Comparison of the Lumbar Flexion Angle and EMG Activity in Trunk Muscles in Individuals with and without Limited Hip Flexion Range of Motion during Visual Display Terminal Work with Cross-Legged Sitting

[Purpose] The purpose of this study was to compare the lumbar flexion angle and electromyography (EMG) measurements of trunk muscle activity in individuals with and without limited hip flexion range of motion (ROM) during visual display terminal (VDT) work with cross-legged sitting. [Subjects] The 15 participants included a control group with sufficient hip flexion ROM (n = 7) and an experimental group with limited hip flexion ROM (n = 8). [Methods] All subjects performed VDT work with cross-legged sitting. The lumbar flexion angle was measured using a three-dimensional motion capture system, and the trunk muscle activity was recorded using a surface EMG system during VDT work with cross-legged sitting. The differences in trunk flexion angle and trunk muscle activity between the two groups were analyzed using independent t-tests. [Results] The lumbar flexion angle was significantly greater in the experimental group than the control group, although trunk muscle activity did not differ between the two groups. [Conclusion] These findings suggest that limited hip flexion leads to greater lumbar flexion during cross-legged sitting.Key words: Cross-legged sitting, Electromyography, Lumbar flexion     

Shoulder impingement: the effect of sitting posture on shoulder pain and range of motion

The re-education of spinal posture is an integral part of shoulder impingement management yet supporting evidence is limited. The purpose of this study was to evaluate the effect of slouched versus erect sitting posture on shoulder pain intensity and range of motion (ROM) in subjects with impingement. A same-subject repeated-measures design was utilized. Maximum active shoulder flexion and associated pain intensity were measured in 28 subjects in slouched and erect sitting postures, using video-analysis and visual analogue scales, respectively. An intra-tester reliability study of the video-analysis system was completed and intra-class correlation coefficients calculated. Shoulder flexion differences between slouched and erect sitting posture were analysed using a repeated-measures analysis of variance (ANOVA). The intra-tester reliability of the video-analysis method was found to be 'excellent' (ICC = 0.99). Flexion ROM was significantly greater in the erect sitting posture (F = 100.3, P < 0.0001); the mean ROM difference between postures was 17.67 degrees (+/- 9.17 degrees). There was no significant difference in pain intensity between postures (F = 1.9, P = 0.179). An erect sitting posture appeared to increase active shoulder flexion in subjects with shoulder impingement, although there were no differences in reported pain intensity. Further research is required to investigate the long-term effects of postural re-education.     

Effects of the posterior pelvic tilt sitting posture on thoracic morphology and respiratory function

[Purpose] We investigated how differences in pelvic angle in the posterior pelvic tilt sitting posture simultaneously affect the thoracic morphology and the respiratory function. [Participants and Methods] The participants were 18 healthy young males. We positioned the pelvis at 0°, 10°, 20°, and 30° of posterior tilt, following which the thoracic expansion volume ratio, thoracic spine tilt angle, and respiratory function were measured. We calculated the thoracic volume and thoracic spine tilt angle by measuring the amount of displacement of reflective markers attached to the thoracic area using the Vicon MX 3D-analysis system. Respiratory function was measured by spirometry. [Results] The expansion volume ratio decreased significantly in response to 10–30° posterior pelvic tilt sitting at the mid-thorax and 30° posterior pelvic tilt sitting at the lowest thorax. The upper thoracic spine level showed a change in anterior tilt at 10–30° posterior pelvic tilt sitting, whereas the lower thoracic spine level showed a change in posterior tilt at 30° posterior pelvic tilt sitting. Respiratory function was significantly lower at 30° posterior pelvic tilt sitting than at 0° posterior pelvic tilt sitting. A positive correlation between thoracic expansion volume ratio and respiratory function was found at 30° posterior pelvic tilt sitting. [Conclusion] Changes in thoracic spine tilt angle due to posterior pelvic tilt sitting may restrict the expansion of thoracic motion during respiration, thereby affecting respiratory function.Key words: Posterior pelvic tilt sitting posture, Thoracic morphology, Respiratory function     

Thoracic position effect on shoulder range of motion, strength, and three-dimensional scapular kinematics.

