OBJECTIVE: This study aimed to explore the association between arm elevation and neck/shoulder pain, and trunk forwarding bending and low back pain among home care workers.
METHODS: Home care workers (N = 116) from 11 home care units in Trondheim, Norway, filled in pain assessment and working hours questionnaire, and wore 3 accelerometers for up to 7 consecutive days. Work time was partitioned into upright awkward posture, nonawkward posture, and nonupright time, i.e. sitting. Within a compositional approach framework, posture time compositions were expressed in terms of log-ratio coordinates for statistical analysis and modeling. Poisson generalized linear mixed models were used to analyze the relationship between arm elevation in upright postures and neck/shoulder pain, and between trunk forward bending in upright postures and low back pain, respectively. Isotemporal substitution analysis was used to investigate the association of pain assessment with the reallocation of time spent in the different postures.
RESULTS: Time spent in awkward postures was modest, especially for the more extreme angles (60° and 90°). Adjusting for age, gender, and body mass index, our study suggested that the compositions of time spent by home care workers in awkward postures were significantly associated with pain assessment (P < 0.01). Isotemporal substitution analysis showed that reallocating 5 min from upright posture with arms elevated below to above 60° and 90° was associated with a 6.8% and 19.9% increase in the neck/shoulder pain score, respectively. Reallocating 5 min from a forward bending posture while upright below to above 30°, 60°, and 90° was associated with 1.8%, 3.5%, and 4.0% increase in low back pain, respectively.
CONCLUSIONS: Although the exposure to awkward postures was modest, our results showed an association between increased time spent in awkward postures and an increase in neck/shoulder pain and low back pain in home care workers. As musculoskeletal pain is the leading cause of sickness absence, these findings suggest that home care units could benefit from re-organizing work to avoid excessive arm elevation and trunk forward bending in workers.

UNASSIGNED: The normal value of the scapular muscle activity ratio during arm elevation is not clear.
UNASSIGNED: To obtain normal values of the scapular muscle activity ratio during arm elevation in healthy individuals.
UNASSIGNED: This cross-sectional study enrolled 47 healthy people. The participants performed shoulder flexion and lowered task with 90-degree movements every 2 seconds. Muscle activities of scapular muscles were measured. For normalization, the maximum isometric contraction of the shoulder flexion was measured at 90∘ (reference contraction). The integrated electromyographic value (IEMG) obtained during the task was normalized by IEMG during the reference contraction and the relative IEMG value was calculated. Then, the scapular muscle activity ratio was computed. The relationship between muscle strength and other factors was also investigated.
UNASSIGNED: The median values for upper trapezius/serratus anterior and upper trapezius/lower trapezius were often approximately 1, and that for upper trapezius/middle trapezius was often between 1 and 2. The shoulder flexion isometric strength and scapular muscle activity ratio showed significant negative correlations in multiple phases.
UNASSIGNED: Normal values for upper trapezius/serratus anterior and upper trapezius/lower trapezius during arm elevation and lowering were generally 1. Low muscle strength may contribute to an abnormal scapular muscle activity balance.

Tracking scapular motion can be challenging. More research is needed to determine the best practices for scapular measurement in multi-planar tasks. The purpose of this study was to compare the repeatability of scapular kinematics during a functional task protocol calculated from different calibration procedures. It was hypothesized that select poses would improve repeatability in specific tasks. The torso, humerus, and scapula were tracked with optical motion capture in two sessions for ten pain-free participants. Scapular calibrations were completed in five poses: neutral, maximum elevation, 90° abduction, hand to contralateral shoulder, and hand to back. Each participant completed eight functional tasks (Comb Hair, Wash Axilla, Tie Apron, Overhead Reach, Side Reach, Forward Transfer, Floor Lift, Overhead Lift). Scapular angles were calculated with five different calibration procedures and extracted at 30° increments of humeral elevation in each task. Mean difference, limits of agreement, intraclass correlations, and minimal detectable change (MDC) were calculated for each task and elevation level. The inclusion of different calibration poses did not markedly improve outcomes over the maximum elevation double calibration for most tasks. Using this calibration procedure, median MDCs were 10.0° for upward rotation, 13.7° for internal rotation, and 9.8° for tilt.

