Playground injury prevention: the need for consistent and national implementation of Australian safety standards.

OBJECTIVES: Hospitalisation rates for injury, including at playgrounds, have not changed in the past decade. There are nine Australian Standards specific to playgrounds. The impact (if any) of these standards on playground injury resulting in hospitalisation is unknown. METHODS: Retrospective data for patients under 18 years presenting to emergency departments and/or admitted between October 2015 and December 2019 due to an injury documented as occurring at a playground were retrieved by the Illawarra Shoalhaven Local Health District Planning, Information and Performance Department. Maintenance and Australian Standard (AS) compliance data for the 401 local playgrounds were requested from the four Local Governments in Illawarra Shoalhaven Local Health District. Descriptive statistics were used. RESULTS: A total of 548 children were treated in emergency departments and/or admitted following playground injury. There was an overall increase of 39.3% in playground injury across the study period, and expenditure rose from $43,478 in 2011 to $367,259 in 2019 (a 744.7% increase). CONCLUSIONS: Playground injury has not decreased in the Illawarra Shoalhaven. Data regarding maintenance and AS compliance are lacking. This is not unique to our region. IMPLICATIONS FOR PUBLIC HEALTH: Without a national approach to adequately resource and monitor playground injury, it is not possible to assess the impact of Australian Standards or any injury prevention program.

A Public Health Review into Two Decades of Domestic Trampoline Injuries in Children within Queensland, Australia.

Trampolining as an activity brings enjoyment and many health benefits, but at the same time it carries an injury risk. Most domestic trampoline users are children who are developing in skill, cognition, risk perception, physical strength and resilience to injury. Several common patterns of child trampoline injuries have been identified and countermeasures outlined in standards have been taken to reduce higher risk injury mechanisms, such as entrapment and falls from the trampoline through design, product and point of sale labelling. In Australia, the first national trampoline standard was published in 2003 which introduced improvements in trampoline design and requirements for labelling and padding. This work investigated the potential impact of these and subsequent changes based on almost two decades of emergency department trampoline injury data collected in Queensland, Australia. These data describe the changing representative proportion and pattern of trampoline injuries in Queensland over time by age, mechanism, gender, severity and nature of injury of injured persons up to the age of 14 years. The interrelationships between different injury characteristics were also analysed to propose the main factors influencing injury occurrence and severity. These findings seem to indicate that safety evolution in the form of enclosure nets, frame impact attenuation and entrapment protection have likely improved domestic trampoline safety. Other factors, such as adult supervision, minimum age and avoidance of multiple users, could further reduce injury but are harder to influence in the domestic setting.

Investigating the Knuckleball Effect in Soccer Using a Smart Ball and Training Machine.

The term knuckleball in sporting jargon is used to describe a ball that has been launched with minimal spin, resulting in a trajectory that is erratic and unpredictable. This phenomenon was first observed in baseball (where the term originated) and has since been observed in other sports. While knuckleball has long fascinated the scientific community, the bulk of research has primarily focused on knuckleball as it occurs in baseball. Following the changes in the design of the soccer ball after the 2006 World Cup, knuckleball and ball aerodynamics were exploited by soccer players. This research examined the properties of a knuckleball in the sport of soccer. We designed and evaluated a system that could reproduce the knuckleball effect on soccer balls based on previous theories and characteristics outlined in our literature review. Our system is comprised of the Adidas miCoach Smart Ball, a companion smart phone app for data collection, a ball-launching machine with programmable functions, and a video-based tracking system and Tracker motion analysis software. The results from the testing showed that our system was successfully able to produce knuckleball behaviour on the football in a highly consistent manner. This verified the dynamic models of knuckleball that we outline. While a small portion of the data showed some lateral deviations (zig-zag trajectory), this erratic and unpredictable trajectory was much smaller in magnitude when compared to examples seen in professional games. The sensor data from the miCoach app and trajectory data from the Tracker motion analysis software, showed that the knuckleballs were consistently reproduced in-line with theoretical dynamics.

Investigation into the Trampoline Dynamic Characteristics and Analysis of Double Bounce Vibrations.

Double bounce is an unusual and potentially very hazardous phenomenon that most trampoline users may have experienced, yet few would have really understood how and why it occurs. This paper provides an in-depth investigation into the double bounce. Firstly, the static and dynamic characteristics of a recreational trampoline are analysed theoretically and verified through experiments. Then, based on the developed trampoline dynamic model, double bounce simulation is conducted with two medicine balls released with different time delays. Through simulation, the process of double bounce is presented in detail, which comprehensively reveals how energy is transferred between users during double bounce. Furthermore, the effect of release time delay on double bounce is also presented. Finally, we conducted an experiment which produced similar results to the simulation and validated the reliability of the trampoline dynamic model and double bounce theoretical analysis.