OBJECTIVES: To determine the effect of thoracic posture on scapular movement patterns, active range of motion (ROM) in scapular plane abduction, and isometric scapular plane abduction muscle force. STUDY DESIGN AND METHOD: Repeated measures design. There were 34 healthy subjects (mean age, 30.2 yrs). Each subject was positioned and stabilized while sitting in both erect and slouched trunk postures. In each sitting posture a three-dimensional electromechanical digitizer was used to measure thoracic flexion and scapular position and orientation in three planes. Measurements were taken with the arm (1) at the side, (2) abducted to horizontal in the scapular plane, and (3) at maximum scapular plane abduction. In each posture, isometric abduction muscle force was measured with the arm at the side and abducted to horizontal in the scapular plane. RESULTS: In the slouched posture, the scapula was significantly more elevated in the interval between 0 to 90 degrees abduction. In the interval between 90 degrees and maximum abduction, the slouched posture resulted in significantly less scapular posterior tilting. There was significantly less active shoulder abduction ROM in the slouched posture (mean difference = 23.6 degrees +/- 10.7 degrees). Muscle force was not different between slouched and erect postures with the arm at the side, but with the arm horizontal muscle force was decreased 16.2% in the slouched position. CONCLUSION: Thoracic spine position significantly affects scapular kinematics during scapular plane abduction, and the slouched posture is associated with decreased muscle force.     

Comparison of lumbar repositioning error according to different lumbar angles in a flexion pattern (FP) subgroup of patients with non-specific chronic low back pain

[Purpose] This study determined the change in lumbar position sense according to lumbar angles in a flexion pattern (FP) subgroup of patients with non-specific chronic low back pain (NCSLBP). [Subjects] Thirteen subjects with FP low back pain participated. [Methods] The lumbar repositioning error (RE) of subjects was measured between a neutral starting position and re-position phases at three angles, in sitting and standing upright positions. [Results] Lumbar RE was significantly greater during lumbar flexion at a 30° angle in the sitting position than in the other tasks. [Conclusion] In the flexion-related subgroup, the lumbar RE measurement may be a more sensitive evaluation method using a lumbar flexion angle of 30° while in the sitting position, compared with other angles in sitting or standing positions.Key words: Flexion pattern, Low back pain, Repositioning error     

Belt effects on lumbar sagittal angles

OBJECTIVE: The study examined the belt effects on the change of lumbar sagittal angles. DESIGN: The effects of pelvic and lumbar belts on lumbar sagittal angles were examined both radiographically and videographically in standing, erect sitting, and slump sitting. BACKGROUND: The resulting changes of lumbar angles when wearing belts with different mechanical characteristics should be different. METHODS: Eighteen healthy male subjects participated in this study. L1/L3, L3/L5, L5/S1 and L1/S1 were measured with the aid of lateral radiographs. The external joint angles were also measured via the motion analysis system. RESULTS: Radiographic data revealed an interactive effect between working posture and the use of a belt (P<0.046) on the change of L1/S1. In standing, both belts increased L1/S1 by increasing almost all the lumbar vertebral angles. In erect sitting, wearing lumbar belt had no effect but the pelvic belt decreased L1/S1 mainly through a decrease in L1/L3. In sitting slump with trunk flexion of 15 degrees, both belts increased L1/S1 and restricting the movement of the pelvis. CONCLUSIONS: Belt effect to the change of lumbar sagittal angles in posture which involve knee flexing and/or trunk flexing seems not as the same as in standing posture. RELEVANCE: This study related internal vertebral angles and externally measured trunk angles with lumbar and pelvic belt usage.     

A Sloped Seat Wedge Can Change the Kinematics of the Lumbar Spine of Seated Workers with Limited Hip Flexion

[Purpose] The purpose of this study was to determine whether a wedge type seat decreases the lumbar flexion angle of seated workers with limited hip flexion. [Subjects] Twelve sedentary workers with limited hip flexion were recruited. [Methods] Three seat surfaces were used: a level surface, a forward-inclining wedge, and a backward-reclining wedge. The angles of lumbar flexion and pelvic tilt were measured using a three-dimensional motion analysis system. Differences in kinematic data of the subjects seated on the three seat surfaces were analyzed using repeated one-way analysis of variance. [Results] The degree of lumbar flexion decreased significantly when using the forward-inclining wedge compared with the level surface and backward-reclining wedge. [Conclusion] These findings suggest that sitting on a forward-inclining wedge may be useful for minimizing the compensatory lumbar flexion of individuals with limited hip flexion who work in a seated position.Key words: Kinematics, Limited hip flexion, Seat wedge     

