Adaptive Alpine Skiing and Para-snowboarding



Fig. 23.1
(a) Photograph courtesy of Brian J. Juriga. (b) Photograph courtesy of Brian J. Juriga



Para-alpine skiing has six different disciplines as follows [17]: downhill, super G, slalom, giant slalom, super combined, and snowboard. The rules for each discipline are different based on various rules adapted for skiers with disabilities from the International Ski Federation. Even skiing with these various disciplines and their disabilities, athletes can still reach speeds of 62–72 mph. Before all disciplines, there is a 1–2 h time of inspection for all the athletes with their coaches of the course to make sure all the equipment is correct.

Downhill is a timed speed-based discipline in which athletes ski down a steep course involving many turns and jumps finishing 450 m (1480 ft.) to 800 m (2600 ft.) lower than when they started. Downhill discipline has the skiers navigating through the least amount of gates, but they are going the fastest and down the steepest terrain with turns and jumps. If an athlete misses one gate, they are disqualified. The winner is the one with the fastest time based in one run. Downhill women’s skis must be at least 200 cm (79 in.) long with a tolerance of 1 cm (0.39 in.), a minimum radius of 45 m (148 ft.), a profile radius of 6 mm (2.6 in.), and curved ski poles. The only difference for men is that the ski length must be at least 205 cm (81 in.). Before all downhill events, at least one practice run is required.

Super G (super giant slalom) discipline is more technical than downhill but not as technical as some of the other disciplines (Fig. 23.2). It is a little slower than the downhill but faster than the slalom or giant slalom. It usually is not as vertical as the downhill and usually has a drop of 400 m (1300 ft.) to 600 m (2000 ft.) from start to finish. It is longer than the giant slalom and the slalom but shorter than the downhill. It is considered a speed event where athletes ski between alternating red and blue gates that are 25 m (82 ft.) apart with a minimum of 30 directional changes. Women need to clear at least 30 gates and men need to clear at least 35 gates. All the parameters for the skis and poles for super G is the same as downhill for men and women, except that the ski minimum radius is 33 m (108 ft.) and a profile radius of 65 mm (2.6 in.).

A330551_1_En_23_Fig2_HTML.gif


Fig. 23.2
Photograph courtesy of Brian J. Juriga (super G)

Giant slalom involves two runs down a course that is straighter and shorter than slalom but with fewer gates and alternating smoother and wider turns than the downhill (Fig. 23.3). It is a lot less vertical from top to bottom ranging from 300 m (980 ft.) to 400 m (1300 ft.). It is considered one of the more technical disciplines. The winner is based on the combined times of both runs. The starting order for the second run always starts with the slowest of the top 15 or 30 going first and the fastest with the top 15 or 30 going at number 15 or number 30. Skiers finishing outside of the top 15 or 30 then have to ski in order based on their times from the first run. At any time after the first run of giant slalom, the bottom 20% of the finishers can be eliminated from competition based on the discretion of the judges. Additionally, ski length is 155 cm (61 in.) for women and 165 cm (65 in.) for men and they use straight poles.

A330551_1_En_23_Fig3_HTML.gif


Fig. 23.3
Photograph courtesy of YouaPa Yang (giant slalom)

Slalom is the most technical discipline of them all (Fig. 23.4). It involves two runs each going down a different course set by a different set of people. There are 40–60 gates for women and 55–75 gates for men, and if a skier misses a gate in either run, they are disqualified. It has the least vertical drop from 140 m (460 ft.) to 220 m (720 ft.) on a bulletproof iced course. Both men and women’s specifics for their equipment are a minimum of 155 cm (61 in.) for women and 165 cm (65 in.) for men in length. Additionally, straight poles are used and the skiers have padding on their shins, forearms, hands, and back. Similar to giant slalom, after the first run, the bottom 20% of the finishers can be eliminated per the judge’s discretion. Also, the starting lineup for the second run always starts with the slowest of the top 15 or 30 going first and the fastest with the top 15 or 30 going out at number 15 or 30. All skiers finishing outside of the top 15 or 30 will then ski in order based on their times from the first run.

A330551_1_En_23_Fig4_HTML.gif


Fig. 23.4
Photograph courtesy of YouaPa Yang (slalom)

Super combined is a discipline that combines either slalom and super G or downhill and slalom (Fig. 23.5). During this discipline the athletes do one run on the downhill or super G and two runs on the slalom. The times for the races are combined with the fastest of the combined times winning the race.

A330551_1_En_23_Fig5_HTML.gif


Fig. 23.5
Photograph courtesy of YouaPa Yang (super combined)

Snowboarding is the final discipline for para-alpine skiing (Fig. 23.6). The course from top to bottom drops between 100 m (330 ft.) and 240 m (790 ft.) for a distance of 400 m (1300 ft.) to 900 m (3000 ft.) for both men and women. It is a course made up of berms, jumps, rollers, and other man-made obstacles that need to be navigated through alternating gates. Unlike snowboard cross in able-bodied athletes where heats of four athletes at a time go at once, in the para-athletes, they go one at a time. They have three runs on the course and their two best runs are combined. Para-snowboarding at this time is only open for standing athletes.

