I would like to post this paper that I started to write on Ultimate Frisbee. It s unfinished but I ran into difficulties in writing it. The worst being the erasure of all my original questionnaires by my computer provider. I left it in unfinished  because I felt the lack of data makes it hard to justify any quantitative conclusions, but this still contains some qualitative observations that I still feel were worth discussing,

Gary Podolsky

Ultimate Frisbee


History of Ultimate
Ultimate is a relatively new sport, having just celebrated its 31st anniversary. Frisbee football was developed at Columbia High school in Maplewood, New Jersey during 1968 and originally allowed tackling (reference 1). Tackling was abandoned after the large number of significant injuries. The rules have undergone several revisions and ultimate is played today according to the 9th edition rules (reference 1-4, appendix 1).

Purpose of this Study
Ultimate players were surveyed about their self reported injuries to find out what type of injuries they are having so that possible causes could be determined and recommendations on injury prevention could be made.

Rules of Ultimate
The game involves two teams of seven players. At least three or four players of both gender are on the field at one time per team. No more than four males or females are on the playing field at one time. If a team is short players of one sex they would be limited to having less than seven players on the field.
The Ultimate disc weighing 165g is harder and flatter than a Frisbee disc and will fly farther and more accurately because of this design. One team gains possession of the disc at the beginning of the game after an agreed flip of the disc before the game. The defensive team starts with the disc and has one player throw the disc towards the opposing offensive team who may begin play by catching or picking up the disc.
Successful passes must then move the disc to members of the offensive team. Players group in formations known as 'stacks' so that they may maximize the use of the playing field. At the same time the defensive team may guard each member of the offensive team including the thrower. If the thrower is unable to complete a pass or runs out of time then the disc turns over to the other team. A goal occurs when a pass is completed behind the other teams goal line. A disc that hits the ground is dead. Play is further complicated by the dynamics of using a disc instead of a ball, because the wind may significantly influence the curve of the disc passes do not have to be straight but may curve around players. Stalls or updrafts that make the disc linger too long in the air predispose players for injuries since too many players from both the offense and defense enter the area making collision more likely. Badly thrown or planned plays are hence called "hospital plays".
Such dangerous plays as well as fouls or picks (cutting off other players) are self-reported by players. Any violation of the rules that is felt to have occurred is discussed and agreed on before play resumes. This is felt by many to be an integral part of the game because referees are not used. One of the central aspects of ultimate is its casual atmosphere and the ' spirit of the game'. The spirit of the game assumes fair play, self-calling of fouls, courtesy and respect of other players.

Comparison of Ultimate with Other Similar Sports
Other disc sports include disc golf, freestyle throwing, and guts (reference 1,2,3). They use discs of different sizes, shapes, and weight that give all different flight characteristics. They will not be discussed further as they are distinct from ultimate and do not involve the same playing skills or injury patterns.Comparison of ultimate with other similar sports.

Ultimate involves sudden bursts of speed often played continuously over 90 minutes with half time and breaks allowed. The Bethesda Conference (reference 5) classified sports based on their static and dynamic components. Ultimate is similar to sports like basketball, ice hockey, and lacrosse all being high dynamic and low static activities (figure 1)
Dynamic forces involve movement and change in a muscle length with low intramuscular forces. Bowling would be a sport with low dynamics while squash would be high.
Static exercises cause large intramuscular forces with little or no change in muscular length. Isometric resistance training is an example of high static.

Figure 1
Ultimate compared to other sports on the basis of dynamic and static forces during competition

 
A. Low dynamic
B. Moderate dynamic
C. High dynamic
l. Low Static
Billiards or Bowling
Baseball or Volleyball
Volleyball, Soccer, or Squash
ll. Moderate Static
Archery or Equestrian
Fencing or Rugby
Basketball, Football, Team Handball or Ultimate
lll. High Static
Gymnastics or Rock climbing
Bodybuilding or Wrestling
Boxing, Cycling, or Kayaking

*Ultimate is grouped as a class IIc sport but does share similarities with both soccer and rugby

The Bethesda conference also stratified the risk for participants with heart disease to play (FIGURE 2). Ultimate would have restrictions similar to other IIa sports (reference 5)
Ultimate may also be described as a contact/collision after the American Association of Pediatrics Classification of Sport (reference 6, figure 2). Risk of participation in sports is stratified according to level of contact for athletes with specific medical conditions. (figure 3)