The relationship beween posture and back muscle endurance in industrial workers with flexion-related low back pain

This preliminary cross-sectional study was undertaken to determine if there were measurable relationships between posture, back muscle endurance and low back pain (LBP) in industrial workers with a reported history of flexion strain injury and flexion pain provocation. Clinical reports state that subjects with flexion pain disorders of the lumbar spine commonly adopt passive flexed postures such as slump sitting and present with associated dysfunction of the spinal postural stabilising musculature. However, to date there is little empirical evidence to support that patients with back pain, posture their spines differently than pain-free subjects. Subjects included 21 healthy industrial workers and 24 industrial workers with flexion-provoked LBP. Lifestyle information, lumbo-pelvic posture in sitting, standing and lifting, and back muscle endurance were measured. LBP subjects had significantly reduced back muscle endurance (P < 0.01). LBP subjects sat with less hip flexion, (P = 0.05), suggesting increased posterior pelvic tilt in sitting. LBP subjects postured their spines significantly closer to their end of range lumbar flexion in 'usual' sitting than the healthy controls (P < 0.05). Correlations between increased time spent sitting, physical inactivity and poorer back muscle endurance were also identified. There were no significant differences found between the groups for the standing and lifting posture measures. These preliminary results support that a relationship may exist between flexed spinal postures, reduced back muscle endurance, physical inactivity and LBP in subjects with a history of flexion injury and pain.     

Development and testing of a pelvic goniometer designed to measure pelvic tilt and hip flexion

OBJECTIVE: To determine the reliability and validity of a pelvic goniometer designed to measure the pelvic tilt and hip flexion during seated posture. BACKGROUND: Assessment of the seated posture requires measurement of the pelvis and hip. Determining accurate pelvic tilt and hip flexion angles during sitting is often difficult using standard techniques. A pelvic goniometer has been designed to measure pelvic tilt and hip flexion angle of persons in a seated posture. METHODS: Validation of the pelvic goniometer was done radiographically. Ten male volunteers sat in three postures--erect, forward or anterior tilt, and posterior tilt. Pelvic tilt and hip angle were recorded using radiographs and the pelvic goniometer. Reliability of pelvic and conventional goniometers was done using seated nondisabled subjects with physical therapists performing measurements. RESULTS: Validation: the average differences and correlation between the pelvic goniometer and radiographic measures were as follows--pelvic tilt: -4.9 degrees, 0.93; hip angle 1.2 degrees, 0.81. Reliability: average range of hip angle across three measures was about 3 degrees for both goniometers. CONCLUSIONS: The data indicate that the pelvic goniometer has utility in measuring pelvic tilt and hip angle, especially within the seated posture. Because it measures both pelvic tilt and hip angle, the pelvic goniometer has an advantage over conventional goniometers that only measure the latter. RELEVANCE: A valid and reliable tool that measures pelvic tilt and hip angle of persons in a seated posture is needed for clinical research and practice. Its applications include wheelchair seating evaluations and ergonomic assessments of seated workers.     

Development of a noninvasive measure of pelvic and hip angles in seated posture

OBJECTIVE: To develop a valid noninvasive means to measure pelvic tilt and hip angle in seated posture. DESIGN: Validation cohort study using radiographs as a criterion standard for pelvic posture. SETTING: Rehabilitation hospital. PARTICIPANTS: Volunteer sample of 10 adult men with no known physical disability. INTERVENTIONS: Radiographs were taken as subjects sat in erect, anterior, and posterior postures. An electromagnetic tracking device was as a pointer to digitize the anterior superior and posterior superior iliac spines and as a 6 degrees of freedom (df) sensor mounted on the thigh and sacrum. MAIN OUTCOME MEASURES: Variables included pelvic tilt and hip flexion angle. Intra- and interrater reliability of radiographic measures was determined by using intraclass correlation coefficient comparison of the results from 2 investigators. Validity was determined by comparing noninvasive measures of pelvic and hip angles to radiographic measures by using correlation, analysis of variance (ANOVA), and regression. RESULTS: Reliability of radiographic measures of pelvic tilt and hip angles were >/=.98. Pelvic tilt comparison: pointer: r=.89, R(2)=.80; 6-df sensor: r=.91, R(2)=.83; hip angle comparison using 6-df sensor: r=.78 with average difference of 4.25 degrees. ANOVA showed that differences between all invasive and noninvasive measures did not differ significantly (P>.05). CONCLUSION: Results indicated excellent reliability of radiographic analysis techniques and represented an improvement over previously published techniques. Noninvasive measures of pelvic tilt and hip angle were shown to be valid.     

