Ventilatory and lactic thresholds in subjects with sickle cell trait.

This study investigated 1) whether ventilatory and lactic thresholds (VT and LT, respectively) are different in sickle cell trait carriers (SCTc) and subjects with normal hemoglobin (control group), and 2) whether the first LT and VT and the second LT and VT are respectively coincident in the two populations. Seven SCTc and 8 control subjects performed an incremental exercise test (IET). Blood lactate concentration and cardioventilatory variables were analyzed at rest and during IET. No significant difference in the ventilatory parameters (notably, maximal oxygen uptake [VO (2max)] and the ventilatory thresholds) or the lactic thresholds was observed between the two groups. In both SCTc and control subjects, the LTs and VTs did not occur at the same exercise intensity. The first VT did not coincide with the first LT, in contrast with the second VT and the second LT, which coincided in both groups. In conclusion, SCTc exhibited normal ventilatory and lactic responses during a progressive and maximal exercise test assessing aerobic physical fitness.