Surrogate thigh model for assessing impact force attenuation of protective pads

The effects of non-Newtonian fluid material midsole footwear on tibial shock acceleration and attenuation

Introduction: Given the possibility of higher ground temperatures in the future, the pursuit of a cushioning material that can effectively reduce sports injuries during exercise, particularly one that retains its properties at elevated temperatures, has emerged as a serious concern. Methods: A total of 18 man recreational runners were recruited from Ningbo University and local clubs for participation in this study. Frequency analysis was employed to investigate whether there is a distinction between non-Newtonian (NN) shoes and ethylene vinyl acetate (EVA) shoes. Results: The outcomes indicated that the utilization of NN shoes furnished participants with superior cushioning when engaging in a 90° cutting maneuver subsequent to an outdoor exercise, as opposed to the EVA material. Specifically, participants wearing NN shoes exhibited significantly lower peak resultant acceleration (p = 0.022) and power spectral density (p = 0.010) values at the distal tibia compared to those wearing EVA shoes. Moreover, shock attenuation was significantly greater in subjects wearing NN shoes (p = 0.023) in comparison to EVA shoes. Performing 90° cutting maneuver in NN shoes resulted in significantly lower peak ground reaction force (p = 0.010), vertical average loading rate (p < 0.010), and vertical instantaneous loading rate (p = 0.030) values compared to performing the same maneuvers in EVA shoes. Conclusion: The study found that the PRA and PSD of the distal tibia in NN footwear were significantly lower compared to EVA footwear. Additionally, participants exhibited more positive SA while using NN footwear compared to EVA. Furthermore, during the 90° CM, participants wearing NN shoes showed lower PGRF, VAIL, and VILR compared to those in EVA shoes. All these promising results support the capability of NN footwear to offer additional reductions in potential injury risk to runners, especially in high-temperature conditions.

Optimization of the Impact Attenuation Capability of Three-Dimensional Printed Hip Protector Produced by Fused Deposition Modeling Using Response Surface Methodology

Fused deposition modeling has provided a cheap and effective method for the rapid production of prototypes and functional products in many spheres of life. In this study, three-dimensional (3D) printing techniques to produce and optimize a hip protector that will assure clinical efficacy are presented. The I-Optimal design was used to optimize the hip protector's significant parameters (infill density, shell thickness, and material shore hardness) to obtain maximum femoral neck force attenuation of the 3D-printed hip protector. A drop impact tower device simulates the impact force at the hip's parasagittal plane during a fall. The results show that the infill density has the most significant influence on attenuation properties, followed by the infill density combined with the material shore hardness. By maximizing all the parameters, it is demonstrated that using an additive manufacturing technique to print hip protectors could be an effective strategy in curbing hip fractures.

Mitigating fuel tank syndrome pelvic injuries - is there potential for rider worn protectors?

OBJECTIVE

The aim of this study was to investigate the feasibility of rider-worn pelvis protection for mitigating injury risk when contacting the motorcycle fuel tank in a crash.

METHODS

A newly developed test apparatus was designed and constructed to simulate the interaction between a rider's pelvis and the motorcycle fuel tank in a frontal crash. Impacts were performed at a velocity of 18 km/h into four motorcycle fuel tanks. Further testing used a rigid fuel tank surrogate and the pelvis surrogate in an unprotected condition and with a series of impact protector prototypes. A subset of prototype samples was also tested at varying tank angles (30°, 37.5°, 45°) and impact speeds (8.5 km/h, 13 km/h, 18 km/h). Analysis of variance was used to determine whether the protector prototypes reduced pelvis response compared to unprotected.

RESULTS

Resultant peak pelvis acceleration was reduced by three pelvis impact protector prototypes compared to an unprotected condition. The reduction in peak acceleration occurred without a significant change in the peak pelvis rotational velocity. The pattern of protector performance was consistent at varying fuel tank angles but only reduced the pelvis response at the highest impact speed tested of 18 km/h.

