SICKLE CELL TRAIT AND THE ATHLETE - Reingoldweb.com

CON S E N SUS STATE M E NTSICKLE CELL TRAIT ANDTHE ATHLETEPurposeIn a recent review of non-traumatic sports deaths in high school andcollege athletes, 1 the top four killers, in order of occurrence, were: cardiovascularconditions, hyperthermia (heatstroke), acute rhabdomyolysistied to sickle cell trait, and asthma. Acute exertional rhabdomyolysis(explosive muscle breakdown) from sickle cell trait is the least understoodof these conditions. The purpose of this Task Force is to raise awarenessof this condition and provide measures to reduce the risk of exertionalcollapse related to sickle cell trait.1

IntroductionSickle cell trait is the inheritance ofone gene for sickle hemoglobin andone for normal hemoglobin. Duringintense or extensive exertion, thesickle hemoglobin can change theshape of red cells from round toquarter-moon, or “sickle.” Thischange, exertional sickling, canpose a grave risk for some athletes.In the past seven years, exertionalsickling has killed nine athletes,ages 12 through 19.Research shows how and whysickle red cells can accumulate in thebloodstream during intense exercise.Sickle cells can “logjam” blood vesselsand lead to collapse from ischemicrhabdomyolysis, the rapid breakdownof muscles starved of blood.Major metabolic problems fromexplosive rhabdomyolysis can threatenlife. Sickling can begin in two tothree minutes of any all-out exertion— and can reach grave levels soonthereafter if the athlete continues tostruggle. Heat, dehydration, altitude,and asthma can increase the risk forand worsen sickling, even when exerciseis not all-out. Despite telltalefeatures, collapse from exertionalsickling in athletes is under-recognizedand often misdiagnosed. Sicklingcollapse is a medical emergency.We recommend confirming sicklecell trait status in all athletes’ preparticipationphysical examinations.As all 50 states screen at birth, thismarker is a base element of personalhealth information that should bemade readily available to the athlete,the athlete’s parents, and the athlete’shealthcare provider, including thoseproviders responsible for determinationof medical eligibility for participationin sports.Knowledge of sickle cell trait statuscan be a gateway to education andsimple precautions that may preventsickling collapse and enable athleteswith sickle cell trait to thrive insport. Nearly all of the 13 deaths incollege football have been at institutionsthat did not screen for sicklecell trait or had a lapse in precautionsfor it. Small numbers preclude cogentevidence to support screening. Allconsidered, however, we believe thateach institution should carefullyweigh the decision to screen based onthe potential to provide key clinicalinformation and targeted educationthat can save lives. Irrespective ofscreening, the institution shouldeducate staff, coaches, and athleteson the potentially lethal nature ofthis condition.BackgroundA condition of inheritance versusrace, the sickle gene is common inpeople whose origin is from areaswhere malaria is widespread. Over themillennia, carrying one sickle genefended off death from malaria, leavingone in 12 African-Americans (versusone in 2,000 to one in 10,000 whiteAmericans) with sickle cell trait. Thesickle gene is also present in thoseof Mediterranean, Middle Eastern,Indian, Caribbean and South andCentral American ancestry; hence,the required screening of all newbornsin the United States.2 SICKLE CELL TRAIT

