Effect of Resting in a Chair,Resting with Range of Motion Exercises,and Back Strengthening Exercises on Pain and the Flexion-relaxation Ratio of Computer Workers with Low Back Pain

[Purpose] This study examined the effects of a relaxation chair and resting with simple range of motion exercises during computer work and low back muscle strengthening exercises after computer work on pain and the flexion-relaxation (FR) ratio of one computer worker with LBP. [Subjects] The subject of this study was a 37 year-old male who complained of severe LBP pain at the L4 level. [Methods] In the study, the subject worked on a computer for 5 h each day for 3 days and followed a different program each day. [Results] In Session 1, the FR ratios before and after work were 19% and 38% (+19%), respectively. The respective VAS scores before and after work were 5 and 8 (+3). In Session 2, the FR ratios before and after work were 18% and 21% (+3%), respectively. The respective VAS scores were 5 and 6 (+1). In session 3, the FR ratios before and work were 22% and 29% (+7%), respectively, and the VAS scores were 5 and 6 (+1). [Conclusion] This study suggests that it is more effective to perform regular, passive exercises to prevent LBP in computer users.Key words: Flexion-relaxation Ratio, LBP, Resting     

Comparison of the Symmetry of Right and Left Lateral Cervical Flexion and Rotation and the Cervical FRR in Young Computer Workers

[Purpose] This study compared the symmetry of right and left lateral cervical flexion and rotation, and the cervical flexion-relaxation ratio (FRR) in young computer workers in Korea. [Subjects and Methods] Twenty computer workers (14 males and 6 females) participated in this study. We measured their right and left lateral cervical flexion, rotation, and FRR. [Results] Right and left lateral flexion and right and left rotation showed no significant differences between the sides. The left cervical FRR was significantly lower than the right cervical FRR. [Conclusion] The cervical FRR, expressed as a numerical value, is a more sensitive marker for measuring neuromuscular changes associated with mild asymmetry than CROM.Key words: Cervical range of motion, Flexion-relaxation ratio, Muscle imbalance     

Effects of Cervical Flexion on the Flexion-relaxation Ratio during Smartphone Use

[Purpose] The purpose of this study was to measure the cervical flexion-relaxation ratio (FRR) and intensity of neck pain and identify the differences according to postures adopted while using smartphones. [Subjects] Fifteen healthy adults with no neck pain, spinal trauma, or history cervical surgery participated in this study. [Methods] The activity of the cervical erector spinae muscle was recorded while performing a standardized cervical flexion-extension movement in three phases (flexion, sustained full flexion, extension). And neck pain intensity was recorded using a visual analog scale (VAS) with values between 0 and 10. Postures held while using a smartphone are distinguished between desk postures and lap postures. The FRR was calculated by dividing the maximal muscle activation during the extension phase by average activation during the complete flexion phase. [Results] No significant differences were found in the FRR between desk posture, lap posture, and baseline, though the intensity of the neck pain increased in the lap posture. [Conclusion] The FRR could be a significant criterion of neuromuscular impairment in chronic neck pain or lumbar pain patients, but it is impossible to distinguish neck pain that is caused by performing task for a short time. Prolonged lap posture might cause neck pain, so the use of smartphones for a long time in this posture should be avoided.Key words: Smartphone, Cervical flexion-relaxation ratio, Electromyography     

