• Injury Prevention
• Ski Injuries
• Knee ACL
• Biomechanics
• Measurement

Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted (Albert Einstein 1879-1955).

Alpine ski racing is an Olympic winter sport where athletes ski one by one down the mountain on a demanding course, often in challenging snow and weather conditions. The Athletes must ski as efficiently as possible, as performance is determined by the racing time measured to 0.01 s, but at the same time they have to adapt speed and trajectory to their technical skills and manage risk responsibly. In this issue, Gilgien et al1 quantify and describe the mechanical characteristics (such as skier speed, turn radius, air drag force, ground reaction force, jump distance and airtime) of World Cup alpine skiing under real race conditions, and interestingly they link these data to the risk of injury. With their biomechanical approach, they add new and valuable information to the field of injury prevention research by identifying factors that contribute to the chain of events that can put the skier in a vulnerable situation.

Skier safety is a priority for the International Ski Federation (FIS). Therefore, the FIS Injury Surveillance System was established prior to the 2006/07 winter season to provide and monitor data on injuries in World Cup skiing and snowboarding. This system is based on injury registration through retrospective athlete interviews, and on average 1 in 3 World Cup alpine skiers report an acute injury each season.2 In World Cup races, there is about 1 injury/100 runs, and most injuries are reported to occur in the downhill discipline, followed by super-G, giant slalom and slalom.2 The long-term goal of the FIS Injury Surveillance System is to prevent injuries among athletes, thus further knowledge of why and how injuries occur is needed.3 Injury causes are most often multifactorial and complex, which means that to identify the most critical factors, a combination of different methodological approaches may be of great value.4

Different methods provide different insights. Systematic video analyses of injuries reported through the FIS Injury Surveillance System have helped shed light on how injuries happen.5 ,6 Most injuries occur when the skier is turning, or landing from a jump. Head and upper body injuries result from crashes, whereas the majority of knee injuries occur while the skier is still skiing. Qualitative research was used to identify potential risk factors for injuries in a study by Spörri et al,7 where they interviewed 61 expert stakeholders in the World Cup ski racing community. The top five categories of perceived risk factors were the ski-binding-boot system, changing snow conditions, speed and course setting, speed in general and athlete physical fitness. Interestingly, the relationship between physical fitness and ACL injuries among younger ski racers was addressed by Raschner et al8 using a different approach, a prospective cohort study. They suggested that core strength is a critical risk factor for ACL injuries.

In this issue, Gilgien et al1 have employed yet another method, a biomechanical approach, to investigate how mechanical characteristics during alpine skiing performance are related to the risk of injury. The mechanics of turning and jumping, as well as skier speed and forces, were significantly different between the downhill discipline, super-G and giant slalom.1 Based on injuries reported through the FIS Injury Surveillance System, they also found that the different disciplines are equally risky when injury rate is corrected for race times. The mechanical characteristics and the specific injury risk within the different disciplines indicate that in super-G and downhill, injuries might be mainly related to higher speed and jumps, and the mechanical energy involved in crashing. In the technical disciplines, injuries might be related to a combination of turn speed and turn radius, resulting in high loads. These data do not allow us to distinguish which variables are directly linked to increased risk of injury. However, identifying factors that seem to play a part in the occurrence of injury is an important step to generate hypotheses and ideas for injury prevention.

Different methodological approaches have contributed to increasing our understanding of why and how injuries occur in alpine ski racing during recent years. Gilgien et al1 emphasise that injury causes are not only multifactorial, but also most likely discipline-specific, and injury prevention efforts should be directed accordingly.