Neck Loads During Head-First Entries into Trampoline Dismount Foam Pits: Considerations for Trampoline Park Safety.

Serious cervical spine injuries have been documented from falls into foam pits at trampoline parks. To address the lack of evidence on how foam pits should be designed for mitigating neck injury risk, this study aimed to quantify neck loads during head-first entry into varying foam pit designs. An instrumented Hybrid III anthropomorphic test device was dropped head-first from a height of up to 1.5 m into three differently constructed foam pits, each using a different mechanism to prevent direct contact between the falling person and the floor (foam slab, trampoline or net bed). Measured neck loads were compared to published injury reference values. In the simplest, foam-only pit design, increasing foam depth tended to reduce peak compressive force. At least one injury assessment reference metric was exceeded in all pit conditions tested for 1.5 m falls, most commonly the time-dependent neck compression criterion. The results highlight the importance of adequate foam depth in combination with appropriate pit design in minimizing injury risk. The risk of cervical spine injury may not be reduced sufficiently with current foam pit designs.

A Measurement of 'Walking-the-Wall' Dynamics: An Observational Study Using Accelerometry and Sensors to Quantify Risk Associated with Vertical Wall Impact Attenuation in Trampoline Parks.

This study illustrates the application of a tri-axial accelerometer and gyroscope sensor device on a trampolinist performing the walking-the-wall manoeuvre on a high-performance trampoline to determine the performer dynamic conditions. This research found that rigid vertical walls would allow the trampolinist to obtain greater control and retain spatial awareness at greater levels than what is achievable on non-rigid vertical walls. With a non-rigid padded wall, the reaction force from the wall can be considered a variable force that is not constrained, and would not always provide the feedback that the trampolinist needs to maintain the balance with each climb up the wall and fall from height. This research postulates that unattenuated vertical walls are safer than attenuated vertical walls for walking-the-wall manoeuvres within trampoline park facilities. This is because non-rigid walls would provide higher g-force reaction feedback from the wall, which would reduce the trampolinist's control and stability. This was verified by measuring g-force on a horizontal rigid surface versus a non-rigid surface, where the g-force feedback was 27% higher for the non-rigid surface. Control and stability are both critical while performing the complex walking-the-wall manoeuvre. The trampolinist experienced a very high peak g-force, with a maximum g-force of approximately 11.5 g at the bottom of the jump cycle. It was concluded that applying impact attenuation padding to vertical walls used for walking-the-wall and similar activities would increase the likelihood of injury; therefore, padding of these vertical surfaces is not recommended.

Analysis of Racing Greyhound Path Following Dynamics Using a Tracking System.

The University of Technology Sydney (UTS) has been working closely with the Australasian greyhound industry for more than 5 years to reduce greyhound race-related injuries. During this period, UTS has developed and deployed several different techniques including inertial measurement units, drones, high-frame-rate cameras, track geometric surveys, paw print analysis, track soil spring-force analysis, track maintenance data, race injury data, race computer simulation and modelling to assist in this task. During the period where the UTS recommendations have been adopted, the injury rate has dropped significantly. This has been achieved by animal welfare interventions that lower racing congestion, and lower transient forces and jerk rates the greyhounds experience during a race. This study investigated the use of a greyhound location tracing system where small and lightweight signal emitting devices were placed inside a pocket in the jackets of racing greyhounds. The system deployed an enhanced version of a player tracking system currently used to track the motion of human athletes. Greyhounds gallop at speeds of almost 20 m/s and are known to change their heading direction to exceed a yaw rate of 0.4 rad/s. The high magnitudes of velocity, acceleration and jerk posed significant technical challenges, as the greyhounds pushed the human tracking system beyond its original design limits. Clean race data gathered over a six-month period were analysed and presented for a typical 2-turn greyhound racing track. The data confirmed that on average, greyhounds ran along a path that resulted in the least energy wastage, which includes smooth non-linear paths that resemble easement curves at the transition between the straights to the semi-circular bends. This study also verified that the maximum jerk levels greyhounds experienced while racing were lower than the jerk levels that had been predicted with simulations and modelling for the track path. Furthermore, the results from this study show the possibility of such a systems deployment in data gathering in similar settings to greyhound racing such as thoroughbred and harness horse racing for understanding biomechanical kinematic performance.

