Variations in Concurrent Validity of Two Independent Inertial Measurement Units Compared to Gold Standard for Upper Body Posture during Computerised Device Use.

Inertial measurement units (IMUs) may provide an objective method for measuring posture during computer use, but research is needed to validate IMUs' accuracy. We examine the concurrent validity of two different IMU systems in measuring three-dimensional (3D) upper body posture relative to a motion capture system (Mocap) as a potential device to assess postures outside a laboratory environment. We used 3D Mocap and two IMU systems (Wi-Fi and Bluetooth) to capture the upper body posture of twenty-six individuals during three physical computer working conditions (monitor correct, monitor raised, and laptop). Coefficient of determination (R2) and root-mean-square error (RMSE) compared IMUs to Mocap. Head/neck segment [HN], upper trunk segment [UTS], and joint angle [HN-UTS] were the primary variables. Wi-Fi IMUs demonstrated high validity for HN and UTS (sagittal plane) and HN-UTS (frontal plane) for all conditions, and for HN rotation movements (both for the monitor correct and monitor raised conditions), others moderate to poor. Bluetooth IMUs for HN, and UTS (sagittal plane) for the monitor correct, laptop, and monitor raised conditions were moderate. Frontal plane movements except UTS (monitor correct and laptop) and all rotation had poor validity. Both IMU systems were affected by gyroscopic drift with sporadic data loss in Bluetooth IMUs. Wi-Fi IMUs had more acceptable accuracy when measuring upper body posture during computer use compared to Mocap, except for trunk rotations. Variation in IMU systems' performance suggests validation in the task-specific movement(s) is essential.

Association between constitution, axiography, orthodontic cast analysis, and upper body posture in women aged 31 to 40 years.

OBJECTIVE: Whether it is primarily the spine that reacts with pain to the negative consequences of everyday stress and possibly the temporomandibular system as a result (ascending chain), or whether incorrect stress in the dental area has an influence on body geometry (descending chain), is still a controversially discussed topic. The aim of this study is to investigate possible relationships between constitutional, axiographic, and dental parameters with upper body posture. MATERIAL AND METHODS: A total of 106 subjectively healthy women between 31 and 40 years of age voluntarily participated in this study. Data collection was done by filling out a questionnaire with constitutional and anamnestic parameters and by evaluating orthodontic casts, axiographic measurements, and video raster stereographic measurements. These data were analyzed using correlations and group comparisons, with the significance level set at p ≤ 0.05. RESULTS: Positive correlations were shown between the constitutional factors of body weight and BMI and the lumbar bending angle (p = 0.01), the kyphosis angle (p = 0.001), and lordosis angle (weight p = 0.05; BMI p = 0.03). In the cast analysis, regardless of the direction of the midline shift (left/right/none), a left lateral tilt can be seen which is greatest at 2.12° with a left midline shift. In addition, the elevated pelvic side correlates with the side of the displacement of the jaw, with the stronger manifestation being on the left side. With a vertical anterior bite in the normal range, the kyphosis angle is 48.09°, while with a deep bite, it is 60.92°, and with an open bite, it is 62.47°; thus, the group in the normal range differs significantly (p = 0.01) from the other two. The greater the protrusion, the smaller the sagittal plane angles (kyphosis angle, lumbar bending angle, each p = 0.03), and the more dorsal the posture (p = 0.04). The lordosis angle differs significantly (p = 0.001) between the group of subjects with a protrusion in the normal range (52.34°) and the group with an increased advancement of the mandible (41.79°). CONCLUSION: There is a correlation between body weight, BMI, midline shift, and protrusion, as well as the vertical anterior step and upper body posture in women between 31 and 40 years of age. Interdisciplinary functional examinations of the temporomandibular musculature, and also sustained orthodontic treatment, can contribute to an improvement in upper body posture.

Musculoskeletal complaints, postural patterns and psychosocial workplace predictors in police officers from an organizational unit of a German federal state police force - a study protocol.

