Dennis Caine and Laura Purcell (eds.)Injury in Pediatric and Adolescent SportsContemporary Pediatric and Adolescent Sports Medicine10.1007/978-3-319-18141-7_5

5. Epidemiology of Pediatric and Adolescent Injury in Adventure and Extreme Sports

Dennis Caine¹ and Omer Mei-Dan²

(1)

Department of Kinesiology and Public Health Education, University of North Dakota, Grand Forks, ND, USA

(2)

Department of Orthopedics, University of Colorado School of Medicine, Aurora, CO, USA

Dennis Caine (Corresponding author)

Email: dennis.caine@email.und.edu

Omer Mei-Dan

Email: OMER.MEIDAN@UCDENVER.EDU

Keywords

EpidemiologyInjuryChildAdolescentPediatricAdventure sportsExtreme sports

Introduction

During the last two decades there has been an explosion in both the popularity and participation in adventure and extreme sports (AES) [1, 2]. According to the Sporting Goods Manufacturing Association (SGMA) analysis of the Sports and Fitness Participation Report (2011 edition), AES are an appealing recreation and athletic option for millions of Americans [3]. The growing popularity of these activities has been driven by youth culture [4, 5] as is evidenced by television networks’ investment in AES programming and their coverage of sports events like the X-games, an Olympic-like competition showcasing the talents in extreme sporting events.

AES, by definition, involve elements of increased risk, and are usually performed in beautiful, exciting, and remote locations or in extreme environments [4]. They tend to be individual sports that are performed by adventurous elite athletes as well as the recreational adventure sports enthusiast in both competitive and noncompetitive settings. These activities often involve speed, height, a high level of physical exertion, and highly specialized gear or spectacular stunts.

Examples of popular AES include BMX; rock and ice climbing; hang-gliding and paragliding; scuba diving; surfing (including wave, wind, and kite surfing); personal watercraft; whitewater canoeing, kayaking, and rafting; BASE jumping and skydiving; extreme hiking; skateboarding; mountain biking; in-line skating; ultra-endurance races; alpine skiing and snowboarding; and ATV and motocross sports [4, 6]. Of these, the more radical and dangerous versions of AES, such as outdoor rock and ice climbing, high-grade white water kayaking, and BASE jumping, are considered “extreme sports” [7].

Participants in AES often train or compete in variable environmental conditions that are weather and terrain related, including wind, snow, water, and mountains [8]. These activities often take place in remote destinations or recreational facilities with little or no access to immediate medical care [9]. Even if medical care is available it usually faces challenges related to longer response and transport times, access to few resources, limited provider experience due to low patient volume, and more extreme geographical and environmental challenges [10].

Mass media showcasing breathtaking stunts and the inclusion of skateboarding, in-line sports, and rock climbing showcased in the 2014 Youth Olympics in Nanjing, and mountain biking at the 2000 Games in Sydney, are all helping to drive the popularity of AES among youth. In the USA, children and adolescents, aged 6–17 years, recorded 2.8 billion annual outdoor recreation outings during 2007–2012, or 92 average outings per participant [11]. The most popular outdoor activities for this age group were road, mountain, and BMX biking (27 % of American youth/13.4 million participants) [11]. In addition, as early as 2002, children and adolescents <17 years were thought to make up 25 % of all backpackers and wilderness campers in the USA [12].

Physical activity in children and adolescents increases physical fitness (both cardiorespiratory fitness and muscular strength), reduces body fat, improves cardiovascular and metabolic disease risk profiles, enhances bone health, and reduces symptoms of depression and anxiety [13]. However, engaging in sports and recreational activities at a young age also involves a risk of injury [14]. By their very nature, participation in AES involves performance in variable and often unpredictable environmental conditions that may be associated with increased injury risk. While we strive for an active population, participation in any physical activity must consider the risk of injury and measures for injury prevention.

Young participants may be particularly vulnerable to injury due to such growth-related factors as the adolescent growth spurt, susceptibility to growth plate injury, differences in maturity status, nonlinearity of growth and, relative to adults, longer recovery and differing physiological response after concussion, and slower acclimatization to extreme weather conditions [15–17]. They might also be at risk because of decreased neuromuscular control, strength, emotional maturity, and judgment compared with adults [18]. The unusual and sometimes risky physical demands of AES may create conditions under which these potential risk factors can more readily exert their influence.

