Prevention of Overuse Injuries in Alpine Skiers
The prevention of overuse injuries is fundamental for sports physicians working with elite athletes. The knowledge of the most frequent types of injuries and the leading mechanisms are key steps to reach this goal. The correct collection and management of the data has also to be considered.
Alpine skiing is defined as “the fastest non-motorised sport on Earth” as well as “the riskiest sport undertaken by man”. Unfortunately, the fun of skiing is closely associated with a high risk of injury.
Considering the settings where alpine skiing has its highest expression—the World Cup, World Championships and Olympic Games—it can be seen that injury rates have always fluctuated, with peaks due to changes in equipment or slope grooming and periods of low incidence rates due to athletes adapting to the changes and adopting safer strategies to tackle the slope.
This peculiarity definitely shifts the focus of attention from external, performance-related factors to internal factors pertaining to the athlete and to his or her training, development and “anthropological” adaptation.
8.1.1 State of Play
In consideration of the numerous injuries sustained by its members, during the 2006–2007 season, the FIS, in collaboration with the department of research of the University of Oslo and the University of Salzburg, set up the FIS ISS (FIS Injuries Surveillance System) with the aim of better understanding the mechanisms of injury and devising preventive measures to protect the athletes’ health.
A 2009 paper by Florenes et al. provided a detailed retrospective analysis of the 2006–2007 and 2007–2008 World Cup seasons. The paper reports that almost 80% of professional skiers have, during the course of their career, sustained at least one severe injury, defined as an injury resulting in absence from training and competition for at least 28 days. Another major finding is the 36% overall injury rate, much higher compared to previous seasons, and the 38% rate of severe injuries, definitely higher than in other sports.
The 2014 publication by Bere, “A systematic video analysis of 69 injury cases in World Cup alpine skiing”, identifies five categories of factors that expose athletes to a greater risk of injury: equipment, snow and weather conditions, speed, the piste and the competitors’ athletic performance.
An analysis of these elements clearly shows that everything that characterises alpine skiing races is a potential source of danger, such that the regulations were modified to account for these factors and attempt to limit the risk. However, although recent years have seen many changes to the regulations regarding piste safety, piste marking and equipment, injuries unfortunately continue to be common in this sport.
8.1.2 Focus on Injury
To better understand the mechanisms of injury, video analyses have been successfully used to characterise knee injuries, i.e. the most common injuries in skiers accounting for over half of all injuries. However, as regards overuse problems, we are still very far from having clear data.
Studies carried out in 2015 demonstrate that there is a major difference between the number of injuries occurring in technical and speed disciplines, with special slalom recording 18% fewer injuries than the other disciplines. Giant slalom, despite being classified by FIS as a technical discipline, has very similar injury rates to the high-speed disciplines, with a difference of only 2% between downhill, super giant and giant slalom.
This could be explained by the fact that giant slalom has the highest recorded ground reaction forces, according to Gilgien’s study, combined with the logical deduction that the ground reaction forces will increase with a smaller turning radius—and high speed—placing the athlete in extreme situations in terms of imbalance management, which can easily result in a loss of balance and a subsequent fall.
Moreover, it has been reported that the majority of accidents occur in the last quarter of the competition, when neuromuscular fatigue is high exposing the system to higher risk.
8.1.3 FIS Intervention
One intervention put in place by FIS in an attempt to limit accidents involved the athletes’ equipment and in particular a change in the skis’ turn radius. In theory, this change was meant to reduce the possibility of completing a carved turn without skidding, by imposing a lateral skid and a decrease in speed. However, Sporri’s 2015 study shows that the values of anterior flexion of the trunk, lateral flexion, rotation on the body’s longitudinal axis and ground reaction forces were virtually unaffected by the new equipment and, according to the athletes, the fatigue necessary for good performance levels had increased.
Sporri’s study also presents other important data regarding skiing-related overuse and degenerative problems, such as low back pain.
8.1.4 Low Back Pain
The incidence of acute and/or chronic low back pain, based on interviews of the top 40 World Cup athletes, is very high, reaching 31% among males and no less than 41% among females. This incidence is more than double the values recorded for the healthy population of the same age.
In addition, according to the international guidelines on low back pain, anterior flexion, lateral flexion and rotation associated with a load—in skiing represented by gravity and ground reaction forces—tend to overload the vertebral discs exposing skiers to musculoskeletal injury.
To better understand low back pain in skiers, it is interesting to read a document issued by the Canadian Paediatric Society in 2009 which states that low back pain in youths needs to be managed differently from that of adults since their musculoskeletal system is still developing. The major risk factors include (1) muscular imbalances due to rapid bone growth and limited soft tissue flexibility; (2) structural differences like the presence of cartilaginous ossification centres which, if subjected to excessive strain during frontal and lateral flexion and torsion, can alter spine morphology predisposing the individual to spondylolysis; and (3) last but not least, inappropriate training loads and quality. The authors’ recommendations for injury prevention focus on properly balancing the training load in relation to the growth period by decreasing training loads and concentrating on correct technique to promote motor control.