BACKGROUND: Police officers are exposed to a particularly high risk of musculoskeletal disorders (MSDs) and psychosocial stress due to their working conditions. Therefore, the aim of this project will be to assess the occupational physical and mental health of police officers from an organizational unit of the police force of a German federal state. METHODS: The aim is to analyze at least 200 active police officers of a state police force in Germany between the age of 18 and 65 years. In a mixed-methods design, a video raster stereography-based measurement of the upper body posture and a modified version of the Nordic Questionnaire (NQ) will be used for investigating their physical health, while the Copenhagen Psychosocial Questionnaire (COPSOQ) and the Operational Police Stress Questionnaire (PSQ-Op) will be used to analyze their mental health. In addition, job-specific psychosocial factors at the workplace will be assessed (using self-designed questions that were previously evaluated in an expert interview). DISCUSSION: To date, there is a lack of current questionnaire-based data on the prevalence of MSDs in police officers, or of MSDs associated with injuries or psychosocial workplace factors. Thus, in this study, these MSDs will be correlated with quantitative upper body posture data. If these results prove an increased physical and/or psychosocial stress, then the existing workplace health promotion measures should be analyzed and modified if necessary.

Standard reference values of the upper body posture in healthy male adults aged between 31 and 40 years in Germany-an observational study.

BACKGROUND: In order to classify and analyze the parameters of upper body posture, a baseline in the form of standard values is demanded. To this date, standard values have only been published for healthy men aged 18-35 and 41-50 years. Data for male adults aged between 31 and 40 years are lacking. METHODS: The postural parameters of 101 symptom-free male volunteers aged 31-40 (35.58 ± 2.88) years were studied. The mean height of the men was 179.89 ± 7.38 cm, with a mean body weight of 86.36 ± 11.58 kg and an average BMI of 26.70 ± 3.35 kg/m2. By means of video rasterstereography, a 3-dimensional scan of the upper back surface was measured in a habitual standing position. The means or medians, confidence interval, tolerance range, and group comparisons and correlations of BMI and physical activity were calculated for all parameters. RESULTS: The habitual standing position was found to be almost symmetrical and the axis aligned in the spine, pelvis, and shoulder region, while the spine position was marginally inclined ventrally. The kyphosis angle of the thoracic spine was greater than the lordosis angle of the lumbar spine. All deviations fell under the measurement error margin of 1 mm/1°. The greater the BMI, the greater was the pelvic and scapular distance. The lower the BMI, the further caudally positioned was the right shoulder. The pelvic and scapular distances were also lower with the increasing athleticism of the participants. CONCLUSION: The upper body posture of men between the ages of 31 and 40 years was found to be almost symmetrical and axis-conforming, with the kyphosis angle, pelvic distance, and shoulder distance enlarging with increasing BMI. Consequently, postural parameters presented in this survey allow for comparisons with other studies, as well as the evaluation of clinical diagnostics and applications.

Systematic changes of the static upper body posture with a symmetric occlusion condition.

BACKGROUND: Temporary occlusal changes and their influence on the upper body statics are still controversially discussed. Furthermore, concrete statements on whether age- or gender-specific differences in neurophysiological reactions exist are missing. Therefore, it is the aim of this study to evaluate the immediate effects of a symmetrical occlusion blocking on the upper body posture. These effects shall be investigated for both genders and for a larger age range. METHODS: In this study, 800 (407f/393 m) subjects volunteered aged from 21 to 60 years. Both genders were divided into four age groups according to decades. The three-dimensional upper body posture was measured by using the rasterstereography (ABW-Bodymapper). The habitual static posture was measured in two dental occlusion conditions (a) in rest position and (b) symmetrical blocking in the bicuspid region by cotton rolls. RESULTS: A significant reduction of the trunk length (0.72 mm; p <  0.001), an increase of the lumbar (0.30°; p <  0.001) and the thoracic bending angle (0.14°; p = 0.001), a reduction of the spinal forward decline (0.16°; p <  0.001) and a reduction of the scapular distance (0.36 mm; p = 0.001) was found. Gender-specific reactions can only be recorded in scapular distance, in that regard men reduce this distance while over all age groups women did not show a significant change. DISCUSSION: Slight gender- and age-independent reactions due to a symmetric occlusion blockade are shown: A gender independent reaction of the spinal related variables in the sagittal plane (thoracic and lumbar flexion angle, trunk length, spinal forward decline). In addition, a gender specific change of the shoulder blade distance could be observed, where men reduced the distance while female did not show a change. However, since these reactions are of a minimum amount, it can be concluded that neurophysiological compensation mechanisms work equally well regardless of age and sex, and the upper body posture of healthy people changes only very slightly due to a temporarily symmetrical altered bite position.

