What are the Exercise-Based Injury Prevention Recommendations for Recreational Alpine Skiing and Snowboarding?

Sports Med (2013) 43:355 366 DOI 10.1007/s40279-013-0032-2 SYSTEMATIC REVIEW What are the Exercise-Based Injury Prevention Recommendations for Recreational Alpine Skiing and Snowboarding? A Systematic Review Kim Hébert-Losier Hans-Christer Holmberg Published online: 6 March 2013 Ó Springer International Publishing Switzerland 2013 Abstract Background Skiing and snowboarding are two activities that significantly contribute to the total number of sportsrelated injuries reported per year. Strength, endurance and cardiovascular fitness are central components in sports injury prevention. Providing exercises and training recommendations specific to recreational skiers and snowboarders is important in both injury prevention and reducing the prevalence and cost associated with alpine winter sports injuries. Objective The aim of this paper was to systematically review the literature for injury prevention recommendations specific to recreational alpine skiers and snowboarders. The focus was to discern recommendations that targeted physical fitness, exercise and/or training in the prevention of musculoskeletal injuries in these two sports. Data Sources Fourteen electronic databases were searched in October 2011 using relevant MeSH terms and key words. Study Selection Articles were included if they addressed injury prevention, recreational alpine skiing or snowboarding and musculoskeletal injuries. Only original research articles published in peer-reviewed journals, and in the English-language, were reviewed. Articles on elite athletes were excluded. K. Hébert-Losier H.-C. Holmberg Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden K. Hébert-Losier (&) Swedish Winter Sports Research Centre, Kunskapens väg 8, Hus D, 83125 Östersund, Sweden e-mail: kim.hebert-losier@miun.se Study Appraisal and Synthesis Methods Two independent reviewers quality assessed articles meeting inclusion criteria using a modified version of the Downs and Black Quality Assessment Checklist. Data on study population, study design, study location and injury prevention recommendation(s) were extracted from articles using a standard form and subsequently categorized to facilitate data synthesis. Results A total of 30 articles met the inclusion criteria and were reviewed, having an average ± standard deviation quality score of 72 % ± 17 % (range: 23 100 %). Overall, 80 recommendations for the prevention of musculoskeletal injuries in recreational alpine skiers and snowboarders were identified and classified into five main groups: equipment (n = 24), education and knowledge (n = 11), awareness and behaviour (n = 15), experience (n = 10) and third-party involvement (n = 20). No recommendations pertained to physical fitness, exercise and/or training per se, or its role in preventing injury. Limitations A comprehensive meta-analysis was not possible because several articles did not report data in sufficient detail. Conclusions The importance of targeting physical fitness in injury prevention is accepted in sports medicine and rehabilitation; yet, there was a paucity of articles included in this review that explicitly investigated this aspect with regards to recreational alpine skiing and snowboarding. The most frequent recommendations for preventing skiing and snowboarding injuries concerned equipment or the involvement of third parties. The dominance of equipmentrelated measures in the injury prevention literature may be rationalized from a sports biomechanics viewpoint, as these activities involve high velocities and impact forces. Nonetheless, this also indicates a need for appropriate levels of strength, endurance and conditioning to meet the technical demands of these sports. Bearing this in mind,

356 K. Hébert-Losier, H.-C. Holmberg future research is encouraged to investigate the role of physical fitness, exercise and training in decreasing the incidence and severity of skiing and snowboarding injuries in recreational athletes. 1 Introduction Alpine skiing and snowboarding are popular activities practiced by millions of individuals worldwide [1, 2]. As such, these sports, through the promotion of maintaining a physically active lifestyle, play an important role in public health [1]. However, considering their notable contribution to the total number of sports-related injuries reported per year [1, 3, 4], they are also an economic burden to society. According to national associations and organizations [5 7], injury rates in skiing and snowboarding range from 2.4 to 2.6 and 3.6 to 7.0 per 1,000 activity days, respectively. Total healthcare expenses per year associated with falls from skates, skis, boards, and blades in Canada cost $C398 million in 2004 [8], the equivalent of $C12.50 per capita per year. The cost is even greater when considering that sports injuries are likely to cause long-term negative effects on health. Injuries are one of the main reasons why people stop participating in health-enhancing physical activities [9]. Moreover, it is proposed that musculoskeletal sporting injuries sustained during youth can impair mobility later in life and have a detrimental influence on the aging population [10, 11]. Hence, sport injury and its prevention are important public health issues and areas of concern [12]. The prevention of sports injuries relies on several levels of operation for optimal implementation [13, 14], and requires active participation from large numbers of individuals. For instance, wearing a helmet is recognized to decrease head traumas in many different sports in which the head is susceptible to collision or impact [15]. Although certain authors have argued that wearing a