A330551_1_En_23_Fig6_HTML.gif


Fig. 23.6
Photograph courtesy of Brian J. Juriga (snowboarding)

Overall six different disability groups for men and women are in the Paralympics as follows [3]: amputee, cerebral palsy/brain injury/stroke, blindness/visual impairment, wheelchair users/spinal cord injuries, intellectual disability, and Les Autres (a group which includes all those that do not fit into any of the previous groups). The amputee athlete groups are categorized into partial or total loss of at least one limb, such as upper extremity or lower extremity and also into single loss or multiple loss of limb. The cerebral palsy group athletes are considered any athletes with nonprogressive brain damage such as cerebral palsy, traumatic brain injury (TBI), stroke, or any similar disability affecting muscle control, balance, and/or coordination. The intellectual disability athletes are those with a significant impairment in intellectual functioning and limitations in adaptive behavior. The spinal cord injury group consists of any disabilities which require an athlete to use a wheelchair and/or a sit ski for competition because of a spinal cord injury or injuries. The visually impaired group is broken up into partial vision, legally blind, and total blindness. The final group termed Les Autres (aka French for “the others”) includes all athletes with a physical disability that does not fall under one of the other five categories. Examples of this include dwarfism, multiple sclerosis, and congenital deformities of the limbs such as that caused by thalidomide.

Classification is very important in para-alpine skiing because it has a significant impact on the success of an athlete in competition. Classification is an evidence-based system with a stated purpose to promote participation in sport by people with disabilities by minimizing the impact on the impairment on the outcome of the competition [17]. The method used in assigning the classification goal is to classify the impairment not the athlete. The overall goal of classification is designed to ensure fair competition between alpine skiers with different types of disabilities. The classification is by the International Classification of Functioning, Disability and Health. Additionally, classification helps in reducing the sports likelihood of one-sided competition and promotes participation. The classification system is internationally accepted, and in the Paralympics, it is based on the degree of function presented by the disability rather than medical diagnosis [17]. Therefore, a complete L2 spinal cord injury can compete against a bilateral above-knee amputee fairly. The classes are determined by a variety of processes that include but are not limited to physical and technical assessment and observation in and out of competition. Over all the classifications are grouped into three general disability groups as follows: standing, sitting, and blind [7].

There are individuals that specialize in sports certification and the process of classification and are called classifiers. Classification is not a onetime thing. It is an ongoing process through an athlete’s career, where their allocated class can consistently be reviewed throughout their career. The classifications are grouped into three general disability types: standing, sitting, and visually impaired [8]. They are then further classified based on medical assessment and their body position when they ski, with the exception of visually impaired skiers who are evaluated purely on medical assessment. Skiers with physical impairment who compete standing are classified from LW1 to LW9 (LW is an abbreviation for “Locomotor Winter”) (Fig. 23.7). Athletes with LW1–LW4 classifications have lower limb impairment and LW5–LW8 classifications are for upper limb impairments (Fig. 23.8). LW9 classification is for athletes with combined arm and leg impairments (Fig. 23.9a–c). The final three LW classifications (LW10, LW11, and LW12) are for skiers with a physical impairment affecting their legs and require them to compete using a sit ski and are allocated different classes depending on their sitting balance (Fig. 23.10a, b). Athletes with a visual impairment ski with a guide. The guide skis in front of the athlete and gives verbal directions to the athlete through a radio-frequency headset and microphone (Fig. 23.11). There are three different classifications based off the amount of visual impairment. The classifications are B1, B2, and B3 (B being an abbreviation for “blind”). Finally, snowboarding athletes are all classified as SB-LL (SB is an abbreviation for “snowboard,” and LL is an abbreviation for “lower limb”) (Fig. 23.12). All of these athletes have leg impairments such as amputations above the ankle, stiffness of the ankle or knee joint, or muscle weakness. These athletes with amputations use prostheses during the races (Fig. 23.13a, b).