Figure 2
Comparison of ultimate with other sports on the basis of contact
Reference 6
Contact Sports

Contact / Collision
Limited contact / Impact
Boxing
Baseball
Field Hockey
Basketball
Ice Hockey
Volleyball
Martial Arts
Skiing
Soccer
 
Ultimate
 

Noncontact Sports

Strenuous
Moderate
Nonstrenuous
Aerobic dance
Badminton
Archery
Fencing
Curling
Golf

Figure 3
Summary of limitations for contact /collision sport
Reference 6

Participation
Atlantoaxial instability
No
Acute Illness
variable, needs individual assessment
Cardiovascular
Carditis
No
Hypertension
Mild
Yes
Moderate
*
Severe
*
Congenital Heart
Review by cardiologist
Disease
Eye
Absence or loss of one
variable, eye guards may allow play
Detached retina
consult ophthalmologist
Inguinal Hernia
Yes
Kidney solitary
No
Enlarged Liver
No
Musculoskeletal disorder
Needs individual assessment
Neurological
Serious head trauma Repeat concussions
individual assessment
Convulsant Disorder
Yes, unless poorly controlled
Ovary solitary
Yes
Respiratory
Pulmonary deficiency
May compete following stress test
Asthmas
Yes
Sickle Cell Trait
Yes
Skin
Boils, impetigo, Herpes, scabies
May compete but no contact
Spleen enlarged
No
Testicle
Absent or undescended
Yes, use protective cup

There is very little published in the sports medicine or orthopedic literature about Ultimate. Marfleet (reference 7) studied injuries among high-level players attending a series of tournaments. This study looked at the incidence of injuries among experienced players.
In Winnipeg personal observation is that there are a high incidence of significant injuries in the spring and early summer among ultimate players corresponding to the beginning of the Ultimate season locally. Injuries occur in the beginner and the elite players. Athletes have had injuries such as ACL tears, ankle fractures and shoulder dislocations similar to the patterns of injuries seen in contact sports such as hockey, rugby, and football. This is unexpected from the popularized image of Ultimate as a carefree sport. This survey was designed to look at what types of injuries are common in Ultimate and how they can be eliminated or minimized.
The ultimate player must also be proficient in catching and throwing a disc using a variety of techniques (reference 1,2,3). One unique skill is "going ho" or horizontal where a player dives while simultaneously catching an out of reach disc. Leaping forward with extended arms and legs, catching the disc, rolling sideways to diminish the forces, and standing again to pass the disc, best does this. Marfleet (reference 7) has shown that if done incorrectly with flexed limbs there is a higher likelihood of injury. (see diagrams)
Protective equipment is neither enforced nor banned. Many to increase their grip during pivoting and cutting wear cleats. Torque generated on the ankles places excessive forces at the ankle and knee. Extrinsic factors also have a role in the occurrence of injuries. The quality of the fields played on is often not optimal and can be hard or uneven. Weather, heat and ultraviolet light are also a concern.

Design
A survey questionnaire (both in French and English) was distributed through the Manitoba Organization of Disc Sports (MODS) for all players whether injured or not to complete. (see appendix 2) Surveys were also distributed at games, sports medicine clinics, athletic therapy clinics, and at a local schools teaching Junior Ultimate. The Canadian Ultimate Players Association and other provincial bodies were also contacted to distribute copies to their members. A modified version of the survey was also sent out to touring teams attending the World Ultimate Championships in Minneapolis in 1998. Due to the unknown number of people reached by the survey it is unknown what the actual prevalence of injuries is but patterns of injuries based on the returned surveys are seen.
All respondents were asked about their injuries. Diagnoses were either self reported or diagnosed by physiotherapists, physicians or others and not verified further. When some answers were imprecise they were contacted to clarify. All information was volunteered and not altered after being received. Results were organized using Microsoft Excel.

Results
Injuries
This study found a high rate of knee and lower limb injuries. Leg injuries were the most common at 29%. The main injuries were 1% MCL, < 1% PCC, 2% quadriceps, 4% hamstrings, 4% leg, 15% knee, and 3% ACL. Not all players gave specifics as to what type of knee injury they sustained but both men and women reported 3% had ACL tears.
On the comment portion of the survey women reported a greater portion of non-contact mechanisms of injury. Ankle injuries were reported in 20% of the players. Other notable injuries involved shin splints 6%, shoulders 6%, and groin, back, fingers, ribs, clavicles and concussions that together accounted for 5% or less. (see diagram)
Other significant injuries were concussions 1%, and eye injuries 1% (see figures showing female and male injury rates, overall injuries)

