Adolescent growth provides a unique opportunity for the growing body to adapt to external stimuli. A positive association between site-specific mechanical loading and increases in regional bone mineral content (BMC) during adolescence is established. Mechanical loads associated with middle-distance running expose the skeleton to a combination of compressive ground reaction forces and muscular contraction. Previous studies concerning musculoskeletal health in active adolescents are largely limited to planar, two-dimensional measures of bone mineral status, using Dual X-ray Absorptiometry (DXA). Intrinsic bone material properties are accurately measured using DXA. However, the interaction between bone material and structural properties that reflects the mechanical integrity of bone require a combination of imaging modalities. Magnetic Resonance Imaging (MRI) provides a three-dimensional geometric and biomechanical assessment of bone. When MRI is integrated with DXA technology, an effective non-invasive method of assessing in vivo bone strength is achieved. The impact of high training volumes on musculoskeletal development of male and female adolescent athletes engaged in repetitive, high magnitude mechanical loading has not been investigated. Specifically, differences in total body and regional bone mineral, bone and muscle geometry, bone biomechanical indices and bone strength at differentially-loaded skeletal sites have not been compared between adolescent middle-distance runners and age- and gender-matched non-athletic controls. Objectives: (i) to investigate the effects of intense sports participation involving mechanical loading patterns on bone mineral, bone and muscle geometry, biomechanical indices and estimated regional bone strength between elite adolescent male and female middle-distance runners and age- and gender-matched controls (ii) to examine factors predictive of total body BMC, distal tibial bone geometry, distal tibial bone strength, and Hip Strength Analysis (HSA)- derived indicators of bone strength at the femoral neck. Methods: Four groups of 20 adolescents were comprised of male (mean (SD) age 16.8 ± 0.6 yr, physical activity 14.1 ± 5.7 hr.wk-1) and female (age 16 ± 1.7 yr, physical activity 8.9 ± 2.1 hr.wk-1) middle-distance runners, and male (16.4 ± 0.7 yr, physical activity 2.2 ± 0.7 hr.wk-1) and female (age 16 ± 1.8 yr, physical activity 2.0 ± 0.07 hr.wk-1) controls. Total body and regional BMC were calculated using DXA. Distal tibial bone and muscle cross-sectional areas (CSA) were assessed using MRI. To calculate distal tibial bone strength index (BSI), a region of interest representing 10% of the mid distal tibia was analysed for DXA-derived bone mineral and was combined with bone geometry and biomechanical properties from MRI assessments. Calculations for femoral neck strength were acquired from DXA-derived HSA software. Results: No differences were found between male athletes and controls for unadjusted BMC at total body or regional sites. After covarying for fat mass (kg), male athletes displayed greater BMC at the lumbar spine (p = 0.001), dominant proximal femur (p = 0.001) and dominant leg (p = 0.03) than male controls. No differences were found in distal tibial bone geometry, bone strength at the distal tibia or HSA-derived indicators of bone strength at the femoral neck between male athletes and controls. Lean tissue mass and fat mass were the strongest predictors of total body BMC (R2 = 0.71), total muscle CSA explained 43.5% of variance in BSI at the distal tibia, and femur length and neck of femur CSA explained 33.4% of variance at the femoral neck. In females, athletes displayed greater unadjusted BMC at the proximal femur (+3.9 ±1.4 g, p = 0.01), dominant femoral neck (+0.5 ± 0.12 g, p = 0.01) and dominant tibia (+4.1 ± 2.1 g, p = 0.05) than female controls. After covarying for fat mass (kg), female athletes displayed greater (p = 0.001) total body, dominant proximal femur and dominant leg BMC than female controls. Female athletes also showed greater distal tibial cortical CSA (+30.9 ± 9.5 mm2, p = 0.003), total muscle (+240.2 ± 86.4 mm2, p = 0.03) and extensor muscle (+46.9 ±19.5 mm2, p = 0.02) CSA, smaller medullary cavity (-32.3 ± 14.7 mm2, p = 0.03) CSA and greater BSI at the distal tibia (+28037 ± 8214.7 g/cm3.mm4, p = 0.002) than female controls. Lean tissue mass and fat mass were the strongest predictors of total body BMC (R2 = 65), hours of physical weekly activity and total muscle CSA explained 58.3% of the variance of distal tibial BSI, and neck of femur CSA accounted for 64.6% of the variance in a marker of femoral neck HSA. Conclusion: High training loads are associated with positive musculoskeletal outcomes in adolescent middle-distance runners compared to non-athletic controls. Exposure to similar high training loads may advantage female adolescent athletes, more than male adolescent athletes compared with less active peers in bone strength at the distal tibia.