helmet does not reduce the overall number of fatalities from skiing and snowboarding incidents [16] and expressed concerns that helmets may increase the number of injuries to the neck [17], more recent literature supports the protective value of helmets in decreasing the risk of head injuries [18, 19] without increasing the risk of neck injuries among skiers and snowboarders [20]. Individuals can decide to wear a helmet and be proactive towards injury prevention. Alternatively, groups of people (e.g. alpine ski school, resort or club) can, by requiring individuals to wear a helmet, positively impact injury prevention. Ski slope personnel, healthcare professionals and event organizers are also important in injury prevention, particularly when considering the value of discerning extrinsic (e.g. daily meteorological conditions) and intrinsic (e.g. musculoskeletal condition and health status) risk factors for the primary prevention of sports injuries [21]. Individual preparation and practice of a sport with respect to known injury factors is vital in the prevention of said injuries. Skiing and snowboarding material and protective equipment has evolved substantially over the last 20 30 years. Although this has contributed towards a decrease in the total number of on-slope injuries, alpine skiing and snowboarding remain some of the riskiest recreational activities in terms of injury incidence [3, 4, 22]. This suggests the need to modify injury prevention strategies and methods currently used. One avenue is to promote interventions that target intrinsic factors in individuals who are susceptible to injury, such as prescribing core exercises in the presence of weakness or decreased activation of the abdominal, spine, back extensors or quadratus lumborum musculature [23]. As alpine skiing and snowboarding involve high velocities and impact forces, the need for appropriate levels of strength, endurance and coordination are indicated [24]. As early as 1965, Howorth highlighted that general gym training, exercises and cardiovascular fitness were essential elements for the prevention of alpine skiing injuries [25]. A number of subsequent studies have also advocated the role of physical fitness in the prevention of alpine skiing and snowboarding injuries [4, 26 28], with a general consensus in sports medicine that implementing specific injury exercise prevention programs is important to the well-being of the active population [29]. However, although presented as a successful means to preventing injury, it remains unclear as to what specific physical training or exercises recreational skiers and snowboarders should perform in preparation for, and during, the snow sport season. The aim of this paper is to systematically review the literature in order to identify injury prevention recommendations specific to recreational alpine skiers and snowboarders. Of particular interest are physical fitness, exercises and/or training that have been recommended for the prevention of musculoskeletal injuries during recreational alpine skiing and snowboarding. 2 Methods 2.1 Data Sources and Search Strategy Fourteen electronic databases were systematically searched in October 2011 using relevant MeSH terms, keywords, Booleans and truncation symbols. The databases searched were: AMED (1985-), CINAHL Ò (1981-), Cochrane Central Register of Controlled Trials (1898-), Cochrane Database of Systematic Reviews (1995-), Database of Abstracts of Reviews of Effects (1994-), EMBASE (1947-), MEDLINE Ò (1948-), PEDro (1929-), PsycINFO Ò (1806-), PubMed (1951-),

Injury Prevention Recommendations in Skiing and Snowboarding 357 SciVerse Scopus (1823-), SPORTDiscus TM (1985-), Web of Knowledge SM (1864-) and Web of Science Ò (1898-). The search strategy employed was: (skiing OR snowboarding) AND ((wounds and injuries) OR injur*) AND ((prevention and control) OR (accident prevention) OR (primary prevention) OR prevent*)). In addition to the systematic electronic database search, the reference lists of all articles subsequently included in the review were manually searched, as were relevant journals and key authors in the field of injury prevention research. A flow diagram of the search strategy and article selection process is illustrated in Fig. 1. 2.2 Inclusion and Exclusion Criteria Articles relevant to the prevention of musculoskeletal injury in recreational alpine skiing and snowboarding were involved in this review. For an article to be included, subjects had to be in good general health with no reported disabilities (e.g. neurological disorder, visual impairment, amputation). Articles that investigated the effect of an intervention on skiing or snowboarding injuries were included, regardless of the type of intervention (e.g. exercise, equipment, audio-visual information) or musculoskeletal injury (i.e. acute or overuse). Only original research and English-language articles published in peerreviewed (abstract available) journals were considered. Excluded were articles on off-piste skiing or snowboarding, and elite alpine skiers or snowboarders. Elite athletes were excluded because skill level is reported to influence the severity and bodily location of skiing and snowboarding injuries, with marked differences in injury patterns between elite and recreational athletes [30 32]. Articles Fig. 1 Flow diagram of the search strategy and article selection process Search strategy 1. skiing OR snowboarding 2. (wounds and injuries) OR injur* 3. (prevention and control) OR (accident prevention) OR (primary prevention) or prevent* 4. 1 AND 2 AND 3 Hits n = 548 Electronic databases 1. AMED (1985-) 2. CINAHL (1981-) 3. Cochrane Central Register of Controlled Trials (1898-) 4. Cochrane Database of Systematic Reviews (1995-) 5. Database of Abstracts of Reviews of Effects (1994-) 6. EMBASE (1947-) 7. MEDLINE (1948-) 8. PEDro (1929-) 9. PsycINFO (1806-) 10. PubMed (1951-) 11. SciVerse Scopus (1823-) 12. SPORTDiscus (1985-) 13. Web of Knowledge SM (1864-) 14. Web of Science (1898-) Excluded n = 345 duplicate titles Titles n = 203 Excluded n = 51 after title screen Abstracts n = 152 Excluded n = 56 after abstract screen Full texts n = 96 Excluded n = 71 after full-texts screen Articles n = 25 Hand search 1. Reference lists of articles 2. Relevant journals and key authors in injury prevention research Articles n = 5 Included n = 30 Study appraisal and data extraction