CONCLUSIONS

The results indicate that there may be potential for using pelvis impact protection to mitigate injury risk by absorbing and/or distributing impact energy that would otherwise be transmitted to the rider's pelvis. However, due to the current paucity in understanding of pelvis biomechanics to anteroposterior loading, it is unknown whether the pelvis acceleration reductions achieved would prevent injury.

Padded rugby clothing to prevent laceration and abrasion injuries from stud raking: a method of assessment

Padded clothing (shoulder padding) is worn in Rugby Union to give players an opportunity to protect themselves. A performance specification for padded clothing has been set out by World Rugby™, with the intention that padded clothing only protects against lacerations and abrasions. Test protocols in this specification provide an assessment of the impact force attenuative properties of the material, this itself will not indicate what injuries they may have the potential to prevent or lessen the severity of. The current study has used previously established biomechanical parameters to develop a mechanical test procedure to assess the ability of padded clothing to prevent or lessen the severity of stud-induced laceration and abrasion injuries. A synthetic skin and soft tissue surrogate was developed and validated to mimic human anatomy. Without the addition of padded clothing, both wearing (abrasion) and tearing (laceration) of the synthetic tissue surrogate were seen. The addition of padded clothing saw no sign of stud-induced injury, even after six repeated trials of the same product, showing padded clothing can prevent or lessen the severity of lacerations and abrasions. The developed testing protocols could be used to assess the safety of any sports stud designs in relation to skin injury as well as the effectiveness of various protective clothing products across the sports industry.

Test systems for the biomechanical evaluation of hip protectors: a systematic review

Various mechanical and biomechanical test systems to evaluate the effectiveness of hip protectors designed to prevent hip fracture as a result of falls were examined in this review. The articles considered were selected systematically. The effect of differences in design criteria was demonstrated, and it was observed that the impact energy employed during testing dramatically affects the performance of the hip protector. Over the past three decades, researchers have continuously experimented with various systems to determine the efficacy of various hip protectors. The primary aim has been to make informed decisions in optimizing hip protector design. This article provides a systematic review of various test systems employed in the determination of the biomechanical efficacy of hip protectors. A systematic literature search was carried out, and 28 relevant articles were included to demonstrate the effect of test systems in the evaluation of the biomechanical effectiveness of hip protectors. Methodological studies illustrated the appropriate use of impact testing systems for the simulation of hip anatomy and fall dynamics in evaluating the effectiveness of hip protectors in preventing a hip fracture. This systematic review has demonstrated the effect of the variability of test systems on the evaluation of impact attenuation by various hip protectors. The lack of standardized test systems accounts for the inconsistencies in the test results of the efficacy of hip protectors. This has been a major challenge in the efforts of researchers to optimize the interventions. The standardization of test systems may require needed improvements immediately as opposed to the development of new interventions in order to ensure that only hip protectors with adequately proven efficacies are deployed for clinical trials or for the protection of the hips of vulnerable individuals from sideways impact.

Muscle tension increases impact force but decreases energy absorption and pain during visco-elastic impacts to human thighs

Despite uncertainty of its exact role, muscle tension has shown an ability to alter human biomechanical response and may have the ability to reduce impact injury severity. The aim of this study was to examine the effects of muscle tension on human impact response in terms of force and energy absorbed and the subjects' perceptions of pain. Seven male martial artists had a 3.9 kg medicine ball dropped vertically from seven different heights, 1.0-1.6 m in equal increments, onto their right thigh. Subjects were instructed to either relax or tense the quadriceps via knee extension (≥60% MVC) prior to each impact. F-scan pressure insoles sampling at 500 Hz recorded impact force and video was recorded at 1000 Hz to determine energy loss from the medicine ball during impact. Across all impacts force was 11% higher, energy absorption was 15% lower and time to peak force was 11% lower whilst perceived impact intensity was significantly lower when tensed. Whether muscle is tensed or not had a significant and meaningful effect on perceived discomfort. However, it did not relate to impact force between conditions and so tensing may alter localised injury risk during human on human type impacts.