Discussion
Knee Injuries
This study found a high rate of significant knee injuries involving the meniscus cartilage and ACL tears. ACL tears cause a significant morbidity (reference 8). Female players have a higher rate of ACL injuries than males in many sports especially those involving landing, stopping, and sudden direction changes.
Women have been found to have an ACL injury rate 2.229 times in soccer and 2.89 times in basketball when compared with men (reference 9)
Many reasons have been postulated and not all are physical
1)
A weaker hamstring and quadriceps ratio. Women tend to activate their quadriceps before their hamstrings as opposed to men who do the opposite. Women have their quadriceps fire before the hamstrings as compared with men. Training with a BAPS board improved proprioception and led to a seven-fold reduction in ACL injuries.
2)
Women are speculated to be more susceptible during days 10-14 of their menstrual cycle because of increased laxity when the estrogen and progesterone level is peak. One study by Dicaprio and Khodiguian (reference 10) suggest a protective effect from oral contraceptives.
3)
Women have different anatomic features such as, an increased Q angle of the knee, increased pronation and increased laxity of joints that may contribute to injury.
4)
Women historically have had decreased levels of encouragement and opportunities to be coached, to practice skills and to play sports. A lack of expert training could potentially lead to an increased number of injuries in women as compared to men. Attitudes are changing toward gender roles in sports (reference 11).

Ireland (reference 12)describes a position of no return. This disadvantageous posture often leads to non contact ACL tears and may be clearly identified on videotaped athletes (reference). Injury is less likely when an athlete assumes a safe position (see figure)

Contrast between "Position of no Return" and " Safe Position"
After Ireland (reference 12)

Position of no return
Back in foreward flexion and rotated to opposite side
Hips in adduction and internal rotation
Knee less flexed and in valgus position
Tibia in external rotation

Safe Position
Back in normal lordosis
Hips flexed and in neutral abduction/adduction
Knees flexed
Tibia in neutral position with no rotation
Landing pattern on both feet and in Control
Weight balanced in center with mid foot stance
Rozzi (Reference 13) describes the coactivation of the hamstrings to reduce ACL strain. The hamstrings stabilize the knee best at >15-30 degrees of flexion and that better hamstring coactivation occurs when the trunk is positioned over the knees. A bad position for the athlete is when an anterior pelvic tilt increases the genu valgus with increased exaggeration of the Q angle. Rozzi also suggests using a tensor wrap to increase knee proprioception, which leads to decreased injury.
After a player has had an ACL reconstruction 5-7% of players will injure their other leg. This is felt to be due to either incomplete rehabilitation or persistent neuromuscular weakness that has not been addressed

Knee Bracing
Knee braces are divided into 3 categories including, prophylactic, rehabilitative, and functional braces.

Prophylactic knee bracing is bracing an uninjured knee to prevent an injury from occurring is controversial. It has been extensively scrutinized in American football. Grace et al 8.(reference 14) showed that football players wearing a single hinged brace had an increased incidence of foot and ankle injuries. Rovere, Haught and Yates (reference 15) found an increase in knee injuries when a brace was used. Albright and Powell (reference 16) showed a decreased injury rate in offensive and defensive football players in practices yet an increase in knee injuries for skill position players (backs and kickers) during games. Ultimate resembles football in many ways. Experience with football suggests against the use of prophylactic braces. (reference16b)

Rehabilitation knee
braces are designed to allow protected motion of a knee after an injury whether surgery is planned or not. Rehab braces are usually given for MCL injuries and are meant to be a temporary aid in recovery. They do not give enough support or flexibility for playing ultimate. An athlete who requires the use of a Rehab brace should not play until their rehabilitation has advanced enough that they no longer require a brace.

Functional knee
braces are designed to improve stability for unstable or postoperative knees in daily activities or sports. They are best used in individuals with low-grade instability such as a partial ligament tear or reconstructed ACL rather than more unstable injuries including damage to the menisci or chondral surfaces and excessive joint laxity. The player must also be knowledgeable in its use, fitting, and care. A thin build also gives a better fit with less slipping. (reference 13,17) Much of the benefit from wearing a functional brace is felt to be due to improvement of the proprioceptive sensing in the injured knee as well as psychological reassurance. Colville et al (reference 18) showed that athletes felt much better wearing braces even if very little improvement in stability occurred. Krister et al (reference 19) demonstrated that wearing a simple elastic compression also increased proprioception in an ACL injured group.
Functional braces generally do not tolerate pivoting sports well and ultimate may be a relative contraindication for their use depending on the person's level of playing and expectations. An objective degree of proprioception and strength should be present before return to play.
ACL tears are significant injuries where the treatment (surgical repair) is expensive and must be followed by a long period of rehabilitation. Correcting predisposing factors that lead towards injury might be more effective.

