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Objective: To examine the relationships between contexts of physical activity, grit, and GPA in a college population. Participants: 875 Undergraduate students from a large, southern university participated between October 2018 and March 2020. Methods: Participants completed an electronic survey evaluating physical activity and grit. The university provided official GPAs. Multiple linear regression models evaluated the correlations between grit, the different physical activity domains, and GPA. Results: Grit was positively associated with domestic physical activity, leisure time physical activity, and GPA. Consistency of interest had no associations with the domains of physical activity or GPA. Perseverance of effort was positively associated with walking, active transport physical activity, domestic physical activity, leisure physical activity, and GPA. Conclusion: Perseverance of effort is related to different domains of physical activity and GPA. Future studies should investigate if increasing leisure time physical activity causes increases in perseverance of effort.

Postural assessments of the lumbar spine lack valuable information about its properties. The purpose of this study was to assess neutral zone (NZ) characteristics via in vivo lumbar spine passive stiffness and relate NZ characteristics to standing lumbar lordosis. A comparison was made between those that develop low back pain during prolonged standing (pain developers) and those that do not (nonpain developers). Twenty-two participants with known pain status stood on level ground, and median lumbar lordosis angle was calculated. Participants were then placed in a near-frictionless jig to characterize their passive stiffness curve and location of their NZ. Overall, both pain developers and nonpain developers stood with a lumbar lordosis angle that was more extended than their NZ boundary. Pain developers stood slightly more extended (in comparison to nonpain developers) and had a lower moment corresponding to the location of their extension NZ boundary. Overall, in comparison to nonpain developers, pain developers displayed a lower moment corresponding to the location of their extension NZ boundary which could correspond to greater laxity in the lumbar spine. This may indicate why pain developers have a tendency to stand further beyond their NZ with greater muscle co-contraction. [ABSTRACT FROM AUTHOR]

A popular posture for using wireless technology is reclined sitting, with the trunk rotated posteriorly to the hips. This position decreases the head's gravitational moment; however, the head angle relative to the trunk is similar to that of upright sitting when using a tablet in the lap. This study compared cervical extensor musculotendon length changes from neutral among 3 common sitting postures and maximum neck flexion while using a tablet. Twenty-one participants had radiographs taken in neutral, full-flexion, and upright, semireclined, and reclined postures with a tablet in their lap. A biomechanical model was used to calculate subject-specific normalized musculotendon lengths for 27 cervical musculotendon segments. The lower cervical spine was more flexed during reclined sitting, but the skull was more flexed during upright sitting. Normalized musculotendon length increased in the reclined compared with an upright sitting position for the C4-C6/7 (deep) and C2-C6/7 (superficial) multifidi, semispinalis cervicis (C2-C7), and splenius capitis (Skull-C7). The suboccipital (R2 =.19–.71) and semispinalis capitis segment length changes were significantly correlated with the Skull-C1 angle (0.24–0.51). A semireclined reading position may be an ideal sitting posture to reduce the head's gravitational moment arm without overstretching the assessed muscles. [ABSTRACT FROM AUTHOR]

ObjectiveTo examine the relationships between contexts of physical activity, grit, and GPA in a college population. Participants: 875 Undergraduate students from a large, southern university participated between October 2018 and March 2020. Methods: Participants completed an electronic survey evaluating physical activity and grit. The university provided official GPAs. Multiple linear regression models evaluated the correlations between grit, the different physical activity domains, and GPA. Results: Grit was positively associated with domestic physical activity, leisure time physical activity, and GPA. Consistency of interest had no associations with the domains of physical activity or GPA. Perseverance of effort was positively associated with walking, active transport physical activity, domestic physical activity, leisure physical activity, and GPA. Conclusion: Perseverance of effort is related to different domains of physical activity and GPA. Future studies should investigate if increasing leisure time physical activity causes increases in perseverance of effort. [ABSTRACT FROM AUTHOR]