358 K. Hébert-Losier, H.-C. Holmberg were not considered if they pertained to the prevention of neurological injuries, hypothermia, eye trauma or other non-musculoskeletal injuries. Letters to the Editor, symposium publications, special technical publications, books, expert opinions and literature reviews were also excluded. For instance, the Skiing Trauma and Safety publication from ASTM International was not considered as a source of articles because they are usually published as a special technical publication or in book format. 2.3 Study Selection Process Duplicate articles from the electronic database search were removed. Then, two independent reviewers each screened all titles, abstracts and full-text versions of articles for inclusion and exclusion criteria. Note that an anonymous third party removed potentially identifiable information, such as authors, affiliations, countries and sources of publication, in order to assure blind reviewing and reduce selection bias. Results from the two independently performed screening processes were compared. If there was disagreement on the inclusion/exclusion of a given study, a third reviewer helped reconcile differences of opinion. The study selection process was repeated for articles that were included through the manual search described above until no additional sources of interest were identified. 2.4 Study Appraisal The two reviewers who screened articles for inclusion/ exclusion also separately assessed the quality of all retained articles using a modified version of the Downs and Black Quality Assessment Checklist [33]. The original checklist is a 27-item tool that appraises the quality of studies based on reporting, external validity, internal validity (bias and confounding) and power. The tool has evidence of high internal consistency (Kuder Richardson 20 = 0.89), test-retest reliability (r = 0.88), inter-rater reliability (r = 0.75), and criterion validity when compared to Global Scores from the Standards of Reporting Trials Group (r = 0.90) [33, 34]. In the case of disagreement between the two reviewers, the same third reviewer was consulted to help reconcile differences of opinion on the quality scores of articles. Note that articles still lacked potentially identifiable information at this stage to reduce assessment bias. The following amendments to the Downs and Black Quality Assessment Checklist [33] were applied for the purpose of this review. In questions 7 10, 13 15, 17 19, 21 24 and 26 27, Not applicable was used as a fourth scoring option. Question 27 was modified and answered with Yes (1 point), No (0 point), Unable to determine (0 point), or Not applicable (question excluded). Age, sex and experience were the core confounders used in answering questions 5 and 25; whereas previous injuries, equipment (owned/rented or condition of use), snow conditions and residents/travellers were the other confounders. To score 2 points in question 5, all core confounders plus one other confounder needed to be stated in the article. For 1 point, two core confounders plus one other confounder had to be reported. Questions from the checklist that were answered Not applicable were not included in calculating the final quality score of articles. The final score for each article was expressed as a percentage by dividing the total number of points scored, by the number of applicable points. Therefore, articles with a high percentage score were of higher quality based on the applied assessment procedure. In addition, the level of evidence for each study was determined using the Oxford Centre for Evidence- Based Medicine 2011 table according to study design [35]. Here, the level of evidence ranged from 1 to 5, with 1 indicating the highest level of evidence. No articles were excluded from this review based on quality score or level of evidence. 2.5 Data Extraction, Synthesis and Analysis Data concerning study population, study design, study location and injury prevention recommendation(s) were extracted from articles using a standard form. The three reviewers categorized injury prevention recommendations into thematic categories to assist data reporting. Descriptive statistics were computed using a statistical software package (STATA Ò 11.2, StataCorp LP, TX, USA) and expressed in terms of means and standard deviations (mean ± SD), minimum to maximum (min max) ranges, counts (n), or percentages (%). 3 Results The initial electronic database search of the literature yielded a total of 548 hits. After removing duplicates, 203 titles remained and underwent the screening process. A further 107 articles were excluded following screening of titles and abstracts, and another 71 articles were excluded following full-text screening. A total of 25 studies from the electronic database search met the inclusion criteria, and an additional five articles were identified through the manual search. Consequently, a total set of 30 articles was retained for review. A summary of the study selection process is illustrated in Fig. 1, and a summary of the data extracted from each article is reported in Table 1.

