Defining and classifying health problems

For recommendations on defining injury and illness, we consider the IOC statement and its female athlete, mental health and para sport supplements to be fully applicable to the snow sports context.13 14 20–22 A health problem is defined as any condition that reduces an athlete’s normal state of full health, irrespective of its consequences for the athlete’s sports participation or performance or whether the athlete seeks medical attention.13 14 Given the remarkably high rates of minor sudden-onset injuries and gradual-onset injuries in some snow sports disciplines,41 47 and given the frequent occurrence of mild respiratory infections, non-infectious respiratory illnesses such as lower airway dysfunction and related illnesses in cross-country skiing,53 54 58 61 this wide definition is appropriate. This is especially important because severe sudden-onset injuries have typically been the major focus of injury surveillance programmes of national and international alpine skiing and snowboarding associations. For the areas of relationship to sports activity, ‘multiple events and health problems’, and ‘subsequent, recurrent or exacerbation of health problems’, there is no need for snow sports-specific recommendations. However, as the authors of the IOC statement encouraged, injury/illness surveillance should discontinue using acute and overuse as a simple dichotomy and implement a more nuanced classification system that describes both injury/illness presentation (sudden or gradual onset) and the underlying mechanisms (acute or repetitive). In this context, classification examples for the ‘mode of onset’ in different snow sports disciplines are provided in table 2.

For the classification of health problems, snow sports-specific standard descriptors for the occurrence of injury (ie, the events/factors leading to the injury situation, the injury situation itself and the injury mechanisms) are suggested in table 3. These suggestions represent a ‘best practice’ compilation of factors that, in an ‘ideal scenario’, could be recorded and reported by any injury/illness surveillance system in the snow sports context. Athletes’ self-reported and staff-collected data should be captured separately and combined to maximise data quality. In addition, if epidemiological data are primarily collected for aetiological analyses of injury mechanisms, we recommend that all available complementary data, such as video recordings, wearable sensor data and/or athletes’ or coaches’ statements on the injury, be compiled and stored, as they contain valuable supplementary information for possible post hoc analysis by experts. In cases where resources are limited (eg, in youth or recreational settings), it should at least be indicated whether the mechanism of injury is classified as direct contact, indirect contact or non-contact, as suggested in the IOC statement.13 14

Classifying sports injury and illness diagnoses

As a minimum standard, we recommend classifying injuries by body area and (if reported by medical staff) tissue type and pathology type. As a minimum standard for classifying illnesses, we recommend noting the symptoms (if reported by medical staff) of the related organ system/region and aetiology, as further explained in the IOC statement.13 14 Where possible, injury and illness diagnoses should be classified using the Orchard Sports Injury and Illness Classification System (OSIICS) or the Sports Medicine Diagnostic Coding System (SMDCS). In cases where these systems do not provide specific enough diagnoses, for example, if an alpine skier suffers a medial talar process avulsion due to torsion in the boot, the closest possible code should be used (eg, OSIICS code: AF2; SMDCS code: AN.30.13; fractured talus), with the medical staff also recording the exact diagnosis separately.

Further examples of snow sports-specific injuries and illnesses with no specific code being directly available (mainly due to different pathophysiologies) include atypical Scheuermann’s disease (DG1; TS.31.20; Scheuermann’s disease); Schmorl’s nodes (LCP/DC1; LS.42.33/TS.52.33; lumbar/thoracic disc prolapse); endplate changes (LGJ/DLJ; n/a; lumbar/thoracic spine joint injury); distal femoral cortical irregularities (TZS, n/a; other stress/overuse injuries to the thigh); boot-induced lower leg contusion (QVT; LE.60.24; pretibial periosteal bruising/haematoma); boot-induced pretibial/medial tibial stress syndromes (QTT/QT1; LE.32.42; anterior shin splints/medial tibial stress syndrome); exercise-induced anterior compartment syndromes (QY2; LE.30.13; acute anterior compartment syndrome) and exercise-induced asthma/bronchoconstriction in subzero temperatures (MPEE; RE.0174; exercise-induced asthma).

