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11:30   Safety & Injury prevention; helmets Chair: David James 11:30 20 mins PERFORMANCE OF CHILDREN AND ADULT ALPINE HELMETS UNDER CHARACTERISTIC FALLING CONDITIONS David Koncan, Roger Zemek, Thomas B. Hoshizaki Abstract: Introduction: Alpine standards test the protective capacity of helmets at high velocity. In some cases, the head impact velocity from falling is lower than what is being tested. Additionally, young children will fall with lower head impact velocities in comparison to adults. It is unknown how well alpine helmets perform under the conditions of “normal” falling. This study is designed to determine the protective capacity of alpine helmets for characteristic fall events, typical for adults and young children. Methods: Drop tests were conducted at three impact sites (front, side, rear) on an angled steel anvil with and without a helmet at characteristic impact velocities (3.3m/s for children, 5.5 m/s for adults). Impact velocities were determined using MADYMO simulations, taking an average head impact velocity for several simulation conditions. Performance was assessed based on peak linear and peak rotational acceleration. Results: The child helmet produced an average reduction in linear and rotational accelerations of 64% and 62% respectively. In comparison, the adult helmet showed reductions in linear and rotational accelerations of 48% and 50% respectively. Average results are shown in Table 1. Table 1 – Average dynamic responses for helmeted and unhelmeted falls. Average value and one standard deviation are presented for the three impacts at each site. Peak Resultant Linear Acceleration (g) Peak Resultant Rotational Acceleration (rad/s2) Impact Site Child-unhelmeted Child-helmeted Adult-unhelmeted Adult-helmeted Child-unhelmeted Child-helmeted Adult-unhelmeted Adult-helmeted Front 91.6±8.0 36.1±7.9 162.0±14.7 108.2±11.2 6241±358 2113±792 15335±1470 6509±1111 Side 78.9±6.5 30.0±2.2 168.0±22.4 86.1±11.1 10550±272 3251±347 19398±1125 7968±1758 Rear 133.8±20.0 41.7±9.6 320.2±18.2 126.8±9.7 5592±283 2825±539 14435±390 9716±1254 Conclusions: The youth helmet performed well under lower impact velocity conditions those tested by standards. In children’s helmets, it is hypothesized that the soft comfort foam is responsible for helping disperse energy at low impact velocities and the liner performs well at high velocity. For adults, peak linear are rotational accelerations are reduced by roughly half, showing the liner performs well at an impact velocity below standards tests. Current helmets reduce the dynamic response of falls, which could reduce the risk of concussions and other brain injuries known to be associated with linear and rotational acceleration. 11:50 20 mins ON-TRACK MEASUREMENTS IN MOTOCROSS: THE CORRELATION OF NECK MUSCLE ACTIVITY AND CONTACT INCIDENTS OF HELMET AND NECK BRACE AND ITS BENEFITS TO FUTURE NECK BRACE DESIGNS Gerrit Thiele, Patricia Kafka, Stefan Litzenberger, Anton Sabo Abstract: Modern Motocross racing is a very demanding and a highly injury rated sport. Within a wide range of injuries, cervical spine injuries are most feared and can even end up in different forms of paraplegia. Worn around the neck and with a non-permanent connection to rider, neck braces primarily offer a protective purpose to prevent cervical spine injuries. Beside the protective purpose, neck braces can have a supporting or a fatigue effect to the rider’s neck muscles, where the effects depend on the specific neck brace design and the contact occurring between helmet and brace. A field test was conducted recording the contact incidents of a neck brace and helmet during on-track measurements by using a self-made sensor construction. The sensor construction was based on 12 electrical push-buttons and was mounted at the helmet’s underside. Contact data was stored using two portable data-logging systems. Additionally muscular activity of m. sternocleidomastoideus and the upper part of m. trapezius were recorded while riding using a portable EMG-system. The data delivered information about a connection of the changes of neck muscle activity and the frequent contact areas of helmet and brace. Related to the data of specific contact areas, it can be explained why driving with neck brace affects the activation levels and distribution of muscular activity of the muscles observed. Low and high frequent contact areas of helmet and brace could be located for total riding time, single laps and specific events, whereby a decreasing trend of contact incidents by increasing riding time could be observed. According to the recent results, the correlation of contact and EMG data could be used for further neck brace design improvements and specific design adaptations to special requirements of several bike sports. 12:10 20 mins HEADFORM MOUNTING PERFORMANCE IN CRICKET STANDARD TESTING Ben Stone, Ben Halkon, Andy Harland Abstract: The current British Standard for head protectors for cricketers specifies a projectile test to ensure that a helmet can prevent the ball penetrating the peak-grille gap and deformation of the grille onto the face. For practical reasons, it is specified that the headform is mounted onto a grounded frame. This study aims to determine whether this “Fixed” mounting technique influences the response of the headform relative to a theoretically preferable “Free” suspension. A pressurised air cannon was used to project a “BOLA”TM ball at three nominal speeds (22, 25 and 28 m/s) and at three target impact locations (136 (Top), 108 (Middle) and 80 (Bottom) mm from the base). High speed video was used to identify the contact duration and accelerometer data were used to assess the peak resultant headform acceleration and velocity during this period. Generally, good agreement between the two scenarios was found in regard to peak resultant headform acceleration, particularly at the 25 and 28 m/s impact speeds. In terms of headform velocity, the two scenarios showed greater variation when the full contact duration was considered, with root mean square deviations ranging from 1.77 – 5.6 in all testing conditions. However, some portions of the impact were considerably more consistent than others. These initial results indicate that the result of the penetration test, as specified in BS 7928:2013, would be independent of the suspension technique particularly given the convergence of results at the specified standard velocity (28 m/s). Future work should look to identify the loading and unloading phases of an impact, and use this to compare headform response. Thus allowing a more in-depth investigation of headform mounting performance and provide more clarity on the use of the Fixed technique in cricket standard tests.