Some suggestions for the prevention of non-contact ACL injuries include:
1) Developing lateral hip strength by doing lunges, side steps and plyometrics. Begin with simple routines and gradually work up to more complex drills. (reference 2) A woman with a trendelenberg gait should definitely do these exercises as this type of walk already suggests a significant lateral hip weakness.
2) Six weeks of pre-training prior to practicing ultimate related skills. Given the short playing season of ultimate, players who begin the activity suddenly are susceptible to injury.
3) Retrograde treadmill running is a useful rehabilitation tool. Having the athletes walking backwards teaches effective co contraction of the hamstrings, quadriceps, and triceps surae.
4) Plyometric drills are used to teach players to land correctly. It is best to land with the knee flexed at 20-30 degrees. It is also important to land softly to avoid excess impact on knees and ankles.
5) Teach eccentric control of the knee by practicing eccentric hamstring curls that in turn help control loads during play.
6) Encourage three step stops rather than sudden stops. The rules of ultimate allow this. This method of deceleration is gentler on the knees.
7) Maintain the ready position - straight back, knees slightly flexed, avoid a rolled back, rounded shoulders and hyper-extended knees. Integrate the proper drills to incorporate the ready position ideally at the beginning and end of drills.
8) For patients recovering from an ACL operation improved neuromuscular control should be demonstrated. All injured patients will tend to favor the uninjured knee. Any limping behavior should be discouraged from the beginning and weight should be distributed evenly.
If the player is aware of these limits playing may be resumed. Changing the pattern of play such as adapting a neutral ready position or taking three step turns can change the forces on the knees and lessen the likelihood of re-injury as recommended by Ireland. (reference 12) The UPA rules do allow for three steps after receiving a disc. Players should develop their skills to habitually use their three steps to come to a full stop.

Any knee requiring functional bracing should be evaluated for surgical repair and adjunct physiotherapy as well.

Ankle Injuries
Ankle strains are common and account for about 10-15 % of sports related injuries (reference 20). In soccer ankle injuries have been higher (17-20% of all injuries)(reference 21) and even higher in futsbal or indoor soccer (23%) (Reference 22). This study made no distinction between Outdoor and Indoor Ultimate the latter being more similar to futsbal. One would expect indoor ultimate to share a higher rate of ankle injury as with futsbal since both involve a smaller playing area with more pivoting. The most common mechanism of injury involves a plantar flexion inversion stress. The anterior talofibular ligament is most commonly injured as a first or second-degree strain. In this survey ankle injuries were reported at 20%. Ankles injuries common in ultimate are often due to a sudden change of direction during play. Players wear a variety of footwear including soccer shoes, cross trainers, and cleats (although metallic cleats are banned on many playing fields).

Ankle Bracing
Similar to knees, ankles may also be braced after injury or prophylacticly. Prophylactic bracing has been shown to be effective (reference 23) however high-topped boots may be enough. Ultimate shares similarities with football, basketball, and soccer all having a high incidence of inversion ankle strains. Athletic taping or ankle braces are commonly used and both give good support although taping loses its strength after a short amount of time (reference 24). One suggestion is to wear a low cut soccer cleat with an internal lace up brace that can be periodically adjusted.
After an injury has occurred some form of functional support will aid in returning function and the ability to play. There is no good evidence on how long to wear a protective brace post injury. Although dependant on the severity of the injury wearing a protective support throughout the phases of healing after inflammation has resolved, muscular strength has returned, and proprioception has also normalized (reference 23). After those parameters are returned any further wearing of support would now be prophylactic. Since some propioceptive deficits may persist in an improperly rehabilitated individual protection is important. The player should also train in gradually increasingly difficult cutting drills so a brace is never used as a substitute for adequate conditioning. Taping gives support but tape has been known to lose support after as little as ten minutes of playing (reference24).
Many players with ankle inversion injuries reported using cleats. A high coefficient of friction between the ground and a player's foot has been associated with a greater risk of injury. (reference 25) Using cleats, although providing better control and performance during a game also increases the risk of injury. One suggestion is to wear good shoes that provide some grip but not quite as much as indoor soccer or football shoes. Cleats if used at all should be used in wet, muddy conditions to provide extra traction. Similarly hard, dry playing fields also provide a high coefficient of friction and should be avoided. The ideal playing field should be level, grassy with soft earth and no stones or irregularities.

