[The effect of supramaximal exercise on the recovery kinetics of lactate]

Blood lactate recovery curves from muscular exercise can be described by a sum of two exponential terms consisting in a rapidly increasing and a slowly decreasing component. A two-compartment model consisting of the previously working muscles and the remainder of the lactate space furnishes the simplest but nevertheless realistic explanation of this evolution pattern. The velocity constants of the rapidly increasing (gamma 1) and the slowly decreasing (gamma 2) components inform respectively on the abilities of the body to exchange and remove lactate. However the blood lactate recovery curves observed in three untrained subjects after 3-min 107-115% VO2max cycling display a transitory plateauing of the lactate concentration between the increasing and decreasing phases of the curves. This levelling off of the concentrations at their highest value was not observed in an endurance trained subject after a 3-min 107% VO2max exercise. Despite the plateauing and consequent less good fit than to the usual evolution curves, the recovery curves could still be accurately fitted by the biexponential time function. After supramaximal exercise the abilities to exchange and to remove lactate are severely impaired. These impairments in the functional properties of the organism are very likely associated with and/or linked to physico-chemical modifications which have been observed as much at the cellular level as in the body fluids during and after supramaximal exercise.