What is Sickle Cell Trait?
Sickle cell trait is a descriptive term for a hereditary condition in which the individual has one normal gene for hemoglobin and one abnormal gene for hemoglobin.1 Hemoglobin is a protein in the red blood cells in your body responsible for oxygen transport. Approximately 99% of the oxygen transported in blood is bound to hemoglobin inside the red blood cells.2
Sickle cell trait is generally a benign condition that does not develop or change over time. In general, it is a condition that does not affect the life span of the individual. As individuals with sickle cell trait get older, they may become unable to concentrate urine normally. This is not usually an issue for high school or college age athletes.1
Sickle cell trait is not a barrier to exercise or participation in sport, however it can lead to serious conditions that can be fatal if not properly managed.3,4
Complications of Sickle Cell Trait (SCT) for Athletes
Exertional sickling with its associated complications is one of the top causes of sudden death in sport7. As a coach, the prevention of an exertional sickling event is imperative. Understanding what may occur during an exertional sickling event and how to manage this condition with your athletes, medical team and parents is extremely important.
Athletes with sickle cell trait are potentially more vulnerable to other serious conditions such as gross hematuria, splenic infarction, exertional heat stroke, severe muscle breakdown (rhabdomyolysis) and potentially even sudden death when participating in strenuous exercise under intense environmental conditions.1,3,5 This is why awareness of sickle cell trait status in athletes by the coaches and medical team is important.
Gross Hematuria: Gross hematuria is defined as visible blood in the urine. Usually from the left kidney, gross hematuria is an occasional complication of sickle cell trait. Any athlete experiencing this should consult a physician for return to play protocol.1
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 Signs and symptoms of an exertional sickling event include intense pain, fatigue, feeling like you cannot continue exercising, muscle cramping and inability to catch your breath4. Exertional sickling is a medical emergency and requires immediate treatment.
Explosive Rhabdomyolysis. Explosive rhabdomyolysis is severe muscle break down in which the result is the release of muscle contents into the bloodstream. Muscle contents such as myoglobin can cause kidney damage and ultimately kidney failure.7 Untreated explosive rhabdomyolysis can be fatal.
High Altitude Participation. Due to the lack of oxygen in high altitudes, athletes with sickle cell trait take a higher risk when participating in this environment. Splenic infarction can occur in athletes with sickle cell trait, particularly at high altitudes. Splenic infarction is tissue death in the spleen caused by a lack of oxygen to this vital organ. Vigorous exercise at altitudes higher than 5,000 feet may increase risk. Splenic infarction causes sudden and sometimes severe pain in the left side of the chest and abdomen. You may experience nausea and vomiting as well. You should consult a doctor immediately if signs and symptoms occur as well as for return to play protocol.1 Any time you are participating in activity at high altitudes, the risk of complications is increased.
Managing the Athlete with Sickle Cell Trait
Physically active individuals with sickle cell trait should be knowledgeable of their condition and take precautions (see list below). Physically active students in elementary, middle or high school should take precautions with physical education class and participating in sports. See our sickle cell trait action plan for help preparing for school and sports.1,3 As a coach, it is important to know basic information about sickle cell trait in order to help prevent an incident in practice or a game. It should be mandatory that athletes with sickle cell trait to do the following:
- Set your own pace
- Gradual acclimatization to heat, humidity and altitude
- Use adequate rest and recovery between intense conditioning sets
- Limit “all-out” exertion of any kind to less than 2-3 minutes
- Be excused from performance tests that require extreme exertion for longer than 2-3 minutes
- Stop activity immediately if any signs or symptoms occur
- Stay well hydrated at all times, especially in hot and humid conditions
- Manage asthma appropriately
- Suspend exercise if feeling ill or while experiencing a fever
- Have access to supplemental oxygen as needed
- Seek proper medical attention when experiencing unusual distress
- DO NOT participate during acute illness, especially one involving fever
Prevention, Recognition and Treatment of Exertional Sickling
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). Coaches should tailor practices and recovery times for individuals with SCT in order to prevent the occurrence of an exertional sickling event.4 Athletes with SCT should be given longer recovery between conditioning repetitions. Coaches should excuse these athletes from participating in timed performance tests, such as serial sprints or timed mile runs and adjust work-to-rest cycles when exercising in the heat. Coaches should stress proper hydration, and not working out if feeling ill or when adjusting to a high-altitude. 4
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.4 If an athlete pushes through these initial symptoms, the result could be deadly. When these symptoms occur, coaches must consult with medical personnel prior to returning the athlete to play.
Should an athlete with SCT exhibit signs and symptoms of a sickling event, he/she should be removed from the activity immediately.4 In the event of a sickling collapse where the athlete is not showing signs of improvement remove them from competition, call 911 immediately and contact your athletic trainer and/or team physician. A sickling collapse should be considered a medical emergency.4 Be sure to communicate the athlete’s sickle cell trait status to emergency medical professionals as soon as they arrive.
The National Athletic Trainers’ Association task force recommends confirming sickle cell trait status (positive or negative) in all athletes’ pre-participation physical exams.8 Knowledge of the trait in athletes can help athletes, coaches and health care professionals to enact simple precautions that enable athletes to thrive in sports while preventing the risk of exertional sickling.
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 before participating in sports.9 However, coaches should strongly encourage athletes and parents to inform them of sickle cell trait status prior to participation as coaches may often be the first responder in case of emergency.
Complications from sickle cell trait are often preventable. The first key to prevention in any case is communication. Coaches should have open communication with parents, athletes and medical personnel regarding sickle cell trait status in order to adjust workouts and practices when necessary.
What is Sickle Cell Anemia?
Sickle cell anemia is the hereditary condition in which the individual has two abnormal hemoglobin genes.1 Sickle cell anemia is a lifelong disease that can cause painful episodes sometimes requiring hospitalization. Sickle cell trait will not develop into sickle cell anemia at any time. Carriers of sickle cell trait usually do not have any of the clinical symptoms of sickle cell anemia however; they may pass this onto their children.4 If an athlete says they have sickle cell anemia they must be cleared by a physician before participating in sport. Sickle cell anemia, unlike sickle cell trait, may prevent participation.
- NCAA Guideline 3c: The Student-Athlete with Sickle Cell Trait. 2009-2010 NCAA Handbook; June 2008.
- Powers, S., Howley, E. Exercise Physiology: Theory and Application to Fitness and Performance, 6th edition. Boston: McGraw Hill; 2007.
- Sickle Cell Trait. ACSM Current Comment. 2011. Available at: www.acsm.org. Accessed August 9, 2011.
- 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.
- 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.
- Sickle Cell Disease (SCD). Centers for Disease Control and Prevention. 2011. Available at: http://www.cdc.gov/ncbddd/sicklecell/traits.html. Accessed May 12, 2011.
- Sickle Cell Trait and Athletics. Sickle Cell Disease Association of America, Inc. 2011. Available at: http://www.sicklecelldisease.org. Accessed May 12, 2011.
- Dugdale DC. Rhabdomyolysis. A.D.A.M. Encyclopedia. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001505. Accessed March 3, 2012.
- Sickle Cell Trait and the Athlete: Consensus Statement. National Athletic Trainers Association. 2011. Available at: www.nata.org. Accessed May 12, 2011.