Previous studies have obtained some pedestrian-friendly vehicle front-end shapes, which show good pedestrian protection ability, but their effectiveness in protecting pedestrian ground contact injury has not been evaluated yet. For this reason, a total of 6 vehicle front-end shapes, 3 each for ‘Good’ front-end shapes (G shapes) and ‘Poor’ front-end shapes (P shapes), and a simulation test sample are selected to design 72 groups of 144 simulations. The results show that compared with the P shapes, the G shapes have better protection against pedestrian-vehicle contact injuries but worse protection against pedestrian-ground contact injuries. The analysis finds that the direct cause of the difference in the protection effect of pedestrian-ground contact injury between the G and P shapes is that the change in the pedestrian's ground impact mechanism leads to the head hitting the ground earlier and at a greater speed, and also higher ground-related weighted injury cost of pelvis (WICpelvis), while the essential cause is most likely the change in the angle of rotation of the pedestrian after the contact due to the difference in the shape of the bumper of the two types of vehicle. In order to further reduce pedestrian-ground contact injuries for the G shapes, 7272 simulations are designed and a simple vehicle braking control method for a specific vehicle model is proposed by combining optimization and regression. Experiments based on the simulation test sample show that a maximum reduction of 84% of the ground-related WIC can be achieved, with the proportion of safe mechanisms up to 74%. Experiments based on the new simulation test sample show a maximum reduction of 43% of ground-related head injury criterion (HIC), and the experiments show that the proportion of safe mechanisms reaches 78%, which verifies the good effect and adaptability of the proposed method.

Concerns about the cumulative effects of head acceleration events in rugby are growing, but how tackle events lead to direct head contact in women's rugby remains underexplored. This cross-sectional study aimed to develop and evaluate a machine learning model to identify characteristics associated with direct head contact and incorrect tackler head placement in elite women's rugby. Match situational and precontact technical characteristics (n = 31) from 1500 randomly selected tackle events were coded visually and retrospectively analyzed from the 2022-23 Women's Six Nations Championship. A machine learning model was developed and evaluated using a grid search with 5-fold cross-validations and F1 scores (i.e., a measure of predictive performance). The top modifiable characteristics associated with the target outcomes across 100 test sets were identified by mutual importance and decision tree modeling. The top modifiable characteristics linked to direct head contact to the tackler were incorrect head placement, coming to balance, and foot placement. Tackle direction, point of contact on the tackler, and multiplayer tackles were key characteristics for incorrect tackler head placement. Tackler drop height, front/oblique tackle direction, and multiplayer tackles were strongly associated with direct head contact to the ball-carrier. Incorrect tackler head placement, the direction of tackle, tackler drop height, and multiplayer tackles are key characteristics in direct head contact events in elite women's rugby. Addressing these characteristics should be prioritized in contact training practices, education resources, and law enforcement to enhance player safety and direct head contact events in the women's game.

Epidemiological analysis has revealed key insights into the frequency, severity, and circumstances surrounding subway-to-pedestrian incidents; however, there remains a lack of available impact test data specific to this impact type that can be used in modelling and countermeasure design studies. To address this gap, nine controlled impact tests were conducted using a cylindrical headform to derive force–penetration relationships for foam, as well as foam encased in 1 mm aluminium or 3 mm ABS shells. These relationships were validated in MADYMO multibody simulations. Building on a previous multibody computational study of subway-to-pedestrian collisions this research evaluates three passive countermeasure designs using a reduced simulation test matrix: three impact velocities (8, 10, and 12 m/s) and a trough depth of 0.75 m. In subway collisions, due to the essential rigidity of a subway front relative to a pedestrian, it is the pedestrian stiffness characteristics that primarily dictate the contact dynamics, as opposed to a combined effective stiffness. However, the introduction of energy-absorbing countermeasures alters this interaction. Results indicate that modular energy-absorbing panels attached to the train front significantly reduced the Head Injury Criterion (HIC) (by 90%) in the primary impact and pedestrian-to-wheel contact risk (by 58%), with greater effectiveness when a larger frontal area was covered. However, reducing primary impact severity alone did not substantially lower total fatal injury risk. A rail-guard design, used in combination with frontal panels, reduced secondary impact severity and led to the largest overall reduction in fatal injuries. This improvement came with an expected increase in hospitalisation-level outcomes, such as limb trauma, reflecting a shift from fatal to survivable injuries. These findings demonstrate that meaningful reductions in fatalities are achievable, even with just 0.5 m of available space on the train front. While further development is needed, this study supports the conclusion that subway-to-pedestrian fatalities are preventable.

