Lumbar postures, seat interface pressures and discomfort responses to a novel thoracic support for police officers during prolonged simulated driving exposures

The Vehicle Seating Intervention Trial: Cross-Over Randomized Controlled Trial to Evaluate the Impact of 2 Car Seat Configurations on Spinal Posture

Driving posture can lead to musculoskeletal pain. Most work focuses on the lower back; therefore, we know little about automobile seat design and neck posture. This study evaluated an automobile driver seat that individualized upper back support to improve head and neck posture. Specifically, we examined the system's impact on anterior head translation with secondary outcomes of spine posture and perceptions of comfort/well-being compared with a control. Forty participants were block randomized to experience either the activated or deactivated version of the same seating system first. Participants completed two 30-minute simulated driving trials, separated by washout, with continuous measures of anterior head translation, spine posture, and pelvis orientation. Perceptions of comfort/well-being were assessed by survey and open-ended questions immediately following each condition. Small, but statistically significant decreases in anterior head translation and posterior pelvic tilt occurred with the activated seat system. Participants reported lower satisfaction with the activated seat system. Order of the 2 seat conditions affected differences in pelvis orientation and participant perceptions of comfort/well-being. An anthropometric-based seat system targeting upper back support can significantly affect head and pelvic posture but not satisfaction during simulated driving. Future work should examine long-term impacts of these posture changes on health outcomes.

Moving Toward Individual-Specific Automotive Seat Design: How Individual Characteristics and Time Alter the Selected Lumbar Support Prominence

OBJECTIVE

To explore how individual characteristics influence selected lumbar support prominence (LSP), seated lumbar flexion, seatback average pressure, contact area, and center of pressure (CoP) location before and after 1 hr of driving.

BACKGROUND

An LSP can alter posture and may reduce low back pain during prolonged driving. Although LSP preference varies across individuals and may change over time, few investigations have explored the time-varying response to individually selected adjustable seat parameters.

METHOD

Forty individuals selected LSP settings in an automotive seat through a series of systematic adjustment trials. The average LSP setting was fixed for a 1-hr driving simulation, followed by one final adjustment trial. Regressions were performed between individual characteristics and selected LSP, lumbar posture, and measures of seatback pressure from the initial adjustment trials. ANOVAs were performed to determine the effect of time and sex on these dependent variables. Discomfort was also monitored throughout the protocol.

RESULTS

Individual's standing lumbar lordosis, selected LSP, and height and mass were significant predictors for seated lumbar flexion, seatback average pressure, and contact area, respectively. Discomfort levels remained low; however, following the driving protocol, individuals altered their posture to decrease lumbar flexion and increase seatback average pressure without significant adjustments to the LSP.

CONCLUSION

These findings highlight individual characteristics to consider in automotive seat design and that the method for determining LSP settings may facilitate appropriate LSP selection.

APPLICATION

A systematic method to determine LSP settings may reduce discomfort and automate seat adjustments, such that only short-term postural adjustments may be required.

Health, Safety, and Wellness Concerns Among Law Enforcement Officers: An Inductive Approach

Background: Although studies have assessed the impact of occupational risk factors on the health of law enforcement officers (LEO's), few have involved (LEO's) as informants in ways that allow their points of view to be heard directly. Thus, the objective of this study is to explore the occupational health, safety, and wellness (OHSW) concerns of (LEO's). Methods: (LEO's) working in Quebec, Canada were invited to answer an open-ended question regarding their OHSW concerns. Using a multi-stage content analysis, the collected answers were analyzed and coded by two members of the research team to identify the most recurrent concerns of (LEO's). Findings: Five themes relating to the OHSW concerns of (LEO's) were identified, namely, the work schedule, occupational stress, work equipment, workplace health promotion, and operational risks. Furthermore, our analyses highlighted differences in the concerns of (LEO's) based on their level of experience and sex. Conclusions/Application to Practice: This study addresses a gap in the literature on the OHSW concerns from the perspective of (LEO's). Overall, our results support that the work schedule and occupational stress associated with law enforcement are the two most recurrent concerns of (LEO's). Thus, the results of this study further stress the need for police organizations to implement strategies and policies, which could mitigate the deleterious effects of these hazards on the overall wellness of (LEO's).

Can training trunk musculature influence musculoskeletal pain and physical performance in military police officers?

To investigate the effect of a Trunk Training (TT) program on the general musculoskeletal pain (GMP) and physical performance of Military Police Officers. Twenty officers were divided into either control group (CG) or TT group (TTG). Both groups performed nine weeks of traditional physical training. However, the TTG had 25-minutes allocated to TT during each scheduled physical training period. Anthropometric, trunk endurance, and physical fitness tests were completed pre- and post-training for both groups. Both groups also answered a weekly questionnaire about their GMP. Post-training, trunk endurance performance was significantly higher (p < 0.05) and the GMP significantly lower (p < 0.05) in the TTG when compared to the CG. Improvement in side plank test scores was associated with a decreased in GMP (r = -0.495, p < 0.05). TT can reduce the perception of GMP in addition to increasing the endurance of the trunk muscles. The side plank was the only physical test associated with GMP. Practitioner summary: Trunk Training can reduce general musculoskeletal pain and increase the endurance of the trunk muscles without a concomitant loss in general fitness in elite Military Police Officers. This research lasted 11 weeks and presents real-world and pragmatic findings.