The severity of health problems

To quantify the severity of health problems, the IOC statement13 14 suggests (1) the use of time loss (defined as the ‘number of days that the athlete is not fully available for training and competition, from the self-reported date of onset until the athlete is fully available for training or competition’) or (2) the athlete’s self-reported consequences, such as the cumulative severity score that can be calculated based on the OSTRC-H2 questionnaire.73 The latter option (2) is preferable when injuries and illnesses are surveyed based on athlete-reported data.13 14 73 Both approaches and all other severity measures mentioned in the IOC statement (ie, clinical outcomes, functional measures, performance measures and patient-reported outcome measures) are also appropriate for injury/illness severity descriptions in snow sports.

Regarding the severity classification by time loss, a major challenge in various snow sports disciplines is identifying when an injured/ill athlete is ‘fully’ recovered and when the time loss ends. Rehabilitation is a gradual process, and different stages of the continuum can be considered fully recovered (eg, ‘return-to-participation’, ‘return-to-sport’ and/or ‘return-to-competition’, as described by Ardern et al).74 In this regard, we support the IOC statement that the ‘number of time-loss days should be counted from the day after the onset that the athlete cannot participate (day 1) through the day before the athlete is fully available for training or competition’.13 14 Nevertheless, such a return may be premature or only partial. For example, a snow sports athlete may fully participate in off-snow training but decide not to train on snow for the moment, as performing the sport in unpredictable and changing snow conditions is not as controllable as training in the gym or on constantly hard surfaces. Another example would be a not-fully-recovered snow sports athlete who accepts an increased risk by returning early to an important event, such as World Championships or Olympic Games but skips the rest of the season or only participates in certain subdisciplines or activities. Given the specific characteristics of snow sports, which often involve high speeds and/or forces, this decision-making process will likely differ from many other Olympic sports, where the risk of reinjury is much lower. We, therefore, agree with the circus-specific extension of the IOC statement18 and recommend a slightly more nuanced method of categorising time loss as full, partial or no time loss.

Examples of such classifications from the snow sports context are presented in table 4. Another more sophisticated solution might be to use the prospective OSTRC-H2 method, which overcomes this issue by capturing severity through a graded scale.

Capturing and reporting athlete exposure

Capturing and reporting exposure is fundamental for expressing injury and illness risk; however, the choice of exposure measures is strongly influenced by discipline and contextual factors as well as the types of health problems of interest.13 14 We advocate the following approaches to harmonise exposure reporting in snow sports.

Reporting measures of occurrence

The IOC statement13 14 recommendations largely apply to the context of snow sports when reporting measures of occurrence. As such, prevalence is calculated based on the number of athletes with a health problem at a given time (point prevalence) or a window of time (period prevalence), while incidence refers to the number of new health problems during a defined time period.13 14 Incidence-based measures are considered more appropriate for sudden-onset health problems, whereas prevalence-based measures are more appropriate for gradual-onset health problems.13 14

As a minimum standard, we recommend expressing injury/illness rates as the number of new injuries or illnesses per 100 athletes per season, as the preferred directly comparable measure of incidence across different snow sports disciplines and contexts of application. For gradual-onset health problems, the period prevalence is reported as the number of injured or ill athletes per 100 athletes per season. One season refers to 1 year/12 months/365 days. Depending on the purpose of the surveillance, more sophisticated exposure denominators may be indicated for specific injury (but not illness) surveillance purposes. A summary of the recommended alternative exposure denominators in relation to specific snow sports disciplines, types of activity and specific application contexts is shown in table 5. When using the OSTRC-H2 questionnaire, we recommend reporting its standard outcome measures, such as the average weekly prevalence.73 Additionally, we encourage reporting injury/illness rates separately for the international competition season period (from approximately November to April) and preseason period (from approximately May to October). The exact dates vary slightly between different snow sports disciplines and levels.

The burden of health problems

In snow sports disciplines such as alpine skiing, freestyle skiing and snowboarding, the rates of severe injuries are relatively high compared with those in other Olympic sports.69 75 In the Beijing 2022 Winter Olympics, for instance, 13 of the 20 joint sprains/ligament tears occurred in Olympic disciplines governed by FIS.69 Consequently, the financial costs of surgeries and extensive rehabilitation and the overall physical, psychological and socioeconomic burdens on snow sports athletes are high. Therefore, we encourage NSSAs to systematically record and report injury and illness burden (defined as the cross-product of incidence and severity) along with the associated costs. For all further aspects regarding the burden of problems, readers are referred to the IOC statement.13 14 In relation to this, we acknowledge that the burden of injury is a latent construct with multilayered implications that depend on various contextual factors, and that these contextual factors extend beyond financial aspects. However, while also relevant to the context of snow sports, we have not explicitly discussed these factors (eg, psychosocial characteristics or long-term health consequences) as they do not differ from those originally described in the IOC statement.

