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     

Differences in lumbar and pelvic angles and gluteal pressure in different sitting postures

[Purpose] To investigate the effects of erect sitting, slouched posture with cross-legged sitting, and erect posture with cross-legged sitting on the lumbar and pelvic angles, and gluteal pressure. [Subjects] For the experiments, 17 healthy women were recruited. [Methods] All subjects were asked to perform three sitting postures: erect sitting, slouched posture with cross-legged sitting, and erect posture with cross-legged sitting. Lumbar and pelvic angles were measured using a three-dimensional motion-capture system, and gluteal pressure was measured using a pressure mat. [Results] Compared to erector sitting, slouched posture with cross-legged sitting showed significantly greater lumbar flexion, posterior pelvic tilt, and left pelvic tilt. Compared to erect sitting, erect posture with cross-legged sitting showed significantly greater lumbar flexion and posterior pelvic tilt. Compared to erect posture with cross-legged sitting, slouched posture with cross-legged sitting showed significantly greater lumbar flexion and posterior pelvic tilt. Compared to erect sitting and erect posture with cross-legged sitting, slouched posture with cross-legged sitting showed significantly greater left gluteal pressure; there was no significant difference in right gluteal pressure. [Conclusion] An erect posture can reduce changes in lumbar and pelvic angles, and gluteal pressure compared to a slouched posture during cross-legged sitting.Key words: Cross-legged sitting, Lumbar and pelvic angles, Gluteal pressure     

Slow Expiration Reduces External Oblique Muscle Activity during Maximum Trunk Flexion

[Purpose] The purpose of this study was to demonstrate the effects of expiration on abdominal muscle activity during maximum trunk flexion. [Subjects] Twenty-one healthy university students (10 men, 11 women) participated in this study. [Methods] Electromyography (EMG) was used to quantify the activity of the right rectus abdominis, external oblique, and internal oblique muscles. The paired t-test was used to examine the significance of differences in the abdominal muscles between maximum trunk flexion with breath holding and slow expiration. [Results] There was a significantly lower EMG activity in the external oblique muscle during maximum trunk flexion with slow expiration. [Conclusion] The results of this study indicate that slow expiration reduces external oblique muscle activity during maximum trunk flexion performed by healthy young subjects.Key words: Expiration, Electromyography, Abdominal muscles     

Comparison of Upper Cervical Flexion and Cervical Flexion Angle of Computer Workers with Upper Trapezius and Levator Scapular Pain

[Purpose] In this study, we compared upper cervical flexion and cervical flexion angle of computer workers with upper trapezius and levator scapular pain. [Subject] Eight male computer workers with upper trapezius muscle pain and eight others with levator scapular muscle pain participated. [Methods] Each subject was assessed in terms of upper cervical flexion angle and total cervical flexion angles using a cervical range of motion instrument after one hour of computer work. [Results] The upper cervical flexion angle of the group with levator scapular pain was significantly lower than that of the group with upper trapezius pain after computer work. The total cervical flexion angle of the group with upper trapezius pain was significantly lower than that of the group with levator scapular pain after computer work. [Conclusion] For selective and effective intervention for neck pain, therapists should evaluate upper and lower cervical motion individually.Key words: Cervical range of motion, Neck pain, Upper cervical flexion     

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     

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     

EMG Activity in the Abdominal Muscles and the Kinematics of the Lumbar Spine during Unilateral Upper-limb Resistance Exercises under Stable and Unstable Conditions

[Purpose] We investigated the effects of unstable conditions on the electromyographic (EMG) activity of the rectus abdominis (RA) and the transverse abdominis–internal oblique (TrA-IO) muscles, and lumbar kinematics during unilateral upper-limb resistance exercises using elastic tubing bands. [Subjects] Twelve healthy males were recruited. [Methods] The subjects performed isometric left shoulder abduction using an elastic tubing band in a sitting position on a chair, and on a Swiss ball. During this exercise, EMG activities of the RA and TrA-IO were recorded using a wireless EMG system, and a three-dimensional motion analysis system monitored lumbar kinematics. Differences in EMG activities of the RA and TrA-IO, the ratio of TrA-IO to RA activity, and lumbar kinematics were compared between the stable and unstable conditions using the paired t-test. [Results] Under the unstable condition, the EMG activities of both muscles were significantly greater than that under the stable condition; however the ratio of TrA-IO to RA activity did not significantly differ between the conditions. The lumbar angle significantly differed only in the coronal plane. [Conclusions] These findings indicate that trunk posture should be considered when performing exercises under unstable conditions.Key words: Swiss ball, Abdominal muscles, Electromyography     

Alterations of spinal range of motion while sitting in hemiplegic patients with or without gait available