Measuring the quality of movement is a need and a challenge for clinicians. Jerk, defined as the quantity of acceleration variation, is a kinematic parameter used to assess the smoothness of movement. We aimed to assess and compare jerk metrics in asymptomatic participants for 3 important movement characteristics that are considered by clinicians during shoulder examination: dominant and non-dominant side, concentric and eccentric contraction mode, and arm elevation plane. In this pilot study, we measured jerk metrics by using Xsens® inertial measurement units strapped to the wrists for 11 different active arm movements (ascending and lowering phases): 3 bilateral maximal arm elevations in sagittal, scapular and frontal plane; 2 unilateral functional movements (hair combing and low back washing); and 2 unilateral maximal arm elevations in sagittal and scapular plane, performed with both arms alternately, right arm first. Each arm movement was repeated 3 times successively and the whole procedure was performed 3 times on different days. The recorded time series was segmented with semi-supervised algorithms. Comparisons involved the Wilcoxon signed rank test (p < 0.05) with Bonferroni correction. We included 30 right-handed asymptomatic individuals [17 men, mean (SD) age 31.9 (11.4) years]. Right jerk was significantly less than left jerk for bilateral arm elevations in all planes (all p < 0.05) and for functional movement (p < 0.05). Jerk was significantly reduced during the concentric (ascending) phase than eccentric (lowering) phase for bilateral and unilateral right and left arm elevations in all planes (all p < 0.05). Jerk during bilateral arm elevation was significantly reduced in the sagittal and scapular planes versus the frontal plane (both p < 0.01) and in the sagittal versus scapular plane (p < 0.05). Jerk during unilateral left arm elevation was significantly reduced in the sagittal versus scapular plane (p < 0.05). Jerk metrics did not differ between sagittal and scapular unilateral right arm elevation. Using inertial measurement units, jerk metrics can well describe differences between the dominant and non-dominant arm, concentric and eccentric modes and planes in arm elevation. Jerk metrics were reduced during arm movements performed with the dominant right arm during the concentric phase and in the sagittal plane. Using IMUs, jerk metrics are a promising method to assess the quality of basic shoulder movement.

Objective: To analyze the mechanism of invasive blood pressure change in radial artery caused by arm elevation by observing pressure, velocity and diameter of radial artery. Methods: Twenty-six hemodynamically stable hepatobiliary surgery patients admitted to the intensive care unit from June to December 2018 after general anesthesia in Tsinghua Changgung Hospital were selected. When the arm was raised, the invasive blood pressure was recorded, and the inner diameter and blood flow velocity of the radial artery were measured by Doppler ultrasound. The data following a normal distribution were compared with paired t test. Results: After arm elevation for 30 s, systolic blood pressure of radial artery decreased and diastolic blood pressure increased significantly((107±16) mmHg vs (120±17) mmHg, (75±6) mmHg vs (71±9) mmHg, t=25.0, -12.6, both P<0.05), but there was no significant difference in mean arterial pressure ((87±10) mmHg vs (87±11) mmHg, t=1.1, P>0.05). The peak velocity, end-diastolic velocity and resistance index of the radial artery increased significantly, and the transverse and longitudinal inner diameters of the radial artery decreased significantly after the arm was elevated for 30 s (t=-63.4, -14.6, -22.5, 31.4, 25.3, all P<0.01). Conclusions: Kinetic pressure compensation and vascular resistance compensation may be the main mechanism of radial artery pressure change when the arm is elevated. Arm elevation can be used as a vascular resistance response test clinically.
目的： 通过观测桡动脉压力、流速、直径等指标，分析抬高上肢导致桡动脉有创血压改变的流体力学机制。 方法： 选择2018年6至12月期间入住清华长庚医院重症监护病房（ICU）的血流动力学稳定的肝胆外科全身麻醉手术后患者26例。分别在抬高上肢前和抬高上肢时，记录有创血压数值，并以多普勒超声测量桡动脉置管处的动脉血管内径和血流速。符合正态分布的数据比较采用配对t检验。 结果： 与抬高上肢前相比，抬高上肢30 s后桡动脉收缩压下降、舒张压上升，分别为（107±16) mmHg比（120±17) mmHg和（75±6) mmHg比（71±9) mmHg，差异均有统计学意义（t=25.0、-12.6，均P<0.05)，但平均动脉压变化差异无统计学意义[(87±10) mmHg比（87±11) mmHg，t=1.1，P>0.05]。与抬高上肢前相比，抬高上肢30 s后桡动脉收缩期峰流速、舒张期末流速和阻力指数均显著增加，而桡动脉横径与纵径则显著减小，前后比较差异均有统计学意义（t=-63.4、-14.6、-22.5、31.4、25.3，均P<0.01)。 结论： 动压代偿和血管阻力代偿可能是抬高上肢时桡动脉压力改变的主要机制，抬高上肢可以作为血管阻力反应性试验在临床应用。.