A330551_1_En_23_Fig7_HTML.gif


Fig. 23.7
Photograph courtesy of YouaPa Yang (lower limb impairment)


A330551_1_En_23_Fig8_HTML.gif


Fig. 23.8
Photograph courtesy of Brian J. Juriga (upper limb impairment)


A330551_1_En_23_Fig9_HTML.gif


Fig. 23.9
(a) Photograph courtesy of YouaPa Yang (upper and lower limb impairment). (b) Photograph courtesy of YouaPa Yang (upper and lower limb impairment) (c) Photograph courtesy of Brian J. Juriga (upper and lower limb impairment)


A330551_1_En_23_Fig10_HTML.gif


Fig. 23.10
(a) Photograph courtesy of YouaPa Yang (sit skiers). (b) Photograph courtesy of Brian J. Juriga (sit skier)


A330551_1_En_23_Fig11_HTML.gif


Fig. 23.11
Photograph courtesy of YouaPa Yang (visually impaired)


A330551_1_En_23_Fig12_HTML.gif


Fig. 23.12
Photograph courtesy of Brian J. Juriga (snowboarding)


A330551_1_En_23_Fig13_HTML.jpg


Fig. 23.13
(a) Photograph courtesy of Brian J. Juriga (prosthesis). (b) Photograph courtesy of Brian J. Juriga (prosthesis)

Alpine classifications are as follows [2, 3, 811]:



  • Skiers with leg impairments standing classes (Fig. 23.14a, b):

    LW1: Double-leg above-knee amputation, significant muscle weakness in both legs, moderate to severe cerebral palsy, incomplete paraplegia, or incomplete equivalent impairment. This class is for athletes with impairments that affect both legs. Athletes can use one or two skies and either poles or outriggers.

    LW2: Single-leg above-knee amputation or one with severe functional impairment like an impaired leg since birth. Athletes ski with one ski and outriggers.

    LW3: Double below-knee amputees, moderate to severe functional impairment in both legs, incomplete paraplegia, spina bifida, mild cerebral palsy (CP5 and CP6), mild coordination problems, muscle weakness in both legs, and/or equivalent. Athletes ski with two skis and poles or outriggers.

    LW4: Single-leg below-knee amputation, functional impairment in one leg, and weakness in one leg but with less activity limitation than LW2. Athletes use two skis and two poles.


  • Skiers with arm impairments standing classes (Fig. 23.15a, b):

    LW5/7-1: Double-arm amputation above the elbow or bilateral arm with limited muscle power and/or coordination problems. Athletes use two skis and no poles.

    LW5/7-2: Double-arm amputation, one above and one below the elbow. Athletes use two skis and no poles.

    LW5/7-3: Double-arm amputation below the elbow. Athletes use two skis and no poles.

    LW6/8-1: Single-arm amputation above the elbow or impairment of one arm such as loss of one hand or arm. Athletes use two skis and one pole only.

    LW6/8-2: Single-arm amputation below the elbow or impairment of one arm such as loss of one hand or arm. Athletes use two skis and one pole only.

    LW9-1: Amputation or loss of one arm and one leg above the knee or equivalent impairment of one arm and one leg above the knee or the same on opposite sides of the body. Some skiers in this class have coordination problems such as spine stability or some loss of control over one side of their body. Athletes use one or two skis and one pole or outrigger.

    LW9-2: Amputation or loss of one arm and one leg below the knee or equivalent impairment of one arm and one leg below the knee on the same side or opposite sides of the body. Some skiers in this class have coordination problems such as spine stability or some loss of control over one side of their body. Athletes use one or two skis and one pole or outrigger.


  • Sport classes LW10–12 sit skiers (aka monoskiers) (Fig. 23.16a–c):


A330551_1_En_23_Fig14_HTML.gif


Fig. 23.14
(a) Photograph courtesy of YouaPa Yang (lower leg impairment classes). (b) Photograph courtesy of YouaPa Yang (lower leg impairment classes)


A330551_1_En_23_Fig15_HTML.gif


Fig. 23.15
(a) Photograph courtesy of Brian J. Juriga (arm impairment standing classes). (b) Photograph courtesy of Brian J. Juriga (arm impairment standing classes)


A330551_1_En_23_Fig16_HTML.gif


Fig. 23.16
(a) Photograph courtesy of YouaPa Yang (monoskier classes). (b) Photograph courtesy of Brian J. Juriga (monoskier classes). (c) Photograph courtesy of YouaPa Yang (monoskier classes)

All sit skiers have various impairments affecting their legs. They are all allocated into different sport classes depending on their level of sitting balance, which is very important for acceleration and balancing during the races.



  • LW10-1: Athletes have paraplegia with very poor active sitting balance (with no upper abdominal function) and limited lower back muscles. Therefore, they have no functional sitting balance. Athletes suffer from spinal cord injury at levels of T7 through T10 (just below the chest) or spina bifida. They rely on their arms to maneuver the sit ski.


  • LW10-2: Athletes have paraplegia with poor active sitting balance (with some upper abdominal function) and limited lower back muscles. Therefore, they have no functional sitting balance. Athletes suffer from spinal cord injuries at levels T7 through T10 (just below the chest) or spina bifida. They rely on their arms to maneuver the sit skies.


  • LW11: Athletes have paraplegia with fair to moderate functional active sitting balance and palpable abdominal contractions and some lower back muscles. This allows them to have good ability in their upper trunk but have very limited control in their lower spinal cords, trunk, and hips. These athletes have spinal cord injury at levels T11-L1 (at and around the waist).