Objective: To determine how ultrawide (UW) and dual displays configurations can influence neck biomechanics and performance compared to a single display. Background: Studies have assessed neck kinematics and performance when using dual displays, but these studies have used screen sizes smaller than today's display size, have inconsistent participant placement, and few have assessed these two variables together. Methods: Seventeen participants completed five tasks on six display configurations. Neck kinematics and performance were tracked for each configuration. Results: Centered configurations produced significantly different median neck rotation angles compared to secondary configurations (p <.001) for three of the tasks. A 34" curved UW display with a longer viewing distance produced similar neck kinematics to a single 24" display with the potential to also reduce screen interactions. When compared to single, the benefit of secondary versus centered monitors was dependent on the type of task being performed. Users may prefer the UW, centered dual, and secondary dual configurations over the single display. Conclusion: The benefit of secondary versus centered displays is dependent on the type of task being performed. Dual displays are still beneficial but should be used with a monitor arm to switch between centered and secondary configurations as necessary. Future work should look at larger UW displays to see if these results hold compared to dual display configurations. Application: The results can be used to make evidence-based guidelines for displays based on size and task. Researchers can use this information to design future studies looking at specific configurations. [ABSTRACT FROM AUTHOR]

Minimal data exist on the neutral position for the lumbar spine, trunk, and thighs when adopting a hybrid posture. This study examined sex differences in the neutral zone lumbar stiffness and the lumbar and trunk-thigh angle boundaries of the neutral zone, and determined if the standing lumbar angle fell within the neutral zone. Passive lumbar flexion and extension moment-angle curves were generated for 31 participants (13 M, 18 F), pooled from two datasets, with trunk-thigh angles available for 10 participants. The neutral zone was defined as the low stiffness zone from both the flexion and extension curves. Males demonstrated significantly greater extensor stiffness. Neutral lumbar and trunk-thigh angles ranged on average −22.2 to 0.2° and 124.2 to 159.6° for males and −17.8 to −1.3° and 143.2 to 159.5° for females, respectively. Standing lumbar angles fell outside the neutral zone for 44% of participants. These neutral zone boundaries may inform kinematics for hybrid chair designs. Practitioner summary: Adoption of a neutral spinal posture may be achieved through hybrid chair design, yet minimal data exists on a physiologically defined neutral zone. Using measures of in vivo lumbar stiffness, the lumbar and trunk-thigh angular boundaries of the neutral zone were defined for both males and females. Abbreviations: EMG: electromyography; MVC: maximal voluntary contraction [ABSTRACT FROM AUTHOR]

While the individual tissues of the vertebral joint demonstrate viscoelastic properties, the global viscoelastic properties of the lumbar vertebral joint are not well established. This study investigated how changes in displacement rate influenced the mechanical response of the porcine cervical spine (a surrogate or model for the human lumbar spine) exposed to acute anterior shear failure loading. Thirty porcine cervical spine specimens (15 C3-C4 and 15 C5-C6) were placed under a 1600 N compressive load and subsequently loaded in anterior shear to failure at one of three randomly assigned displacement rates (1 mm/s, 4 mm/s, or 16 mm/s). Ultimate anterior shear force, ultimate displacement, average stiffness, and energy stored until failure were calculated. Load rate in the elastic region was also calculated to compare the load rates used in this study to those used in previous studies. Changes in displacement rate affected the C3-C4 and C5-C6 specimens differently. C5-C6 specimens tested at 16 mm/s had an ultimate force that was 28% and 23% higher than at 1 (p = 0.0215) and 4 mm/s (p = 0.0461), respectively. The average stiffness to failure of the C5-C6 specimens tested at 16 mm/s was 52% higher than at 4 mm/s (p = 0.0289). No such differences were found for the C3-C4 specimens. An increase in the anterior shear displacement rate did not necessarily demonstrate viscoelasticity of the vertebral joint. Specimen intervertebral levels were affected differently by changes in anterior shear displacement rate, which may have been a result of anatomical and postural differences between the two levels. Future studies should further investigate the effect of displacement rate on the spine and the inconsistencies between different specimen levels. [DOI: 10.1115/1.4001885]