[Purpose] The purpose of this study was to determine alterations of spinal range of motion while sitting, in hemiplegic patients with or without gait available. [Subjects] There was a gait group (GG) of 6 subjects, and a non-gait group (NGG) of 6 subjects, both with hemiplegia after a stroke. [Methods] The subjects in both groups were given an intervention focusing on ankle dorsi-flexion of the affected foot only once for 30 minutes. The Spinal Mouse was used to gain data of the spinal range of motion before and after the intervention and 30 minutes later for follow-up test. [Results] Only in the gait group, lumbar spinal range of motion showed a significant difference when using flexion extension. Sacral hip and inclination were both increased gradually when upright flexion and flexion extension were used. [Conclusion] Facilitating foot for ankle dorsi-flexion is effective on spinal range of motion especially sacrohip, lumbar spine and inclination only for the subjects in the gait group. The results suggested that ankle dorsi-flexion exercise influences spinal range of motion in a sitting position.     

Hip Muscle Activity during Isometric Contraction of Hip Abduction

[Purpose] This study aimed to determine the effect of varying hip flexion angle on hip muscle activity during isometric contraction in abduction. [Subjects] Twenty-seven healthy men (mean age=21.5 years, SD=1.2) participated in this study. [Methods] Surface electromyography (EMG) was recorded of the upper portion of the gluteus maximus (UGM), lower portion of the gluteus maximus (LGM), tensor fasciae latae (TFL), and gluteus medius (GMed) during isometric contraction under two measurement conditions: hip flexion angle (0, 20, 40, 60, and 80 degrees) and abduction of the hip joint at 20, 40, 60, and 80% maximum strength. Integrated EMG (IEMG) were calculated and normalized to the value of maximum voluntary contraction (MVC). [Results] Results indicated that the IEMG of both the UGM and LGM increased significantly with increases in hip flexion angle, whereas the IEMG of the TFL decreased significantly. The maximum activities of the UGM and the LGM were 85.7 ± 80.8%MVC and 38.2 ± 32.9%MVC at 80 degrees of hip flexion, respectively, and that of the TFL was 71.0 ± 39.0%MVC at 40 degrees of hip flexion. [Conclusion] The IEMG of the GMed did not change with increases in hip flexion angle. Hip flexion angle affected the activity of the GM and TFL during isometric contraction in abduction.Key words: Hip abductor, Electromyography, Muscle activity     

Effects of Visual Display Terminal Works on Cervical Movement Pattern in Patients with Neck Pain

[Purpose] This study examined changes in the onset of neck movement in young adults with and without mild neck pain (MNP) during visual display terminal (VDT) work. [Subjects] Ten control subjects and 10 subjects with MNP who were VDT workers were recruited. The upper (UC) and lower cervical (LC) spine angles in the sagittal plane were collected using an ultrasound-based motion analysis system during VDT work for 5 min. [Results] The MNP group had faster movement initiation in the UC and LC compared with the control group during VDT work. [Conclusion] These findings suggest that young adults with MNP should be cautious when performing VDT work while sitting.Key words: Movement onset time, Neck pain, VDT work     

Influence of Hip Joint Position on Muscle Activity during Prone Hip Extension with Knee Flexion

[Purpose] This study investigated the selective activation of the gluteus maximus during a prone hip extension with knee flexion exercise, with the hip joint in different positions. [Subjects] The subjects were 21 healthy, male volunteers. [Methods] Activities of the right gluteus maximus, right hamstrings, bilateral lumbar erector spinae, and bilateral lumbar multifidus were measured using surface electromyography during a prone hip extension with knee flexion exercise. Measurements were made with the hip joint in each of 3 positions: (1) a neutral hip joint position, (2) an abduction hip joint position, and (3) an abduction with external rotation hip joint position. [Results] Gluteus maximus activity was significantly higher when the hip was in the abduction with external rotation hip joint position than when it was in the neutral hip joint and abduction hip joint positions. Gluteus maximus activity was also significantly higher in the abduction hip joint position than in the neutral hip joint position. Hamstring activity was significantly lower when the hip was in the abduction with external rotation hip joint position than when it was in the neutral hip joint and abduction hip joint positions. [Conclusion] Abduction and external rotation of the hip during prone hip extension with knee flexion exercise selectively activates the gluteus maximus.Key words: Prone hip extension with knee flexion, Hip joint position, Electromyography     

Hip rotation range of motion in sitting and prone positions in healthy Japanese adults

