A theoretical model for injury causation in extreme sports. Adapted from 
When evaluating risk in the preseason, ideally a sport-specific functional test will be utilized to obtain data, tease out areas of weakness, and match a specific training program precisely to the task the athlete requires. The best strength programs are those that balance impairment management and the continued training of an athlete’s strengths. Current research states that the best time to implement injury prevention programs is during off-season or preseason, with continued maintenance during the season .
The demands vary from sport to sport. For example, backcountry skiing and snowboarding will have obvious varied requirements than mountaineering or climbing. Due to this, preventative measures will be broken down into the following: skiing/snowboarding, climbing/mountaineering, and mountain biking.
26.2 Backcountry Skiing and Snowboarding
Skiing and snowboarding continue to be the most popular winter recreational activities. An estimated 8.2 million people participated in snowboarding and 11.5 million in skiing in 2010 . Although injury rates fluctuate, snowboarding injury rates seem to currently be slightly higher . The demands of skiing vary slightly between alpine racing, recreational resort skiing/snowboarding, and backcountry touring.
As there is not significant high-level evidence for epidemiology of backcountry and side country skier injuries, correlations will be drawn from alpine skiing with special considerations of modifiable intrinsic factors unique to backcountry participation. For example, if an injury is sustained in the backcountry, medical care access is limited. Therefore, even a minor knee sprain can become a life-threatening injury due to terrain, weather, and ability to self-extricate from the location. As a result, injury prevention and optimal physical fitness is an imperative component to safety in the backcountry.
Aerobic and anaerobic conditioning should be primary consideration to decrease fatigability of the athlete. The aerobic and anaerobic training should be specifically tailored for the participant and their demands. Athletes in slope style or terrain park competitions will require less aerobic capacity and more anaerobic training than a ski mountaineer (“SkiMo”) racer. Skiing and snowboarding require muscle groups to act statically and dynamically based on athlete positioning within the sport. In general, these muscle groups include trunk rotation, trunk lateral flexion, hip extension, hip abduction, hip external rotators, and hip adductors .
Preseason workouts should isolate these areas of weakness, especially after fatigue-based training to tease out possible failure of form or control. Fatigue is known to have a negative impact on balance control while physical fitness has an effect on reaction time during exercise . Depending on how the athlete reaches the top of the slope to be skied ascent needs to be considered. Backcountry skiers often spend numerous hours climbing the slopes they expect to ski. This increases the risk of fatigue for the actual ski run(s), thus, risk for falls increases linearly. It is essential that these athletes have a strong aerobic capacity, as well as a training program that focuses on slow steady climbing to utilize fat oxidation rather than depleting muscle glycogen stores. A superior cardiovascular base fitness, paired with appropriate clothing and pacing, helps to minimize excessive sweating during the climb, and this decreases risk of hypothermia and form fatigue or instability in backcountry winter travelers.
Although literature is relatively limited in backcountry injuries, alpine racers present numerous studies evaluating physical fitness and its correlative factors to injury rates . The knee is the most common area of injury in skiers (the MCL and ACL specifically). When developing specific training programs for different demographics, it is important to compare incidence of injury between skiers and snowboarders. Wrist injuries accounted for 27.6 % of snowboarding injuries and only 2.8 % of skiing injuries, and ACL composed 1.7 % of snowboard injuries compared to 17.2 % of skiing injuries . Shoulder injuries are not a primary focus of this chapter as most shoulder injuries are secondary to trauma or falls rather than poor mechanics or overuse; it is important to note that 4–11 % of skiing injuries and 8–16 % of snowboarding injuries are about the shoulder complex . Thus, extrinsic factors of equipment and protective gear may be of interest when considering the shoulder, as well as intrinsic factors including proper fall education, and prevention of falls.
Most injuries tend to occur when a skier is off-balance. Primarily falls transpire when the athlete’s weight is on the tail of the ski, attempting to recover from this backseat position or combating an imminent fall . As a result, kinematics and control of lower extremities in dynamic situations are extremely important for prevention . Considering frequency of injuries in above stated situation, sagittal plane control, in specific, posterior to anterior weight shifting comfort, and control are crucial.