Objective: To compare the impact of multiple computer monitor configurations on health and performance outcomes compared to the use of a single monitor.Background: Multiple monitor configurations are used in office settings to promote increased productivity by providing more screen space; however, it is unknown if there are health-related trade-offs to increased productivity.Method: A systematic review was conducted according to the PRISMA statement guidelines and adapted the best evidence synthesis.Results: Eighteen studies were included in our review. There was strong evidence that implementing dual monitors is in line with users' preference. There was also moderate evidence for controlled laboratory studies demonstrating that multiple monitors may increase task efficiency with decreased desktop interaction; however, implementing multiple monitors may also result in nonneutral neck postures for users.Conclusion: More research needs to be conducted on biomechanical exposures when using larger displays. Longitudinal field studies should be conducted to determine the influence of monitor interventions on health, productivity, and well-being. All studies must consider task complexity and user positioning and should measure health and productivity outcomes together. Researchers must also consider up-to-date purchasing trends when choosing the monitor configurations and sizes for their studies.Application: Regulatory bodies and practitioners can use the results to develop evidence-based monitor guidelines and inform decision-making in practice, respectively. Researchers can use this information to design future studies on monitor configurations that incorporate current purchasing trends. [ABSTRACT FROM AUTHOR]

BACKGROUND: Along with quantitative measures, pain symptoms may help inform early interventions to prevent prolonged standing induced low back pain (LBP); however, the relationship between quantitative and qualitative measures has not been assessed. OBJECTIVE: Determine the relationship between qualitative and quantitative measures of pain development during prolonged standing induced LBP development. METHODS: Thirty-five participants performed two-hours of standing. A visual analog scale (VAS) and the Short-Form McGill Pain Questionnaire were used to assess the participant's LBP every 7.5-minutes. Participants were classified as a pain developer (PD) based on VAS scores or three consecutive pain symptom reports. RESULTS: Pain symptom reports occurred 31.3 (±24.8) minutes earlier than the VAS reports. Eight participants (44%) were non-PDs with the VAS and PDs with the symptom method (p = 0.0047). CONCLUSIONS: A subset of participants who were not categorized as LBP developers during prolonged standing using the VAS method still report LBP symptoms. The inclusion of pain symptom reporting could provide additional information for practitioners when identifying individuals who would benefit from early interventions for standing induced LBP. [ABSTRACT FROM AUTHOR]

Occupations requiring prolonged periods of static standing are associated with the development of low back pain (LBP). Certain individuals are susceptible to LBP development during prolonged standing (pain developers, PDs) while others are not (non-pain developers, NPDs). Linear centre of pressure (COP) measures suggest that standing balance control is negatively influenced following prolonged standing, and that PDs and NPDs may be differentially affected. The objective of this study was to determine if nonlinear standing balance control, quantified on COP, using sample entropy, is altered after 2-h of standing. Thirty two participants stood for 2-h. Separate 2-min standing trials, performed with eyes open and eyes closed, were collected before and after the 2-h standing protocol. Sample entropy, median power frequency and RMS amplitude of the COP time-series, was calculated from the 2-min standing trials for all participants. For comparison, participants were classified, post hoc, as PDs or NPDs according to visual analog scale pain scores. Sample entropy decreased after 2-h of standing for both PDs and NPDs, however, the decrease for NPDs was only 21% of the decrease observed in PDs. This study demonstrated that nonlinear control of upright standing changes after 2- hours of standing, resulting in an increase in COP regularity post 2- hours of standing for both PDs and NPDs. PDs displayed a greater change in COP regularity, which is supported by the theory that increased COP regularity occurs with pain/pathology. [ABSTRACT FROM AUTHOR]