  • LW12-1: Athletes with low level paraplegia with normal or slightly decreased trunk function and some leg function. Athletes have good sitting balance. Skiers with leg impairments in sport classes LW1-4 often fit this sport class. Therefore, they can choose if they want to ski sitting or standing in the beginning of their career.


  • LW12-2: Athletes with low-level paraplegia with normal or slightly decreased trunk function but have double-leg amputations above the knees.





  • Visually impaired sport classes B1–B3 (Fig. 23.17a–e):

    B1: These athletes are either totally blind or do not have the ability to perceive light in either eye and are also unable to recognize the shape of a hand at any distance. They cannot recognize the very large letter E (15 × 15 cm in size) at the top of the Snellen eye chart from just 25 cm away. During the race, these athletes are required to wear eye shades.

    B2: The athletes in this class have a slightly higher visual acuity than the athletes in the B1 class. They are able to recognize the shape of a hand and have a standard vision of <2/60 and/or visual field of less than 5°. They are unable to recognize the big E (15 × 15 cm in size) at the top of the Snellen eye chart from a distance of 4 m.

    B3: The athletes in this class have the least severe visual impairment of the three alpine skiing classifications. Their standard vision is between 2/60 and 6/60 (20/200 Snellen) and have a restricted field of vision greater than 5° but less than 20°.

    In the IPC Alpine Skiing visually impaired classification, all athletes require a guide. The athlete’s guide is obviously a great athlete and skier since he/she has to ski in front of the Paralympic xathlete and verbally gives turn-by-turn directions and other instructions to the athlete skiing down behind them.


  • Para-snowboarding classification (Fig. 23.18):

    SB-LL: Athletes with a physical impairment affecting one or both legs who competes standing.

    SB-UL: Athletes with a physical impairment affecting one or both arms who competes standing.


  • Adaptive alpine (downhill) skiing equipment [3, 7, 12, 13]:

    Currently there are many different options for adaptive skiing equipment for those with limb deficiencies. These athletes have the option to ski either sitting or standing. There are different varieties of equipment for these athletes based on whether they have an upper or lower extremity limb deficiency (Fig. 23.19a, b). Most of the time, upper extremity amputees or deficiency athletes will typically ski standing up with or without adaptive equipment. If the athlete does decide to use something, it is usually a prosthesis with a hand to hold a ski pole or a specialty made terminal device with a ski pole attached to its end (Fig. 23.20). An example of this is an outrigger which is a modified forearm crutch called a Lofstrand attached to ski tips (Fig. 23.21). These ski tips are usually modified with a special locking and release system. In this way, they can be locked into a fixed position such as a flat position for skiing or flipped up to a pointed position for gripping the snow to push and/or pull them forward and backward, essentially acting as a walking crutch. These types of outriggers are called a flip-ski [12].


A330551_1_En_23_Fig17_HTML.gif


Fig. 23.17
(a) Photograph courtesy of Brian J. Juriga (visual impairment classes). (b) Photograph courtesy of Brian J. Juriga (visual impairment classes). (c) Photograph courtesy of Brian J. Juriga (visual impairment classes). (d) Photograph courtesy of Brian J. Juriga (visual impairment classes). (e) Photograph courtesy of Brian J. Juriga (visual impairment classes)


A330551_1_En_23_Fig18_HTML.gif


Fig. 23.18
Photograph courtesy of Brian J. Juriga (para-snowboarding classes)


A330551_1_En_23_Fig19_HTML.gif


Fig. 23.19
(a) Photograph courtesy of YouaPa Yang (downhill skiing equipment). (b) Photograph courtesy of YouaPa Yang (lower extremity limb deficiency)


A330551_1_En_23_Fig20_HTML.gif


Fig. 23.20
Photograph courtesy of Brian J. Juriga (prosthesis)


A330551_1_En_23_Fig21_HTML.gif


Fig. 23.21
Photograph courtesy of Brian J. Juriga (outrigger)