This cross-sectional study aims to identify the situational characteristics, ball-carrier technical variables, and Tackle Ready recommended techniques associated with performance outcomes in elite women's Rugby Union. Using retrospective video analysis, 43 tackler and ball-carrier technical characteristics for 1500 tackle events in the 2022-23 Women's Six Nations Championship were assessed, considering match situation and performance outcomes. Rate ratio (RR) was determined using propensity rates. Effective tackles were associated with match situations involving two defenders, forwards tackling forwards, defensive teams moving forwards, and tackles initiated closer to attackers at ball reception. Seven out of the 22 coded Tackle Ready techniques were significantly associated with superior performance outcomes. Techniques associated with the greatest likelihood of effective tackle outcome included wrap and clamp (RR 46.8) and ear to body (RR 20.9). Tackles made to the hip and leg of the ball-carrier increased the risk of missed tackles. This study provides the first analysis of tackle characteristics associated with performance outcomes in women's rugby, providing a reference to inform coaching practice and the implementation of tackle education resources and law changes. Further research is warranted to explore techniques associated with injury risk, and interactions between match situations and subsequent tactical/technical tackle actions.

To protect high-speed trains in derailments, reinforced concrete (RC) derailment containment walls are often built beside the track. The resulting problem is that derailed trains hit the surrounding RC derailment containment wall. This paper aims to investigate high-speed train post-derailment impact responses and evaluate the crashworthiness and containment capacity of the RC derailment containment wall. The finite element (FE) models of the eight-vehicle marshalling high-speed train and RC wall were developed and verified against single rail vehicle derailment test, eight-vehicle marshalling train-to-train impact test, and RC structure drop tower tests. FE simulations of the train post-derailment crash on a curve of 400 m radius were performed in LS-DYNA. Results show that the RC wall is capable of protecting high-speed trains from running off the wall in post-derailment collisions up to 150 km/h, while the train may fall off high-speed railway bridges with a derailment velocity beyond 150 km/h. The vehicles of the derailed train successively hit the RC wall due to the multi-vehicle coupling effect of trains. The number of vehicles hitting the wall increases with the increase in derailment velocity. This study provides engineering help for designing RC walls and protecting high-speed train occupants in post-derailment collisions on a curve.

AimsTo measure the quality of life in children with impaired walking who receive a mobility assistance dog (MAD).MethodsThe parents of ten children who received a MAD completed the cerebral palsy quality of life questionnaire, before receiving their dog and at one, three, and six-month follow-up. Data were analyzed to assess changes for each participant and to the group.ResultsThe group showed a positive change in the domains of social well-being and acceptance, feelings about functioning, and emotional well-being and self-esteem after six months. Children with less impairment (GMFCS I-II) showed a change in social-wellbeing and acceptance, feelings about functioning, participation, physical health, and emotional-wellbeing and self-esteem after six months. Children with more impairment (GMFCS III-IV) showed no change at any timepoint measured.ConclusionsThis novel therapeutic area of receiving a MAD demonstrated some positive quality of life changes after six months for a small group of children with impaired walking. These are preliminary findings in a small sample and this intervention would benefit from further study.

Introduction: Subway–pedestrian collisions are a significant and growing problem, but they are poorly understood. This study presents the first subway–pedestrian collision model with the aim of evaluating the baseline safety performance of an R160 NYC train and track combination and the potential safety effects of drainage trough depth. Methods: A baseline simulation test sample of 384 unique impacts (8 velocities (2–16 m/s), 24 positions (standing jumping and lying), and 2 track types (flat and crossties)) was created in MADYMO. The full simulation test sample (N = 1920) included with various depth drainage troughs (0–1 m). Head injuries and wheel and third rail contacts were evaluated. Results: Limb–wheel contact occurred in 60% of scenarios. Primary and secondary contact HIC15 showed similar high severity, with an HIC15 < 2000 (88% risk of AIS 4+) in 29% of results for both train and ground contact. Impact velocity strongly influences primary contact HIC15 with limited effect on secondary contact. Impact velocities between 6 and 16 m/s showed little change in wheel contact. Increasing the trough depth up to 0.5 m showed a decrease in wheel contact probability with little increase in secondary contact. No further benefits were found above 0.5 m. Conclusions: A subway–pedestrian collision model is presented which predicts that wheel–pedestrian contact risk can be reduced with a 0.5 m drainage trough. The model suggests that slower impact velocities may reduce head injury risk for primary contact; however, this will have less effect on injuries caused by secondary and wheel contact.