[Purpose] The aim of this study was to elucidate the difference in hip external and internal rotation ranges of motion (ROM) between the prone and sitting positions. [Subjects] The subjects included 151 students. [Methods] Hip rotational ROM was measured with the subjects in the prone and sitting positions. Two-way repeated measures analysis of variance (ANOVA) was used to analyze ipsilateral hip rotation ROM in the prone and sitting positions in males and females. The total ipsilateral hip rotation ROM was calculated by adding the measured values for external and internal rotations. [Results] Ipsilateral hip rotation ROM revealed significant differences between two positions for both left and right internal and external rotations. Hip rotation ROM was significantly higher in the prone position than in the sitting position. Hip rotation ROM significantly differed between the men and women. Hip external rotation ROM was significantly higher in both positions in men; conversely, hip internal rotation ROM was significantly higher in both positions in women. [Conclusion] Hip rotation ROM significantly differed between the sexes and between the sitting and prone positions. Total ipsilateral hip rotation ROM, total angle of external rotation, and total angle of internal rotation of the left and right hips greatly varied, suggesting that hip joint rotational ROM is widely distributed.Key words: Hip rotation, ROM, Positions     

Measuring seated hip extensor strength using a handheld dynamometer: an examination of the reliability and validity of the protocol

[Purpose] The purpose of this study was to examine the reliability and validity of measurements of hip extensor muscle strength using a handheld dynamometer (HHD) with subjects in a sitting position. In doing so, we also aimed to establish a modified method of measurement for patients with flexion contractures in the trunk and lower extremities. [Subjects and Methods] In 20 healthy males, hip extensor muscle strength was measured using a handheld dynamometer in sitting, prone, and standing positions by contracting the hip extensor muscle isometrically with the knee flexed at 90 degrees. For each position, we investigated the relative and absolute reliability and validity of the measurements, and compared muscle strength between the different positions. [Results] The reliability and validity of measurements were highest in the sitting position and higher in both the sitting and standing positions as compared with those in the prone position. [Conclusion] Our findings suggest that measurements taken in a sitting position are accurate in assessing hip extensor muscle strength and would be applicable to patients with flexion contractures in the trunk and lower extremities.Key words: Hip extensor strength, Reliability, Bland-Altman analysis     

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     

Comparison of the Hamstring Muscle Activity and Flexion-Relaxation Ratio between Asymptomatic Persons and Computer Work-related Low Back Pain Sufferers

[Purpose] The purpose of this study was to compare the hamstring muscle (HAM) activities and flexion-relaxation ratios of an asymptomatic group and a computer work-related low back pain (LBP) group. [Subjects] For this study, we recruited 10 asymptomatic computer workers and 10 computer workers with work-related LBP. [Methods] We measured the RMS activity of each phase (flexion, full-flexion, and re-extension phase) of trunk flexion and calculated the flexion-relaxation (FR) ratio of the muscle activities of the flexion and full-flexion phases. [Results] In the computer work-related LBP group, the HAM muscle activity increased during the full-flexion phase compared to the asymptomatic group, and the FR ration was also significantly higher. [Conclusion] We thought that prolonged sitting of computer workers might cause the change in their HAM muscle activity pattern.Key words: Computer work-related LBP, Flexion-Relaxation ratio, Hamstring     

Fatigue-induced changes in phasic muscle activation patterns during dynamic trunk extension exercise

OBJECTIVE: To investigate the influence of fatigue on phasic muscle-activation patterns during dynamic trunk extension exercise. DESIGN: Fifteen healthy volunteers performed dynamic trunk-extension exercise through a 30-degree range-of-motion (ROM) exercise to task failure at an intensity of 50% of maximum. Electromyography (EMG) signals were recorded unilaterally from the lumbar extensor, gluteus maximus, and biceps femoris muscles, and signal amplitude was analyzed in 10-degree increments during the unfatigued and fatigued states (0-10 degrees from torso horizontal to the ground was considered extension, and 11-20 and 21-30 degrees of flexion relative to this were considered midphase and flexion, respectively). RESULTS: Lumbar extensor EMG was approximately 75% of maximum EMG, with no differences being observed with respect to ROM or fatigue state. The gluteus maximus demonstrated an altered phasic activation pattern with fatigue, with an increased recruitment during the extension phase (fatigued-state extension-phase EMG: 89.1 +/- 8.3% > flexion phase EMG: 37.8% +/- 9.1%). The biceps femoris demonstrated a similar response during both the fatigued and unfatigued states (fatigued-state extension EMG: 77.8 +/- 5.4% > midphase EMG: 65.8 +/- 5.7% > flexion EMG: 46.8 +/- 4.0%; unfatigued-state extension EMG: 46.1 +/- 3.7% > flexion EMG: 27.1 +/- 2.6%). CONCLUSIONS: During this exercise, as one moves from flexion to extension, hip extensor muscle activity increases, whereas lumbar extensor activity does not. Additionally, fatigue results in an altered recruitment pattern, with the hip extensors being activated to a greater extent in the extension phase. These findings suggest that when this exercise is performed in the prone position, it can be used to stimulate the lumbar and hip extensor muscles, but the specific exercise protocol in terms of set/repetition number and ROM will influence which muscles are primarily targeted.     

