Preventing Exertional Sickling in Athletes with Sickle Cell Trait

February 01, 2019

By Kathleen Choate, ATC, CSCS, CEAS, Athletic Trainer

Sickle cell disease is a blood disorder that causes red blood cells to sickle or change to a crescent shape.  Sickle cell trait (SCT) is the heterozygous version of sickle cell disease.4  While SCT is often thought of as a benign condition, we are learning more and more about how it can contribute to life threatening conditions such as rhabdomyolysis and exertional sickling.  SCT occurs in about 8% of Americans with African lineage, but can also be found in individuals with Caribbean, Arab, East Indian, and Mediterranean lineage.1,4

While the blood cells in an individual with SCT are typically normal, in situations where an individual puts forth maximal effort, the blood cells can sickle which causes them to get stuck and block off blood vessels.  Exercise inducing sickling are typically short sprints or gassers (although it can be any exercise with sustained maximal effort) and typically take place in the beginning of practice (although it can take place at any point in a practice).4

In the case of a SCT athlete with exertional sickling, they may experience the following symptoms:  muscle cramping (the muscle will look and feel normal), pain, swelling, weakness, tenderness, inability to catch one’s breath, fatigue, and/or the athlete slumps to the ground.2,3,4  Rhabdomyolysis, AKA “Uncle Rhabdo,” is a more well-known condition that is likely to occur with a severe case of exertional sickling.  It can occur when there is a breakdown of skeletal muscle and can cause renal failure.  You do not need SCT to get rhabdomyolysis, but SCT does increase the risk of getting it.  Some additional factors that put a SCT athlete at risk include exercising at a higher elevation, exercising in the heat, lack of heat acclimation, dehydration, asthma, and illness.3

How do we prevent these conditions in an athlete with SCT?  The first step is knowing who has SCT.  At this point in time it’s routine for babies to be tested for it, but not all athletes have been tested or recall whether they have it.  Athletes that have never been tested or do not recall their status should be encouraged to get tested for it.  These athletes should be given conditioning programs that progress more slowly.4  If these athletes ever appear to be struggling, they should be evaluated by the athletic trainer or other on-site medical expert.4  Water should be available and encouraged throughout practice to prevent dehydration for all athletes as well as precautions for practicing in the heat to prevent heat illness.  Since most people consider SCT to be a benign condition, athletes, parents, and coaches should be educated on how to identify and manage it.2,3

If you or an athlete are experiencing any of the above symptoms, consult with your athletic trainer or other medical professional immediately.


1. Blinder, M. A., & Russel, S. (2014). Exertional sickling: Questions and controversy. Hematology Reports,6(4). doi:10.4081/hr.2014.5502

2. Casa, D. J., Guskiewicz, K. M., Anderson, S. A., Courson, R. W., Heck, J. F., Jimenez, C. C., . . . Walsh, K. M. (2012). National Athletic Trainers Association Position Statement: Preventing Sudden Death in Sports. Journal of Athletic Training,47(1), 96-118. doi:10.4085/1062-6050-47.1.96

3. Exertional Sickling. (2015, March 04). Retrieved January 23, 2019, from

4. Mitchell, B. L. (2018). Sickle Cell Trait and Sudden Death. Sports Medicine - Open,4(1). doi:10.1186/s40798-018-0131-6