Recent data suggest that the risk and severity of injury in some AES are high [19]. For example, researchers reviewed 2000–2011 National Electronic Injury Surveillance System (NEISS) data for seven popular sports featured in the Winter and Summer X Games: surfing, mountain biking, motocross, skateboarding, snowboarding, snowmobiling, and snow skiing [20]. Of the four million injuries reported for extreme sports participants, 11.3 % were head and neck injuries. Of all head and neck injuries, 83% were head injuries and 17% neck injuries.

This chapter illuminates the epidemiologic approach to understanding the incidence and characteristics of injury affecting pediatric and adolescent AES participants, and what is known about risk factors and preventive measures with the hope of generating understanding and further research. It is beyond the scope of this chapter to provide an in-depth review of the incidence and distribution of injury in AES.

Epidemiology of Injury

Injury epidemiology is the study of the distribution and determinants of varying rates of injuries in human populations for the purpose of identifying and implementing measures to prevent their development and spread. A model outlining the epidemiologic approach to sports injury prevention was first proposed by Willem van Mechelen and his colleagues [21]. First, research establishes the extent of injury, including both incidence and severity. Second, research explores its etiology (i.e., the causes and implications of injury). Third, research creates a prevention strategy to reduce the injury burden. Last, research evaluates the effectiveness of the implemented prevention strategy by reexamining the extent of injury.

The epidemiologist in sports medicine is concerned with quantifying injury occurrence (how much) with respect to who is affected by injury, where and when injuries occur, and what is their outcome (step 1), for the purpose of explaining why and how injuries occur (step 2) and identifying strategies to control and prevent them (steps 3 and 4) [22]. The study of the distribution of varying rates of injuries (i.e., who, where, when, what) is referred to as descriptive epidemiology. The study of the determinants of an exhibited distribution of varying rates of injuries (i.e., why and how) and the identification and implementation of preventive strategies is referred to as analytical epidemiology [23].

Descriptive Epidemiology

Descriptive reports represent the most common type of epidemiologic research published in the AES injury literature and arise from anecdotal reports and case series. Much of the available data on injury in AES arise from aggregate records kept by professional associations, hospital trauma registries, hospital admissions, competitive events, and national injury registries. Observational studies, including surveys and cohort studies are infrequent. Analytical research is sparser. The important aspects of the descriptive epidemiology of sports-related injuries are discussed below with the purpose of highlighting their various contributions to understanding the distribution of AES injuries [24].

In descriptive epidemiology the researcher attempts to quantify the occurrence of injury. We often first learn of a youth injury or fatality suffered through participation in AES in media reports. For example, on July 27, 2014, a New Zealand newspaper reported a 16-year-old mountain biker who received multiple injuries after falling on a mountain-bike track and was air-lifted to a regional hospital [25]. On August 29, 2010, ESPN news reported that Peter Lenz, motorcycle racer, had been run over and killed by a 12-year-old motorcycle racer during an accident at the Indianapolis Motor Speedway [26]. Reports like these are not uncommon in the news media. However, typically no information is provided on the frequency of such events.

Case reports/series are often used to report unusual injuries sustained by an individual or a group of individuals. For example, an 18-year-old male sustained multiple fracture/dislocations of his left foot while practicing parkour, an extreme sport that is gaining popularity in the USA [27]. Participants of this sport, known as parkouristes, try to overcome obstacles in their environment by simply jumping or scaling an obstacle, but sometimes this is done in a very acrobatic manner [27].

The most basic measure of injury occurrence is a simple count of injured persons or fatalities. For example, in May 2014, the Division of Hazard Analysis, US Consumer Product Safety Commission, reported that during January 2010 to August 2010 there were 169 ATV-related injuries affecting children and adolescents <16 years of age, or 25.8 % of all ED-treated ATV-related injuries [28]. These count data are useful in providing an estimate of the relative frequency of injuries as well as an estimate of the morbidity load on a clinic. However, they have limited epidemiologic utility and should not be confused with rates [29].

In order to investigate the rate and distribution of injuries it is necessary to know the size of the source population from which the injured individuals were derived, or the population at risk. The two most commonly reported rates in the sports injury literature are prevalence and incidence. Prevalence pertains to the total number of cases, new or old, that exist in a population at risk at a specific period of time. For example, 47 % of the German Junior National climbing team and 28 % of recreational climbers had stress reactions in the fingers [30]. A limitation of prevalence data is that only injuries present during the time of the survey period are registered, and thus data are not necessarily representative of all injuries in a population.