Evaluating Martial Arts Punching Kinematics Using a Vision and Inertial Sensing System.

Martial arts has many benefits not only in self-defence, but also in improving physical fitness and mental well-being. In our research we focused on analyzing the velocity, impulse, momentum and impact force of the Taekwondo sine-wave punch and reverse-step punch. We evaluated these techniques in comparison with the martial arts styles of Hapkido and Shaolin Wushu and investigated the kinematic properties. We developed a sensing system which is composed of an ICSensor Model 3140 accelerometer attached to a punching bag for measuring dynamic acceleration, Kinovea motion analysis software and 2 GoPro Hero 3 cameras, one focused on the practitioner's motion and the other focused on the punching bag's motion. Our results verified that the motion vectors associated with a Taekwondo practitioner performing a sine-wave punch, uses a unique gravitational potential energy to optimise the impact force of the punch. We demonstrated that the sine-wave punch on average produced an impact force of 6884 N which was higher than the reverse-step punch that produced an average impact force of 5055 N. Our comparison experiment showed that the Taekwondo sine-wave punch produced the highest impact force compared to a Hapkido right cross punch and a Shaolin Wushu right cross, however the Wushu right cross had the highest force to weight ratio at 82:1. The experiments were conducted with high ranking black belt practitioners in Taekwondo, Hapkido and Shaolin Wushu.

Greyhound racing ideal trajectory path generation for straight to bend based on jerk rate minimization.

This paper presents methods for modelling and designing an ideal path trajectory between straight and bend track path segments for racing greyhounds. To do this, we numerically generate clothoid and algebraic curve segments for racing quadrupeds using a sequential vector transformation method as well as using a helper equation for approaching ideal clothoid segments that would respect greyhound kinematic parameters and boundary conditions of the track. Further, we look into the limitations of using a clothoid curve for racing dog track path design and propose a smooth composite curve for track transition design which roughly maintains G3 curvature continuity for smooth jerk to overcome limitations of a clothoid transition. Finally, we show results from race data modelling and past injury data, which provide a strong indication of clothoid curve segments improving the dynamics and safety of racing greyhounds while reducing injuries.

Analysis of Agile Canine Gait Characteristics Using Accelerometry.

The high rate of severe injuries associated with racing greyhounds poses a significant problem for both animal welfare and the racing industry. Using accelerometry to develop a better understanding of the complex gait of these agile canines may help to eliminate injury contributing factors. This study used a single Inertial Measurement Unit (IMU) equipped with a tri-axial accelerometer to characterise the galloping of thirty-one greyhounds on five different race tracks. The dorsal-ventral and anterior-posterior accelerations were analysed in both the time and frequency domains. The fast Fourier transform (FFT) and Morlet wavelet transform were applied to signals. The time-domain signals were synced with the corresponding high frame rate videos of the race. It was observed that the acceleration peaks in the dorsal-ventral accelerations correspond to the hind-leg strikes which were noted to be fifteen times the greyhound's weight. The FFT analysis showed that the stride frequencies in all tracks were around 3.5 Hz. The Morlet wavelet analysis also showed a reduction in both the frequency and magnitude of signals, which suggests a speed reduction throughout the race. Also, by detecting abrupt changes along the track, the wavelet analysis highlighted potentially hazardous locations on the track. In conclusion, the methods applied in this research contribute to animal safety and welfare by eliminating the factors leading to injuries through optimising the track design and surface type.

The relationship between compression garments and electrocardiogram signals during exercise and recovery phase.

BACKGROUND: The direction of the current research was to investigate whether electrocardiogram (ECG) signals have been impacted by using compression garments during exercise and recovery phase. Each subject is non-athletes, conducted two running tests, wearing either non-compression garments (NCGs) or compression garments (CGs) throughout experiments and 2-h of the recovery phase. Experiment 1 (number of participants (n) = 8; 61.4 ± 13.7 kg, 25.1 ± 3.8 years, 165.9 ± 8.3 cm) focused on the exercising phase while Experiment 2 (n = 14; 60.9 ± 12.0 kg, 24.7 ± 4.5 years, 166.0 ± 7.6 cm) concentrated on the recovery phase. Electrocardiogram (ECG) data were collected through wearable biosensors. RESULTS: The results demonstrated a significant difference between compression garments and non-compression garments at the end of the tests and from 90 min onwards during the recovery phase (p < 0.05). Corrected QT (QTc), ST interval and heart rate (HR) indicated the significant difference between NCGs and CGs. CONCLUSION: Based on the findings, the utilization of compression garments showed a positive influence in non-athletes based on the quicker recovery in HR, ST, and QTc.