Relationship between iliopsoas muscle thickness and hip angle during squats in different pelvic positions

[Purpose] This study aimed to investigate the relationships among the changes in iliopsoas muscle thickness, hip angle, and lower limb joint moment during squatting in different pelvic positions to help in performing hip-dominant squatting exercises. [Participants and Methods] The participants were seven healthy adult males. The measurement task consisted of squatting with 60 degrees of knee flexion in three positions: the anterior, neutral, and posterior pelvic tilt positions. The iliopsoas muscle thickness was measured in the center of the inguinal region using ultrasonography. A three-dimensional motion analysis system was used to measure the joint angles and joint moments. [Results] There were no significant differences in pelvic angles between the pelvic positions. The hip angle differences were significantly higher in the anterior and neutral pelvic tilt positions compared to those in the posterior tilt position. Only the anterior pelvic tilt position had a significantly positive correlation with iliopsoas muscle thickness and hip angle differences. [Conclusion] Squatting in the neutral or posterior pelvic tilt position was not associated with hip angle and iliopsoas muscle thickness changes, whereas squatting in an anterior pelvic tilt position was associated with changes in the iliopsoas muscle thickness and hip flexion angle. Our findings suggest that activation of the iliopsoas muscle might be necessary to promote hip-dominant squatting.Key words: Squats, Iliopsoas muscle, Pelvic position     

Comparison of the Forward Head Angle and the Lumbar Flexion and Rotation Angles of Computer Workers Using Routine and Individually Fixed Computer Workstations

[Purpose] This study compared the forward head angle and the lumbar flexion and rotation angles of computer workers using routine and fixed computer workstations. [Subjects] Ten male workers voluntarily consented to participate in the study. [Methods] A 3-D motion analysis system was used to measure the angles of the forward head and lumbar flexion. All subjects performed computer work for 30 minutes using both types of workstation. [Results] When working at the fixed workstation, the forward head angle was less than that observed when the routine workstation was used. At the fixed workstation, the lumbar flexion and rotation angles were less than that at the routine workstation. [Conclusion] The computer workstation individually fixed for standard posture may have prevented poor sitting posture.Key words: Computer workstation, Forward head angle, Sitting posture     

Differences in end-range lumbar flexion during slumped sitting and forward bending between low back pain subgroups and genders

Patterns of lumbar posture and motion are associated with low back pain (LBP). Research suggests LBP subgroups demonstrate different patterns during common tasks. This study assessed differences in end-range lumbar flexion during two tasks between two LBP subgroups classified according to the Movement System Impairment model. Additionally, the impact of gender differences on subgroup differences was assessed. Kinematic data were collected. Subjects in the Rotation (Rot) and Rotation with Extension (RotExt) LBP subgroups were asked to sit slumped and bend forward from standing. Lumbar end-range flexion was calculated. Subjects reported symptom behaviour during each test. Compared to the RotExt subgroup, the Rot subgroup demonstrated greater end-range lumbar flexion during slumped sitting and a trend towards greater end-range lumbar flexion with forward bending. Compared to females, males demonstrated greater end-range lumbar flexion during slumped sitting and forward bending. A greater proportion of people in the Rot subgroup reported symptoms with each test compared to the RotExt subgroup. Males and females were equally likely to report symptoms with each test. Gender differences were not responsible for LBP subgroup differences. Subgrouping people with LBP provides insight into differences in lumbar motion within the LBP population. Results suggesting potential consistent differences across flexion-related tasks support the presence of stereotypical movement patterns that are related to LBP.     