Athletes with lower extremity amputees or deficiencies also have multiple prosthetic options. The differences in these athletes are that their deficiencies are either transtibial or transfemoral. They have the option of skiing either sitting or standing. Usually the athletes with a single lower extremity deficiency ski standing with or without a prosthesis (Fig. 23.22a, b). An athlete with a unilateral transfemoral limb deficiency will usually ski with a single ski with bilateral outriggers (Fig. 23.23). Most sit skiers are athletes with bilateral lower extremity limb deficiencies or amputees that are most commonly at the transfemoral level (Fig. 23.24). Lower extremity skiing prosthetics have a major difference for an athlete skiing with a transfemoral deficiency and using a prosthesis versus a transtibial deficiency prosthesis, that is, the socket and the addition of a knee unit. The knees typically involve a single axis to start and can be advanced to a more dynamic option as they advance in skill. In all types of prosthetic knees, the center of gravity should always be set in front of the ankle. The anterior socket brim where the athlete places their extremity into should be 1 in. behind the prosthetic toe. The prosthetic knee length is based on individual needs but usually is reduced in size to create a flexed lower limb in an athletic stance. Usually additional modifications are made for foot dorsiflexion if warranted with additional external knee support. The advanced prosthetic users even have prosthetics that can eliminate the boot altogether. This is by molding the plantar surface of the ski foot after the boot sole and then attached directly to the binding, thereby, eliminating the boot altogether. This advanced option alone eliminates excessive weight and, more importantly, enhances energy transfer to make the ski more effective in its performance. Another way to ski with a lower extremity prosthesis is to use a traditional foot as the terminal devices form so the limb-deficient athlete can pop the ski off and continue to ambulate normally with the prosthesis in the ski boot. This traditional foot comes in two different forms as follows: a solid ankle cushioned heel (SACH) foot or a dynamic response foot, which is usually designed to be used in conjunction with an adjustable multiflex ankle (Fig. 23.25). This gives a more natural ankle motion, as well as comfort and stability on uneven ground. No matter which type of the aforementioned foot used, either one requires a 1 in. heel wedge providing a forward cantor when the prosthesis is in the ski boot [12].

A330551_1_En_23_Fig22_HTML.gif


Fig. 23.22
(a) Photograph courtesy of YouaPa Yang (lower leg deficiency with prosthesis). (b) Photograph courtesy of YouaPa Yang (lower leg deficiency without prosthesis)


A330551_1_En_23_Fig23_HTML.gif


Fig. 23.23
Photograph courtesy of Brian J. Juriga (unilateral transfemoral limb deficiency)


A330551_1_En_23_Fig24_HTML.gif


Fig. 23.24
Photograph courtesy of Brian J. Juriga (bilateral lower limb deficiency)


A330551_1_En_23_Fig25_HTML.gif


Fig. 23.25
Photograph courtesy of Brian J. Juriga (SACH foot)

Depending on the disability, other terms to know when working with alpine skiing athletes with limb deficiencies are as follows. Three-track skiing is a stand-up skier using both one ski and two handheld outriggers or two skis and one outrigger (Fig. 23.26). Outriggers are there to help the limb-deficient athlete compensate for stability and also help them initiate their turns. The three-track disability group usually includes, but is not limited to, amputees, post-polio, and some congenital birth defects. When learning how to ski with their deficiencies, instructors usually use two forms of teaching, if needed, depending on the circumstances. Two-track skiing with a tether is used to give extra help to somebody learning to steer their skis. This tether system is connected to the front of the ski tips in conjunction with a ski bra. This system allows an instructor to make the turn for the skier so they can learn the feel of the turn until they are able to progress to making turns themselves. This tether system is not limited to usage in limb-deficient athletes or skiers. It is also used when teaching children how to ski. A four-track skiing system is used by athletes that have leg strength and/or stability issues, as well as whole-body disabilities affecting all or multiple joints and muscles. Examples of this include cerebral palsy, multiple sclerosis, post-polio, spinal cord injury, stroke, muscular dystrophy, spina bifida, and some limb-deficient athletes. This is another form of stand-up skiing with or without a tether. Usually a tether is used when learning how to ski with their disability or those who just want to experience skiing and are able to stand. However, those that compete at a higher level usually use two skis with two handheld outriggers for balance providing four points of contact with the snow. Additionally, sometimes a rope or cord is placed between the tips of the two skis to help athletes keep skis together which help for control purposes. This is especially helpful for the athletes who are very weak with lower extremity muscles, such as in the case of some with spina bifida [12] (Fig. 23.27).

A330551_1_En_23_Fig26_HTML.gif


Fig. 23.26
Photograph courtesy of YouaPa Yang (three-track skiing)


A330551_1_En_23_Fig27_HTML.gif


Fig. 23.27
Photograph courtesy of YouaPa Yang (spina bifida)

Sit skis, otherwise known as single monoskis or double bi-skis, are usually used by athletes with bilateral lower limb functional impairments such as bilateral lower extremity amputees, spina bifida, and spinal cord injuries, specifically as follows (Fig. 23.28):


  1. 1.


    Monoski disability groups: brain trauma, double amputee, post-polio, muscular dystrophy, cerebral palsy, spinal cord injuries below level of T4, multiple sclerosis, and spina bifida

     

  2. 2.


    Bi-ski disability groups: cerebral palsy, multiple sclerosis, muscular dystrophy, amputees, spinal cord injuries, spina bifida, severe epilepsy, and severe balance impairment

     


A330551_1_En_23_Fig28_HTML.gif


Fig. 23.28
Photograph courtesy of YouaPa Yang (sit skier)

Sit skis consist of a seating system that is either an off-the-shelf seat or an individualized custom-molded seat. The custom-molded seat is typically preferred. It is aligned and mounted on a frame with a shock absorber and suspension below their seating system which allows it to absorb impact on uneven terrain and to assist with turning. Additionally, the seating system has a removable hard external shell to protect the athlete from injury [12].