Discussion of other injuries
Players' skills
'Laying out' for the reception of a pass is a necessary skill that should be carefully taught to new players

The use of Equipment
Helmets
Ultimate does have some concussions but there is insufficient evidence to support that wearing a type of helmet would be beneficial in preventing or decreasing the severity of sustained injuries. Education of players on the proper management of concussions and avoiding dangerous play would be more effective. Other equipment such as padding for knees, shin guards, and gloves may be left up to the players discretion for comfort since relatively few injuries developed to support their use to prevent injuries.

Street drugs

There is no evidence that this is greater in ultimate. As with many other amateur sports there is likely a lower incidence of alcohol, drug, and nicotine abuse than in the general non-athletic population.(personal observation and opinion). Likewise no one volunteered the use of any performance enhancing substances on the survey.

Socioeconomic level
This is difficult to assess. Respondents were aged 13-44 and composed of many young professionals, and university and high school students. Locally ultimate does not appear to be played in the inner city. Players who tour must have free time and money to afford to tour.

Disabled
This was not specifically assessed and one volunteered any disabilities. Disabled This was not specifically assessed and one volunteered any disabilities.

Uniforms

Ultimate clothing and shoes closely resemble soccer equipment. Soccer jerseys are commonly worn but during pick-up games colored versus white t-shirts distinguish teams. Arms and knees are frequently abraded. Cleats of varying types are used the most common being soccer the football. Metallic cleats are banned on most fields.

Skin Abrasions
Abrasions are common in ultimate and were not counted as injuries on the survey since they occur frequently and are self-limited. The risk of HIV transmission has been reported in sports and remains controversial (reference 24) but is of very real concern. The Canadian Academy of Sport Medicine, American College of Sport Medicine, and United States Olympic Committee have implemented guidelines to address this issue (figure 4).

Figure 4

Recommendations towards Blood in Sport
(reference 24)
Different sports have different risks of exposure Greatest risk: boxing, tae kwon do, and wrestling Moderate risk: basketball, field hockey, judo, hockey, soccer, football, team handball. Lowest risk: all others. Ultimate involves frequent abrasions with the ground and incidental contact with other players would be a moderate risk sport.

Guidelines
1. All athletes are warned of the risk with sexual contact and IV drug use.
2. Potentially infectious skin infections are covered.
3. Injured athletes should perform his or her own wound care.
4. Other athletes should not handle the athletes' blood.
5. Lacerations with substantial bleeding should be resolved before return to play.
6. Clothing soaked with blood should be removed and all exposed parts washed before return to play.
7. Only disposable towels and bandages are used.
8. Universal precautions be taken with any athlete
9. Disposable gloves be used and changed for each individual.
Individual with HIV should have access to play and do not present a risk to other players. The risk is felt to be very small or negligible. Hepatitis B is more transmissible than HIV and has been transmitted in hot tubs that athletes have shared with open sores. Players should be knowledgeable in taking universal precautions when they have open wounds.
Since there are no formalized referees in ultimate games, team captains should have first aid kits available.

Recommendations
Ultimate is a very young and growing sport with a significant number of injuries related to play. Many of these injuries may be prevented with proper conditioning, training, conduct and equipment. Players with any medical illnesses should receive a physical exam conducted by a medical doctor prior to participating. Players should also be familiar with blood borne infection precautions.
Equipment should include comfortable clothes and shoes. Cleats are not recommended although they may help to improve performance since they have been shown to increase injuries in similar sports. Ankle braces have been shown to reduce injuries although knee braces do not.
Players should know the rules well prior to playing and have the necessary skills to play well. Skills specific to ultimate should not be assumed but taught since the game is distinct from other sports. A pre-season conditioning program should be encouraged. Injury programs have been shown to reduce the occurrences of injuries in the similarly high risk sports of skiing and basketball (reference 12) and a similar intervention could be done in ultimate.
The spirit of the game should be maintained though serious consideration should be given to referees.