慢性腰痛患者站立位躯干屈伸运动时腰背肌的功能变化研究

目的:研究慢性腰痛(CLBP)患者在站立位矢状面屈伸运动时腰背肌功能状况的变化,揭示其改变的可能机制及临床意义。方法:慢性非特异性腰痛患者25例和健康人25例,在站立位进行躯干的屈曲伸展运动,运用表面肌电图(sEMG)仪和摄像系统同步采集记录双侧L2/3、L4/5水平最长肌、多裂肌在站立位、前屈运动、完全屈曲及回到直立位不同运动时相的sEMG值。结果:两组受试对象站立位时,最长肌及多裂肌均方根(RMS)值差异无显著性意义(P>0.05);前屈运动时,最长肌及多裂肌RMS值增大,完全屈曲时,最长肌及多裂肌RMS值减小,腰痛组在前屈运动和完全屈曲时,最长肌和多裂肌RMS值较健康对照组增大,差异具有显著性意义(P<0.05);由屈曲位回至直立位时,腰痛组最长肌和多裂肌的RMS值明显小于健康对照组,差异具有显著性意义(P<0.05);腰痛组最长肌和多裂肌的屈曲-放松比较健康对照组降低,差异具有显著性意义(P<0.05);运动时相对两组受试对象的最长肌和多裂肌RMS值影响均有显著性意义(P<0.05)。结论:在躯干屈伸运动中,健康人腰背肌存在屈曲-放松现象(FRP),腰痛患者腰背肌功能发生疼痛适应性改变,表现为屈曲-放松反应缺如和主动活动机能不足。     

The Effects of the Nintendo Wii Exercise Program on Chronic Work-related Low Back Pain in Industrial Workers

[Purpose] The purpose of this study was to investigate the effects of a Nintendo Wii exercise program on chronic work-related LBP compared with stability exercise. [Methods] Twenty-four workers participated in this study. All of the participants were diagnosed with chronic LBP by a physician. Participants were randomly assigned to three groups: a control group (CG), lumbar stabilization exercise group (LSE), and Nintendo Wii exercise group (NWE). Participants were treated 3 times a week for 8 weeks. Each session lasted 30 minutes. [Results] The results demonstrated that exercise programs improved significantly physical functions related to LBP. In health-related QOL, the Nintendo Wii exercise program significantly improved both the mental and physical health composites, but other groups had significant improvement only in the physical health composite. [Conclusion] The Nintendo Wii exercise program could be a biopsychosocial intervention for work-related LBP in factory workers.Key words: Low back pain, Exercise, Nintendo Wii     

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     

Spinal kinematics and trunk muscle activity in cyclists: a comparison between healthy controls and non-specific chronic low back pain subjects-a pilot investigation

The aim of this pilot study was to examine whether differences existed in spinal kinematics and trunk muscle activity in cyclists with and without non-specific chronic low back pain (NSCLBP). Cyclists are known to be vulnerable to low back pain (LBP) however, the aetiology of this problem has not been adequately researched. Causative factors are thought to be prolonged forward flexion, flexion-relaxation or overactivation of the erector spinae, mechanical creep and generation of high mechanical loads while being in a flexed and rotated position. Nine asymptomatic cyclists and nine cyclists with NSCLBP with a flexion pattern disorder primarily related to cycling were tested. Spinal kinematics were measured by an electromagnetic tracking system and EMG was recorded bilaterally from selected trunk muscles. Data were collected every five minutes until back pain occurred or general discomfort prevented further cycling. Cyclists in the pain group showed a trend towards increased lower lumbar flexion and rotation with an associated loss of co-contraction of the lower lumbar multifidus. This muscle is known to be a key stabiliser of the lumbar spine. The findings suggest altered motor control and kinematics of the lower lumbar spine are associated with the development of LBP in cyclists.     

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     

Effects of the Sustained Computer Work on Upper Cervical Flexion Motion

[Purpose] The purpose of this study was to evaluate the effect of sustained computer work on cervical flexion, especially the upper cervical region. [Subjects] We recruited 11 sedentary workers who used a computer for at least 4 hours a day. [Methods] Total range of cervical flexion, upper cervical flexion, and their ratio were measured before and after 1 hour of computer work. [Results] The total range of cervical flexion was not significantly different between pre-and post-measurement. However, upper cervical flexion, and the ratio between the upper cervical flexion and total cervical flexion significantly decreased after 1 hour of computer work, compared to pre-measurement. [Conclusion] Sustained computer work affects the range of cervical flexion, especially in the upper cervical region.Key words: CROM, Cervical kinematics, Upper cervical     

Association of low back pain with muscle stiffness and muscle mass of the lumbar back muscles,and sagittal spinal alignment in young and middle-aged medical workers