Single bicycle crashes, i.e., falls and impacts not involving a collision with another road user, are a significantly underestimated road safety problem. The motions and behaviours of falling people, or fall kinematics, are often investigated in the injury biomechanics research field. Understanding the mechanics of a fall can help researchers develop better protective gear and safety measures to reduce the risk of injury. However, little is known about cyclist fall kinematics or dynamics. Therefore, in this study, a video analysis of cyclist falls is performed to investigate common kinematic forms and impact patterns. Furthermore, a pipeline involving deep learning -based human pose estimation and inverse kinematics optimisation is created for extracting human motion from real -world footage of falls to initialise forward dynamics computational human body models. A bracing active response is then optimised for using a genetic algorithm. This is then applied to a case study of a cyclist fall. The kinematic forms characterised in this study can be used to inform initial conditions for computational modelling and injury estimation in cyclist falls. Findings indicate that protective response is an important consideration in fall kinematics and dynamics, and should be included in computational modelling. Furthermore, the novel reconstruction pipeline proposed here can be applied more broadly for traumatic injury biomechanics tasks. The tool developed in this study is available at https://kevgildea.github.io/KinePose/.

Bike positional configuration changes strongly affect cycling performance. While consensus has emerged on saddle height optimisation, there is none for the relationship between other bike positional variables and cycling performance. Accordingly, this systematic review examines the effect of all major positional variables on performance in cycling, assessing differences between cycling disciplines and sex where possible. The systematic review, conducted per PRISMA guidelines, searched databases including Embase, Web of Science, Medline, and CINAHL, screening 16,578 studies. Of these, 47 were fully analysed. Study quality assessment using the NIH tool revealed none rated "good", 5 "fair" and 33 "poor". The analysis involved 724 participants (90 female, 454 male, 180 sex unstated). Studies focused on trunk angle/upper body position, handlebar height, Q factor, foot position, saddle fore-aft/height, seat tube angle and crank length. Participant cycling disciplines were often unspecified and few papers address women cyclists specifically. Key findings were associated with changing saddle height, trunk angle and saddle fore-aft. For trunk angle, accounting for the biomechanical and physiological effects as well as aerodynamic changes is important. Saddle fore-aft affects the hip angle and trunk angle. There are no clear recommendations for crank length, handlebar height, Q factor or cleat position.

The tackle contest is the most common and most injurious match contact event in rugby and is an indicator of performance. Tackle Ready is World Rugby's tackle technique education program. Limited research has characterized the tackle contest in women's rugby. The purpose of this study is to: (1) identify the match situational characteristics, ball-carrier and tackler technical actions demonstrated in elite women's Rugby Union and (2) to determine the extent to which Tackle Ready recommended tackle techniques were exhibited. Technical characteristics for 1500 tackle events in the 2022-2023 Women's Six Nations Championship were visually assessed according to a predefined coding framework and the Tackle Ready program. Tackles lacked full completion (0.2%) of the 22 coded Tackle Ready techniques with 47% of the recommended techniques demonstrated in each tackle on average (range 15%-98%). A high proportion of tackles involved two defenders (48%), approaching ball-carriers from the side (38%) or oblique angles (39%), in an upright position (30%), and with initial contact made with the arm (51%). Incorrect pre-contact head positioning and head placement upon contact accounted for 50% and 15% of tackles, respectively, and there was a mean of 14 (95% CI 11-18) head and neck contacts to a tackler and 18 (95% CI 14-22) head and neck contacts to a ball-carrier per game. Targeted interventions to encourage adoption of recommended techniques are needed to reduce tackle-related injury risk in women's rugby. This study provides valuable context for future discussion across law enforcement, coach education and gender-specific tackle coaching in the women's game.