Lumbar Extension during Stoop Lifting is Delayed by the Load and Hamstring Tightness

[Purpose] This study investigated the relationship between lumbar pelvic rhythm and the physical characteristics of stoop lifting. [Subjects and Methods] Participants performed a stoop lifting task under two conditions: with and without load. We assessed the lumbar kyphosis and sacral inclination angles using the SpinalMouse^® system, as well as hamstring flexibility. During stoop lifting, surface electromyograms and the lumbar and sacral motions were recorded using a multi-channel telemetry system and flexible electrogoniometers. [Results] In the initial phase of lifting, lumbar extension was delayed by load; the delay showed a negative correlation with sacral inclination angle at trunk flexion, whereas a positive correlation was observed with electromyogram activity of the lumbar multifidus. Additionally, a positive correlation was observed between sacral inclination angle and hip flexion range of motion during the straight leg raise test. [Conclusion] We found that a disorder of the lumbar pelvic rhythm can be caused by both load and hamstring tightness. In the initial phase of stoop lifting, delayed lumbar extension is likely to lead to an increase in spinal instability and stress on the posterior ligamentous system. This mechanism shows that stoop lifting of a load may be harmful to the lower back of people with hamstring tightness.Key words: Lifting, Lumbar pelvic rhythm, Hamstring flexibility     

Effect of the Individual Strengthening Exercises for Posterior Pelvic Tilt Muscles on Back Pain,Pelvic Angle,and Lumbar ROM of a LBP Patient with Excessive Lordosis: A Case Study

[Purpose] The purpose of this study was to document the effect of individual strengthening exercises for posterior pelvic tilt muscles on back pain, pelvic tilt angle, and lumbar ROM of a low back pain (LBP) patient with excessive lordosis. [Subjects] The subject was a 28 year-old male with excessive lordosis who complained of severe LBP at the L3 level. [Methods] He performed individual strengthening exercises for the posterior pelvic tilt muscles (rectus abdominis, gluteus maximus, hamstring). [Results] Pelvic tilt angles on the right and left sides recovered to his normal ranges. Limited lumbar ROM increased, and low back pain decreased. [Conclusion] We suggest that an approach of individual resistance exercises is necessary for the effective and fast strengthening of the pelvic posterior tilt muscles in case of LBP with excessive lordosis.Key words: LBP, Lordosis, Posterior pelvic tilt     

An exploratory study on the impact of static and dynamic sitting postures on lumbar and pelvic mobility during visual display terminal work

[Purpose] Limited studies exist on the impact of sustained work at a visual display terminal (VDT) on the position and motion of the pelvis and lumbar spine. We evaluated the changes in movement of the lumbar column and pelvis during VDT work. [Participants and Methods] We evaluated the sitting posture of 20 healthy adults while they performed VDT work. The effects of the sitting posture on lumbo-pelvic position and motion were captured using a three-dimensional accelerometer. Between-posture effects of VDT work were evaluated using an analysis of variance (ANOVA). A two-way ANOVA was used to assess the root mean square (RMS) values of the 80-min VDT work period for each posture. A one-way ANOVA was used to evaluate pre- and post-work changes in RMS values during the finger floor distance test (FFD). [Results] People in the dynamic sitting balance chair (DSBC)-based posture demonstrated significantly higher pelvic RMS values than those in reclining and upright sitting postures. The DSBC-based posture was also associated with significantly higher pre- and post-work lumbar and pelvic RMS values during the FFD than in the reclining and upright sitting postures. [Conclusion] The dynamic balance chair may be an effective method of establishing a pattern of spinal exercise during prolonged sitting.Key words: Dynamic sitting posture, Visual display terminal, Acceleration sensor     

Relationships between forward head posture and lumbopelvic sagittal alignment in older adults with chronic low back pain