Optimizing Backrest Geometry to Minimize Interfacial Pressure Concentrations in the Mid-To-Lumbar Region During Leg Press Resistance Training

The leg press is a resistance training (RT) exercise common to both weight- and powerlifting, where spine-related injuries remain prevalent. Here, the elevated loading has the potential to result in increased pressure on vertebral bodies and introduce the risk of spinal injury. This study therefore investigates back interfacial pressure under leg press loading conditions and offers design recommendations to minimize spatial pressure concentrations. A pressure mat was used to assess the back-backrest interfacial pressure distribution of 15 subjects executing RT leg-presses at 50% bodyweight, over 16 different back-support geometries. Real-time forces, knee angles, and pressures were captured. The resulting data show that more prominent (?2.1 cm) back-supports, positioned 19cm above the seat pan typically produced greater peak pressures (41.8±7.2 kPa). Conversely, less prominent supports (~0.7 cm) generally achieved lower peak pressures (with greater distribution). Our data suggest that the most prudent choice for fixed-shape backrests to best distribute interfacial pressure on leg-press devices is to incorporate shallow convex supports (~0.7 cm), and locate them away from P=19 cm. The result is surprising as this prominence location is a common ergonomic feature. If an adjustable backrest is considered, peak pressures may be reduced by up to 26±8% (9.7±3.1 kPa) compared to flat geometries.

Changes in external ischial tuberosity width at varying trunk-thigh angles between sexes using two measurement methods

This study examined the influence of two methods and various trunk–thigh (TT) angles on external ischial tuberosity width (EITW) for 45 men and 45 women. In the experiment, the impress and seat pressure methods were applied at TT angles of 60°, 75°, 90°, and 105°. When the impress method was used, EITW remained highly consistent across the four measured TT angles with differences of 2.8 and 2.1 mm for men and women, respectively. Conversely, in the seated pressure method, EITW increased with TT angle such that differences in EITW across a full TT angle range were 11.5 and 11.7 mm for men and women, respectively. Irrespective of method, differences in EITW between genders measured approximately 12.6–13.7 mm across all TT angles. Correlation analyses revealed that hip circumference was positively related to EITW in all cases, whereas the relationship of hip width and depth with EITW varied by method and gender. Because of inherent differences in EITW between genders, these findings suggest that gender variability should be considered in seat cushion design.

Spinal mobility in radiographic axial spondyloarthritis: criterion concurrent validity of classic and novel measurements

Background

Limitations in spinal mobility are a characteristic feature of Axial Spondyloarthritis. Current clinical measurements of spinal mobility have shown low criterion-concurrent validity. This study sought to evaluate criterion-concurrent validity for a clinically feasible measurement method of measuring spine mobility using tri-axial accelerometers.

Methods

Fifteen radiographic-Spondyloarthritis patients were recruited for this study. Two postural reference radiographs, followed by three trials in forward, left and right lateral bending were taken. For all trials, three measurements were collected: tape (Original Schober’s, Modified Schober’s, Modified-Modified Schober’s, Lateral Spinal Flexion Test and Domjan Test), followed immediately by synchronized radiograph and accelerometer measurements at end range of forward and bilateral lateral flexion. The criterion-concurrent validity of all measurement methods was compared to the radiographic measures using Pearson’s correlation coefficients. A Bland-Altman analysis was conducted to assess agreement.

Results

In forward bending, the accelerometer method (r = 0.590, p = 0.010) had a stronger correlation to the radiographic measures than all tape measures. In lateral bending, the Lateral Spinal Flexion tape measure (r = 0.743, p = 0.001) correlated stronger than the accelerometer method (r = 0.556, p = 0.016). The Domjan test of bilateral bending (r = 0.708, p = 0.002) had a stronger correlation to the radiographic measure than the accelerometer method.

Conclusions

Accelerometer measures demonstrated superior criterion-concurrent validity compared to current tape measures of spinal mobility in forward bending. While a moderate correlation exists between accelerometer and radiographs in lateral bending, the Lateral Spinal Flexion Test and Domjan Test were found to have the best criterion-concurrent validity of all tests examined in this study.

What is the best way to collect maximum forward lumbar spine flexion values for normalizing posture to range of motion?

Spine angles are an important measure in biomechanics research and are commonly normalized to a percentage of range of motion. However, standardized methods to collect the reference posture trials for this normalization do not exist. The purpose of this study was to determine posture (seated or standing) and number of trials that should be collected and how to calculate the angle that best represents the maximum range. Forty healthy adults (22 females, 18 males) completed 12 reference trials: 1 upright standing, 5 standing flexion, and 5 seated flexion trials. The maximum lumbar angle was found for each flexion trial. Additionally, different methods to calculate the maximum were applied by taking the maximum of the 5 standing, 5 seated, and all 10 flexion trials. An interaction was found between posture, order, and trial number. 42.5% and 57.5% of participants reached their maximum angle during seated and standing flexion respectively which may be due to back- vs hip-dominant movement strategies. 85% of participants achieved their maximum at some point during the first six flexion trials. The maximum angle of all 10 flexion trials was significantly greater than the angle of the first standing or seated trial only but not significantly greater than the maximum of all seated or standing flexion trials respectively. Secondarily, no differences in the maximum lumbar angle were found between sexes. This study suggests that 6 flexion trials, involving both standing and seated flexion, should be collected to best represent the maximum end range of spine flexion.