Injury Prevention Recommendations in Skiing and Snowboarding 359 Table 1 Summary of the reviewed articles (n = 30) and injury prevention recommendations Study (year) Quality Design; level of Population (n) Injury Prevention Recommendation (%) a evidence b Boldrino and Dann (1998) [64] Bouter et al. (1989) [65] Corra et al. (2004) [38] Dohjima et al. (2001) [66] Ettlinger et al. (1995) [42] Ferrera et al. (1999) [67] Fournier and De Preux (1997) [68] Franz et al. (2008) [69] Hildebrandt et al. (2011) [70] 63.2 Case-control; 3 Snowboarders (381); M (279), F (101) Equipment: wear protective equipment (wrist guards) Education and knowledge: learn basic techniques and use correct biomechanical form Experience and skill: train basic techniques and control of speed. Beginners, intermediate and advanced snowboarders should participate in formal instruction Awareness and behaviour: do not self-teach. Develop self-control Third-party involvement: cableways should use ski patrollers to watch for and control speed. Provide and promote comprehensive training in snowboarding schools. Snowboarding organizations need to consider safety measures and limit dangerous aims. Manufacturers and retailers of snowboarding equipment should make specific campaigns to target high-risk groups. Organizers should display videos of individuals snowboarding safely and conservatively during competitive events to promote safe snowboarding 73.7 Case-control; 4 Skiers (1,148) Equipment: adjust bindings. Avoid rented or borrowed skis. Consider type of skis and age of skiing equipment 83.3 Retrospective cohort; 3 Skiers (794); snowboarders (293); M (634), F (453) 77.8 Case-control; 3 Skiers (5,048); snowboarders (2,552); M (5,320), F (2,280) Equipment: use helmets Awareness and behaviour: prosecution of dangerous behaviours such as excessive speeding, jumping where not permitted or skiing under the effect of alcohol or drugs. The awareness that skiing beyond one s technical ability can be life threatening is important Third-party involvement: enforce the use of helmet by law Equipment: use head, wrist, knee and buttock protective equipment Experience and skill: get training from professional instructors Awareness and behaviour: recognize the risks of injuries during snowboarding. Snowboard in good snow conditions 44.4 Non-RCT; 3 Skiers (4,000) Education and knowledge: recognize the risks of ACL injuries and provide information of mechanisms of injury. Education is cost-effective in reducing risks of ACL injury 69.2 Retrospective cohort; 3 41.7 Retrospective case-series; 4 88.9 Retrospective cohort; 3 Snowboarders (71); M (58), F (13) Skiers (100); M (82), F (13) Equipment: use of helmets in children Skiers (63); snowboarders (10); M (56), F (17) Awareness and behaviour: recognize potentially dangerous situations and understand the profile of the phantom-foot ACL injury mechanism Equipment: use soft shell boots with a stiff inner boot to support the ankle, helmets, padding, and wrist guards Experience and skill: get training in proper snowboarding techniques Third-party involvement: physicians should consider head and spinal injuries in all snowboarding injured if indicated by the mechanism of injury Awareness and behaviour: choose slopes according to skiing expertise. Take extra caution on overcrowded slopes. Do not ski on slopes in lack of snow Third-party involvement: slope authorities should mark obstacles. Actual snow conditions should be conveyed to skiers Equipment: use spinal protectors. Proper fit and adjustment of equipment. Education and knowledge: focus injury prevention programmes on: safe skiing and snowboarding practices, avoiding collisions and properly maintaining equipment. Take lessons to learn hill rules, regulations and appropriate conduct Experience and skill: take lessons to increase skiing and snowboarding ability Awareness and behaviour: ski or snowboard on courses appropriate to ability level Third-party involvement: further develop terrain parks and maintain trails 89.5 Cross-sectional; 4 Skiers (1,450); M (805), F (645) Education and knowledge: know the FIS rules Awareness and behaviour: recognize that dangerous behaviours can be penalized Third-party involvement: ski resorts, the media, and schools focus on educating high-risk groups

360 K. Hébert-Losier, H.-C. Holmberg Table 1 continued Study (year) Quality Design; level of Population (n) Injury Prevention Recommendation (%) a evidence b Jørgensen et al. (1998) [43] Kroncke et al. (2008) [71] Langran and Selvaraj (2002) [37] Levy et al. (2007) [72] Machold et al. (2002) [63] Macnab and Cadman (1996) [73] Macnab et al. (2002) [74] McKenna and Hammond (2007) [36] 69.2 RCT; 2 Skiers (763); M (443), F (320) Education and knowledge: audio-visual videos are efficient means of transferring information about safety to downhill skiers. A change in individual behaviour regarding binding adjustment can prevent injuries 68.4 Cross-sectional; 4 Inline skaters, skaters, snowboarders (333); M (227), F (106) 100 Case-control; 4 Skiers (623); snowboarders (299); ski boarders (61); M (588), F (395) 54.5 Non-RCT; 3 Stores renting or selling equipment to the general population (54) Equipment: use PPE Education and knowledge: education about the importance of PPE use. Increase PPE compliance Third-party involvement: increase PPE compliance through