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 Togu-exercise on Lumbar Back Strength of Women with Chronic Low Back Pain

[Purpose] The present study analyzed the effect of the Togu exercise program on the lumbar back strength of middle-aged women who did not perform regular exercise, and presents an effective exercise method for middle-aged women with chronic low back pain symptom. [Subjects] The subjects were 16 women with chronic low back pain attending N University, Chungcheong-do, Korea. [Methods] Height, weight, body fat, and body mass index (BMI) were measured using a body composition analyzer (Inbody 720, Biospace, Korea), which utilizes bioelectrical impedance analysis. Using isokinetic lumbar muscle strength measurement equipment [Isomed 2000, Back system, (Germany)], peak torque/body weight, total work and average power of flexion and extension of the lumbar region were measured. For lumbar stabilization exercises, an air cushion (Germany), jumper (Germany), and aero step (Germany) were employed. First, warm-up exercise was conducted for 10 minutes, followed by 10 sets of the 3 main exercises using the above tools with 10-second rest intervals. The main exercise was done for 40 minutes in total. [Results] The paired sample t-test showed significant in the Togu exercise group peak torque of flexion, peak torque of extension, total work of flexion, total work of extension, average power of flexion, average power of extension, after the exercise showed a significant difference in the Togu exercise group. [Conclusion] The trunk muscle actiation program for middle-aged women had a significant effect on muscle strength and low back pain. Therefore the trunk muscle activation program is effective at increasing muscular strength of middle-aged women, and the results suggest improve muscle strength is effectively stabilizaties the lumbar region.Key words: Isokinetic, Lumbar stabilization, Togu     

Effect of low back pain on the muscles controlling the sitting posture

[Purpose] The purpose of the current study was to reveal the association between posture control and muscle activity by measuring the trunk and hip joint muscle activities in the upright and slump sitting positions in both the healthy participants and patients with recurrent lower back pain. [Participants and Methods] We recruited eleven patients of recurrent lower back pain and ten healthy participants. During the maintenance of the two types of posture, upright and slump, we collected the surface electromyography data. We assessed the following muscles: rectus abdominis, external oblique, thoracic erector spinae, lumbar erector spinae, internal oblique, lumbar multifidus, iliacus, serratus anterior, rectus femoris, tensor fascia latae, and gluteus maximus. We studied the differences in spinal–pelvic curvature and muscle activity between the upright and slump positions in each group. [Results] In the healthy group, comparison of the muscle activity in upright and slump positions for both the trunk (external oblique, internal oblique, lumbar erector spinae, and lumbar multifidus), and the hip muscles (iliacus and gluteus maximus) showed a significant decrease in activity in the slump position. In the group with recurrent lower back pain, although the external oblique, lumbar erector spinae and lumbar multifidus showed reduced activity in slump position, these values were smaller when compared to those in the healthy group. [Conclusion] This study aimed to clarify the relationship between posture (upright and slump) and the activity of the trunk and hip joint muscles in the healthy participants and the patients with recurrent lower back pain. The results indicated that postural changes caused by recurrent lower back pain significantly affected the activity of the muscles involved in controlling the posture.Key words: Sitting posture, Muscle control, Low back pain     

Effects of abdominal drawing-in during prone hip extension on the muscle activities of the hamstring,gluteus maximus,and lumbar erector spinae in subjects with lumbar hyperlordosis

[Purpose] The purpose of this study was to compare the effects of an abdominal drawing-in maneuver (ADIM), measured using a pressure bio-feedback unit, on the activities of the hamstring, gluteus maximus, and erector spinae muscles during prone hip extension. [Subjects and Methods] Thirty healthy adult subjects (14 male, 16 female), were recruited. Subjects’ lumbar lordosis and pelvic tilt angles were measured, and based on the results, the subjects were divided into two groups: a hyperlordotic lumbar angle (HLLA) group (n=15) and a normal lordotic lumbar angle (NLLA) group (n=15). The muscle activities of the hamstring and gluteus maximus, and of the erector spinae on the right side of the body, were recorded using surface electromyography. [Results] When performing ADIM with prone hip extension, the muscle activity of the gluteus maximus of the HLLA group significantly improved compared with that the NLLA group. [Conclusion] This study demonstrated that ADIM with prone hip extension was more effective at eliciting gluteus maximus activity in the HLLA group than in the NLLA group. Therefore, ADIM with prone hip extension may be useful for increasing the gluteus maximus activity of individuals with lumbar hyperlordosis.Key words: Abdominal drawing-in maneuver, Hyperlordotic lumbar angle, Prone hip extension