Submaximal exercises and attentional processes

In young male athletes, we studied whether an aerobic exercise, carried out at two different submaximal intensities, is capable to influence attentional processes. In particular we measured blood levels of lactate and glucose and attention after a 30 min test performed at 60% and at 80% of VO2max. Attention was studied by using a typical reaction time paradigm and a parallel double task of both visual and auditory recognition. Measurements were carried out before the exercise, after 10 and 20 min from its beginning, at its end and, finally, 10 min after the conclusion. During a 30 min aerobic exercise, there is an increase of blood lactate, whereas the blood glucose remains unmodified. Moreover, a significant worsening of attentional processes is detectable only at 80% of VO2max, when the blood lactate overcomes a concentration of 4 mmol/l. Since it has been recently shown that a large increase of blood lactate is associated with an improvement of excitability of the primary motor cortex, we conclude that, during an intense exercise, in the frontal cortex the lactate could carry out a protective role against fatigue, by favoring the activity of primary motor cortex, albeit at the expense of attentional processes.