PSYCHOMOTOR PERFORMANCE DURING PROLONGED EXERCISE ABOVE AND BELOW THEBLOOD LACTATE THRESHOLD

Previous investigations from this laboratory have demonstrated that du ring graded exercise with exercise intensities increasing every 3 min until exhaustion the multiple choice reaction time (RT) decreased unti l the intensity exceeded the lactate threshold (LT) by approximately 2 5%, and then rapidly increased. The aim of this study was to follow up changes in RT during prolonged exercise at constant intensities above and below LT and to relate these changes to changes in venous blood l actate [La-](b), and plasma catecholamine [CA](pl) concentration respo nses to the exercise. For this purpose eight young soccer players exer cised for 20-min on a cycle ergometer at 10% above LT, and nine exerci sed for 60 min at an intensity 30% below LT. During both tests RT, hea rt rate (HR), as well as [La-](b), and [CA](pl) were measured. Above L T, RT decreased from the 5th min until the end of exercise, whilst HR, [La-](b), and [CA](pl) increased progressively. Significant inverse c orrelations were ascertained between RT and plasma adrenaline (r = -0. 651) and noradrenaline concentrations (r = -0.678). During exercise be low LT, RT decreased up to approximately 40 min, then it reached a nad ir, and stabilized at this level. This was accompanied by only small c hanges in [La-](b) and [CA](pl). The present findings would indicate t hat young athletes are able to maintain for a relatively long time, or even increase, their psychomotor performance during endurance exercis e both below and above the LT.