BackgroundMuscle stiffness of the lumbar back muscles in low back pain (LBP) patients has not been clearly elucidated because quantitative assessment of the stiffness of individual muscles was conventionally difficult. This study aimed to examine the association of LBP with muscle stiffness assessed using ultrasonic shear wave elastography (SWE) and muscle mass of the lumbar back muscle, and spinal alignment in young and middle-aged medical workers.MethodsThe study comprised 23 asymptomatic medical workers [control (CTR) group] and 9 medical workers with LBP (LBP group). Muscle stiffness and mass of the lumbar back muscles (lumbar erector spinae, multifidus, and quadratus lumborum) in the prone position were measured using ultrasonic SWE. Sagittal spinal alignment in the standing and prone positions was measured using a Spinal Mouse. The association with LBP was investigated by multiple logistic regression analysis with a forward selection method. The analysis was conducted using the shear elastic modulus and muscle thickness of the lumbar back muscles, and spinal alignment, age, body height, body weight, and sex as independent variables.FindingsMultiple logistic regression analysis showed that muscle stiffness of the lumbar multifidus muscle and body height were significant and independent determinants of LBP, but that muscle mass and spinal alignment were not. Muscle stiffness of the lumbar multifidus muscle in the LBP group was significantly higher than that in the CTR group.InterpretationThe results of this study suggest that LBP is associated with muscle stiffness of the lumbar multifidus muscle in young and middle-aged medical workers.     

Rehabilitation Exercises to Induce Balanced Scapular Muscle Activity in an Anti-gravity Posture

[Purpose] The purpose of this study was to compare the intramuscular balance ratios of the upper trapezius muscle (UT) and the lower trapezius muscle (LT), and the intermuscular balance ratios of the UT and the serratus anterior muscle (SA) among prone extension (ProExt), prone horizontal abduction with external rotation (ProHAbd), forward flexion in the side-lying position (SideFlex), side-lying external rotation (SideEr), shoulder flexion with glenohumeral horizontal abduction load (FlexBand), and shoulder flexion with glenohumeral horizontal adduction load (FlexBall) in the standing posture. [Methods] The electromyographic (EMG) activities of the UT, LT and SA were measured during the tasks. The percentage of maximum voluntary isometric contraction (%MVIC) was calculated for each muscle, and the UT/LT ratios and the UT/SA ratios were compared among the tasks. [Results] The UT/LT ratio with the FlexBand was not significantly different from those of the four exercises in the side-lying and prone postures. The UT/SA ratio with the FlexBall demonstrated appropriate balanced activity. [Conclusion] In an anti-gravity posture, we recommend the FlexBand and the FlexBall for inducing balanced UT/LT and UT/SA ratios, respectively.Key words: Scapular muscle exercise, Balanced scapular muscle activity, Electromyography     

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     

Effects of the Different Screwdriver Handle Sizes on the Forearm Muscles Activities and Wrist Motion during Screw-driving Work

[Purpose] This study investigated the difference screwdriver handle size has on forearm muscle activities and wrist motion during screw-driving work. [Subjects] Fourteen males aged 20–30 years, were recruited. [Methods] We measured the forearm muscle activities using a MP 150 System and wrist motion using a 3D motion system. The subjects performed screw-driving tasks with different screwdriver handle sizes. [Results] The wrist flexion and ulnar deviation angles and flexor carpi ulnaris muscle activity significantly increased and wrist extension angle significantly decreased during screwdriver work with a thin handle. [Conclusion] We consider that industrial workers should perform screw-driving work using a screwdriver with a thick handle.Key words: Handle size, Screw-driving work, Wrist pain     

Comparison of Isolation Ratios of the Scapular Retraction Muscles between Protracted Scapular and Asymptomatic Groups