Comparison between the musician-specific seating position of high string bow players and their habitual seating position - a video raster stereographic study of the dorsal upper body posture.

BACKGROUND: Effects of playing high stringed bow instruments on the upper body posture have not been analysed so far. The instrument-specific seating position when playing in an orchestra is compared to the habitual seating position. METHODS: Three dimensional back scans were performed in 13 professional violinists and viola players of a radio orchestra (8 f / 5 m). Trunk position in their habitual seating position and in the instrument- specific seating position imitating playing was compared. Statistical differences were calculated using Wilcoxon Matched Pairs Test with Bonferroni Holm correction. RESULTS: Significant differences were found between the seated position with instrument and without (p < 0.001, 0.03, 0.02 or 0.01) in the spine (trunk length, sagittal trunk decline, lumbar bending angle, maximal rotation, standard deviation rotation, lumbar lordosis), the shoulder (scapula distance, scapula rotation, scapula angle right) and pelvis distance. CONCLUSIONS: Playing an instrument changes the static seating position by increased rotation of the spine and specific shoulder adaptations holding the instrument (left arm) and the bow (right arm), with minor effects on the pelvis. This forced position may result in chronic health effects. The method used in this study is an approach to better understand the involved muscular structures and possible resulting health damages.

Standard values of the upper body posture and postural control: a study protocol.

BACKGROUND: Decisions on orthopedic interventions on upper body posture and its control have usually resulted from comparisons with the healthy state. Therefore, practitioners as well as scientists in human movement science or orthopedics need access to such kind of data which are patient-centered and well measured. Until now, these data have been missing concerning upper body posture as well as postural control and their control. That is why the aim of the current project is to measure these data with healthy participants across the lifespan. RESULTS: For standard value determination tolerance range and confidence intervals will be calculated. In addition, Pearson- or Spearman-Rank correlations will be used as well as two-sample-t-tests or Mann-Whitney-U-tests for specific group differences. All tests will be two-sided with the level of significance of 5 %. DISCUSSION: This project aims at improving classifications in adaptations of upper body posture and postural control. Measured standard values have not been determined before to this extent. Therefore, interventional effects may become better quantifiable and justiciable.

The impact of a total hip replacement on jaw position, upper body posture and body sway.

OBJECTIVES: The purpose of this study was to examine whether, and to what extent, a total hip replacement can influence the position and the movement of the jaw, the upper body posture and body sway. METHODS: Twenty test subjects (6 females, 14 males) participated in this study pre- and post-total hip replacement, in addition to a healthy control group of 20 subjects (5 females, 15 males). The measurements were conducted by means of an ultrasound system to measure jaw condyle position and movement of the lower jaw, a three-dimensional back scan to analyze upper back posture, and a static and dynamic force plate to measure body sway. For statistical analysis the Wilcoxon-Matched-Pairs-Test or Man-Whitney-U-Test, including a Bonferroni-Holm correction, respectively, was used. RESULTS: After surgery, the mean values of the left and right jaw condyles of the test group moved posterior, and the left condyle position was located more caudally. There were no significant differences concerning the jaw position between the two groups. There was little change in upper body posture in both groups. The test group had a more anteriorly inclined thoracic spine and a less pronounced lumbar lordosis. During static body sway measurements, increased fluctuations in the test group after surgery could be seen. CONCLUSION: Differences between both groups in the pre- and post-surgical condition could be detected. These differences were more prominent when the measured body segments were more distally located with respect to the hip region.