UNASSIGNED: Gender differences in scapular kinematics during arm elevation have been reported. Because women wear brassieres (bras) daily, their scapular motion may be restricted by the garment; however, the influence of bra wearing on this motion has not been reported. Therefore, using a three-dimensional electromagnetic tracking device, we investigated the influence of bra wearing on shoulder kinematics during arm elevation.
UNASSIGNED: The subjects were 19 healthy women, and the shoulder on the dominant side was evaluated. Subjects performed scapular plane arm elevation while wearing or not wearing bras. Kinematic data were recorded using an electromagnetic tracking device. The glenohumeral elevation angle, scapular upward and internal rotation angles, and the posterior tilt angle were determined from the recorded data. The angles were calculated at 20°-120° arm elevation, and the data were compared between the two conditions.
UNASSIGNED: The scapular upward and internal rotation angles and the posterior tilt angle were significantly smaller with the subjects wearing bras than not wearing bras. In contrast, the glenohumeral elevation angle was significantly greater when bras were warn.
UNASSIGNED: Bra wearing may influence shoulder kinematics. Consequently, great care should be taken to account for this factor during the evaluation of kinematics in female subjects.

UNASSIGNED: Rotator cuff tears can influence shoulder kinematics and severely impair function. However, there have been no studies on three-dimensional (3D) shoulder kinematics in massive rotator cuff tear (MRCT) patients. Hypothesizing that MRCT patients could demonstrate significantly changed scapular kinematics during arm elevation in the scapular plane, we compared 3D scapular kinematics in the scapular plane between MRCT patients and healthy elderly subjects.
UNASSIGNED: We assessed 15 shoulders of 11 MRCT patients and 16 shoulders of 16 healthy subjects. With the subjects seated, we used an electromagnetic tracking system to calculate the upward rotation, posterior tilt, and internal rotation of the scapula at 10° increments from 30° to 120° with respect to the thorax. We performed two-way analysis of covariance with the initial position of the scapular motion as the covariate and performed multiple comparisons using the Bonferroni method.
UNASSIGNED: MRCT patients exhibited significantly higher scapular upward rotation than did the healthy subjects (P < 0.05). There were no significant differences between groups with regard to posterior tilt and internal rotation.
UNASSIGNED: This study indicated that when MRCT patients elevated their arms, they exhibited a significantly higher scapular upward rotation at low- to mid-range elevations compared with that of healthy subjects. This difference may have resulted from a compensatory effect in response to the decreased elevation torque caused by the loss of rotator cuff function. These results may assist rehabilitation strategies to improve active arm elevation in MRCT patients.