BACKGROUND: With the increase of tablet usage in both office and industrial workplaces, it is critical to investigate the influence of tablet usage on spine posture and movement. OBJECTIVE: To quantify spine kinematics while participants interacted with a tablet or desktop computer. METHODS: Fourteen participants volunteered for this study. Marker clusters were fixed onto body regions to analyze cervical and lumbar spine posture and sampled at 32 Hz (Optotrak Certus, NDI, Waterloo, Canada). Participants sat for one hour in total. Cervical and lumbar median angles and range of motion (10th to 90th % ile angles) were extracted from amplitude probability distribution functions performed on the angle data. RESULTS: Using a sloped desk surface at 15°, compared to a flat desk, influenced cervical flexion (p = 0.0228). Completing the form fill task resulted in the highest degree of cervical flexion (p = 0.0008) compared to the other tasks completed with cervical angles between 6.1°-8.5° higher than emailing and reading respectively. An interaction between device and task (p = 0.0061) was found for relative lumbar median spine angles. CONCLUSIONS: Increased lumbar flexion was recorded when using a computer versus a tablet to complete various tasks. Task influenced both cervical and lumbar spine posture with the highest cervical flexion occurring while completing a simulated data entry task. A work surface slope of 15° decreased cervical spine flexion compared to a horizontal work surface slope. [ABSTRACT FROM AUTHOR]

During their commute, pedestrians encounter a variety of staircase designs. One such design is the oblique staircase that allows pedestrians to descend at an angle. The purpose of this study was to assess the influence of an oblique path of descent on heel and toe clearance, and toe placement on a step. Sixteen participants descended a staircase on an angled path at three angles: 0° (perpendicular), 25°, and 45°. Toe placement and foot clearances were compared between the descent angles and feet. An increase in descent angle demonstrated increased clearance of the heel apex compared with straight descent; however, the aspect of the foot closest to the stair changes in angled descent, moving from the apex to the side of the heel. A greater portion of the foot was placed on the stair tread during angled descent. Future work should address the influence of angled descent on fall risk. [ABSTRACT FROM AUTHOR]

Background Approximately 50% of a sample population will develop prolonged standing induced low back pain. The cause of this pain may be due to their lumbar spine posture. The purpose of this study was to investigate differences in lumbar posture between 17 participants categorized as a pain or non-pain developers during level ground standing. A secondary purpose was to evaluate the influence of two standing aids (an elevated surface to act as a foot rest and declined sloped surface) on lumbopelvic posture. Methods Four sagittal plane radiographs were taken: a normal standing position on level ground, when using an elevated foot rest, using a declined sloped surface, and maximum lumbar spine extension as a reference posture. Lumbosacral lordosis, total lumbar lordosis, and L1/L2 and L5/S1 intervertebral joint angles were measured on each radiograph. Findings There was a significant difference between the lumbosacral lordosis angle and L5/S1 angles in upright versus maximum extension; however, this was independent of pain group. The elevated surface was most effective at causing lumbosacral spine flexion. Interpretation Potentially successful postures for eliminating low back pain during prolonged standing mainly influence the lower lumbar lordosis. Future work should assess the influence of hip posture on low back pain development during standing. [ABSTRACT FROM AUTHOR]

Objective: We evaluated the effect of work surface angle and input hardware on upper-limb posture when using a hybrid computer workstation.Background: Offices use sit-stand and/or tablet workstations to increase worker mobility. These workstations may have negative effects on upper-limb joints by increasing time spent in non-neutral postures, but a hybrid standing workstation may improve working postures.Method: Fourteen participants completed office tasks in four workstation configurations: a horizontal or sloped 15° working surface with computer or tablet hardware. Three-dimensional right upper-limb postures were recorded during three tasks: reading, form filling, and writing e-mails. Amplitude probability distribution functions determined the median and range of upper-limb postures.Results: The sloped-surface tablet workstation decreased wrist ulnar deviation by 5° when compared to the horizontal-surface computer when reading. When using computer input devices (keyboard and mouse), the shoulder, elbow, and wrist were closest to neutral joint postures when working on a horizontal work surface. The elbow was 23° and 15° more extended, whereas the wrist was 6° less ulnar deviated, when reading compared to typing forms or e-mails.Conclusion: We recommend that the horizontal-surface computer configuration be used for typing and the sloped-surface tablet configuration be used for intermittent reading tasks in this hybrid workstation.Application: Offices with mobile employees could use this workstation for alternating their upper-extremity postures; however, other aspects of the device need further investigation. [ABSTRACT FROM AUTHOR]