Study population characteristics

Regarding the characteristics of the study population, the IOC recommends reporting, at minimum, the athlete’s age, sex and performance level.13 14 The authors of the statement also encourage sport-specific consensus groups to define what constitutes ‘elite’, ‘subelite’ and ‘recreational’ athletes in their respective contexts.13 14 We suggest that study population characteristics are described primarily by the existing classification framework outlined by McKay et al 76 (tier 0: sedentary; tier 1: recreationally active; tier 2: trained/developmental; tier 3: highly trained/national level; tier 4: elite/international level and tier 5: world-class). However, in addition to this classification framework information, we recommend also reporting the athletes’ (1) world ranking positions according to the FIS points or analogous systems and (2) the type of competition they most frequently participate (eg, in youth competitions; FIS competitions; Continental Cups, such as European, North American, South American, Asian, Australia/New Zealand; World Cup (WC); professional snow sports events not governed by FIS (eg, X Games); master competitions and mass participation sporting events).

Data collection methods

For the purpose of longitudinal injury/illness surveillance conducted in snow sports as part of national sports association initiatives (eg, by NSSAs or National Olympic Committees (NOCs)), we recommend combining athlete-reported and staff/physician-reported data as an ideal complementary approach. Data reported accurately by athletes are usually more sensitive (especially for less severe and gradual-onset injuries) but less specific (because medically informed diagnoses are usually lacking). In contrast, collecting injury/illness data by team staff/medical personnel may increase data specificity and help verify and correct incomplete/incorrect information provided by athletes. However, early-stage health problems may go undetected unless medical treatment is actively sought by the athlete. Electronic data capture tools, real-time data processing solutions and instant feedback/query capabilities may improve response rates and practical usability. In this context, for example, validated standard methods for prospective injury/illness surveillance, such as the OSTRC-H2 questionnaire, could be implemented in web-based platforms and combined with continuously updated team medical records and a supplementary retrospective interview at the end of an observation period to verify the accuracy and completeness of all OSTRC-H2-based entries, as has been done in previous studies.47 77

For the purpose of longitudinal injury/illness surveillance conducted in snow sports as part of international sports association initiatives, a previous study revealed that retrospective interviews with FIS WC athletes/coaches regarding injuries during the previous 6 months provided the most complete picture of injuries incurred by skiers and snowboarders.78 This approach was reported to be superior to alternative methods, such as prospective injury reports by FIS technical delegates or prospective medical team registration by selected teams. An alternative and promising approach that FIS is currently used in alpine skiing is to exploit data from injury status applications to capture as much detailed information on injury/illness occurrence and causation as possible. A limitation of such an approach is, however, that only injuries/illnesses with substantial time loss are reported, while less severe health problems are neglected. Thus, complementary injury/illness surveillance initiatives by national bodies such as NSSAs and NOCs following the recommendations of the present statement are essential.

For injury and illness surveillance during multiday events, dedicated injury and illness registration forms completed by the medical staff responsible for the event are considered most appropriate. An example of a snow sports-related study using such methodology is the study of Kastner and colleagues which investigated the injuries and illnesses occurring during the 53rd FIS Nordic World Ski Championships in Oberstdorf.64

The newest versions of injury and illness surveillance approaches emphasise monitoring mental health in addition to physical health. For more detailed information on corresponding minimum standards, please refer to the mental health supplement to the IOC statement21 and its supplemental material 1–3 (https://bjsm.bmj.com/content/57/21/1351%23supplementary-materials), where (1) an athlete’s weekly questionnaire for monitoring physical and mental health problems (for longitudinal use based on athlete reporting), (2) a medical report for injury, illness and mental health problems (for longitudinal use based on reporting by the medical staff) and (3) a daily medical report on injuries, illnesses and mental health problems (for event-related use based on reporting by the medical staff) can be accessed and downloaded.

For injury surveillance as part of the systematic registration routine in ski resorts, customised injury registration forms completed by the responsible medical staff of the ski resorts are standard. An example of such a form that is used by the slope rescue service in Sölden, Austria, can be found as an English-translated version in the online supplemental material file B.