BackgroundAbnormal posture creates abnormal stress and strain in many spinal structures which are considered predisposing factors for chronic mechanical low back pain.PurposeTo examine the relationships among pain intensity, forward head posture (decreased craniovertebral angle) and lumbopelvic sagittal alignment (pelvic incidence, pelvic tilt, sacral slope, and lumbar lordosis) in chronic mechanical low back pain patients.MethodsA cross-section correlational study was conducted on one hundred patients. A numerical-pain-rating scale was used to determine pain intensity. Standardized standing lateral radiographs were analyzed to measure the spinopelvic angles. Reported data were analyzed using correlation coefficients, and regression analyses.ResultsLumbar lordosis had very strong positive correlations with each pain intensity and sacral slope. Pain intensity had a strong positive correlation with sacral slope. Moderate positive correlations highlighted between pelvic tilt and craniovertebral angle. Moreover, the pelvic incidence had weak positive correlations with each sacral slope and pelvic tilt. Negative correlations were strong between pelvic tilt and each of pain intensity, lumbar lordosis and sacral slope. Craniovertebral angle had moderate negative correlations with each of pain, lumbar lordosis, and sacral slope. However, the pelvic incidence had no relations with pain, craniovertebral angle lumbar lordosis. Overall, an association of demographic data and measured variables had a significant effect on the pain multi-regression equation prediction model. They accounted for 76.60% of the variation in pain.ConclusionAbnormal spinopelvic posture relates to chronic mechanical low back pain. There are significant associations among pain intensity, FHP and lumbopelvic sagittal alignment in chronic mechanical low back pain patients.     

Immediate effects of dynamic sitting exercise on the lower back mobility of sedentary young adults

[Purpose] The aim of this study was to investigate the effects of dynamic sitting exercises during prolonged sitting on the lower back mobility of sedentary young adults. [Subjects and Methods] Seventy-one subjects aged between 18–25 years participated in this study. Following a randomized crossover study design, subjects were randomly assigned to two groups: sitting only and dynamic sitting exercise. The dynamic sitting exercise was a combination of lower back hyperextension and abdominal drawing-in movements which were repeated 6 times in a 1-minute period and performed every 20 minutes during a 2-hour sitting session. Lumbar range of movement was measured with the modified-modified Schober test, and the pain intensity was evaluated using the visual analog scale. [Results] After the experiment, the lumbar range of movement was significantly impaired in the sitting only group; however, it was significantly improved in the dynamic sitting exercise group. There were significant differences in lumbar range of movement of both flexion and extension between the groups. No significant difference in pain intensity between the groups was found. [Conclusion] These results suggest that dynamic sitting exercises during prolonged sitting can prevent decreases in lumbar range of movement in both back flexion and extension following a 2-hour sitting period.Key words: Back exercise, Flexibility, Long sitting     

Influence of neck pain on cervical movement in the sagittal plane during smartphone use

[Purpose] Smartphone use reportedly changes posture. However, how neck posture is altered in smartphone users with neck pain is unknown. This study examined changes in the posture of young adults with and without mild neck pain (MNP) when using a smartphone. [Subjects] Thirteen control subjects and 14 subjects with MNP who used smartphones were recruited. [Methods] The upper cervical (UC) and lower cervical (LC) angles in the sagittal plane were measured using an ultrasound-based motion analysis system while the seated subjects used a smartphone for 5 min. [Results] During smartphone use, the MNP group exhibited greater UC and LC flexion angles than the control group. [Conclusion] These findings suggest that young adults with MNP are more careful and more frequently utilize a neutral neck posture than young adults without MNP when using a smartphone while sitting.Key words: Smartphone, Cervical flexion, Young adult     

Characteristics of the scapula movement during shoulder elevation depend on posture

[Purpose] This study aimed to clarify the differences in scapular movement during flexion and abduction of the shoulder joint with different postures. [Participants and Methods] This study included 15 male participants. Their shoulder flexion and abduction and angles of the scapular upward rotation, scapular anterior tilt, scapular external rotation, and thoracic spine flexion were measured. Measurements were taken in three positions: the control, thoracic spine flexion, and thoracic spine extension positions using a three-dimensional motion capture system. [Results] In the shoulder flexion, the amount of change in the scapular external rotation was significantly greater in the thoracic flexion than in the thoracic extension. In shoulder abduction, the amount of change in the scapular anterior tilt and external rotation was significantly greater in the thoracic flexion than in the thoracic extension. A comparison of the scapular angles in shoulder flexion and abduction showed that the upward rotation, posterior tilt, and external rotation were significantly greater in abduction than flexion. [Conclusion] To avoid posture-induced incoordination of the scapula and thorax movement during shoulder elevation, postural adjustment of the thoracic spine based on the movements is necessary for the shoulder joint exercises.