data. Industrial surveillance and epidemiologic data suggest that repetitive lifting is a risk factor for low back pain. Previous studies examining the effect of fatigue have either been constrained to isolated trunk movement, or have not explored the internal load distribution and potential alteration in the loading patterns. Methods. Sixteen healthy male subjects performed repetitive lifting in the sagittal plane with a load equal to 25% of their maximal lifting capacity, at a maximal lifting rate. Changes in lifting performance were determined from the power transferred to the box, joint kinematics, and joint kinetics. Data from three cycles at the start and end of the exercise were tested for the effect of fatigue using repeated‐measures analysis of variance. Results. Fatigue was documented by a reduction in average lifting force and hip and spine torque generation, whereas internal joint load sharing was relatively unchanged. The fatigue was associated with decreased knee and hip motion, and increased lumbar flexion. Decreased postural stability also was evident. Conclusions. The significant decrease in postural stability and force generation capability because of the repetitive lifting task indicated a higher risk of injury in the presence of unexpected perturbation. Multijoint coordinated lifting tasks provide a more realistic protocol to study neuromuscular fatigue.

Range of Motion and Lordosis of the Lumbar Spine : Reliability of Measurement and Normative Values

Study Design. Repeated measures for intratester reliability were performed. Objectives. To investigate the intratester reliability of a new measurement technique that evaluates lumbar range of motion in three planes using a pelvic restraint device, and to examine the reliability of lumbar lordosis measurement by inclinometer technique. Preliminary normative data on lumbar range of motion and lumbar lordosis were collected for comparison with the findings of previous studies. Summary of Background Data. Various noninvasive measurement methods have been developed for recording lumbar range of motion. However, pelvic movement was not effectively restricted during the use of these measurement techniques. The use of the pelvic restraint device to measure lumbar range of motion has not been investigated previously. Very few studies have investigated the reliability of quantifying lumbar lordosis by the inclinometer technique. Methods. Normative values were measured in 35 healthy men, and 12 of these subjects were included for the reliability study. Pelvic motion was limited by the pelvic restraint device during lumbar range of motion measurement in standing. An inclinometer was used for evaluation of lumbar flexion, extension, lateral flexion, and lumbar lordosis, whereas a lumbar rotameter was used to measure axial rotation. Results. Good intratester reliability was shown in the lumbar range of motion and lordosis measurement. Most of the intraclass correlation coefficient and Pearson’s r values (accompanied with nonsignificant paired t tests) were greater than 0.9, and most of the intrasubject coefficients of variation were less than 10%. The values of lumbar range of motion in three planes and lumbar lordosis found in the current study were comparable with those from most of the previous studies on these measurements in the normal population. Conclusions. Inclinometer and lumbar rotameter measurements with the use of a pelvic restraint device are reliable for measuring lumbar spine range of motion. Use of the inclinometer technique to record lumbar lordosis also is a reliable measure.

Translation and validation study of Chinese versions of the neck disability index and the neck pain and disability scale.

Study Design. Cultural translation and psychometric testing. Objective. To translate and validate the Iranian versions of the Neck Disability Index (NDI-IR) and the Neck Pain and Disability Scale (NPDS-IR). Summary of Background Data. The widely used the NDI and the NPDS scales have not been translated and validated for Persian-speaking patients with neck pain. This was to provide a validated instrument to measure functional status in patients with neck pain in Iran. Methods. The translation and cultural adaptation of the original questionnaires were carried out in accordance with the published guidelines. One hundred and eighty-five patients with neck pain were participated in the study. Patients were asked to complete a questionnaire booklet including the NDI-IR, the NPDS-IR, the Iranian SF-36, and a visual analog scale (VAS) of pain. To carry out the test-retest reliability, 30 randomly selected patients with neck pain were asked to complete the questionnaire booklet 48 hours later for the second time. Results. Cronbach &agr; coefficient for the NDI-IR was 0.88 and for the 4 subscales of the NPDS-IR was found to be satisfactory (ranging from 0.74 to 0.94). The NDI-IR and the NPDS-IR subscales showed excellent test-retest reliability (intraclass correlation coefficient ranged from 0.90 to 0.97; P < 0.01). The correlation between the NDI-IR and the NPDS-IR subscales and functional scales of the SF-36 showed desirable results, indicating a good convergent validity (Pearson correlation coefficients ranged from −0.31 to −0.70). The correlation between the NDI-IR and the VAS was 0.71 and between the NPDS-IR subscales and the VAS ranged from 0.63 to 0.79 (P < 0.01). Conclusion. The Iranian versions of the NDI and NPDS are reliable and valid instruments to measure functional status in Persian-speaking patients with neck pain in Iran. They are simple and easy to use and now can be applied in clinical settings and future outcome studies in Iran and other Persian speaking communities.

An assessment of complex spinal loads during dynamic lifting tasks.

Study Design. An electromyogram‐assisted free‐dynamic lifting model was used to quantify the patterns of complex spinal loads in subjects performing various lifting tasks. Objectives. To assess in vivo the three‐dimensional complex spinal loading patterns associated with high and low risk lifting conditions that matched those observed in industrial settings. Summary of Background Data. Combined loading on the spine has been implicated as a major risk factor in occupational low back disorders. However, there is a void in the literature regarding the role of these simultaneously occurring complex spinal loads during manual lifting. Methods. Eleven male subjects performed symmetric and asymmetric lifting tasks with varying speed and weight. Reactive forces and moments at L5‐S1 were determined through the use of electrogoniometers and a force plate. An electromyogram‐assisted model provided the continuous patterns of three‐dimensional spinal loads under these complex lifting tasks. Results. The results showed that complex dynamic motions similar to those observed in risky industrial tasks generated substantial levels of combined compressive and shear loads. In addition, higher loading rates were observed under these conditions. Unlike loading magnitudes, loading rate was a better indicator of dynamic loading because it incorporated both the duration and magnitude of net muscle forces contributing to total spinal loading during the lifting conditions. Conclusions. Quantification of spinal combined motions and loading in vivo has not been undertaken. This study provided a unified assessment of the effects of combined or coupled motions and moments in the internal loading of the spine. Dynamic lifting conditions similar to those observed in risky industrial situations generated unique complex patterns of spinal loading, which have been implicated to pose a higher risk to the spinal structure. The higher predicted loading and loading rate during asymmetric lifting conditions can be avoided by appropriate ergonomic workplace modifications.