parental, health professional and peer reinforcement; development of more comfortable gear; and mandatory use of PPE in public areas Equipment: use of wrist guards during snowboarding Experience and skill: more than 5 days of experience in the current season and at least 1 week of experience in total has a protective effect against injury Awareness and behaviour: recognize potential for injury Third-party involvement: develop an efficient release binding system for ski boards Equipment: use helmets Education and knowledge: increase education and public awareness of the importance of wearing helmet and decrease the obstacles to use of helmets Third-party involvement: helmet loaner programmes or routine inclusion of helmets in rental packages have potentials of decreasing incidence and severity of head injuries from skiing and snowboarding 85.2 RCT; 2 Snowboarders (721) Equipment: use wrist guards, particularly during the learning phase 72.2 Case-control; 3 Skiers (1,936) c ; snowboarders (156) c ; M c (1,210), F c (882) Equipment: use sex-specific equipment. The role of helmets in both protection and possible causation of head injury needs objective research Experience and skill: sex-specific training and psycho-motor skill development are important Awareness and behaviour: planning jumping manoeuvres and increasing awareness of safety measures among youths have the potential of decreasing injury incidence Third-party involvement: greater injury prevention programme foci, particularly prior to school initiated events. Physicians have a role in the prevention of sports injury and should ask about fitness, knowledge of safety rules and use of appropriate equipment. Design of helmets could be improved to decrease disturbance of hearing and vision, and the composition of the materials should consider snow and rigid object impacts. Ski resorts should police for dangerous behaviours and actively reinforce desired behaviour 78.9 Cross-sectional; 4 Skiers (32); snowboarders (23) Equipment: use helmets, with mandatory wear of helmets under the age of 13 years 71.4 Qualitative case series; 4 Snowboarders (9); M (8), F (1) Experience and skill: number of boarding weeks count in injury prevention. Formal exhibitions and individual modelling may be helpful when learning through observing others Education and knowledge: develop new approaches to promote use of protective devices and their benefits. Target groups of snowboarders with no discernible leader Awareness and behaviour: identify dangerous situations and locations Third-party involvement: strategically position reminders of injury prevention strategies and information at lift ends or at ski resort exits. Make public and visible recommendations regarding skills needed to manage given snowboarding slopes. Seek ways to increase the level of prevention talk among snowboarders to understand how social norms are established and sustained. Consider the value of reducing the severity of injuries, not only of decreasing the rate of injuries, in injury prevention

Injury Prevention Recommendations in Skiing and Snowboarding 361 Table 1 continued Study (year) Quality Design; level of Population (n) Injury Prevention Recommendation (%) a evidence b Equipment: use equipment to prevent head injuries and that protect the occiput 100 Case-control; 3 Skiers (158); snowboarders (143); M (197), F (104) Nakaguchi et al. (1999) [75] Awareness and behaviour: make public and recognize the high risk of injuries from snowboarding, especially during jumps and when beginning. Beginners should be discouraged from trying jumping manoeuvres Third-party involvement: establish programmes to instruct safe technique and improve general condition of snowboarders Equipment: use wrist-guards 81.5 RCT; 2 Snowboarders (5,029) M (3,229), F (1,800) Rønning et al. (2001) [62] Skiers (20) M (10), F (10) Equipment: use helmets according to standard norms 60 Prospective cohort; 3 Ruedl et al. (2011) [76] Third-party involvement: the information that helmets do not affect reaction time to peripheral stimuli should be included in campaigns promoting use of helmets in skiers and snowboarders ACL anterior cruciate ligament, F female, FIS International Ski Federation, M male, PPE personal protective equipment, RCT randomized controlled trial Individual quality scores (in %) calculated from dividing the total points scored over the total applicable points of a modified version of the Downs and Black Quality Assessment Checklist [33] Individual levels of evidence based on study designs according to the Oxford Centre for Evidence-Based Medicine 2011 table. Lower numbers indicate higher levels of evidence Number of injuries a b c 3.1 Quality Score The average quality score of the 30 articles reviewed was 72 % ± 17 % (range: 23 100 %) based on the modified version of the Downs and Black Quality Assessment Checklist. The level of evidence ranged between 2 and 4 based on the Oxford Centre for Evidence-Based Medicine 2011 table. Articles were most often of level 3 (n = 14, 46.7 %) or 4 (n = 13, 43.3 %). Case-control (n = 7, 23.3 %) and retrospective cohort (n = 7, 23.3 %) studies were the most frequent study designs of the 30 articles reviewed. 