[Purpose] The purpose of this study was to compare the isolation ratios of scapular retraction muscles between protracted scapular and asymptomatic groups. [Subjects] Seven males with protracted scapular and seven asymptomatic males aged 20–30 years were recruited. [Methods] We measeured the rhomboid, middle trapezius (MT), and lower trapezius (LT) muscles activities, and calculated the isolation ratio. [Results] The rhomboid and MT isolation ratio of the protracted scapular group was not significantly different from that of the asymptomatic group. The LT isolation ratio of the protracted scapular group was significantly lower than that of the asymptomatic group. [Conclusion] We suggest that a proper retraction exercise, for patients with protracted scapular posture is one that includes exercises for selectively strengthening the lower trapezius muscle.Key words: Lower trapezius, Protracted scapular, Scapular retraction exercise     

A Study on the Differences of Quadriceps Femoris Activities by Knee Alignment during Isometric Contraction

[Purpose] This study attempted to identify how genu varum or valgum affects the electromyographic activities of the vastus medialis, vastus lateralis, and rectus femoris during knee isometric contraction. [Subjects] Fifty-two healthy young adults were enrolled in this study. They were enrolled and classified into three groups by knee alignment conditions: the genu varum, genu valgum, and control groups. [Methods] The electromyographic activity ratio of the vastus medialis to the vastus lateralis and rectus femoris were calculated using the percentage of maximum voluntary contraction. The participants contracted their quadriceps during isometric contraction at 30 and 60° of knee flexion. [Results] The genu varum group had more activity in the vastus medialis than in the vastus lateralis and rectus femoris, whereas the genu valgum group had more activity in the vastus lateralis and rectus femoris than in the vastus medialis. There was a significant difference in the muscle activity ratio between the vastus medialis and vastus lateralis by angle of knee flexion degree only in the genu valgum. There were no significant differences in any of the three groups in terms of the muscle activity ratio of the vastus medialis to the rectus femoris by angle of knee flexion. [Conclusion] The quadriceps femoris was used for different strategies according to knee alignment during isometric contraction at 30 and 60°. This study suggests that rehabilitation training programs used to strengthen the quadriceps should consider the knee alignment conditions of the target subjects.Key words: Electromyography, Quadriceps muscle, Isometric contraction     

Effects of Strength and Endurance Training of Superficial and Deep Neck Muscles on Muscle Activities and Pain Levels of Females with Chronic Neck Pain

[Purpose] To compare muscle activities and pain levels of females with chronic neck pain receiving different exercise programs. [Subjects and Methods] One hundred females with chronic neck pain participated in this study. They were randomly allocated into 4 groups (n = 25) on the basis of the exercises performed as follows: strength-endurance exercise, craniocervical flexion exercise, combination of strength-endurance and craniocervical flexion exercise and control groups. Pain, disability levels and changes in the muscle activities of the cervical erector spinae (CE), sternocleidomastoid (SCM), anterior scalenes (AS) and upper trapezius (UT) muscles were evaluated before and after the interventions. [Results] After 12 weeks of exercise intervention, all three exercise groups showed improvements in pain and disability. The muscle activities during the typing task were significantly different from the control group in all three exercise groups for all muscles except those of the extensor muscles in the craniocervical flexion exercise group. [Conclusion] The results of this study indicate that exercises for the cervical muscles improve pain and disability. The exercise programs reduced the activities of almost all cervical muscles.Key words: Chronic neck pain, Exercise, Muscle activity     

A comparison of symptomatic and asymptomatic office workers performing monotonous keyboard work--2: neck and shoulder kinematics

Prolonged static posture has been identified as a major risk factor for work-related neck and upper limb disorders (WRNULD) in computer users. Previous research has mainly examined working postures in healthy pain-free individuals. The present study examined whether symptomatic subjects exhibited the same kinematic patterns as asymptomatic controls during a prolonged computer task. In a Case-Control comparison, female office workers performed the same computer task using the same adjustable computer workstation for 1h. Three-dimensional (3D) kinematics were measured in the head-neck, thorax and shoulder (upper arm) segments. Case Group subjects (n=21) displayed trends for increased head-neck flexion angles and greater ranges of movements than the Control Group (n=17). There were also small but significant differences between groups in side flexion and rotation angles of the head-neck region. The shoulder joints displayed significantly greater flexion and abduction angles on the right in both groups, although no group differences were observed. The increased neck flexion angles were associated with significantly higher activity in the upper trapezius muscle and with neck and shoulder discomfort. The individual differences in postural habits appeared to be independent of the physical environment. These results suggest motor control changes are associated with the presence of WRNULD.     