Sports physiotherapists and coaches are tasked with evaluating the movement quality of athletes across the spectrum of ability and experience. However, the accuracy of visual observation is low and existing technology outside of expensive lab-based solutions has limited adoption, leading to an unmet need for an efficient and accurate means to measure static and dynamic joint angles during movement, converted to movement metrics useable by practitioners. This paper proposes a set of pose landmarks for computing frequently used joint angles as metrics of interest to sports physiotherapists and coaches in assessing common strength-building human exercise movements. It then proposes a set of rules for computing these metrics for a range of common exercises (single and double drop jumps and counter-movement jumps, deadlifts and various squats) from anatomical key-points detected using video, and evaluates the accuracy of these using a published 3D human pose model trained with ground truth data derived from VICON motion capture of common rehabilitation exercises. Results show a set of mathematically defined metrics which are derived from the chosen pose landmarks, and which are sufficient to compute the metrics for each of the exercises under consideration. Comparison to ground truth data showed that root mean square angle errors were within 10° for all exercises for the following metrics: shin angle, knee varus/valgus and left/right flexion, hip flexion and pelvic tilt, trunk angle, spinal flexion lower/upper/mid and rib flare. Larger errors (though still all within 15°) were observed for shoulder flexion and ASIS asymmetry in some exercises, notably front squats and drop-jumps. In conclusion, the contribution of this paper is that a set of sufficient key-points and associated metrics for exercise assessment from 3D human pose have been uniquely defined. Further, we found generally very good accuracy of the Strided Transformer 3D pose model in predicting these metrics for the chosen set of exercises from a single mobile device camera, when trained on a suitable set of functional exercises recorded using a VICON motion capture system. Future assessment of generalization is needed.

OBJECTIVE:Occupant impact safety is critical for train development. This paper proposes a systematic procedure for developing validated numerical occupant crash scenarios for high-speed trains by integrating experimental, computational, and inverse methods.METHODS:As the train interior is the most potentially injury-causing factor, the material properties were acquired by mechanical tests, and constitutive models were calibrated using inverse methods. The validity of the seat material constitutive model was further verified via drop tower tests. Finite element (FE) and multibody (MB) models of train occupant-seat interactions in frontal impact were established in LS-DYNA and MADYMO software, respectively, using the experimentally acquired materials/mechanical characteristics. Three dummy sled crash tests with different folding table and backrest configurations were conducted to validate the numerical occupant-seat models and to further assess occupant injury in train collisions. The occupant impact responses between dummy tests and simulations were quantitatively compared using a correlation and analysis (CORA) objective rating method.RESULTS:Results indicated that the experimentally calibrated numerical seat-occupant models could effectively reproduce the occupant responses in bullet train collisions (CORA scores >80%). Compared with the train seat-occupant MB model, the FE model could simulate the head acceleration with slightly more acceptable fidelity, however, the FE model CORA scores were slightly less than for the MB models. The maximum head acceleration was 30 g but the maximum HIC score was 17.4. When opening the folding table, the occupant's chest injury was not obvious, but the neck-table contact and "chokehold" may potentially be severe and require further assessment.CONCLUSIONS:This study demonstrates the value of experimental data for occupant-seat model interactions in train collisions and provides practical help for train interior safety design and formulation of standards for rolling stock interior passive safety.

Introduction: Single Bicycle Crashes (SBCs) are common, and underreported in official statistics. In urban environments, light rail tram tracks are a frequent factor, however, they have not yet been the subject of engineering analysis. Method: This study employs video-based analysis at nine Dublin city centre locations and introduces a predictive model for crossing success on tram tracks, utilising cyclist crossing angles within a Surrogate Measure of Safety (SMoS) framework. Additionally, Convolutional Neural Networks (CNNs) were explored for automatic estimation of crossing angles. Results: Modeling results indicate that cyclist crossing angle is a strong predictor of crossing success, and that cyclist velocity is not. Findings also highlight the prevalence of external factors which limit crossing angles for cyclists. In particular, kerbs are a common factor, along with passing/approaching vehicles or other cyclists. Furthermore, results indicate that further training on a relatively small sample of 100 domain-specific examples can achieve substantial accuracy improvements for cyclist detection (from 0.31AP0.5 to 0.98AP0.5) and crossing angle inference from traffic camera footage. Conclusions: Ensuring safe crossing angles is important for cyclist safety around tram tracks. Infrastructural planners should aim for intuitive, selfexplainable road layouts that allow for and encourage crossing angles of 60 degrees or more - ideally 90 degrees. Practical Applications: The SMoS framework and the open-source SafeCross1 application offer actionable insights and tools for enhancing cyclist safety around tram tracks.