On the topic of motor control, it is worth mentioning the studies by Panjabi, Hides and Richardson which, although dating back to the early 1990s, remain the cornerstones of research in this field and as such are constantly cited in the recent literature.
In 1996, Hides reported that after the first episode of low back pain, the multifidus is unable to recover its full function independently despite spontaneous symptom remission and that at 10 weeks there is a clear decline in multifidus muscle tone. This, together with Gardner-Morse’s findings, highlights how a 10% decline in tone can affect the muscle’s stabilising function. These data prepared the way for a possible explanation of the low back pain relapse.
O’Sullivan in 1997 further developed the work done by Panjabi in 1992. Panjabi had explained that spinal instability can be identified as an area of laxity around the neutral zone which is more extensive than the symptoms ascribable to the single passive stabilisers and less extensive than those ascribable to dysfunction of the overall force of the more superficial mobiliser muscles. Instability is therefore considered an inability of the stabilising systems of the spine to maintain the neutral zone within its physiological limits.
O’Sullivan expands on these concepts and notes that the co-contractions of the deep abdominal muscles (transversus abdominis and obliquus abdominis internus) and the multifidus, by acting on the thoracolumbar fascia, are the main stabilisers of the neutral zone. Abnormality of the passive structures, such as spondylolysis and/or spondylolisthesis, requires an increase of the neuromotor system to control motor dynamics. He concludes by stating that in a setting of spinal instability, the control group, which did not undergo any programme of stabilising exercises and instruction to incorporate the skills acquired in daily life, had markedly negative outcomes.
In 2005 Hicks defined low back pain as a deviation of the lumbar-pelvic complex from its native physiological and anatomical state. In parallel, consistent with Richardson, he mentions “core training” as a method to facilitate the co-contraction of the deep abdominal muscles (transversus abdominis and obliquus abdominis internus) and multifidus which needs to be integrated into exercises and functional activities.
Stabilising exercises or “core training” are considered the treatment of choice for segmental vertebral instability, which is identified by a series of tests well described by Corkery et al.’s 2014 paper entitled “An exploratory examination of the association between altered lumbar motor control, joint mobility and low back pain in athletes”.
Assessment of lumbar ROM
Assessment of hip ROM especially in internal rotation
Passive SLR (straight leg raise)
Active SLR with one leg or two legs simultaneously
Identification of aberrant movements during ROM, such as “painful arc”, “Gower’s sign” and inversion of lumbar-pelvic rhythm
Beighton ligamentous laxity scale
Among these tests, the SLR plus two-leg SLR associated with the Trendelenburg test are the most sensitive for assessing motor control.
In addition to this sensitive test battery for selecting those subjects with low back pain likely to respond better to motor control exercises, it should be noted that there is a close correlation between results on the Functional Movement Screen (FMS) tests and previous episodes of low back pain that may have altered the individual’s general movement pattern.
Based on this view, it is clear that the athlete with low back pain requires a comprehensive assessment in order to institute the most suitable treatment allowing a reasonably fast return to play.
In conclusion, an interesting systematic review by Scheepers in 2015 analysed studies published between 1970 and 2013 in an attempt to answer the question “what intervention is to be preferred to guarantee a fast return to sports?”. The study concluded that, for adult athletes for whom conservative treatment has proved ineffective, stabilisation surgery may be considered to enable return to sports, although to date there are no clear data on the quality of post-surgery sporting performances.
8.1.5 Prevention: The Concept
The issue of prevention has been widely addressed. A variety of classifications have been used to organise this complex topic; qualifiers such as “active” and “passive”, “direct” and “indirect” and “primary”, “secondary” and “tertiary” are combined with the term “prevention” to define the actions that can be undertaken to analyse, understand and contrast both chronic and acute sports injuries.
Recent studies conclude that prevention is an extremely complex phenomenon. Much effort is still required to gain an in-depth understanding of the processes resulting in injury, an understanding that goes beyond the mere biomechanics of the event—just as the adoption of any practice isolated from the overall context (warming up, stretching, proprioceptive exercises, etc.) does not appear to be decisive. To approach prevention coherently, information on the mechanism of injury needs to be incorporated within a model where the study of internal and external risk factors is central to modifying risk.
The advantage of this model is to accommodate the strengths and weaknesses of each sector of research and highlight the contribution of each to understanding and preventing sporting accidents.
The position of the federation and working group is in favour of this type of approach. The project presented for long-term athlete development (LTAD) is aimed at developing adequate motor skills for the practice of this complex discipline. Evidence-based teamwork, starting from the motor tests, enables us to customise athlete training loads and monitor the athlete’s health through the use of instruments and scales to measure and assess fatigue. Instruments for training monitoring support rational working methods.
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