Based on this video analysis of 20 injury situations, the main mechanism of anterior cruciate ligament injury in World Cup alpine skiing appeared to be a slip-catch situation where the outer ski catches the inside edge, forcing the outer knee into internal rotation and valgus. A similar loading pattern was observed for the dynamic snowplow. Injury prevention efforts should focus on the slip-catch mechanism and the dynamic snowplow.

BackgroundWe have limited insight into the mechanisms of anterior cruciate ligament (ACL) injuries in alpine skiing, particularly among professional ski racers.ObjectiveTo describe the mechanisms of ACL injury in World Cup alpine skiing.DesignDescriptive video analysis.SettingWorld Cup alpine skiing.Methods20 cases of ACL injuries reported through the International Ski Federation Injury Surveillance System for three consecutive World Cup seasons (2006–2009) were obtained on video. Seven international experts performed visual analyses of each case to describe the injury mechanisms in detail (skiing situation, skier behaviour, biomechanical characteristics).ResultsThree main categories of injury mechanisms were identified: the slip-catch, landing back-weighted and the dynamic snowplow. The slip-catch mechanism accounted for half of the cases (n=10), and all these injuries occurred during turning, without or before falling. The skier lost pressure on the outer ski, and while extending the outer knee to regain grip, the inside edge of the outer ski abruptly caught in the snow, forcing the knee into internal rotation and valgus. The same loading pattern was observed for the dynamic snowplow (n=3). The landing back-weighted category included cases (n=4) where the skier was out of balance backwards in-flight after a jump and landed on the ski tails with nearly extended knees. The suggested loading mechanism was a combination of tibiofemoral compression, boot induced anterior drawer and quadriceps anterior drawer.ConclusionA consistent pattern was observed where the main mechanism of ACL injury in World Cup alpine skiing appeared to be a slip-catch situation where the outer ski suddenly catches the inside edge, abruptly forcing the outer knee into internal rotation and valgus. A similar loading pattern was observed for the dynamic snowplow. Injury prevention efforts should focus on the slip-catch mechanism and the dynamic snowplow.

No abstract

Purpose-The purpose of this paper is to understand the difference in purchase decision behavior of compression sportswear by Baby Boomers and Generation Y. Design/methodology/approach-Two methods were used for data collection: a simulation study with 17 Baby Boomers and 23 Generation Y subjects using eye-tracking technology; and a questionnaire from a sample of 82 Baby Boomers and 84 Generation Y consumers. Findings-Generation Y are more inquisitive and focus greatly on technical information. Baby Boomers are more confident with their choices, taking a shorter time to reach a purchase decision; they are more concerned with aspects that protect the wearer. Research limitations/implications-Limited demographic information was collected from participants in the simulation study, further research is required in this area. Practical implications-This study provides important insights into the purchase decision behavior of Baby Boomers and Generation Y for compression sportswear. By providing better understanding of some of the key drivers for purchase decisions it enables marketers to develop more effective marketing plans to engage with these important consumer groups. Social implications-The focus and findings of this study provide further understanding of the motivations of two significant consumer cohorts. This study provides further momentum to the body of cohort research already available. Originality/value-This study addresses a gap in literature with reference to the comparison of consumer behavior of generational cohorts when purchasing compression sportswear. Findings can be applied in other areas of sportswear and to other countries.

Activity trackers are a simple and mostly low-priced method to capture physiological parameters. Despite the high number of wrist-worn devices, there is a lack of scientific validation. The purpose of this study was to assess whether the activity trackers represent a valid alternative to gold-standard methods in terms of estimating energy expenditure (EE) and maximum oxygen uptake (VO2max). Twenty-four healthy subjects participated in this study. In total, five commercially available wrist-worn devices were tested with regard to their validity of EE and/or VO2max. Estimated values were compared with indirect calorimetry. Validity of the activity trackers was determined by paired sample t-tests, mean absolute percentage errors (MAPE), Intraclass Correlation Coefficient, and Bland-Altman plots. Within the tested devices, differences in scattering in VO2max and EE could be observed. This results in a MAPE > 10% for all evaluations, except for the VO2max-estimation of the Garmin Forerunner 920XT (7.3%). The latter significantly underestimates the VO2max (t(23) = –2.37, p = 0.027), whereas the Garmin Vivosmart HR significantly overestimates the EE (t(23) = 2.44, p = 0.023). The tested devices did not show valid results concerning the estimation of VO2max and EE. Hence, the current wrist-worn activity trackers are most likely not accurate enough to be used for neither purposes in sports, nor in health care applications.