Sickle Cell Trait & Decreased Aerobic Capacity

When Dale Lloyd II, a freshman cornerback at Rice University, fell to the ground unconscious during a practice on Sept. 24, 2006, and died the next day, his family and team were stunned. Lloyd was an healthy 19-year-old, but he did not know that he had inherited sickle cell trait, a medical condition that affects oxygen-carrying red blood cells. If you or someone close to you has sickle cell trait, you can participate in intensive exercise and sports, but you should follow precautions recommended by the National Collegiate Athletic Association.

Sickle Cell Trait

A person with sickle cell trait has inherited a copy of a defective gene from one parent and a copy of a healthy gene from the other parent. The red blood cells of a sickle cell trait person appear to be a normal round shape in regular lab tests. However, during unusually intense exercise, the sickle cell trait condition can cause oxygen-carrying red blood cells made by the defective gene to change from the normal circular shape to a sickle shape, setting off a chain reaction that can kill people unexpectedly.

Aerobic Capacity

Aerobic capacity is a technical concept used to measure the body's ability to exercise and can be determined by a treadmill test or a timed run. A sickle cell trait person taking these tests will show normal aerobic capacity when compared with controls. Problems develop when a sickle cell trait person is subjected to unusual physical stress. For example, Dale Lloyd had sprinted 100 yards for a total of 16 consecutive times, when he collapsed, according to a story in the July 27, 2010, issue of "USA Today."

Exercise Danger

In the United States, sickle cell trait appears in both African-Americans and Caucasians, but is more frequent among African-Americans. During the decade prior to 2010, eight college football players with sickle cell trait died during training, according to an article in the April 11, 2010, issue of "The New York Times," titled "In NCAA, Question of Bias Over a Test for a Genetic Trait."

NCAA Requires Testing

The NCAA recommends that sickle cell trait athletes slowly build up their intensity while training; that they be allowed to set their own pace during conditioning; that they be given rest and recovery times between repetitions of exercises; that they stop activity immediately upon experiencing abnormal muscle pain, weakness, fatigue or lack of breath; that they stay well-hydrated at all times, especially in hot and humid weather; that they stop consuming caffeinated drinks; that they monitor asthma symptoms; that they refrain from extreme exercise during illness; and that they modify training when adjusting to a change in altitude.

NCAA Recommended Precautions

The NCAA recommends that sickle cell trait athletes slowly build up their intensity while training; that they be allowed to set their own pace during conditioning; that they be given rest and recovery times between repetitions of exercises; that they stop activity immediately upon experiencing abnormal muscle pain, weakness, fatigue or lack of breath; that they stay well-hydrated at all times, especially in hot and humid weather; that they stop consuming caffeinated drinks; that they monitor asthma symptoms; refrain from extreme exercise during illness; and modify training when adjusting to a change in altitude.

Sickle Cell Trait & Decreased Aerobic Capacity