In the past four decades, exertionalsickling has killed at least 15 footballplayers. In the past seven years alone,sickling has killed nine athletes: fivecollege football players in training,two high school athletes (one a 14-year-old female basketball player),and two 12-year-old boys trainingfor football. Of 136 sudden, nontraumaticsports deaths in high schooland college athletes over a decade,seven (5 percent) were from exertionalsickling. 1The U. S. military tied sickle celltrait to sudden death during recruitbasic training. The relative risk ofexercise-related death in sickle celltrait was about 30. 2 In other words,recruits with sickle cell trait were 30times more likely to die during basictraining. The main cause of deathwas rhabdomyolysis — and the riskof exertional rhabdomyolysis wasabout 200 times greater for thosewith sickle cell trait. 3In sickle cell trait, strenuousexercise evokes four forces that inconcert foster sickling, (1) severehypoxemia, (2) metabolic acidosis;(3) hyperthermia in muscles, and(4) red-cell dehydration.Evidence supports this syndrome.Military research shows that, duringintense exertion and hypoxemia,sickle cells can accumulate in theblood. 4 Recent research also showsthat systemic dehydration worsensexertional sickling. 5 Field studies inAfrica suggest that sickle-trait runnersare limited not in single sprintsbut in middle distance or altituderunning. 6 The pattern in Americanathletes is similar.Sickling Collapse: Footballand Other SportsThe first known sickling death incollege football was in 1974. Adefensive back from Florida rana conditioning test on the first dayof practice at altitude in Colorado.He had collapsed on the first day ofpractice the year before. This time,near the end of the first long sprint,at about 700 meters, he collapsedagain — and died the next day. Themost recent sickling death, a freshmandefensive back at Rice Universityin the fall of 2006, is similar. Hecollapsed after running 16 sprints of100 yards each — and died the nextmorning. The cause of death forboth athletes was acute exertionalrhabdomyolysis associated withsickle cell trait.Up to 13 college football playershave died after a sickling collapse.The setting and syndrome in mostare similar: Sickling players may be on-fieldonly briefly, sprinting only800–1,600 meters, often earlyin the season. Sickling can also occur duringrepetitive running of hills orstadium steps, during intensesustained strength training, if thetempo increases late in intenseone-hour drills, or at the end ofpractice when players run “gassers.” Sickling can even occur rarely inthe game, as when a running backis in constant action during a long,frantic drive downfield. 7Sickling collapse is not limited tofootball. It has occurred in distanceracing and has killed or nearly killedseveral college or high school basketballplayers (two were females) intraining, typically during “suicidesprints” on the court, laps on a track,or a long training run.The harder and faster athletes go,the earlier and greater the sickling,which likely explains why exertionalcollapse occurs “sooner” in collegefootball players sprinting than inmilitary recruits running longerdistances. Sickling can begin in onlytwo to three minutes of sprinting —or in any other all-out exertion — andsickling can quickly increase to gravelevels if the stricken athlete struggleson or is urged on by the coach.Sickling Collapse:Telltale FeaturesSickling collapse has been mistakenfor cardiac collapse or heat collapse.But unlike sickling collapse, cardiaccollapse tends to be “instantaneous,”has no “cramping” with it, and theathlete (with ventricular fibrillation)who hits the ground no longer talks.Unlike heat collapse, sickling collapseoften occurs within the first halfhour on-field, as during initialwindsprints. Core temperatureis not greatly elevated.Sickling is often confused withheat cramping; but, athletes whohave had both syndromes knowthe difference, as indicated by thefollowing distinctions:1. Heat cramping often has aprodrome of muscle twinges;whereas, sickling has none;2. The pain is different —heat-cramping pain is moreexcruciating;3. What stops the athlete is different— heat crampers hobble to a haltSICKLE CELL TRAIT 3

with “locked-up” muscles, whilesickling players slump to theground with weak muscles;4. Physical findings are different —heat crampers writhe and yellin pain, with muscles visiblycontracted and rock-hard;whereas, sicklers lie fairly still,not yelling in pain, with musclesthat look and feel normal;5. The response is different — sicklingplayers caught early and treatedright recover faster than playerswith major heat cramping. 7This is not to say that all athleteswho sickle present exactly the sameway. How they react differs, includingsome stoic players who just stop,saying “I can’t go on.” As the playerrests, sickle red cells regain oxygenin the lungs and most then revertto normal shape, and the athletesoon feels good again and ready tocontinue. This self-limiting featuresurely saves lives.Precautions and TreatmentNo sickle-trait athlete is ever disqualified,because simple precautionsseem to suffice. For the athlete withsickle cell trait, the following guidelinesshould be adhered to:1. Build up slowly in training withpaced progressions, allowinglonger periods of rest andrecovery between repetitions.2. Encourage participation in preseasonstrength and conditioningprograms to enhance the preparednessof athletes for performancetesting which should be sportsspecific.Athletes with sickle celltrait should be excluded fromparticipation in performance testssuch as mile runs, serial sprints,etc., as several deaths have occurredfrom participation in this setting.3. Cessation of activity with onset ofsymptoms (muscle ‘cramping’, pain,swelling, weakness, tenderness;inability to “catch breath,” fatigue).4. If sickle-trait athletes can set theirown pace, they seem to do fine.5. All athletes should participate ina year-round, periodized strengthand conditioning program that isconsistent with individual needs,4 SICKLE CELL TRAIT

