Sickle Cell Anemia

What is Sickle Cell Anemia?

Sickle cell anemia is the genetic inheritance of one gene for sickle hemoglobin and one for normal hemoglobin.  During intense exercise, especially in the heat and during dehydrated states, the sickle hemoglobin can change the shape of the red blood cells from round to quarter-moon (sickle).

This becomes a problem, especially during intense exercise because the sickled cells can become log-jammed in the blood vessels and prevent blood flow.   This log-jam can lead to ischemic rhabdomyolysis, the rapid breakdown of muscle tissue due to lack of blood, this can lead to death.  This sickling can begin early on during exercise and worsen during exercise. 

Sickling often can be confused with heat cramps but there is a difference.
  • During heat cramps there are typically muscle twinges before onset, during sickling there are none
  • The pain is intense during heat cramps, during sickling the pain feels different
  • Crampers typically hobble around with "locked-up" muscles, sicklers have weak muscles
  • Heat crampers will writhe in pain with contracted muscles while sicklers will lay still with flacid muscles
  • Sicklers may have difficulty breathing.  Some people with the trait also have secondary asthma.
Sickling may begin early after only being on the field exercising for a short time, early in the season.  May also occur during high intensity repetitive running or during end of practice conditioning.
Treatment and Management

Athletes that carry the sickle cell trait or gene are not disqualified from sports or activity but they do need to be identified and properly educated and given proper precautions.

Gradual acclimation to hot environments and intense exercise is key along with proper hydration and nutrition.  Proper conditioning is also important.  If symptoms begin such as: cramping, pain, swelling, weakness, or inability to catch breath, cease activity to allow recovery.  Typically they will recover and can rejoin activity.  The athlete needs the appropriate work to rest ratio during hot environments. 

If necessary the person should be cooled by ice or ice water submergance to reduce the core temperature and to receive proper emergency care immediately.


All infants are now tested for sickle cell trait/anemia at birth.  It is more common for African-
American individuals to carry the trait, 1 in 12, but it is present in other ethnicities as well.  Carrying one sickle gene helped fend off malaria generations ago. 

NATA Position Statement