Appendix 1. Rules of Ultimate
Appendix 2. Survey

References

1. The Complete Book of Frisbee by Victor A Malaforte, 1998 American Trends Publishing Co. Alameda, CA 94501 510 814-9639,
2. Ultimate Fundamentals of the Sport by Irv Kalb and Tom Kennedy Revolutionary Publications Santa Barbara
3. Frisbee Players' Handbook by Mark Panna and Dan Poynter. Para Publishing Santa Barbara 1978
4. UPA Rules of Ultimate , Ninth edition Ultimate Players' Association.1992
5. 26th Bethesda conference: Recommendations for determining eligibility for competition in athletes with cardiovascular abnormalities. Jan 6-7,1994 Med Sci Sports Exerc 1994;26 (10 suppl):S223-293.
6.American Association of Pediatrics Committee on Sports Medicine and Fitness: Medical conditions affecting Sports Participation. Pediatrics 1994;94(5), pp757-760.
6b. Preparticipation Physical Evaluation second edition. Published by the physician and Sportsmedicine. McGraw-Hill Health.1992
7. Marfleet P, Ultimate Injuries: a survey Br J Sp Med 1991;25(4) pp 235-40
8. Fetto JF, Marshall JL, The natural history and diagnosis of anterior cruciate ligament insufficiency, Cl Ortho and Related Res,1980 :140:29-36
9. National Collegiate Athletic Association. NCAA Injury Surveillance System, 1990-1996. Overland Park, KS: National Collegiate Athletic Association;1996.
10a Arendt et al, Anterior Cruciate Ligament Injury Pattern Among Collegiate Men and Women. J Athl Training April0June 1999;Vol.34(2)p 86-92. 10a2 Heitz et al: Hormonal Changes throughout the menstrual cycle and increased anterior cruciate laxity in females. J Ath Training 1999, 34(2) 144-149.
10b. Dicaprio,Khodiguion: Effect of phase of menstrual cycle and oral contraceptives in knee laxity Med Sci in Sports and Exercise Vol 31 (5) May 1999 supplement pS295.
11. our athletic daughters
12. Ireland ML: Anterior Cruciate Ligament Injury in Female Athletes: epidemiology. J Athletic Training 34(2) 150-54.
13. Rozzi et al: Symposium Anterior cruciate ligament injury in the female athlete. Med Sci in Sports and Exercise Vol 31 (5) May 1999 supplement pS344
14. Grace TG, Skippes BJ, Newberry JC,et al: Prophylactic knee braces and injuries to the lower extremity. J Bone Joint Surg 70A: 422,1988
15. Rovere GD, Haupt HA, Yate CS: Prophylactic knee bracing. Am J Sports Med 15:471,1987.
16. Albright JP, Powell JW, Smith W, et al: Medial collateral strains in college football. Am J Sports Med 22:12,1994. 16.Committee on Sports Med: Knee Brace Use by Athletes. Pediatrics 81:738,1988.
17. Deakon R,Zarnet R: Handbook of Sports Medicine 1999 McGraw- Hill 1st ed. New York pp785-793. 18.Colville M.Lee, Cuilio J: The Lennox Hill Brace. An evaluation in effectiveness in treating knee instability. Am J Sports Med 17.141-146,1989.
19.Kuster M et al: The benefits of wearing a compression sleeve after ACL reconstruction. Med and Sci in Sp and Exercise 368-371.
20. MacAudley D: Ankle Injuries: same joint different sports. Med Sp Exercise S409-S410 1999
21.Ticker JB: Soccer futsbal and indoor p603-604 Handbook of Sports Medicine 1999 McGraw-Hill 1st ed. New York
22.Johnson DL, Neef RL: Soccer: outdoor pp604-605 Handbook of Sports Medicine 1999 McGraw-Hill 1st ed. New York. Sittler et al: The efficiency of a semirigid ankle Stabilizer to Reduce Acute Ankle Injuries in Basketball- Arandomized Clinical Study at West Point. Am J Sp. Med 22:4 pp454-460.
23. Safran et al: Lateral ankle sprains a comprehensive review Part 2: treatment and rehabilitation with an emphasis on the Athlete. Med Sc Sp Exercise S438-S445 .1999.
24.Boland A, Sieler S: Manual of Sport medicine Lippencott Raven, Philedelphia 1998 pp121-125.
24b.When Sport and HIV share the Bill, the smart money goes on common sense. JAMA 1992(267) 10:1311-1314. 26. Sevier T, Roush M: Infections in Athletes, Manual of Sports Medicine 201-215 Lippincott-Raven. Philedelphia.1998.


Addtional references