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Overview of Sickle Cell Trait

This is an inherited condition of abnormal hemoglobin production. This condition rarely results in a sickling crisis and is managed differently from sickle cell disease. An exertional sickling crisis usually occurs when athletes or military personnel with this condition overexert themselves, resulting in sickling of red blood cells, which causes clotting and ischemic rhabdomyolysis.1 Most individuals with sickle cell trait do not have painful crises and can participate in regular recreational and competitive activities, but abnormalities of red blood cell parameters may influence their aerobic exercise tolerance.2,3 Dehydration, viral illness, abrupt changes in altitude, and exercising in heat conditions are risk factors for developing exertional sickling.1,4

Comorbidities to Consider

  • Clients with this condition may have temporary states of anemia and develop complications if they develop rhabdomyolysis.

Client Examination

Keys to Examination of Clients

  • If sickling crises occurs, monitor hemoglobin levels and renal function before allowing a return to strenuous training and competitive activities.4

  • Screen athletes for this condition so that if a crisis occurs, it can be identified and treated as a medical emergency.

Recommended Baseline Testing of Fitness Levels

  • Competitive athletes with this condition may choose to be tested for the rate of red blood cell sickling during strenuous exercise to better understand their risk for developing an exertional sickling crises.1

Exercise Prescription


Type: Aerobic and recreational activities

Intensity: No limitations

Duration: No limitations

Frequency: No limitations

Getting Started

Clients can choose to participate in any type of recreational or competitive pursuits, but they should have proper conditioning to participate in activities and should be counseled on how to recognize symptoms of a sickling crisis.1 Counsel them to avoid all-out exertion of any activity for longer than 3 minutes and to use rest periods with full recovery when performing interval training.1 Clients should properly hydrate during exercise and adjust training programs for hot and humid conditions. They should be counseled to increase their training programs slowly to acclimatize to temperature, humidity, and altitude.1


1. +
Eichner  ER. Sickle Cell Trait. J Sports Rehabil 16(3);197–203, 2007.
2. +
Connes  P, Reid  H, Hardy-Dessources  MD,  et al. Physiological responses of sickle cell trait carriers during exercise. Sports Med 38(11):931–946, 2008.  [PubMed: 18937523]
3. +
Connes  P, Hue  O, Tripette  J,  et al. Blood rheology abnormalities and vascular cell adhesion mechanisms in sickle cell trait carriers during exercise. Clin Hemorheol Microcirc 39:179–184, 2008.  [PubMed: 18503123]
4. +
Markaryus  JN, Catanzaro  JN, Katona  KC. Exertional rhabdomyolysis and ...

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