goals, abilities and sport-specificdemands. Athletes with sicklecell trait who perform repetitivehigh speed sprints and/or intervaltraining that induces high levelsof lactic acid should be allowedextended recovery betweenrepetitions since this type ofconditioning poses special riskto these athletes.6. Ambient heat stress, dehydration,asthma, illness, and altitudepredispose the athlete withsickle trait to an onset of crisisin physical exertion.a. Adjust work/rest cycles forenvironmental heat stressb. Emphasize hydrationc. Control asthmad. No workout if an athlete withsickle trait is ille. Watch closely the athlete withsickle cell trait who is new toaltitude. Modify training andhave supplemental oxygenavailable for competitions7. Educate to create an environmentthat encourages athletes withsickle cell trait to report anysymptoms immediately; anysigns or symptoms such as fatigue,difficulty breathing, leg or lowback pain, or leg or low backcramping in an athlete withsickle cell trait should be assumedto be sickling. 7In the event of a sickling collapse,treat it as a medical emergency bydoing the following:1. Check vital signs.2. Administer high-flow oxygen,15 lpm (if available), witha non-rebreather face mask.3. Cool the athlete, if necessary.4. If the athlete is obtunded oras vital signs decline, call 911,attach an AED, start an IV, andget the athlete to the hospital fast.5. Tell the doctors to expectexplosive rhabdomyolysis andgrave metabolic complications.6. Proactively prepare by havingan Emergency Action Plan andappropriate emergency equipmentfor all practices and competitions.Immediate Action CanSave LivesWhat We Can DoThough screening is done at birth;many athletes do not know theirsickle-trait status, rendering selfreportin a questionnaire unreliable.Many institutions have employedscreening strategies to rectify this.A recent survey of NCAA DivisionI-A schools found that 64 percent(of respondents) screen. 8 The NFLScouting Combine screens for sicklecell trait. All considered, despiteno evidence-based proof yet thatscreening saves lives, each institutionshould carefully weigh the decisionto screen in the absence of documentednewborn screen results.The Consensus of this task force is:1. There is no contraindication toparticipation in sport for theathlete with sickle cell trait.2. Red blood cells can sickle duringintense exertion, blocking bloodvessels and posing a grave risk forathletes with sickle cell trait.3. Screening and simple precautionsmay prevent deaths and helpathletes with sickle cell traitthrive in their sport.4. Efforts to document newbornscreening results should be madeduring the PPE.5. In the absence of newborn screeningresults, institutions shouldcarefully weigh the decision toscreen based on the potential toprovide key clinical informationand targeted education that maysave lives.6. Irrespective of screening, institutionsshould educate staff, coaches,and athletes on the potentiallylethal nature of this condition.7. Education and precautions workbest when targeted at those athleteswho need it most; therefore,institutions should carefully weighthis factor in deciding whetherto screen. All told, the case forscreening is strong.SICKLE CELL TRAIT 5

GlossaryAcute ischemic rhabdomyolysis:the rapid breakdown of muscle tissuestarved of bloodAcute rhabdomyolysis: a serious andpotentially fatal condition involvingthe breakdown of skeletal musclefibers resulting in the release of musclefiber contents into the circulationContraindication: circumstance orcondition that makes participationunsafe or inappropriateExertional rhabdomyolysis:muscle breakdown triggered byphysical activityExertional sickling: hemoglobin(red blood cell) sickling due tointense or sustained physical exertionHyperthermia: body temperatureelevated above the normal rangeHypoxemia: decreased oxygencontent of arterial bloodIschemia: a deficiency of blood flowto tissueMetabolic acidosis: a condition inwhich the pH of the blood is tooacidic because of the productionof certain types of acidsNontraumatic: not related toa physical injury caused by anexternal forceObtunded: having diminishedarousal and awareness; mentally dullSickling collapse: the collapse of anathlete who shows features consistentwith exertional sicklingVentricular fibrillation: a conditionin which there is uncoordinatedcontraction of the cardiac muscleof the ventricles in the heart6 SICKLE CELL TRAIT