Duty belt or load-bearing vest? Discomfort and pressure distribution for police driving standard fleet vehicles

Police working in active duty have a high prevalence of musculoskeletal pain, with lower back pain being the most frequently reported. As a part of uniform regulations, Swedish police are mandated to wear body armour and duty belts at all times during work. This study aimed to investigate the effect of different load carriage designs on invehicle sitting pressure and self-rated discomfort among police. Results showed less discomfort when wearing the alternate load carriage system incorporating a load-bearing vest and thigh holster compared to the standard load carriage system consisting of a duty belt. Pressures in the lower back were reduced when wearing the load-bearing vest whereas pressures in the upper back region increased. Relocating appointments away from the waist has the potential to improve sitting positions and the ergonomic situation for police when driving fleet vehicles.

Engineering movement into automotive seating: Does the driver feel more comfortable and refreshed?

The concept of introducing movement in automotive seating was investigated. Three seat conditions, a control (no movement) and two movement conditions (fore-aft and cushion-backrest) were compared. Movement was introduced at a fixed speed, slow, smooth and within a small range. Ten participants took part in a 60 min simulated drive for each condition - single blind, repeated measures, and balanced order. Discomfort ratings were collected for six body areas and overall discomfort, together with a wellbeing questionnaire. Driver posture and Seat Fidgets and Movements (SFMs) were captured. There was a trend for lower ratings of discomfort, overall and in the neck, shoulders, lower back, buttocks, and ankles with both seat movement conditions. Wellbeing ratings were also better with movement. Significant differences were found at minute 60 for buttock discomfort - less discomfort with seat movement. Overall discomfort and SFMs frequency increased with time driving. Generally, passive seat movement was well received.

Quebec Serve and Protect Low Back Pain Study: A Web-based Cross-sectional Investigation of Prevalence and Functional Impact Among Police Officers

STUDY DESIGN

Web-based cross-sectional study.

OBJECTIVE

The aim of this study was to describe the prevalence and the burden of low back pain (LBP) and chronic low back pain (CLBP) among Quebec police officers.

SUMMARY OF BACKGROUND DATA

Police officers have work-related factors associated with LBP, but chronicity and impacts of this condition have been little explored among this population.

METHODS

Between May and October 2014, a web-based cross-sectional study was conducted among police officers working in the province of Quebec (Canada). Nine police organizations accepted to disseminate the email invitation to their members. The survey included the French-Canadian version of the Nordic Musculoskeletal Questionnaire and other items regarding functional impact of LBP and associated treatments.

RESULTS

A total of 3589 police officers completed the questionnaire. Mean age was 38.5 ± 8.7 years, 32.0% were women, and 67.4% reported being car-patrol officers. A majority reported LBP symptoms in the past 12 months (67.7%) and 96.5% of them perceived that presence of LBP was totally/partially linked to their work in the police force. Prevalence of CLBP among all responders was 28.7%. Police officers reporting CLBP, as compared to those reporting acute or subacute LBP symptoms in the past 12 months, were more likely to report LBP-related reduction of work activities (64.4% vs. 45.7%; P < 0.001) and more working days lost in the past 12 months (average of 11.9 ± 43.5 vs. 1.5 ± 9.8; P < 0.001). A greater proportion also reported LBP-related health care visits in the past 12 months (86.2% vs. 64.2%; P < 0.001) and current use of pain medications/complementary alternative medicines (90.1% vs. 69.7%; P < 0.001).

CONCLUSION

CLBP is a frequent and burdensome condition among Quebec police officers. Our results underline the importance for police organizations to promote CLBP prevention and to implement workplace management programs.

LEVEL OF EVIDENCE

3.

A preliminary study of the measurement of external ischial tuberosity width and its gender differences

[Purpose] Using two measurement methods, this study measured the external ischial tuberosity widths (EITW) of both males and females and investigated gender differences in these EITW values. [Subjects and Methods] Fifteen male and 15 female Taiwanese were recruited for this study. Their EITWs were measured using the impress and the seated pressure methods, and compared. [Results] The results show that the EITW values obtained using the impress method were similar to those reported by previous studies, but gender differences were observed in the measurements when that method was used (male: 11.96 cm; female: 13.53 cm). However, the males had non-significantly greater EITW values than the females when the seated pressure method was used (male: 13.42 cm; female: 13.30 cm), and this was probably due to the distinct characteristics of the buttocks of the two sexes and the seated pressure method. [Conclusion] The authors of this study propose that 12.0 and 13.5 cm are respectively the ideal design parameters for male and female EITWs in Taiwan, although13.5 cm might be more appropriate for male EITWs in the design of relatively hard seat or saddle surfaces.