Poor trunk, hip abductor, and hip external rotator strength and control have been widely accepted as a risk factor for ACL injuries . Raschner and colleagues performed a 10-year longitudinal study looking at ACL injuries in young competitive ski racers and specifically found that trunk strength is a predominant critical factor for ACL injuries. Thus, dynamic trunk control in various body positions will be an essential component of the injury prevention training .
Moreover, double leg exercise versus single need to be considered based on type of activity. For example, telemark skiing may require more single leg control, versus snowboarding, which will require more double leg consideration in a prevention program. Although no single program is appropriate for everyone, the principles of progression can be applied across athletes. The general equation of progression takes the athlete from controlled exercises on stable surfaces, to more dynamic surfaces, to rotational forces for unpredicted direction changes, and then lastly to the above components without visual dependency. This is conducted, all while maintaining optimal posturing and stability. Within each phase of strength training and control, the athlete will be progressed from double limb support to single limb support, controlling if appropriate to the relevant sport.
Finally, when discussing injury prevention in backcountry skiing, it is essential to briefly discuss the role avalanche injury and death play on this population. In a 21-year review of avalanche fatalities between 1984 and 2005, backcountry skiers had the greatest number of deaths when compared to other backcountry travelers. Asphyxia caused ~75 % of deaths while trauma accounted for 24 % . Experienced 36-year-old male backcountry travelers accounted for the highest demographic killed by avalanches, and the majority of these individuals were equipped with backcountry avalanche recovery equipment, including beacon, probe, and shovel . Continued emphasis on understanding and avoiding avalanche prone slopes is an essential part of an injury prevention program for backcountry travelers.
Extreme skiing and snowboarding (both in bounds and in the backcountry) present a moderate risk of injury to athletes participating in these activities. Through understanding the modifiable injury risks, a preseason training program can be developed to decrease these injuries. Programs should focus on aerobic and anaerobic conditioning, static positioning for endurance, balance, hip and trunk strength, and dynamic control through various positions in order to decrease the theoretical risk of injury within these athletes. As discussed previously, a preseason training program will not guarantee injury prevention as high-level skiing and snowboarding deal with numerous extrinsic variables like terrain, conditions, and equipment, but it will allow the athlete to improve physical conditioning, balance, and muscular control prior to the season. Studies need to be performed to evaluate the efficacy of these preseason training programs in this population of athletes.
26.3 Mountain Biking
Mountain biking is an evolving sport that requires the negotiation of rough terrain and obstacles at relatively fast speeds. It is estimated that between 2006 and 2012, 17 % of Americans over the age of 6 mountain bike . Due to the growing popularity and the physically demanding nature of mountain biking, there has been an overall increase in injuries. The most common injuries (60–75 %) are soft-tissue abrasions, lacerations, and contusions and are considered minor in nature . However, the risk of serious injury including fracture, spinal injury, and even death are present. The majority of injuries sustained in this sport are due to falls , and thus, the majority of research available is focused on traumatic injuries. A few articles have looked at overuse syndromes in mountain bike athletes.
A 2008 review states this in terms of prevention “that riders should be well trained, ride within the level of their capability, learn to dismount safely and use a well-maintained bike without handlebar ends. They should also wear helmets with facial protection, padded gloves and shorts, use cushioned seats and shin protection” . Although prevention literature is far less prevalent than traumatic literature, it has been established that anywhere from 50 to 90 % of participants have pain from overuse in the following areas: lumbar spine, buttocks, and knees [17, 18].
Overall, it is estimated that overuse injuries are less common in mountain bikers when compared to road cyclists. This is likely due to geometry of a mountain bike being more upright resulting in a more natural position and less hip and lumbar flexion. Also, due to the nature of mountain biking, riders are often changing positions as they attempt to negotiate rocks, roots, drops, and other obstacles on the course. Despite these differences, overuse injuries continue to be a reality for mountain bikers.