A monoski interfaces with a single ordinary alpine ski via a metal or plastic block in the shape of a boot sole that clicks into the binding of the ski (Fig. 23.29a, b). This complex is also known as a “ski foot.” Monoski in general is designed for independent skiers that are more advanced with good upper body strength and balance [12].

A330551_1_En_23_Fig29_HTML.gif


Fig. 23.29
(a) Photograph courtesy of Brian J. Juriga (monoski). (b) Photograph courtesy of YouaPa Yang (monoski)

A bi-ski is made up of two specialty shaped skies that can be skied independently. They are attached via a pivot with additional bindings attached to it. The apparatus is then attached to the ski frame. In general, monoskis are more commonly used by more advanced skiers, whereas bi-skis are most commonly used by athletes with more impaired balance and beginners. They are also skied with the assistance of an instructor using a tether. Both the monoskier and the bi-skier use outriggers for stability, turning, and as a modified forearm crutch, the Lofstrand as mentioned earlier. The customized sit ski’s frame allows for both rearward and downward movement of the top part of the frame in relation to the lower portion of the frame in loaded conditions. There is also a pivotally attached link arm to the lower frame that allows a forward end and rear end to be attached to a ski or skis. Additionally, a footrest can be modified to be attached to the forward end of the frames’ lower portion for non-amputee-seated skiers [12].

The sit ski shock absorber/suspension functions twofold. First, it is to help absorb some of the impact from the terrain for the athlete, and second, it is to minimize transfer of vibration and force between the lower and upper frame. This shock absorber/suspension can be modified by the athlete via a piston and spring depending on what type of discipline they are competing and how much compression is needed. Its overall goal is to keep the athletes sit ski on the snow as much as possible, while they are skiing by compressing to absorb the impact on the front of the ski and then uncompressing appropriately to rebound or extend off the terrain with the middle to back of the ski. With regard to terminology, slow dampening means the same as tightening the adjustment, otherwise compressing the piston and spring. In contrast to fast dampening which is the same as loosening the adjustment, otherwise uncompressing the piston and spring. Besides the previously mentioned ways to adjust the shock absorber/suspension system, the athlete also has to function in droop and sag. Droop is the rebounding or off-loading of the shock absorber/suspension system when the weight of the skier is removed. Sag is the comparative compression of the suspension at rest while it is off loaded versus with the weight of the skier on it. So how does all this make sense by watching a skier take a jump when you observe the weightlessness of midair flight that allows the suspension to completely extend? Apparently, the most optional sag ranges between 20 and 30% of the total shock being absorbed. Therefore, when the athlete adjusts their spring preload, they would use the length of the exposed shaft without the weight on the suspension. Then determine 20–30% of that length for adjustment. Tightening the spring will decrease sag and loosening the spring will increase the sag [12].

There are a couple more important factors that need to be considered and adjusted on the shock absorber/suspension system as well. High-speed rebound (HSR) dampening is what controls the rebound speed of the shock on uneven terrain at high speeds. If the shock absorber/suspension system feels loose or soft, by tightening the HSR, one will slow down the rebound speed. On the other hand, loosening the HSR will increase the rebound speed for when the suspension feels hard. The importance of the HSR is that it allows the shock absorber/suspension system to recover. If the HSR does not recover fast enough, it will result in what is termed a packed shock. This means that the shock absorber/suspension is not recovering fast enough to handle uneven terrain, and there is an increased risk of a wreck. Low-speed rebound (LSR) dampening controls the rebound shock speed in low-energy situations such as going on smooth terrain or small moguls. If the shock absorber/suspension system is not rebounding fast enough to absorb successive uneven terrain or moguls, then LSR can be loosened to decrease the resistance and to increase the rebound speed [12].

High-speed compression (HSC) dampening’s main job is to control the compression speed of the shock on uneven terrain at high speed. Tightening the HSC slows the compression speed and the suspension giving more resistance. On the flipside, loosening the HSC provides less resistance and increases compression speed. HSC’s importance is seen in high-impact landings as it affects the bottoming resistance of the shock. Low-speed compression (LSC) dampening controls the compression speed of the shock in low-energy situations such as turning in smooth terrain and light uneven terrain like smaller moguls. Therefore, if compression resistance is too low, then the suspension may compress too much to the point of bottoming out during regular turns on smooth terrain. Additionally, turning down the LSC will allow the athletes ski to engage more quickly at the top of their turn. However, if the athlete feels their ride is too harsh over relatively smooth terrain or the ski is engaging into a turn too quickly, then he/she can decrease the compression resistance by loosening the LSC [12].

The last factor to consider in these highly adaptive sit skis are the types of frames. These frames vary for disability level, type of skiing, and alignment. Typically all frames weigh between 30 and 50 lbs. There are a plethora of different types of monoski frames; however, there are five most common ones as follows:


  1. 1.


