Cardiorespiratory responses during three repeated incremental exercise tests in sickle cell trait carriers.

This study investigated the cardioventilatory responses during heavy exercise in sickle cell trait carriers (SCTc) and subjects with normal hemoglobin (control group). Eight SCTc and six control subjects repeated three incremental exercise tests (Iet) separated by 10-min recoveries. Cardioventilatory parameters were analyzed at rest and during the first and third Iet. No significant difference in the ventilatory parameters [notably, maximal oxygen uptake (VO2max) and the ventilatory thresholds] was observed between the two groups. The time course of power output showed a significant difference between the first and third Iet from 80% of VO2max to VO2max (P < 0.05) in both groups. In conclusion, SCTc exhibited normal ventilatory responses during three successive Iet, which strongly suggests that this population, despite the presence of HbS in their red blood cells, is not limited during this type of aerobic exercise.