What is Sickle Cell Trait (SCT)?
Sickle cell trait is the inheritance of one gene for normal hemoglobin (HbA) and one abnormal (mutated β1-globin) gene for sickle hemoglobin (HbS).^1,2 Individuals with sickle cell trait are at risk of experiencing exertional sickling which can be fatal. Exertional sickling may occur during bouts of high-intensity exercise as a result of the sickle hemoglobin causing red blood cells to become sickle shaped.

What is Sickle Cell Anemia (SCA)?
Sickle cell anemia, commonly referred to sickle cell disease, occurs as a result of the inheritance of² abnormal hemoglobin genes.¹ It is a lifelong disease that may carry other complications.

What is exertional sickling?
Exertional sickling is a potentially life-threatening condition resulting from the sickling of red blood cells during intense exercise. Sickling results in muscular ischemia and collapse, whereby the athlete may experience intense muscular pain, rhabdomyolysis, and other serious metabolic problems.² The athlete initially will still be conscious and able to talk and may complain of muscular pain, however this is not to be confused with muscle cramping. Exertional sickling is a medical emergency and requires immediate treatment.

What are the complications with exercise?
Exertional sickling has been referred to as an intensity syndrome.³ High intensity exercise is the main culprit for a sickling event. Sickling collapses often occur either after only a few minutes of high intensity exercise or toward the end of a longer fast-paced activity.⁴

Prevention, Recognition and Treatment of Exertional Sickling

Prevention. It is imperative for athletes and the coaches and athletic trainers that care for them to be aware when an athlete has sickle cell trait (SCT). Tailoring practices and recovery times for individuals with SCT can help prevent the occurrence of an exertional sickling event.⁵ Athletes with SCT should be given longer recovery between conditioning repetitions. They should also avoid participating in timed performance tests, such as serial sprints or timed mile runs during extreme environmental heat conditions. Athletes with SCT may need to adjust work-to-rest cycles when exercising in the heat. Proper hydration should be stressed, as well as not working out if feeling ill or when adjusting to a high-altitude.⁵

Recognition. One of the initial complaints of an individual experiencing sickling is muscular pain and weak muscles. The athlete will often slump to the ground due to weakness and inability to continue exercising or even standing. This is different from muscle cramping because with sickling there is no visible, involuntary muscular contraction. Other signs and symptoms may include: muscle swelling and tenderness, the inability to catch one’s breath, and fatigue.⁵ If an athlete is initially allowed to rest after exhibiting these symptoms, this may allow the sickling red cells to regain their normal shape and regain oxygen throughout muscles, lungs, and other organs². However, if an athlete pushes through these initial symptoms, the result could be deadly.

Treatment. Should an athlete with SCT exhibit signs and symptoms of a sickling event, he/she should be removed from the activity immediately.⁵ In the event of a sickling collapse where the athlete is not showing signs of improvement, the administration of oxygen (151 pm) is the gold standard, as well as calling 911 if vital signs are declining². A sickling collapse should be considered a medical emergency.5 When the athlete is being transported to advanced medical care, it is essential that the athletic trainer notify the attending physician about the presence of SCT, the suspected exertional sickling, and advise the appropriate medical personnel to be prepared to treat explosive rhabdomyolysis and its metabolic complications.⁵

Governing Bodies/SCT Screening
The National Athletic Trainers’ Association task force recommends confirming sickle cell trait status (positive or negative) in all athletes’ pre-participation physical exams(PPE).⁶ SCT may be self-reported via the history section of the PPE or confirmed through SCT testing⁵, such as is now mandated in the NCAA. Knowledge of the trait in athletes can help athletes, coaches and health care professionals to simple precautions that enable athletes to thrive in sports while preventing the risk of exertional sickling.

The NCAA has mandated that as of August 1, 2010, all Division I student- athletes beginning their first year of eligibility, transfers and student-athletes trying out for a team are required to complete a sickle-cell solubility test, show documentation of a prior test or sign a written release declining the test.⁷ Student-athletes returning are not required to be given a sickle cell solubility test, however, male athletes who practice with women’s teams are required to be tested.⁷ As of right now, this legislation stands only for Division I NCAA institutions. The NCAA will soon be recommending that all Division II athletes also be screened for SCT or sign a waiver declining the test.

Currently, the National High School Federation has no recommendations for screening athletes for sickle cell trait. The mandated pre-participation physical should have a question about the athlete’s sickle-cell status. Sickle cell status is tested at birth and the results may be able to be found in state newborn screening records and/or with your primary care provider. Currently, no medical organization is calling for universal screening for SCT.⁸

Sideline Management Considerations
The NATA Position Statement: Preventing Sudden Death in Sports recommends that athletic trainers have access to supplemental oxygen during training or competition, particularly when it is known that athletes with SCT will be participating. In the event of an exertional sickling collapse, the athlete should be removed from the activity immediately, and high-flow oxygen at 15 L/min with a non-rebreather face mask should be administered.⁵ The athlete’s vital signs should be continuously assessed, and if vital signs decline, EMS should be summoned immediately. Oxygen should continue to be administered and vital signs monitored until transport. The athletic trainer should ensure that the EMS and attending physician is aware of the athle te’s SCT status and the current condition of exertional sickling with metabolic explosive rhabdomyolysis.⁵

Weather Considerations
Exertional sickling may occur in various environmental conditions; however, the NATA’s recent position statement on Preventing Sudden Death in Sports recommends using extra precaution by modifying work to rest cycles and ensuring hydration when exercising in the heat.⁵ Furthermore, when adjusting to a new high-altitude environment, the athlete should either avoid exercising in this new environment or ensure supplemental oxygen will be available during training or competition.⁵

SCT References

1. Tsaras G, Owusu-Ansah A, Boateng FO, Amoateng-Adjepong Y. Complications associated with sickle cell trait: a brief narrative review. Am J Med. 2009; 122:507-512.
2. Anderson S, Eichner ER. National Athletic Trainers’ Association Consensus Statement: Sickle cell trait and the athlete. http://www.nata.org/consensus-statements. Accessed April 23,2012.
3. Eichner ER. Pearls and pitfalls: exertional sickling. Curr Sport Med Rep. 2010;9(1):3-4.
4. Eichner ER. Sickle cell considerations in athletes. Clin Sports Med. 2011;30:537-549.
5. Casa DJ, Guskiewicz KM, Anderson SA, et al. National Athletic Trainers' Association Position Statement: Preventing Sudden Death in Sports. J Athl Train. 2012;47(1):96-118.
6. NCAA Division I Proposal No. 2009-75-B. Question and Answer Document. NCAA, June 2, 2010.
7. Martin, D. Sickle Cell Trait. NFHS Sports Medicine Handbook. 2011; 113-115.

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