    Bramble frame: American design made up of stainless steel and aluminum. The skier’s position is in a reclined position. The Bramble uses a dual swing suspension also with a shock-absorbing system [12] (Fig. 23.30).

     

  2. 2.


    Nissin frame: Japanese design made up of aircraft grade aluminum which is lighter weight. The skier’s position is more upright in an athletic stance alignment. The Nissin uses a pivot suspension that functions like a toe wound if it was compressed with a shock-absorbing system [12] (Fig. 23.31).

     

  3. 3.


    Tessier frame: French design made of stainless steel known for its agility and speed. Tessier’s shock absorber/suspension system can be modified by using either a Fournales FT which is a pneumatic shock absorber with a hydraulic damper or an Ohlins shock absorber with a viscous oil under gas pressure allowing the oil and gas to be kept apart by a floating piston. The Tessier also uses a linkage suspension [12].

     

  4. 4.


    Praschberger frame: Austrian design that is similar to the Tessier. It is made of stainless steel and is also used for agility and speed but is also known as a good frame for slalom. The Praschberger uses a linkage type of suspension also similar to the Tessier with a shock-absorbing system [12] (Fig. 23.32).

     

  5. 5.


    Hands on Concept (HOC) frame: A newer American-designed frame which is a hybrid of all these earlier frames. It is made up of mainly aluminum with some stainless steel. The athlete is set up in more of an athletic upright stance position like the Nissin, and it uses a lower shock absorber/suspension system like the Nissin [12] (Fig. 23.33).

     


A330551_1_En_23_Fig30_HTML.gif


Fig. 23.30
Photograph courtesy of Arthur Jason De Luigi (Bramble frame)


A330551_1_En_23_Fig31_HTML.gif


Fig. 23.31
Photograph courtesy of Arthur Jason De Luigi (Nissin frame)


A330551_1_En_23_Fig32_HTML.gif


Fig. 23.32
Photograph courtesy of Brian J. Juriga (Praschberger frame)


A330551_1_En_23_Fig33_HTML.gif


Fig. 23.33
Photograph courtesy of Arthur Jason De Luigi (HOC frame)

Additionally, there is a cart ski design as an option for athletes with greater impairments such as quadriplegia from a cervical spine injury. Finally, the sit ski is completed with a ski on skis and binding(s). The binding usually does not change; however, the ski varies between events based on specific requirements for that discipline [12].

All frames require individualized settings for their bindings to connect their buckets to their skis. These individualized settings are based on the athlete’s ski level. Most of the time, the styles are dependent on the ski brand. For example, Marker 30 fits Marker and Head Skis, whereas Salomon 920 fits Salomon and Atomic skis. These are just some of the many combinations used by these athletes [12].

There is a misnomer in Paralympic or any type of adaptive skiing that there are all kinds of different medical conditions and injuries to be worried about. Medical conditions in all of the adaptive sports are similar to both able-bodied athletes and other standing adaptive athletes, no matter if they are using a wheelchair or other sitting equipment to do their sport. The main difference is the athlete’s injury pattern usually from upper extremity overuse or traumatic injuries is different. For example, upper extremity injuries are more common in spinal cord-impaired athletes using sitting equipment to compete. This is in contrast to lower extremity injuries, which are more common in ambulatory athletes that are impaired (i.e., single-leg amputee skiing) and nonimpaired skiers.

Overall, the injury rate in Winter Games is 10% for the amount of athletes competing from alpine skiing and sled hockey; however, 77% of all these injuries are usually due to a secondary acute traumatic event [1, 1417]. This ranges from huge massive wrecks to minor wrecks to simply landing on an outrigger. Currently, lower limb fractures and ligament knee injuries are the most common injuries in standing alpine skiing. Athletes in the seated alpine skiing classes usually have more upper limb injuries overall. However, concussions and other head injuries, as well as neck injuries, are on a rise approaching the aforementioned injuries in both standing and seated athletes. In general, in winter alpine sports, contusion, fractures, and concussions overall are more prevalent because of the impact potential and speed.

Medical care of the Paralympic alpine athlete is very multifunctional including all but not limited to the following [3]: pre-existing trauma, pre-existing medical conditions, musculoskeletal, neurologic, vascular, cardiac, dermatologic, infections, endocrine, gastrointestinal, genitourinary, psychological, and environmental. What this means is that a medical provider needs to be very familiar with the medical history of all the athletes he/she is taking care of when traveling with the team. It is important to have access to their medical cards and files and become familiar with them.

Previous pre-existing trauma situations to consider when taking care of your athletes are the following: presence of hardware (screws, plates, and/or pins), history of fractures (as previous skeletal injuries may appear or new X-rays), history of splenectomy, history of nephrectomy, and history of prior traumatic brain injury. Previous pre-existing medical conditions include those such as multiple sclerosis, cerebral palsy, muscular dystrophy, spina bifida, diabetes, history of clots or pulmonary embolisms, history of autonomic dysreflexia, UTI’s (almost all sit skiers), altitude illness, and impaired thermoregulation issues.