The deformation associated with a ballistic shield defeating a projectile can interact with the user’s upper extremity, resulting in the release of the shield, placing those behind the device at risk. This injury mechanism is known as behind-shield blunt trauma (BSBT). Previous studies investigating these interactions have used testing conditions not representative of those present during these behind-shield events and lacked sufficient testing to determine statistically relevant outcomes. In the present work, the loading present during ballistic shield deformation was characterized through testing using an Anthropomorphic Test Device (ATD) upper extremity placed behind a level III ballistic shield. Digital image correlation (DIC) and post-impacting X-ray imaging were used to assess the ballistic shield’s deformation. The data collected from ballistic testing informed the development of a projectile used with a pneumatic impactor for the application of BSBT in a lab-based setting. Using the projectile, ballistic impacts were replicated on the ATD upper extremity and translated to 5th and 95th percentile cadaveric arms. Load data were collected for the hand and forearm using piezoelectric force sensors embedded in the projectile. Similarly, PMHS were impacted in a stepwise fashion of increasing energy until fractures were identified using X-ray imaging. A novel scaling technique was developed where Partial Least Squares (PLS) was used to determine critical variables relating donor anthropometrics to peak impact force. The scaling equations generated using this technique offer future researchers the opportunity to employ a larger range of specimens when determining injury thresholds for the hand and forearm. Through the characterization of the conditions present during BSBT, the injury thresholds to these mechanisms were assessed for understudied populations. Additionally, this work presents scaling techniques that could reduce the number of specimens required to determine future upper extremity injury limits. The information presented within this work provides an important step in developing new standards for ballistic shields to better protect users from BSBT. / Thesis / Master of Applied Science (MASc) / The deformation of a ballistic shield associated with stopping a bullet can interact with the user’s arm, causing them to drop the shield and placing the user in further danger. This work aimed to assess the risks to the hand and forearm over a range of male sizes using mechanical and biomedical tools. Ballistic loading was characterized using a crash test dummy arm to understand the conditions present during the event. The injuries associated with this loading were assessed using cadaveric specimens and a custom projectile for replicating the impacts. Mathematical techniques were used to translate the injury thresholds to the exact user sizes – providing relevant metrics for future ballistic shield standards. The results of this work present methods for recreating ballistic testing in a lab-based setting and for scaling forces associated with the hand and forearm, allowing future researchers to use a broader range of specimens for injury assessment.

Work-related musculoskeletal disorders (WMSDs) continue to occur despite an increasing understanding of the risk factors that initiate these disorders. Ergonomics is commonly seen as a health and safety approach that has no influence on performance, a perspective potentially hindering intervention proposals in practice. Highlighting potential performance benefits can facilitate intervention cost-justification, along with the traditional focus on reducing exposure to injury risk. The main objective of this research was to examine the dual influences (i.e., on performance and injury risk) of two distinct types of interventions: adding adjustability, as a commonly advocated approach when considering ergonomics early in the (re)design phase to change task demands; and using exoskeletons to enhance worker capacity. A simulated drilling task was used, which was considered informative as it entailed diverse demands (precision, strength, and speed) and permitted quantifying two dimensions of task performance (productivity and quality). The dual influences of three levels of workstation adjustability were examined first; increasing adjustability improved performance, with this benefit occurring only when a given level of adjustability also succeeded in reducing ergonomic risk. Across examined conditions, several significant linear associations were found between risk (e.g., Strain Index score) and performance metrics (e.g., completion time), further supporting an inverse relationship between these two outcomes. The dual influences of three distinct passive exoskeletal designs were investigated/compared subsequently, in a simulated overhead drilling task and considering the potential moderating effects of tool mass and precision requirements. Specific designs were: full-body (Full) and upper-body (Arm) exoskeletons with attached mechanical arms; and an upper-body (Shl) exoskeleton providing primarily shoulder support. Both designs with mechanical arms increased static and median total muscle activity while deteriorating quality. The Shl design reduced shoulder loading while increasing dominant upper arm loading and deteriorating quality in the highest precision requirements. Influences of both increasing precision and tool mass were fairly consistent across the examined designs. As such, no single design was obviously superior in both physical demands and performance. Although future work is needed under more diverse/realistic scenarios, these results may be helpful to (re)design interventions that achieve dual benefits on performance and injury risks. / PHD