3.2 Study Population Twenty-nine of the 30 articles reported their sample size, which ranged from 9 to 7,600 individuals. When totalling the sample sizes from each article, 32,740 subjects were represented in this review (67.2 % skiers; 32.1 % snowboarders). Other population groups investigated in parallel with alpine skiers and snowboarders were ski boarders, telemark skiers, skateboarders and inline skaters. The injury prevention recommendations relevant to the latter population groups were excluded from analysis. Sex distribution was described in 24 articles totalling 16,426 males and 8,576 females. This is detailed in Table 1. Calculating a mean age from the total study population proved difficult due to the heterogeneity of articles and various methods used to report age. An approximation of age was nonetheless attempted through the pooling of reported values. The estimated mean age from this method was 28.3 ± 7.6 years, and the maximum age for one individual was 83 years. 3.3 Injury Prevention Recommendations A total of 80 injury prevention recommendations were identified from the 30 articles reviewed and grouped into five main thematic categories (see Table 2). These five main categories (and number of recommendations made in each category) were equipment (n = 24, 30 %), education and knowledge (n = 11, 13.8 %), awareness and behaviour (n = 15, 18.8 %), experience (n = 10, 12.5 %), and third-party involvement (n = 20, 25 %). Twenty-two articles (73.3 %) contained recommendations that pertained to more than one of these five categories, with the remaining eight articles (26.7 %) presenting recommendations that were specific to only one of the five categories. None of the reviewed articles recommended specific physical fitness, exercises and/or training for the prevention of musculoskeletal injuries in recreational alpine skiing or snowboarding. The recommendations from the 30 articles could be divided further into 17 subcategories (see Table 2). Within this classification format, a total of 111 recommendations

362 K. Hébert-Losier, H.-C. Holmberg Table 2 Injury prevention recommendation classification Main category N (%) Subcategory N (%) Equipment 24 (30) Binding 3 (2.7) Helmet 16 (14.4) Wrist guards 6 (5.4) Other (i.e. boots, spine protectors, PPE, padding, knee bracing) 6 (5.4) Education and knowledge 11 (13.8) Rules, regulations, etiquette 3 (2.7) Behaviours (i.e. speed, jump, alcohol, drug, risk taking, 6 (5.4) equipment use, defensive skiing) Equipment (education) 4 (3.6) (Theoretical) technique and skill 2 (1.8) Awareness and behaviour 15 (18.8) Risk, types and mechanism of injury 3 (2.7) Dangerous situations 9 (8.1) Ability and skill level 9 (8.1) High-risk groups (identification) 3 (2.7) Experience and skill level 10 (12.5) Formal instruction 9 (8.1) On slope experience, days/week 2 (1.8) Third-party involvement 20 (25) Ski hill (i.e. resorts, instructors, facilities, patrollers, retailers) 9 (8.1) Public/governmental institutions, schools, media, hospitals, 16 (14.4) health centres and equipment designers Individuals (i.e. parents, health professionals, coaches) 5 (4.5) PPE personal protective equipment were identified. The use of a helmet (n = 16, 14.4 %) together with third-party initiated strategies from public or governmental institutions (n = 16, 14.4 %) were the most frequent strategies recommended for the prevention of skiing and snowboarding injuries. Furthermore, the recognition and awareness of potentially dangerous situations and conditions (n = 9, 8.1 %), skill and ability level of individuals (n = 9, 8.1 %), participation in courses (n = 9, 8.1 %), and initiatives from third parties such as ski resorts, ski patrollers and sport retailers (n = 9, 8.1 %) were identified as important players in injury prevention. It should be noted that out of the 30 articles reviewed, eight based their recommendations on original research (i.e. assessing the effect of an intervention on injury prevention). The other articles suggested injury prevention methods primarily based on retrospective analyses of injury incidences or previous work from other authors. The results also indicate that ten studies collected data before 1995, ten others between 1995 and 2001 and seven subsequent to 2001. Three articles did not specify the time period of their data collection. 4 Discussion This review attempted to identify the injury prevention recommendations, particularly those focusing on physical fitness, exercise and training, reported in the literature for recreational alpine skiers and snowboarders. However, no article explicitly investigated physical training factors in injury prevention, or made recommendations such as prescribing specific strength, endurance, flexibility or neuromuscular control exercises. Several sources indicated that skiing and snowboarding ability, skill level and experience were important for injury prevention [36, 37]; which is associated to a certain extent with an individual s level of conditioning. Nonetheless, it is of concern that no specific exercises have yet been investigated and recommended in the scientific literature for the prevention of injuries in recreational alpine skiers and snowboarders. The lack of published data in this area is perhaps due to the innate challenges of performing an exercise-based injury prevention study in recreational skiers and snowboarders. A study would require a relatively large sample size, long follow-up time, and extensive documentation and attention to confounding variables for valid, reliable and conclusive results. In place of exercise training, equipment-related strategies for preventing injuries in alpine skiing and snowboarding dominated the literature. A third of the recommendations obtained from the articles reviewed concerned equipment, with more than half of these regarding helmets. The significant role of equipment in the prevention of alpine skiing and snowboarding injuries is understandable from a sports biomechanics perspective. Even at a recreational level, these activities are associated with high velocities and impact forces that illustrate the importance of developing and using tailored sporting