This study analyzed New York Subway incident cases from 2019 to expand on the current understanding of subway train to human collisions. From the 263 incident cases available, 185 (70%) involved train to pedestrian contact. The fatality data were compared with published literature covering 1990 to 2007, showing reasonable agreement in age-, gender-, and borough distributions. The location of incidents was typically the station platform (84%). Four primary behaviors were exhibited by pedestrians before impact with the train. Jumping from the platform was the most common, followed by falling from the platform, walking along the tracks, and standing too close to the edge of the platform. A higher fatality rate was found for collisions that occurred at elevated stations (40%) compared with below-ground stations (27%). The two primary collision types were frontal- and side impact (on the train). The most common impact velocity was 40 to 48 km/h (25 to 30 mph). The most likely outcome of these interactions was a fatality (31%) with only 9% of subway–human interactions resulting in mild injuries. The data suggested that policies based on proactive countermeasures could reduce a significant portion of subway train–human collisions as the majority of preimpact activity occurred on the station platform. Further investigation into the difference in elevated and below-ground collisions may yield useful information, especially relating to the potential protection offered by the drainage trough. When simulating subway–human collisions for countermeasure design, equal consideration should be given to the three impact position types: standing, lying, and jumping.

The mechanical and structural properties of passive skeletal muscle are important for musculoskeletal models in impact biomechanics, rehabilitation engineering and surgical simulation. Passive properties of skeletal muscle depend strongly on the architecture of the extracellular matrix (ECM), but the structure of ECM and its realignment under applied deformation remain poorly understood. We apply second harmonic generation (SHG) microscopy to study muscle ECM in intact muscle samples both under deformation and in the undeformed state. A method for regional relocation was developed, so that the same ECM segment could be viewed before and after applying deformations. Skeletal muscle ECM was viewed at multiple scales and in three states: undeformed, under compression and under tension. Results show that second harmonic generation microscopy provides substantial detail of skeletal muscle ECM over a wide range of length scales, especially the perimysium structure. We present images of individual portions of skeletal muscle ECM both undeformed and subjected to tensile/compressive deformation. We also present data showing the response of the perimysium to a partial thickness cut applied to a section under tensile deformation. STATEMENT OF SIGNIFICANCE: Second Harmonic Generation (SHG) microscopy is an imaging technique which takes advantage of a non-linear and coherent frequency doubling optical effect that is present in a small number of biological molecules, primarily collagen Type I, II and myosin. Collagen I is the most abundant collagen type in skeletal muscle, making SHG a promising option for visualisation of the skeletal muscle extracellular matrix (ECM). SHG microscopy does not require fixing or staining. This short communication presents the application of SHG microscopy to skeletal muscle ECM to improve our understanding of how collagen fibres reorganise under applied tensile and compression, including microscopic observations of collagen fibre reorganisation for intact samples by using a method to re-identify specific regions in repeated deformation tests.

Abstract Background Incisional hernias occur after up to 40 per cent of laparotomies. Recent RCTs have demonstrated the role of prophylactic mesh placement in reducing the risk of developing an incisional hernia. An onlay approach is relatively straightforward; however, a variety of techniques have been described for mesh fixation. The biomechanical properties have not been interrogated extensively to date. Methods This ex vivo randomized controlled trial using porcine abdominal wall investigated the biomechanical properties of three techniques for prophylactic onlay mesh placement at laparotomy closure. A classical onlay, anchoring onlay, and novel bifid onlay approach were compared with small-bite primary closure. A biomechanical abdominal wall model and ball burst test were used to assess transverse stretch, bursting force, and loading characteristics. Results Mesh placement took an additional 7–15 min compared with standard primary closure. All techniques performed similarly, with no clearly superior approach. The minimum burst force was 493 N, and the maximum 1053 N. The classical approach had the highest mean burst force (mean(s.d.) 853(152) N). Failure patterns fell into either suture-line or tissue failures. Classical and anchoring techniques provided a second line of defence in the event of primary suture failure, whereas the bifid method demonstrated a more compliant loading curve. All mesh approaches held up at extreme quasistatic loads. Conclusion Subtle differences in biomechanical properties highlight the strengths of each closure type and suggest possible uses. The failure mechanisms seen here support the known hypotheses for early fascial dehiscence. The influence of dynamic loading needs to be investigated further in future studies.