Task Force ParticipantsThe following individuals and associations were members of the Inter-AssociationTask Force on Sickle Cell Trait and the Athlete. Their participation is not anendorsement of this document. For a complete list of supporting associations,please visit http://www.nata.org/statements/consensus/sct_endorsements.htm.Co-ChairsScott Anderson, ATCE. Randy Eichner, MDAt-Large MembersMary L. Anzalone, MDJames C. Puffer, MDBrock Schnebel, MDAmerican Academy of PediatricsJorge Gomez, MDAmerican College ofSports MedicineMichael F. Bergeron, PhD, FACSMDon Porter, MDAmerican Medical Society forSports MedicineJames Moriarity, MDAmerican Orthopaedic Societyfor Sports MedicineJames C. Walter II, MDAmerican Osteopathic Academyof Sports MedicineJeffrey Bytomski, DOAngela Cavanna, DO, FAOASMAssociation of Black CardiologistsB. Waine Kong, PhD, JDCollege of American PathologistsMichael J. Dobersen, MD, PhDGatorade Sports Science InstituteJeff KearneyCraig Horswill, PhDMagie Lacambra, MEd, ATCMilitary MedicineFred Brennan, Jr., DONational Association ofBasketball CoachesReggie MintonNational Association of EMTsConnie Meyer, MICTNational Association ofMedical ExaminersJeffery Barnard, MDNational Athletic Trainers’AssociationVeronica Ampey, MS, ATCDouglas Casa, PhD, ATC, FACSMTerry Dewitt, PhD, ATCScott Galloway, ATC, LATChris A. Gillespie, MEd, ATC, LATEric Howard, EdD, MS, ATCBob Toth, MS, ATCTorrance Williams, ATC, LATNational Basketball AthleticTrainers’ AssociationDionne Calhoun, ATCNational CollegiateAthletics AssociationDavid Klossner, PhD, ATCJohn W. Scott, PhD, MDTracy Ray, MDNational Federation of StateHigh School AssociationsBob ColgateNational Football LeagueGary W. Dorshimer, MD, FACPNational Strength andConditioning AssociationAvery Faigenbaum, EdD, CSCSProfessional Football AthleticTrainers’ SocietyCorey Oshikoya, ATCThe Sickle Cell DiseaseAssociation of America, Inc.National Medical AssociationBetty S. Pace, MDThe Sickle Cell Foundation ofGeorgia, Inc.Rudolph Jackson, MDWomen’s Basketball CoachesAssociationMarsha SharpSICKLE CELL TRAIT 7

Reference1. Van Camp SP, Bloor CM, Mueller FO, Cantu RC, Olson HG. Nontraumatic sports death in high school and college athletes.Med Sci Sports Exerc. 1995;27:641-647.2. Kark JA, Ward FT. Exercise and hemoglobin S. Semin in Hematol. 1994;31:181-225.3. Gardner JW, Kark JA. Fatal rhabdomyolysis presenting as mild heat illness in military training. Milit. Med. 1994;159:160-163.4. Martin TW, Weisman IM, Zeballos RJ, Stephenson RS. Exercise and hypoxia increase sickling in venous blood from anexercising limb in individuals with sickle cell trait. Am J Med. 1989;87:48-56.5. Bergeron MF, Cannon JG, Hall EL, Kutlar A. Erythrocyte sickling during exercise and thermal stress. Clin J Sport Med.2004;14:354-356.6. Marlin L, Etienne-Julan M, Le Gallais D, Hue O. Sickle cell trait in French West Indian elite sprint athletes. Int J Sports Med.2005;26:622-625.7. Eichner ER. Sickle cell trait. J Sport Rehab, 2007 (May), in press.8. Clarke CE, Paul S, Stilson M, Senf J. Sickle cell trait preparticipation screening practices of collegiate physicians. Clin J SportMed. 2006;16:440a.REPRINTED WITH PERMISSION FROM THE NATIONAL ATHLETIC TRAINERS ASSOCIATION© AMERICAN ORTHOPAEDIC SOCIETY FOR SPORTS MEDICINE, 2008, ALL RIGHTS RESERVED8 SICKLE CELL TRAIT