Effect Of Compression Garments On Cardiovascular Function During Recovery Phase.

The aim of this present research was to determine whether the cardiovascular function has been affected by wearing compression garments during the recovery phase. Fourteen subjects (men, $\text{n}=$7; women, $\textbf{n}=$7; $24.7 \pm 4.5$ years, $166.0 \pm 7.6$ cm; $60.9 \pm 12.0$ kg) completed a running protocol on a treadmill. Each subject participated in two running experiments, using either compression garments (CGs) or non- compression garments (NCGs) during exercise and 2 hours recovering time. Electrocardiogram (ECG) signals were collected during 2 hours recovery using wearable sensors. The present work indicated a statistically significant difference between CGs and NCGs from 90 minutes recovery onwards $( \mathrm {p}<0.05)$. ECG parameters showed some significant difference in heart rate (HR), ST and corrected QT (QTc $) ( \mathrm {p}<0.05)$. Therefore, the cardiovascular function was positively influenced by the application of CGs during the recovery phase.

The Effectiveness Of Compression Garments On EEG During a Running Test.

The specific purpose of this present paper was to investigate whether the EEG activity has been affected by wearing whole body compression garments during a running test. Ten subjects (men, n=5; women, n=5; age: 24.11 ± 4.48 years; height: 163.56 ± 7.70 cm; chest: 87.78 ± 6.92 cm; weight: 58.67 ± 10.96 kg; BMI: 21.77 ± 2.63 kg.m-2) completed a running protocol on a treadmill. Each subject participated in two running trials, wearing either a compression garment (CG) or a non-compression garment (NCG) during exercise. Electroencephalogram (EEG) signals were collected during exercise using wearable sensors. The present study revealed a statistically significant difference between CGs and NCGs in alpha, beta and theta power spectral density (p<0.05). Therefore, the brain activity was influenced by the application of CGs during the running test. This result would also recommends an application of CGs in training as well as in competition.

Increasing injuries as trampoline parks expand within Australia: a call for mandatory standards.

OBJECTIVE: To quantify an apparent increase in indoor trampoline park related injuries in children and young people across Australia, and to understand the implications for current regulatory standards. METHODS: Retrospective analyses of three state-based Injury Surveillance databases, identifying children and adolescents presenting to emergency departments between the years 2005 and 2017, who had sustained injuries during trampolining activity at an indoor trampoline park. RESULTS: Across the three datasets, 487 cases were identified. No cases were recorded prior to 2012, the year the first indoor trampoline park opened. At least half occurred among those aged 10-14 years. In Victoria, 58% were male, with 52% in Queensland and 60% in Western Australia being male, respectively. Hospital admission rates in these states were 15%, 11.7% and 14.5%, respectively. The most frequent injury types were dislocations, sprains and strains, followed by fractures, with some head and spinal injuries. CONCLUSIONS: Across several states in Australia, the incidence of indoor trampoline park related injuries is concerning, as these venues are increasing in number. Some injuries can be serious and result in lifelong disability for children or adolescents. Implications for public health: National safety standards that apply to indoor trampoline park operators are not currently mandatory; injury prevention efforts would be assisted if such standards were mandatory.

Full-face motorcycle helmet protection from facial impacts: an investigation using THOR dummy impacts and SIMon finite element head model.

OBJECTIVE: Facial impacts are both common and injurious for helmeted motorcyclists who crash; however, there is no facial impact requirement in major motorcycle helmet standards. This study examined the effect of full-face motorcycle helmet protection on brain injury risk in facial impacts using a test device with biofidelic head and neck motion. A preliminary investigation of energy absorbing foam in the helmet chin bar was carried out. METHOD: Flat-faced rigid pendulum impacts were performed on a THOR dummy in an unprotected (no helmet) and protected mode (two full-face helmet conditions). The head responses of the dummy were input into the simulated injury monitor finite element head model to analyse the risk of brain injury in these impacts. RESULTS: Full-face helmet protection provides a significant reduction in brain injury risk in facial impacts at increasing impact speeds compared with an unprotected rider (p<0.05). The effect of low-density crushable foam added to the chin bar could not be distinguished from an unpadded chin bar impact. CONCLUSIONS: Despite the lack of an impact attenuation requirement for the face, full-face helmets do provide a reduction in head injury risk to the wearer in facial impacts. The specific helmet design factors that influence head injury risk in facial impacts need further investigation if improved protection for helmeted motorcyclists is to be achieved.