The £198M demolition industry sector is part of the construction industry, worth approximately £2.2bn in the UK p.a albeit such a small fraction it is nevertheless the largest provider of secondary building products, handles 32 million tonnes (approximately) of waste each year and is principally responsible for clearing brownfield sites in readiness for new build. Sustainable demolition activities are at the forefront of the UK Government and many NGO s policies on waste reduction, increased recycling and reclamation of waste building products at the end of life cycle. However, there are problems in developing more sustainable demolition processes based on historical methods of working, in particular, those involving manual handling activities. Whilst the UK construction industry boasts reduced accident and incident rates the demolition sectors rates are in the ascendency, rising by 43% overall from 1996 to 2009. That said, it would appear that those working within the sector are unaware of the rise in accidents which has steadily increased by 100% since 2000. Despite the demolition sector s increased use of mechanical applications for structural demolition, the prolonged and prolific method of stripping out buildings by hand remains a major risk and causal factor for injuries. The results of this research have identified the causation of such an increase in accident occurrence and has offered an insight into how the reduction of accident and incident may be accomplished. This research is unique in that practising exponents of the demolition sector have participated in providing exclusive evidence of methodology, accident reporting and waste handling protocols that give clear indications of a gulf in current thinking by government, NGO s and the enforcing authorities. The research has also identified failings in product and building design that create unsustainable conditions for safe, efficient and cost effective demolition, dismantling and handling of materials at end of life. This realisation also opens up the debate on the role of designers and their contribution to a safe and sustainable demolition process.

Background: Lower extremity (LE) musculoskeletal injuries in soccer players are extremely common. These injuries can result in many days of lost time in competition, severely impacting players and their respective teams. Implementation of group injury prevention programs has gained popularity due to time and cost-effectiveness. Though participation in group injury prevention programs has been successful at reducing injuries, programs often target a single injury and all players do not benefit from participation. Players with a greater number of risk factors are most likely to sustain an injury, and unfortunately, less likely to benefit from a group injury prevention program. The purpose of the proposed research is to determine if targeting these high risk players with one-on-one treatment will result in a reduction in the number of risk factors they possess. Objectives: 1) Determine the effectiveness of one-on-one intervention for reducing the number of risk factors for LE musculoskeletal injury in soccer players with 3 or more risk factors; 2) Assess the effectiveness of matched interventions on reducing the magnitude of identified risk factors. Hypothesis: Fifty percent or more of subjects receiving one-on-one intervention will have a reduction of ≥ 1 risk factor(s). Design: Quasi-experimental pretest-posttest design. Subjects: NCAA Division I men’s and women’s soccer players. Methods: All subjects were screened for modifiable risk factors using a battery of tests which assessed mobility, asymmetry in fundamental movement pattern performance, neuromuscular control, and pain with movement. Players with ≥ 3 risk factors (“high risk”) were placed in the treatment group and received one-on-one treatment from a physical therapist. An algorithm was created with interventions matched to specific deficits to determine the treatment each subject received. Subjects in the intervention group were treated twice per week for four weeks. Players with < 3 risk factors (“low risk”) were placed in the control group and did not receive one-on-one intervention. Analysis: The primary outcome measure was proportion of treatment successes, defined as a reduction of ≥ 1 risk factor(s). Secondary outcomes included analysis of within group and between group differences. Results: Thirteen subjects were treated with one-on-one intervention, with twelve having a reduction of at least 1 risk factor at posttest. The proportion of treatment successes in the intervention group was 0.923 (95%CI 0.640-0.998). The proportion of high risk subjects that became low risk at posttest was 0.846, which was statistically significant (p = 0.003). Within group differences were noted in active straight leg raise (left; p = 0.017), hip external rotation (right, p=0.000; left, p = 0.001) thoracic spine rotation (left; p=0.026), and upper quarter neuromuscular control measures (left inferolateral reach, p = 0.003; left composite, p = 0.016). A statistically significant between group difference was noted in risk factor change from pretest to posttest (p = 0.002), with the median risk factor change in the intervention group and control group being -3 and -1, respectively. Conclusion: Utilizing one-on-one interventions designed to target evidence-based risk factors is an effective strategy to reduce LE musculoskeletal injury risk factors in high risk individuals.