With the recent attention to ‘sitting disease’, health practitioners and scientists are promoting standing in the workplace to decrease sedentary time, despite a high prevalence of low back pain (LBP) development during prolonged standing. The purpose of this study was to assess how a seated break inserted between bouts of prolonged standing would influence LBP development, posture and movement. A total of 20 participants stood for 45 minutes, sat for 15 minutes and repeated this sequence while lumbar and thoracic angles were measured, and LBP visual analogue scale reports were taken. Of the sample, 55% participants reported LBP in standing. A stand to sit ratio of 3:1 did not provide lasting recovery of LBP from standing and pain developers utilised a limited range of their lumbar spine angle and increased thoracic extension, resulting in static postures that caused tissue aggravation that was not resolved after 15 minutes of sitting. Prolonged standing in the workplace has the potential to result in LBP for some workers and alternate ways to reduce sedentary time should be investigated. Practitioner Summary:Recommending standing to replace sitting should be undertaken with caution. A ratio of 3:1 (stand to sit) did not mitigate standing induced LBP. Practitioners should consider the interplay between standing and seated work and provide a variety of activities to reduce sedentary time tailored to work, preference and tolerance for an activity. [ABSTRACT FROM PUBLISHER]

Highlights: [•] We examined temporospatial, lower limb kinematics in staircase descent. [•] We looked at 3 different angles of descent down a staircase. [•] Adaptations at an angle were mainly seen in step width, length. [•] Stance, swing, and double support phase proportions were unchanged. [•] Older adults may have an issue with performing these adaptations. [Copyright &y& Elsevier]

In this paper, a computerised system for measuring muscle thicknesses of the transverse abdominus (TrA), internal oblique and external oblique muscles based on ultrasonography is presented. The system is designed to allow for quantitative analysis of changes in muscle recruitment and activity, which facilitates the study of such changes and its relationship with low back pain. The abdominal muscle area was localised and imaged under different standing conditions using B-mode ultrasonography. To account for issues such as misalignments due to probe and subject motion as well as speckle noise inherent to ultrasonography, automatic ensemble registration is performed on the acquired images using a sequential quadratic programming approach based on a novel log-Rayleigh likelihood function. Regions of interest are then automatically identified based on the medial border of the TrA for the purpose of quantitative muscle thickness measurements. Experimental results show that the proposed system achieves registration errors of under 0.4 mm when compared with ground-truth measurements, as well as allow for the measurement of muscle thickness changes in the millimetre range. The proposed system is currently in operational use as an analysis tool for studying the relationship between abdominal muscle thickness changes and postural changes. [ABSTRACT FROM PUBLISHER]

OCCUPATIONAL APPLICATIONSThe National Occupational Research Agenda for Musculoskeletal Health in the United States identified that with the changing nature of the traditional office environment, mobile devices are now frequently used for longer durations, warranting research on the impacts of mobile computing on musculoskeletal health. A recent study of office workers showed that those with "smartphone overuse" were six times more likely to report neck pain. Working in pain may also result in withdrawal and less proactive extra-role behaviors at work (such as making recommendations at work and willing to help colleagues). We found that 30-minutes of mobile device use resulted in pain reporting in the neck and upper back when the device was used with neck flexion. This musculoskeletal pain could lead to acute concerns during the workday and long-term problems over time.