Filed under: Heat acclimation
Approximately 300 million people around the world have sickle cell trait (SCT), including approximately 9% of African Americans. It is a hereditary condition in which red blood cells are affected, but most people who have it never experience symptoms. (It is important to note that SCT is not the same as sickle cell disease [SCD]. Sickle cell disease [or sickle cell anemia] can lead to other serious clinical risks and can cause severe symptoms. Those with the SCD usually have a shorter lifespan.)
Individuals with SCT usually can participate in normal physical activity and sports, as SCT doesn’t seem to adversely affect performance. In fact, some studies have found that those with SCT excel in short-distance power activities such as sprinting and jumping.
While SCT is largely a benign condition, there have been related complications such as exertional rhabdomyolysis and exercise-related sudden death. They have been found in non-SCT individuals as well, but they occur at higher rates in those with SCT and are a “hot topic” in military, and civilian communities; the National Collegiate Athletic Association even requires screening for all its Division I and II athletes.
It has been suggested that those with SCT may be more prone to sudden death from dehydration, heat illness, and high-intensity exercise; however, these factors and the role of prevention standards, medications, and the use of dietary supplements are still being studied. In both military and civilian SCT populations, collapsing during exercise is most commonly observed during times runs and sprints within the first few weeks of conditioning. SCT Recruits who have difficulty passing the Physical Readiness Test are also at higher risk for collapse. Military leaders should be aware of safe training guidelines and take universal precautions. Effective prevention tactics include heat acclimatization, hydration, gradual physical conditioning, and addressing progressively worse symptoms early on.
All newborns in the United States are screened for both SCT and SCD as part of a public health imperative. Each military branch has its own policies regarding SCT. The Army does not screen for SCT but promotes universal precautions for all soldiers, whereas the Air Force, Navy, and Marines all screen for SCT after accession. Further testing and counseling may be done for those who are positive for SCT. If you are unsure about SCT and exercise, consult with your physician, especially if you are starting a new exercise routine.