Parallel changes in the onset of blood lactate accumulation (OBLA) and threshold of psychomotor performance deterioration during incremental exercise after training in athletes

During aerobic exercise with increasing intensities choice reaction time (CRT) progressively shortens up to 60-80% of maximal workload, and then it rapidly increases. The aim of this study was to determine whether workload associated with the shortest CRT operationally called "the psychomotor fatigue threshold" is related to the metabolic response to exercise. Thirteen male soccer players (aged 23.3 +/- 1.0 yrs) participated in this study. Before and after 6 weeks of training in the pre-competition period they underwent treadmill test at 0 grade with running speed increasing every 3 min by 2 km/h starting from 6 km/h until exhaustion. At each stage of exercise CRT, heart rate, respiratory gas exchange and blood lactate [LA] were measured and the workload corresponding to [LA] of 4 mmol/l (OBLA) was recorded. After training, CRT was significantly shortened at rest (from m +/- SEM = 345 +/- 12 to 317 +/- 12 ms) and during exercise (from 304 +/- 10 to 285 +/- 11 ms at the psychomotor fatigue threshold and from 359 +/- 13 to 331 +/- 13 ms, p<0.001at the last stage). Both OBLA and the psychomotor fatigue threshold were shifted towards greater running velocities (by 0.92 +/- 0.26 and 0.85 +/- 0.22 km/h, respectively). The psychomotor fatigue threshold exceeded OBLA both before and after training. Significant correlations were ascertained between OBLA and psychomotor fatigue threshold (r = 0.97) and between the changes in OBLA occurring during training and those in psychomotor fatigue threshold (r = 0.88). It is concluded that endurance training not only increases exercise tolerance due to its influence on metabolism but also facilitates psychomotor performance during heavy exercise. (C) 2010 Elsevier B.V. All rights reserved.