Globally, there is an increasing tendency for occupational legislation and practice to require that employers actively involve their employees in the process of identifying, assessing and addressing the risk of injury in the workplace. Despite this, there is a paucity of research evaluating the effectiveness of participatory ergonomics in reducing occupational injury outcomes. In particular, a review of the literature fails to identify research that reports a change in the risk of injury at the level of the individual worker. The objectives of this study were to determine whether a participatory ergonomics approach to the control of workplace hazards and manual hazards in particular, could reduce the occurrence and severity of injury among a working population at risk.The research design was that of a longitudinal pre-post intervention study, with one intervention and three comparison groups. The observational period between 1 July 1988 and the 31 October 1995, comprised a 4.3 year pre-intervention period and a 3- year post-intervention period. The Intervention Group was a population of hospital cleaners at a high risk of injury. Three comparison groups were used, namely orderlies from the same hospital, cleaners from a similar hospital, and all the cleaners in the State of Western Australia. The primary outcome measure of occurrence was that of a lost- time injury (LTI).To obtain parameters of injury severity, each LTI was measured in terms of the associated CP1-adjusted workers' compensation claim cost and the number of hours lost from work (duration). The data were obtained three years after the observational period, to improve the likelihood that the claims had been finalised. Aggregate level LTI data were obtained for all four groups. Individual-level data were also obtained for the Intervention Group and the Orderly Services Group, whether injured or not. These ++ / data included the age, gender, hours worked and work experience of the subjects. Also, where there was an LTI, it was determined whether or not the mechanism of injury was from manual handling. Using these data, two analytical approaches were then undertaken. Study 1 assessed the aggregate-level LTI data of the four groups. Study 2 evaluated individual-level data for the Intervention Group and the Orderly Services Group.The results demonstrate statistically significant post-intervention reductions In all measures of LTI occurrence for the Intervention Group. In particular, after allowance for age, gender and work experience, there was a two thirds reduction in the rate of LTI per hour worked. No reduction in injury occurrence was observed for any of the comparison groups. The severity of each injury, as measured by claim cost and duration, did not change after the intervention for the Intervention Group.This study indicates that a small group of unskilled workers, with the facilitation of an ergonomist, can successfully undertake an iterative process of identifying and assessing hazards and make recommendations for their control. In doing so, even where the primary focus is on manual handling hazards, a reduction in the risk of injury from both manual handling and non-manual handling mechanisms can be achieved. Participatory ergonomics, by investing hazard management skills within employees, increases the likelihood that solutions to problems will be accepted, and should release ergonomists to consult to a greater number of workplaces than if they work independently of employee participation. The evaluation of interventions in a variety of workplace settings is recommended, to confirm participatory ergonomics as an effective tool for the reduction of the global burden of occupational injury.

Background: Muscle, joint and bone injuries affect mobility and stability, which in turn limits physical activity. Screening tests such as the Functional Movement Screen (FMS) are used to assess an individual’s mobility and stability to determine whether any movement dysfunctions exist. Screening tests aim to establish an individual’s injury risk with the goal of guiding an intervention program. The Evaluation of Mobility Screen (EMS) is a screening test that has been developed at the Sports Science Institute of South Africa. The EMS has been adapted from the FMS by exchanging the Rotatory Stability test for the Seated Rotation test. The current use of screening tools is limited because of the lack of normative data sets that represent the diversity of age, gender and physical activity levels in the general population. Most current published data represent athletes or younger populations. By establishing the relationship between screening outcomes and variables such as age, gender and physical activity level, the effectiveness of screening tests may be improved. Aim: To describe associations between EMS scores for males and females across different age groups and levels of physical activity. Objective: To evaluate and compare differences in EMS scores relating to age, gender and physical activity levels. Methods: This was a quantitative study, with a descriptive, correlational design. The sample consisted of 135 males and 127 females between the ages of 18 and 60. The EMS data were collected at the HighPerformance Centre, in the Sports Science Institute of South Africa, Cape Town. Results: There was no difference between the total scores of males and females (median = 17). The two youngest groups (20-30 and 31-40 years) scored the highest (median = 17), while the oldest group (51-60 years) scored the lowest (median = 15). Gender had a significant effect (p < 0.05) on five subtests (Single Leg Hurdle, Shoulder Mobility, Asymmetric Leg Raise, Stability Push Up and Seated Rotation). Age had a significant effect (p < 0.05) on three subtests (Overhead Squat, Single Leg, Hurdle Split Squat). Physical activity level had a significant effect (p < 0.05) with two subtests (Single leg Hurdle and Stability Push Up). Conclusion: Gender, Age and Physical Activity are associated with changes in EMS scores. EMS total scores declined as age increased. While the total scores remain similar between genders, there were clear variations within the different subtests. The oldest participants (51-60 year) scored the lowest throughout all subtests. Males scored higher in the strength components, while females scored higher in the flexibility components. Physical activity levels did not have a clear pattern as expected but still demonstrated association with two subtests. The results add to the sentiment that the focus should move away from the composite scoring system, and towards analyzing individual subtest scores. Future studies should also investigate if subtest scores can be improved by targeted intervention programs.