Most of the time, a medical provider needs to combine the neurovascular and musculoskeletal systems into just one neuromusculoskeletal system. The reason for this is because with most of these athletes that get injured musculoskeletally, they may not be able to feel their injuries as much due to their impairments. Therefore, it is important to distinguish insensate athletes that do not have normal sensation versus sensate athletes [3]. In working with the insensate athletes, medical providers need to look more carefully for occult musculoskeletal injuries because of their lack of sensation such as in the following injuries: fractures, subluxations, dislocations, and visceral injuries. The sensate athlete’s injuries may have the same outcome as able-bodied athletes but possibly with greater consequences.

Almost all sit-skiing athletes are also wheelchair dependent and during off season train on land with wheelchairs, so they have an increased risk of shoulder injuries. These shoulder injuries range from but are not limited to the following: shoulder pain in general, rotator cuff injuries, subacromial bursitis, acromial clavicular joint abnormalities, coracoacromial ligament thickening, subacromial spurs, distal clavicle osteolysis, shoulder dislocations, shoulder subluxations, labral injuries, impingement syndrome, and biceps tendonitis [3]. The three most common injuries to the shoulder are the rotator cuff tendonitis, tear or impingement, labrum injury, and acromial clavicular joint separation.

Some of the risk factors to consider in these athletes for shoulder injuries are as follows: repetitive overuse motion, increased pressure in shoulder joint during propulsion as well as stopping with their wheelchairs or sit skies, muscular imbalances in the shoulder due to weakness, and cervical injuries affecting certain dermatomal patterns that stimulate muscles in the shoulder [3].

Overall, all upper limb injuries including shoulder injuries are very disabling because these athletes rely on their upper limb so much for weight bearing, transfers, and ambulation in addition to all of the demands placed on the upper limbs in the able-bodied populations. Therefore, it is important to be aware of all the presenting signs and symptoms of these shoulder injuries, which present similarly in the impaired athlete as they do in the nonimpaired athlete. They may or may not feel it as much or may actually feel it more if they have a history of an additional cervical injury previously affecting or not affecting sensation.

Despite increase repetitive overuse, sit ski athletes and wheelchair athletes do not have a higher incidence of shoulder pain than the nonathletic sit ski and wheelchair users. It has been found that participation in athletic competition appears to be protective from shoulder pain likely due to increased strength and endurance in the athletic population. Hopefully with better modifications of wheelchairs and sit skis, these athlete’s shoulder injuries can be reduced by easier and more ideal propulsion techniques.

Besides a fracture, one needs to consider lateral epicondylitis. Other things to consider include medial epicondylitis, common extensor tendon strain, osteoarthritis, and olecranon bursitis. One of the main things to remember is ulnar nerve entrapment. Ulnar nerve entrapment is the second most common upper limb nerve entrapment syndrome (second only to carpal tunnel syndrome entrapping the medium nerve at the wrist). Any wheelchair user in general, athlete or nonathlete, is at a higher risk for ulnar neuropathy at the elbow [3, 11, 18, 19]. Ulnar nerve entrapment usually presents as numbness and tingling into the fifth finger and the ulnar side of the fourth finger. They usually have pain and tenderness in the ulnar groove, and if tapped, they may complain of the previously mentioned fingers feeling like they fall asleep, making the pain and numbness worse. This typically happens more when the elbow is bent. When the ulnar neuritis is very severe and/or chronic, they may also have weakness and atrophy with muscle wasting in the hand’s intrinsic muscles, which may or may not be irreversible. They may also complain of difficulty with finger coordination. Diagnosis is made by the history, physical exam, X-rays, electrodiagnostic testing, MRI, and/or musculoskeletal ultrasound. Each treatment is tailored to the athlete’s needs. Most wheelchair athletes or nonathletes will be nonmobile if they are required to restrict weight bearing. The other option may be limiting activity involving the upper limb, especially trying to avoid bending the elbow. Make sure they avoid leaning on it or putting any pressure on it as well. Additionally, one can wrap a towel around the elbow when they are asleep at night to keep from bending the elbow or wear an elbow pad backward. Other treatment options include NSAIDs, bracing/splinting, and nerve gliding exercises. Medical providers can also try neuroprolotherapy or if they are musculoskeletal ultrasound proficient, they can attempt nerve hydrodissection. When the above fails, then surgery is the next option. This includes a cubital tunnel release, ulnar nerve anterior transposition, or medial epicondylectomy.

Only gold members can continue reading. Log In or Register to continue

Feb 25, 2018 | Posted by in SPORT MEDICINE | Comments Off on Adaptive Alpine Skiing and Para-snowboarding
Premium Wordpress Themes by UFO Themes