Previous studies had obtained some pedestrian-friendly vehicle front-end shapes, which shown good pedestrian protection ability, but their effectiveness in protecting pedestrian ground contact injury is not evaluated yet. For this reason, a total of 6 vehicle front-end shapes, 3 each for G shapes (pedestrian-friendly vehicle or ‘Good’ front-end shapes) and P shapes (pedestrian-unfriendly or ‘Poor’ vehicle front-end shapes), and a simulation test sample (containing 3 vehicle speeds * 4 pedestrian models * 2 pedestrian gaits) were selected to design 72 groups of 144 simulations. The results show that compared with the P shapes, the G shapes have better protection against pedestrian-vehicle contact injuries but worse protection against pedestrian-ground contact injuries. The analysis found that the direct cause of the difference in the protection effect of pedestrian-ground contact injury between the G and P shapes is that the change of the pedestrian's ground impact mechanism led to the head hitting the ground earlier and at a greater speed, and also higher ground-related WICpelvic (Weighted Injury Cost of Pelvis), while the essential cause is most likely the change in the angle of rotation of the pedestrian after the contact due to the difference in the shape of the bumper of the two types of vehicle front-end shapes. In order to further reduce pedestrian-ground contact injuries for the G shapes, 7272 simulations were designed relying on the simulation test sample, and a simple vehicle braking control method for a specific vehicle model was proposed by combining optimization and regression. Experiments based on the simulation test sample showed that a maximum reduction of 84% of the ground-related WIC (Weighted Injury Cost) could be achieved, with a ‘safe’ mechanisms proportion up to 74%. Experiments based on the new simulation test sample showed a maximum reduction of 43% of ground-related HIC (Head Injury Criterion) and the proportion of safe mechanisms reached 78%, which verified the good effect and adaptability of the proposed method. These findings provide strong support for better understanding the mechanisms generating pedestrian-ground contact injury and for developing better protection methods to reduce the severity of pedestrian-ground contact injury.

This research explores the underlying roles of effectuation and causation logic as they impact upon firm resilience in Small and Medium Sized Enterprises (SMEs) in the unprecedented disruption caused by Covid-19. Because Covid-19 provides a unique and powerful discontinuance to internal and external environments, it requires firm adaptation in a wide variety of areas, as they seek to find a new “normal”. Our study contributes to the literature by applying effectuation to understand how an SME can experiment and learn in the face of disruption, and then subsequently causally adapt their resources and networks to achieve resilient outcomes. It adds to knowledge about the interaction between effectual and causal logic, leading to a more nuanced explanation of how and why an SME might apply each logic when responding to disruption caused by Covid-19.

INTRODUCTION The required fidelity of synthetic materials in surgical simulators to teach tissue handling and repair requirements should be as accurate as possible. There is a poor understanding of the relationship between choice of muscle surrogates and training outcome for trainee surgeons. To address this, the mechanical characteristics of several candidate synthetic muscle surrogates were measured, and their subjective biofidelity was qualitatively assessed by surgeons. METHODS Silicone was selected after assessing several material options and 16 silicone-based surrogates were evaluated. Three of the closest samples to muscle (Samples 1.1, 1.2, 1.3) and one with inserted longitudinal fibres (1.2F) were mechanically tested in the following: compression and tension, needle puncture force and suture pull-out in comparison with real muscle. The four samples were evaluated by 17 Plastic and Orthopaedic surgeons to determine their views of the fidelity with regard to the handling properties, needle insertion and ease of suture pull-out. RESULTS The mechanical testing showed the surrogates exhibited varying characteristics that matched some of the properties of muscle, though none recreated all the mechanical characteristics of native muscle. Good biofidelity was generally achieved for compression stiffness and needle puncture force, but it was evident that tensile stiff was too low for all samples. The pull-out forces were variable and too low, except for the sample with longitudinal fibres. In the qualitative assessment, the overall median scores for the four surrogate samples were all between 30 and 32 (possible range 9-45), indicating limited differentiation of the samples tested by the surgeons. CONCLUSIONS The surrogate materials showed a range of mechanical properties bracketing those of real muscle, thus presenting a suitable combination of candidates for use in simulators to attain the requirements as set out in the learning outcomes of muscle repair. However, despite significant mechanical differences between the samples, all surgeons found the samples to be similar to each other.