Mechanisms of Head and Neck Injuries Sustained by Helmeted Motorcyclists in Fatal Real-World Crashes: Analysis of 47 In-Depth Cases.

Despite an improved understanding of traumatic head and neck injury mechanisms, the impact tests required by major motorcycle helmet standards have remained unchanged for decades. Development of new test methods must reflect the specific impact loads causing injury in real crashes as well as test criteria appropriate for the observed injury profiles. This study analysed a collection of in-depth crash investigations of fatally injured helmeted riders in the Adelaide metropolitan region between 1983 and 1994 inclusive to review the head and neck injury patterns that resulted from specific types of impact. Inertial brain injury was sustained in 49% of examined cases, most often resulting from facial impacts but also in a large proportion of tangential, run over, and occipital impact cases. Focal brain and brainstem injury was also common (53%) and regularly associated with skull vault (11/12) and skull base fractures (22/31). Prevention of these fractures in impacts outside the area of required protection and in impacts with a straight edge would provide a significant increase in helmeted rider protection. Cervical spinal cord injury was sustained in facial, straight edge, and tangential impacts on the head. Motorcycle helmets are effective for preventing local skull fractures in impacts for which they are designed, whereas other serious injuries such as basilar skull fracture (BSF) and inertial brain injury persist despite helmet protection. Further impact test procedures should be developed for injurious impact types not currently assessed by major helmet standards, in particular facial impacts, and using test criteria based on commonly observed injuries. This study provides the necessary link, from impact load to injury, for guiding impact test development.

Australian trampoline injury patterns and trends.

OBJECTIVES: To examine national trampoline injury patterns and trends in the context of improved product safety standards and trampoline design modifications. METHOD: Review of National Hospital Morbidity data. RESULTS: There were an average 1,737 trampoline injuries reported nationally each year from 2002 to 2011. Both injury frequency and rate grew. Statistically significant rate increases were observed among all age groups, although both are highest among children aged 5-9 years. From 2008/09 there is a possible decreasing trend among the 5-9 age group. Falls predominate and 81% of falls result in fracture. Non-fall injuries increased annually as a proportion of all hospitalised injury although they did not comprise more than 2.4% in any one year. CONCLUSIONS: History provides no evidence of an observable effect of voluntary Australian Standards for trampoline safety on population rates for trampoline injury. The major design modification--netted enclosures--could contribute to the risk of injury by leading parents to falsely believe that a netted enclosure eradicates the risk of injury.

Influence of voluntary standards and design modifications on trampoline injury in Victoria, Australia.

PURPOSE: To examine the influence of the voluntary Australian trampoline standard (AS 4989-2006) and market-driven design modifications on relevant trampoline injuries. METHODS: Trend and intervention analysis on frequencies and proportions of hospital-treated trampoline-related injury in Victoria, Australia, extracted from the Victorian Emergency Minimum Dataset from 1 July 1999 to 30 June 2013. The injuries relevant to the AS were contact with spring and frame, and multiple-user injury. Falls from trampolines were relevant for netted trampolines, a market-driven modification. RESULTS: Frequency of all trampoline injuries increased by 11.4% (95% CI 10.0% to 11.7%) on average each year. Spring and frame, and fall injuries increased to a lesser extent (8.7%, 95% CI 6.9% to 9.8% and 7.3%, 95% CI 5.8% to 8.3%, respectively). Multiple-user injuries increased by 21.0% (95% CI 16.3% to 21.9%). As a proportion of all trampoline injuries, spring and frame injury and falls injury decreased, while multiple-user injuries increased. The intervention analysis showed no significant change in spring and frame injuries associated with the AS (p=0.17). A significant increase was found for multiple-user injuries (p=0.01), in particular for the 0-year to 4-year age group (p<0.0001), post 2007. CONCLUSIONS: There was little evidence for an effect of the voluntary standard on spring and frame injury and none for multiple-user injury. Netted trampolines appear to be associated with a decrease in falls from trampolines but an increase in injuries to multiple users. A mandated trampoline safety standard and a safety campaign including warnings about multiple users is recommended. Continued monitoring of injury data will be required.