Injury Prevention Recommendations in Skiing and Snowboarding 363 equipment for preventing impact injuries. Yet the biomechanical characteristics of these two sports also impose high demands on participating individuals, in that equipment cannot be considered sufficient to minimize musculoskeletal injury incidences [28]. Of further consideration is that, albeit assisting in decreasing the number of on-slope injuries, advances in technology and material have led to the commercialization of more sophisticated, aggressive and high-performance sporting equipment (i.e. boots, skis and snowboards) that may put recreational skiers and snowboarders at considerable risk of injury if they use equipment beyond their technical abilities [38, 39]. Omitting equipment-related recommendations, other significant injury prevention strategies sourced from the reviewed articles included discerning potentially dangerous situations, participating in skiing or snowboarding courses, developing individual skill levels and experience, and increasing the involvement of third parties. Regarding the former, several authors have described precise mechanisms that are likely to cause specific injuries during skiing and snowboarding, such as rotational backward or forward falls that cause anterior cruciate ligament (ACL) injuries in skiers [40 42]. In an attempt to decrease injury rates, Ettlinger et al. [42] developed an interactive training programme that included video-, instructor-, group- and kinaesthetic-based training sessions about backward falls with twisting mechanisms and their link to knee injuries. The method was successful in that the number of serious knee sprains decreased by 62 % subsequent to the implementation of the programme. Using instructional ski videos alone, Jørgensen et al. [43] found a 30 % reduction in the risk of injuries in groups of recreational downhill skiers who were shown the video, in contrast to those who were not. These studies indicate that effective strategies for injury prevention in skiing and snowboarding are not exclusively equipment based, that they include other areas, and could involve specific exercise and conditioning programmes. Brotherhood highlighted in 1985 that noticing signs of fatigue during alpine skiing was important for avoiding injuries based on a review of the physiological demands of the sport [44]. Similarly, Morrissey et al. [27] suggested, in 1987, a series of resisted movements, muscle stretches and cardiovascular training sessions to decrease the incidence of various musculoskeletal injuries resulting from alpine skiing based on the known physiological and biomechanical loads experienced during skiing. For instance, resisted knee flexion, knee extension and internal tibial rotation, and stretching of the hamstring and calf muscles were recommended for preventing knee injuries. These approaches are commended, but the nature of alpine skiing and snowboarding, including velocities, forces, slope conditions and equipment has changed considerably since these two publications [45]. Notably, carving skis and snowboards were not in frequent use in the 1980s, and they have influenced on-slope manoeuvring and injury mechanisms. For instance, whereas backward twisting falls were recognized as one of the most common causes of ACL injuries in downhill skiers [46, 47], forward twisting falls have become more common mechanisms in ACL injuries since the introduction of carving skis [40, 41]. The ski, binding, plate and boot systems also permit a more direct force transmission that increases the aggressiveness of the ski to snow interaction whilst turning [48]. In addition to advancements in skiing and snowboarding sports, equipment and technology, the understanding of human physiology and its response to sports and exercise has also continued to evolve [49], along with training methodologies and concepts. For instance, core training for stabilization has become a key component in exercise prescription over the past decade. A well-trained abdominal, spine, back extensor and quadratus lumborum musculature is now believed essential for optimal sports performance and injury prevention [23]. Likewise, neuromuscular training is recognized to have a prophylactic effect on knee injuries in non-contact sports [50, 51]. Integrating neuromuscular exercises in training programmes to prevent knee injuries is recommended for recreational skiers and snowboarders in light of the high loads and variations in recruitment patterns of the quadriceps muscles reported in recreational alpine skiing [52, 53]. In theory, the concurrent increase in sports biomechanics and the understanding of human