Arterial blood lactate concentrations and pH were measured on seven black male sickle
cell trait (SCT) carriers before, during and after incremental exhaustive bicycle
exercise (25 W increments per minute) and compared with those of six control individuals
of the same ethnic origin having a similar physical fitness level. The object of the
experiment was to determine if SCT has an effect on lactate kinetics. At volitional
exhaustion which was reached at a comparable overall mean absolute work rate for both
groups, oxygen consumption expressed per kilogram body mass was significantly lower
for the SCT carriers than for the control volunteers. Lactate concentrations were
higher for the SCT carriers after the 150 W exercise step but differences reached
statistical significance only at exhaustion. Concentrations were distinctly higher
for the SCT group during the following 40 minutes of recovery. While there were no
observable differences in blood pH between the SCT and control subjects during the
exercise, this variable became significantly lower for the SCT than for the control
group 8 minutes after the end of exercise. Lactate recovery curves were fitted by
a biexponential time function where the two velocity constants inform on the body's
overall ability to exchange and remove lactate. The ability to remove lactate was
comparable for the two groups. The present results do not warrant drawing a definite
conclusion on impairment of the ability to exchange lactate in the presence of SCT.
However, SCT carriers are likely to produce more lactate than control subjects reaching
exhaustion at similar mean absolute work rate during exhaustive incremental bicycle
exercise.
Key words
Lactate kinetics - lactate production - incremental exercise - passive recovery -
blood pH - arterial blood
