Shealy J.E.,Rochester Institute of Technology |
Ettlingen C.F.,Vermont Safety Research |
Scher I.,Guidance Engineering |
Johnson R.,University of Vermont
ASTM Special Technical Publication | Year: 2015
Skiing and snowboarding are common activities at ski resorts that may result in injury. In 1980, The National Ski Areas Association (NSAA) commissioned the first 10-Year Interval national injury study. This is the fourth such study. The objective of the study was to obtain estimates of the prevalence, incidence, and nature of snow sports injuries across the US. These studies are used to evaluate injury trends. The method for the study was to obtain Ski Patrol Incident data from selected ski resorts in the US on the basis of size and geographical location. The data were weighted by the % of resort visits based on size and location. National skier and snowboarder control demographic data came from the NSAA 2010 National Demographic Study. Resort visit totals came from the NSAA 2010 Kottke National End-of-Season Survey. A retrospective stratified study design was used. Statistical package for the social sciences (SPSS) was used to evaluate incidence trends using linear regression. Incidence rate differences were evaluated using t-test. Prevalence was evaluated using Chi-Square tests. The 0.05 level of significance was used. The sample areas generated 13 145 incident reports and 4 618 194 visitation days. The weighted skiing incident rate was 3.1 per 1000 visits in 1980, 2.7 in 1990, 2.6 in 2000, and 2.5 for 2010. The weighted 2010 snowboard rate was 6.1 per 1000 visits; it was 3.3 in 1990, and 7.0 for 2000. Ultimately, skiing injury rate continues to decrease. Snowboarding injury rate has decreased since the last study: injury patterns for snowboarding versus skiing is unchanged, injury patterns for males versus females is unchanged, incidence of jumping related incident reports has declined since last report, the prevalence of collision incidents with fixed objects on the slope decreased, and Terrain Parks are not associated with increase in injury rates or prevalence of jumping injuries. Copyright © 2015 by ASTM International, West Conshohocken, PA. All rights reserved.
Ettlinger C.F.,Vermont Safety Research |
Dodge D.,Vermont Safety Research |
Johnson R.J.,University of Vermont |
Shealy J.E.,Rochester Institute of Technology |
Sargent M.,University of Vermont
Journal of ASTM International | Year: 2010
Releasable ski bindings have helped to reduce the risk of lower leg injury but have not been effective in abating the risk of injury to the knee's anterior cruciate ligament (ACL). The authors theorized that if binding retention requirements were better understood, bindings could be developed that would eliminate excess retention under conditions associated with known mechanisms of injury, while providing an appropriate margin of retention during controlled skiing maneuvers. Currently, release/retention requirements for Alpine bindings are defined simply by a moment (couple). But the moment sensed by a skier's leg at release is dependent on not only the release moment to which the binding has been adjusted also but by where on the ski the load is applied. During the Winter of 2006-2007, the authors developed the instrumentation, protocols, and methods of data reduction and analysis necessary to express retention requirements of Alpine skiers in terms of load and load position on a virtual ski of infinite length. During the Winter of 2007-2008, 15 experienced skiers were fitted with a pair of skis in which one ski was equipped with a platform for measuring forces transverse to the long axis of the ski boot in a plane parallel to the bottom of the sole. Each subject in the study performed a series of skiing, recovery, and climbing maneuvers. Video and audio records of those maneuvers were synchronized with the 90 min of recorded data, allowing the data to be classified by skiing activity and reduced to a force and moment resolved about an axis approximating the skier's tibia. The force was then divided into the moment resulting in the position (lever arm) of the force necessary to produce the moment. Using current standards, the moment was scaled as a percentage of the recommended release moment. Loads applied to the inside edge of the rear body of the ski, an area commonly associated with ACL injuries, were rarely found to be both more than 45 cm from the tibia and more than 40 % of the recommended. The few events in this "zone of ACL vulnerability" were associated with loss of control while skiing backward at low speed. From these observations, a release simulating platform was developed, which isolated the binding from the ski. The platform sounded an alarm if the moment sensed by the simulator exceeded 50 % of the recommended release moment and the load was applied in the "zone of vulnerability." In more than 120 min of skiing, the alarm never sounded, indicating that no inadvertent release would have taken place if the simulator had been an active release binding. However, subjects were able to initiate the alarm, thus simulating a release, by attempting to twist out of the binding with only the tail end of the ski engaged with the snow surface. The authors believe that the database and analytical techniques developed in this study may help to optimize the overall release/ retention capabilities of future bindings. Copyright © 2010 by ASTM International.