Finally, regardless of the data collection methodology used, we strongly recommend that all injury and illness data be reported with reference to the STROBE Extension for Sport Injury and Illness Surveillance (STROBE-SIIS) checklist.13 14 Table 6 and table 7 provide illustrative examples based on injury and illness data from the Norwegian NOC database, which have been provided with kind permission for illustration in this study and are reported in accordance with the recommendations of the IOC statement, the STROBE-SIIS and this snow sports-specific extension.

Regarding aspects of research ethics and data security, the recommendations of the IOC statement are also applicable to snow sports, whereby data should only be collected when pertinent to the specific surveillance/research question. Data protection and confidentiality must be assured, with access limited to only those individuals in the entourage identified through clear consent mechanisms. The collection of sensitive data should be conducted in an environment that is private, safe and respectful.

Specific considerations for injury and illness surveillance in youth snow sports athletes

Athletes should start developing a thorough understanding of their physical and mental health as early as possible, which would aid in meaningful injury and illness registration/management throughout their careers. In a qualitative study in which stakeholders from different Olympic sports were interviewed, athletes, in particular, emphasised the need for awareness and better education on injury prevention at their early career stages to facilitate their learning process and influence their future prevention behaviour and sporting success.79 Moreover, in the context of snow sports, stakeholders explicitly acknowledge the value of knowledge and experience when managing and dealing with risks.80 To this end, regular educational workshops for youth athletes, coaches and parents organised by regional or national federations are recommended. As stakeholders from the snow sports context suggested, young athletes, in particular, might benefit from educational interventions that focus on developing risk assessment and management skills.80 However, whether such approaches effectively protect the health of young, aspiring snow sport athletes remains to be verified in future research.

For U12 athletes with a competitive focus, we recommend that coaches prospectively record all relevant injury and illness information in close cooperation with parents and, if possible, medical staff. From the U14 level upwards, young athletes should record their injuries/illnesses in parallel with their coaches, and the reports should be compared and consolidated approximately twice a year. Again, medical staff should be involved in recording routines wherever possible. At the U16 level, or when athletes acquire an appropriate degree of autonomy, validated standard methods such as the OSTRC-H2 questionnaire may be used. In such cases, a retrospective interview performed by a physician is recommended immediately after reporting, or at least at the end of the season, to clarify and verify all self-reported data.42 50 Moreover, biological maturation and the load-sensitive phases of accelerated growth play a key role in the pathophysiology of various injuries and illnesses.81–83 Thus, we suggest that epidemiological studies of youth-level athletes adopt indicators of biological maturation (such as age at peak height velocity and maturity offset as defined by Mirwald and colleagues)84 and information on all sports activities performed.

Specific considerations for injury and illness surveillance in female snow sports athletes

Injury and illness surveillance of female snow sports athletes should include documentation of female-specific factors associated with health problems or consequences that could affect sports participation or performance. Moore et al 20 published a supplemental paper to the IOC statement identifying 10 female health domains (see tables 1–3 in their work). These domains also apply unrestrictedly to the snow sports context. Regarding epidemiological studies of female athletes, the same supplemental paper outlined female-specific population characteristics that can be collected when monitoring female athletes, depending on the research question or rationale for surveillance. These characteristics may include the age of menarche, menstrual cycle data (eg, cycle length, cycle phase at the point of injury/illness, ovulation status, amount of blood loss and cycle-based symptoms), contraceptive use (yes/no), type and formulation of contraception used, pregnancy status (yes/no), pregnancy stage and duration.85 If postpartum, relevant information may include the mode of delivery for childbirth, postpartum trauma history, postpartum training data, breastfeeding status (yes/no), caregiving responsibilities and mental health status. As stated previously, only data pertinent to the specific research question should be collected. As with other sensitive data, female-specific data (eg, menstrual cycle data or pregnancy status) should not be shared with anyone who does not need it. Questions about potentially sensitive health topics should use culturally sensitive language, and relevant health data should be collected by an individual in a trusted professional role with trauma-informed skills to address potential allegations of harassment and abuse. The reporting of female-specific surveillance data should follow the STROBE-SIIS checklist adapted to include the female health domains.20 It is important to restrict reporting to health complications only (eg, amenorrhea, iron deficiency anaemia and deep vein thrombosis) and avoid reporting normal female health domains (ie, pregnancy, menarche menstruation) as ‘illnesses’.