The two types of injury incidence most commonly reported in the sports injury literature are clinical incidence and incidence rates. Clinical incidence refers to the number of incident injuries divided by the total number of athletes at risk and usually multiplied by some k value (e.g., 100) [31]. For example, Flores et al. [32] reported an annual rate of 72.1 outdoor recreational injuries per 100,000 population (95 % CI = 38.6–105.6). The injury rate was highest in the 15- to 19-year age group (214.0 per 100,000 population, 95 % CI = 98.2–329.7). While clinical incidence may serve as an indication of clinical or resource utilization, it does not account for the potential variance in exposure of participants to risk of injury [31]. For example, the 15–19-year-old age group in the Flores et al. [32] may have been differentially exposed to the risk of injury.

Incidence rate (IR) refers to the number of incident injuries divided by the total time-at-risk and usually multiplied by some k value (e.g., 1,000) [31]. It is the preferred measure of incidence in research studies because it can accommodate variations in exposure time of individual participants. Different units of time-at-risk, varying in precision, have been used to calculate incidence rates in the AES literature. These include reporting the number of injuries per k time exposures (one time exposure is typically defined as one individual participating in 1 h of activity in which there is the possibility of sustaining a sport-related injury) and per k element exposures (one element exposure is defined as one individual participating in one element of activity in which there is the possibility of sustaining an athletic injury). Examples of exposure elements used in AES include climbs, summits, surfing days, personal watercrafts (PWC) in operation, (scuba) dives, and (BASE) jumps.

A difficulty that arises in comparing incidence rates from different studies relates to the injury definition employed. A review of the AES literature reveals that few common operational definitions exist for injury both within and between sports. Definitions include such criteria as presence of a new symptom or complaint, decreased function of a body part, decreased athletic performance, time loss, and consultation with medical or training personnel [19]. Clearly, if injury is defined differently across studies, a meaningful comparison of injury rates is compromised due to different criteria for determining numerator values.

Who Is Affected by Injury?

As might be expected, injury rates are most often categorized according to sport participation (e.g., sport climbing, ice climbing) and the way in which participants are organized for sports (e.g., recreational or competitive). Two recent edited texts on AES provide limited data on the incidence of pediatric and adolescent injury across a range of activities [4, 19]. Most of the data reported arise from estimates of clinical incidence. For example, in 2004–2005, the 15–19-year-old (214 injuries/100,000 population; 95 % CI: 98.2–329.7) and 10–14-year-old (187.1 injuries/100,000 population; CI: 84.3–289.9) age groups recorded the highest injury rates in outdoor recreational activities treated in EDs in the USA, followed by the 20–24-year-old group (121.1 injuries/100,000 population; CI: 72.9–169.3) [32].

IR data arising from a retrospective cross-sectional study have recently been reported for youth rock climbers, aged 11–19 years [33]. An overall IR of 4.44 injuries per 1,000 climbing hours (95 % CI: 3.74–5.23) was reported for elite and recreational climbers. Recreational climbers incurred a rate of 4.71 per 1,000 climbing hours (95 % CI: 3.64–6.09) compared to 4.27 per 1,000 h among elite climbers.

Where Does Injury Occur?

Determination of “where” injury occurs involves identification of the anatomical and situational locations of injury. Identifying the anatomical location highlights the body parts that are more likely to be injured which can, in turn, assist in the development of preventive measures to reduce the number and severity of these injuries [34]. Anatomical locations include body region of injury (e.g., upper extremity) as well as specific body parts (e.g., shoulder, ankle). For example, a common injury site associated with skateboarding is the wrist, accounting for 32 % of all hospital-reported skating injuries, and 25 % of all wrist injuries are fractures [35]. Notably, 76.7 % of patients in this study were elementary and high school students.

Environmental location provides information on the distribution of injury by where in the environment the injury occurred. Environmental locations reported in AES injury literature include surface or terrain on which the activity takes place, for example indoor or outdoor climbing or grade of terrain associated with mountaineering; geographical location, for example public areas versus skate parks for skateboarders; proximity to others or obstacles (e.g., overcrowding among personal watercraft riders); and whether the injury occurred in practice or competition. Information on high-risk settings is of course useful in identifying important targets for further study, including application of preventive measures. For example, IRs for youth rock climbing reveal a higher risk for indoor (4.31 per 1,000 h; 95 % CI: 3.59–5.13) vs. outdoor climbing (2.94 per 1,000 h; 95 % CI: 1.2–5.79) [32]. Notably, several hospitals reported an increase in the frequency of skateboarding injuries when a skate park was opened [36, 37].

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