OBJECTIVE: To investigate the association and the exposure-response relationship between work above shoulder height and shoulder pain or disorders.
METHODS: A systematic search was performed in Medline, Embase, and Health and Safety Science Abstracts. Included were articles with prospective cohort, case-control, cross-sectional, or intervention study designs. Quality assessment was based on an evaluation scheme adjusted to study design and normalized to 100%. The cut-off for sufficient quality to include articles was above 40% and cut-off for high-quality articles was above 50% of maximal score. The level of strength of evidence for an association between exposure and effect was assessed according to the GRADE guidelines.
RESULTS: Thirty-four articles were included. Articles that document large effects (higher risk estimates; OR ≥ 2) have higher quality score, include analyses of severe arm elevation, more often use clinical outcome, and report an exposure-response relationship compared to studies reporting lower risk estimates. The studies that reported large effects were all significant. An exposure-response relationship was found in many high-quality studies when relating exposure intensity of arm elevation (level of arm elevation, amplitude) as well as duration of arm elevation, especially > 90°.
CONCLUSIONS: We conclude on a limited evidence for an association between arm elevation at work and shoulder disorders. Severe arm elevation with elbows above shoulder level (i.e., > 90°) shows a moderate evidence for an association with shoulder disorders.

The aim was to examine associations between cumulative occupational shoulder exposures and different diagnoses related to surgery for subacromial impingement syndrome (SIS).
We re-analysed data from a previous register-based cohort study of the Danish working population (2,374,403 persons) with follow-up 2003-2008. The outcomes were eight different SIS-related diagnosis codes (M19, M75.1-5, and M75.8-9) in combination with SIS-related surgery codes. Occupational shoulder exposures were estimated by combining occupational codes with an expert-rated job exposure matrix. Cumulative exposure estimates were calculated for 10-year time windows and expressed as exposure-years. We used a logistic regression technique equivalent to discrete survival analysis.
Exposure-response relationships were found between most occupational shoulder exposures and the different SIS-related diagnosis codes. For arm-elevation-years, M19, M75.1, and M75.4 reached maximum adjusted odds ratio (ORadj) of 2.0-2.4, while the maximum ORadj for M75.3 was 1.6; we found intermediate values for the remaining diagnoses. The relationships were almost similar for repetition-years and shoulder-load-years. For force-years, maximum ORadj of 1.7-1.9 was seen for M19, M75.1, and M75.4, while M75.3 reached a maximum ORadj of 1.3. For HAV-years, M19, M75.1, and M75.4 reached maximum ORadj of 1.5-1.7, while M75.3 reached a maximum ORadj of 1.1.
We found associations between all occupational shoulder exposures and the eight different SIS-related diagnoses; exposure-response relationships were found for most diagnoses. The highest risks were seen for M19 (acromioclavicular osteoarthritis), M75.1 (rotator cuff syndrome), and M75.4 (impingement syndrome), and the lowest for M75.3 (calcific tendinitis).

This study aimed to evaluate the effect of arm posture on activation of the anterior and posterior regions of supraspinatus and the superior and middle regions of infraspinatus during resisted isometric arm elevations. Thirty-one healthy participants performed 18 isometric resistance exertions against a force cube in three elevation planes (flexion, scaption, abduction) and three elevation angles (30°, 90°, 150°) in maximal and sub-maximal resistance conditions. EMG data were obtained using four pairs of fine wire electrodes. The mean activation of each region and the activation ratios were compared across postures using ANOVAs. Supraspinatus anterior was significantly more active during abduction and scaption, and in higher elevation angles, while the posterior region showed similar activation levels across postures. Infraspinatus regions were more active during flexion with more relative activation of the infraspinatus superior at 90° flexion. The results suggest that regional activation of supraspinatus and infraspinatus should be considered for assessment and rehabilitation purposes. In any clinical setting where it is important to reduce the stress on the supraspinatus anterior, isometric flexion exercises performed with arm in low elevation angles could provide the opportunity to strengthen the posterior region of supraspinatus with limited stress on the anterior region. Beside external rotation exertions, resisted flexion tests may be useful for evaluation of infraspinatus regions.