In order to prevent or mitigate the negative consequences of traffic crashes, automakers are developing active safety systems, which aim to prevent or mitigate collisions.  These systems are expensive to develop and as a result automakers and regulators are motivated to forecast the potential benefits of a proposed safety system before it is widely deployed in the vehicle fleet. The objective of this dissertation was to develop a methodology for predicting fleet-wide benefits for emerging crash avoidance systems as if all vehicles were equipped with a system.  Forward Collision Avoidance Systems (FCAS) were used as an example application of this methodology. The methodology developed for this research includes the following components: 1) identification of the target population, 2) development and validation of a driver model, 3) development of injury risk functions, 4) development of a crash severity reduction model, and 5) computation of fleet-wide benefits.  This dissertation presents a general methodology for each of these components that could be used for any active safety system.  Then a specific model is constructed for FCAS. FCAS could potentially be applicable to 31% of all collisions, 6% of serious injury crashes, and 7% of fatal crashes.  Annually, this accounts for 3.3 million collisions and 18,367 fatal crashes.  We developed a model of driver braking in response to a forward collision warning. Next we used logistic regression to develop injury risk functions that predicted the probability of injury given the crash severity ("V) and occupant characteristics.  Finally, we simulated 2,459 real-world rear-end collisions as if the driver had an FCAS with combinations of warnings, brake assist, and autonomous braking.  We found that between 3.4% and 7.2% of crashes could be prevented and that many more could be mitigated in severity.  These systems reduced the number of injured (MAIS2+) drivers in rear-end collisions between 32% and 55%.  In total, the systems could prevent between $184 and $338 million in economic costs associated with crashes per year. / Ph. D.

More motorcyclists are fatally injured each year in guardrail crashes than passengers of any other vehicle, while only accounting for three percent of the vehicle fleet. Since motorcyclists account for a high percentage of these fatalities, the goal of zero deaths on the road cannot be achieved without addressing the safety of motorcyclists. The objective of this research was to determine the factors that lead to serious or fatal injury in motorcycle barrier crashes, given that a crash occurred. The likelihood of serious or fatal injury in barrier crashes was significantly influenced by both barrier type and rider trajectory after striking the barrier. A national study of motorcyclist fatality risk using the Fatality Analysis Reporting System (FARS) and General Estimates System (GES) showed that crashes with guardrail than crashes were about 7 times more likely to be fatal than those with the ground, based on the most harmful event reported. An analysis of 1,000 riders in barrier crashes in three states showed that the odds of serious injury were 1.4 times greater in guardrail crashes than in concrete barrier crashes. These analyses did not take into account the trajectory of the rider after striking the barrier, since this was unknown. The police accident report for 350 barrier crashes in New Jersey was used to determine the rider trajectory in those crashes. Being ejected from the motorcycle after impacting the barrier significantly increased the odds of serious injury over crashes where the rider was not ejected. While providing insight into factors influencing injury severity, these analyses do not provide an understanding of the nature of injuries incurred in these crashes. To further understand how injuries were caused in motorcycle-barrier crashes, we developed a methodology for determining injury mechanisms in motorcycle-barrier collisions. Using this methodology, we investigated 9 serious motorcycle-to-barrier crashes. In these crashes, as well as in an analysis of 106 barrier crashes in Maryland, the thorax and lower extremities most commonly suffered serious injury. Of particular concern are the posts and top of the rail, both of which can lead to lacerations and blunt trauma. / Ph. D.

No description available.