The most common site of overuse is the knee, with a leading diagnosis of patellofemoral pain syndrome (PFPS) from abnormal stress at the patellofemoral joint resultant of poor biomechanics of the knee joint . PFPS can be influenced by local factors including tight quadriceps, decreased vastus medialis obliquus contraction strength and timing, tight iliotibial band, or patella alta/baja. Proximal factors also have a significant role in PFPS. Hip strength and control, particularly the hip abductors and external rotators, control the position of the femur under the patella. Abnormal movement in the frontal and transverse planes at the hip joint results in decreased contact area between femur and patella and thus increasing the stress in the tissue and increasing risk of pain or injury . The knee joint is essentially a two-dimensional joint sandwiched between two three-dimensional joints, the hip and ankle. The knee is often the site of pain, but the cause is often due to dysfunction at one of the two three-dimensional joints. Early onset of fatigue, poor strength, or inappropriate length of structures around these joints can all perpetuate increased stress at the knee.
Iliotibial band (ITB) syndrome is another common overuse injury noted in mountain bikers. ITB syndrome presents as intense pain in the lateral aspect of the knee and is self-reported to decrease pedal stroke power. Because the ITB crosses the lateral aspects of the hip and knee, similar to PFPS, excessive transverse and frontal plane motions can affect the lower extremity strain.
Relationships between fatigue and change in cycling mechanics and biomechanics are very prevalent in this population . Dingwell et al. demonstrate that when an athlete is exhausted on a stationary bike, the trunk, hip, knee, and ankle kinematics change . Abt et al. demonstrate that following exercises that fatigue the core will also result in altered cycling mechanics at the knee and ankle . Based on these findings, it stands to reason that athletes with poor lower extremity and core strength and endurance will likely present with altered cycling mechanics increasing the risk of injury.
Additional research has shown that women are 1.94 times more likely to be injured and 4.17 times more likely to sustain a fracture than males of similar skill level. Males make up 80 % of mountain bike injuries due to their increased numbers in the sport, and when this variable is controlled and compared to women, women are almost twice as likely to be injured across skill levels . The most common reason reported by women for crashing is losing control of their bikes . The demands of mountain biking requires significant core and upper body strength in order to control the bike in rough terrain and keep the athlete’s body on the bike. Less upper body strength reduces one’s ability to control the bike over difficult terrain . It is proposed that a specific trunk and upper body-strengthening program may decrease the incidence of losing control of the bike within the female population.
Low back pain is another common overuse complaint within the mountain biking community. The constant and unnatural forward lean position on the bike, combined with the repetitive motion and mircotrauma, increases the strain on the low back and increases the risk of overuse injury. Lastly, lumbar spine pathology is thought to occur via mechanisms such as spinal extensor hyperactivity, elongation stress on noncontractile structures, or decreased movement of fluid in lumbar disks . Core strength and endurance can help to maintain a neutral spine and active intrinsic shock absorption throughout the region decreasing strain on the noncontractile structures.
Addressing the aforementioned intrinsic factors like flexibility and strength will help to decrease overuse injury risk, but without a proper bike fit, the efforts will likely fall short of alleviating pain. Fitting a bike to the athlete is a specific skill that is beyond the scope of this chapter but needs to be considered when working with patients in this demographic. Seat height, forward/back position of the seat, head tube angle, and handlebar attachments all have been shown to contribute to overuse injury in mountain bike athletes .
Over 50 % of mountain bike athletes complain of overuse type injuries with the butt, spine, and knees being the most common area of pain. Despite this high number of overuse injuries, majority of research continues to be on traumatic injuries. However, there is growing research to support the use of preseason strengthening, aerobic capacity, and dynamic control in the use of injury prevention. Further research in this area is warranted to determine the effectiveness of these programs. Mountain biking requires a significant amount of hip, quadriceps, and hamstring strength to propel the bike, as well as core and upper extremity strength to control the position of the rider on the bike. Thus, a training program should focus on lower extremity strength and endurance, core static and dynamic control, and upper extremity strengthening programming, particularly for females.
26.4 Mountaineering and Climbing
When discussing injury risk and prevention for this population, it is important to understand the differences between traditional mountaineering, alpine climbing, tradition (trad) climbing, and sport climbing. We will focus on alpine climbing and sport climbing since those are currently the two areas with the greatest growth in participation and tend to encompass components of the other styles.