physiology should translate into the use of targeted exercises for the prevention of sport injuries. In contrast, the results from this systematic review of the literature indicate that employing an integrative approach to injury prevention is not currently undertaken in recreational alpine skiing and snowboarding research. There appears to be a need to further use integrative methods to update the training programmes prescribed by Brotherhood [44] and Morrissey et al. [27] more than 20 years ago to prevent injuries in alpine snow sports, and define new recommendations for recreational skiers and snowboarders. The finding that not many of the reviewed articles collected their data after 2001 further emphasizes the need for more recent empirical evidence in the field of snow sport injury prevention through exercise training and conditioning. This review did not detect any intervention studies that assessed the effects of prescribed training programmes on the incidence and severity of recreational alpine skiing and snowboarding injuries. Future skiing and snowboarding research should consider using this approach in studying injury prevention, particularly when taking into account its successful use in other sporting activities. For instance, Kiani et al. [54] researched the effects of an injury prevention programme for female soccer players aged 13 19 years, including training motor skills, control and activation

364 K. Hébert-Losier, H.-C. Holmberg patterns. The result showed a 77 % reduction in incidence of knee injuries in players that adhered to the programme in contrast to those designated as controls. Even if a much smaller reduction in the incidence of knee injuries is seen in alpine skiers compared with that reported for soccer players, a similar intervention programme has the potential to considerably reduce the healthcare costs and morbidities associated with snow sport participation. In light of the proposed role of fatigue in causing on-slope injuries and fatalities [28, 55, 56], research is encouraged to further explore the effects of endurance training on alpine snow sport injury prevention. For instance, there are substantial reductions in glycogen stores and augmentations in blood lactate levels and muscle damage markers with recreational alpine skiing [57 59], whose negative effects (e.g. fatigue, inflammatory responses and decreased neuromuscular function leading to injuries) are reported to decrease with proper training due to a better utilization of glycogen stores, lower production of lactate and increase in circulating anti-inflammatory cytokines at a given exercise intensity [60, 61]. Caution is always advised in the generalization of research findings to a range of populations or circumstances. Although the proportion of skiers and snowboarders in the current review 67 % and 32 %, respectively reflects recent worldwide approximations [7], it may not reflect the on-slope distribution of skiers and snowboarders across seasons, alpine resorts or geographical areas. The current review was limited to English-language articles, meaning that relevant articles in other languages and their associated data were excluded. Although this could be perceived as a limitation, it is believed that all essential information within the field was extracted from the English-language articles that met the inclusion criteria. It is also appropriate to recall that descriptive statistics were used to summarize the review findings and that no meta-analysis was performed. Many of the included articles, particularly those with a lower quality score, did not report data in sufficient detail to allow for a comprehensive meta-analysis. Indeed, the methodological quality of most of the articles reviewed was low (i.e. less than or equal to three), with only three randomized controlled trials being identified [43, 62, 63]. The constraints associated with the descriptive statistics of this review are counterbalanced through its systematic methods, expansive selection of databases, quality appraisal tools and strategies employed to reduce source of bias (e.g. article blinding and independent reviewers) that strengthen the results. 5 Conclusions The goal of this review was to isolate recommendations for injury prevention that pertain to the exercise, training and physical fitness of recreational alpine skiers and snowboarders, but none were found. The main focus in injury prevention research for recreational alpine skiers and snowboarders is equipment, with helmets being the most researched. Although sports medicine encourages injury prevention programmes to include sport-specific exercises, none of the reviewed articles explicitly investigated aspects of physical fitness or made recommendations about exercises for strength, endurance, flexibility or coordination pertaining to alpine skiing and snowboarding. Hence, future research should study the role and effect of purposefully prescribed exercises in decreasing the incidence and severity of musculoskeletal injuries sustained during recreational alpine skiing and snowboarding. Until then, recreational alpine skiers and snowboarders, coaches and healthcare professionals must resort to knowledge derived from other sports injury prevention research for evidencebased exercise programmes. 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