Lactic response in sickle cell trait carriers in comparison with subjects with normal hemoglobin

The objective of this study was to assess lactic response (mmol/L) during incremental exercise in a specific population of men and women with sickle cell trait.

Athletic men and women from the French West Indies showing no anemia and/or alpha thalassemia.

Anemia was ruled out by hemoglobin level, and alpha thalassemia was ruled out by hemoglobin S percentage with concomitant hemoglobin level and mean corpuscular volume. Comparison was made with control subjects with normal hemoglobin, matched for physical fitness, anthropometric data, and sex. All subjects performed an incremental exercise test using a cycle ergometer. Peak oxygen uptake (mL/min) was predicted from an equation at peak exercise. Heart rate (beats/min) was noted continuously, and blood samples were collected for lactic response determination every minute during the incremental exercise test and at 1, 3, and 5 minutes of recovery.

Comparison of peak oxygen uptake and heart rate values showed no significant differences in subjects with sickle cell trait versus control subjects during the incremental exercise test. In contrast, analysis of variance revealed significantly lower lactic response time courses during the incremental exercise test and at peak exercise (p < 0.05) in the sickle cell trait group, whereas the heart rate time course was lower during recovery (p < 0.05).

We conclude that the lower lactic response exhibited by subjects with sickle cell trait during incremental exercise was the result of an adaptive process in red blood cells in relation to either lower lactate production or greater lactate uptake capability than in individuals with normal hemoglobin.