Adaptive Patterns of Movement during Downward Reach and Pick-up Movements in Knee Osteoarthritis Patients with Mild Low Back Pain

[Purpose] Patients with severe bilateral knee osteoarthritis (KOA) often suffer from low back pain (LBP). However, few studies have examined the relationship between LBP and KOA in downward reach and pick-up movements. [Subjects] Eight KOA patients with LBP (LBP group), 8 KOA patients without LBP (NLBP group), and 7 healthy participants (Control group), without osteoarthritis or low back pain, were recruited for this study. [Methods] All subjects were asked to pick up a bottle with one hand, placed at the diagonal on the opposite side of the body. A 3D motion analysis system was used to record trunk and lower limb movements. [Results] The knee flexion angle on the side ipsilateral to the bottle was significantly smaller in both KOA groups than in the controls in the downward reach and pick-up movements. KOA patients showed a significantly lower trunk flexion angle and greater pelvis anterior tilt angle than the controls. In addition, no significant differences were found between the LBP and NLBP group. [Conclusion] We suspect that severe knee pain due to OA determines the priority of movement in strategic planning for the execution of pick-up movements. The knee strategy was abandoned by our severe knee OA patients, even when they had mild LBP.Key words: Knee osteoarthritis, Low back pain, Pick-up movement     

How Different Knee Flexion Angles Influence the Hip Extensor in the Prone Position

[Purpose] The present study examined the effects of knee flexion angle on hip extensor muscle activity. [Subjects and Methods] Twenty healthy subjects maintained knee flexion angles of 0°, 30°, 60°, 90° and 110° in the prone position and performed maximal voluntary contraction in hip extension. Maximum torque in hip extension at the different angles was measured, and surface electromyogram activities of the gluteus maximus (GM), biceps femoris (BF) and semitendinosus (ST) were recorded and normalized by the maximum voluntary isometric contraction (MVIC). [Results] The maximum torque of the hip extensor showed significant decreases between 0°and 60°, 90° and 110° of knee flexion. The muscle activity of BF was significantly high at 0°, and GM showed a significantly higher activity than both BF and ST at 60°, 90°and 110° of knee flexion. [Conclusion] The maximum torque in hip extension and muscle activities of BF and ST were significantly high at 0° but they decreased at knee flexion angles of more than 60°. Therefore, we consider that more than 60° of knee joint flexion is required to increase GM activity, and to reduce the muscle activities of BF and ST.Key words: Gluteus maximus, Hamstring muscle, Prone hip extension     

Effects of Thoracic Mobilization and Manipulation on Function and Mental State in Chronic Lower Back Pain

[Purpose] The aim of this study was to evaluate the changes in function and mental state after thoracic mobilization and manipulation in patients with chronic lower back pain (LBP). [Subjects and Methods] Thirty-six subjects were randomly divided into mobilization group (group A), manipulation group (group B) and control group (group C). The Oswestry disability index (ODI) was used to measure the functional impairment of patients with LBP. A multiple spinal diagnosis was used to measure the range of motion (ROM) of vertebra segments. The Fear-avoidance beliefs questionnaire (FABQ) was used to investigate the mental state of LBP patients. [Results] Group A and group B were significantly different from group C in terms of the ODI. Between groups, there was no difference in ROM during trunk flexion. Group A and group B were also significantly different from the control group in extension ROM. The FABQ of group B was significantly different from that of group A. [Conclusion] Application of mobilization or manipulation to thoracic lumbar vertebrae has a positive effect on function, mental state, and ROM in patients with lower back pain.Key words: LBP, Mobilization, Manipulation