Valentina Perciavalle

Elevated blood lactate is associated with increased motor cortex excitability.

No information has yet been provided about the influence of blood lactate levels on the excitability of the cerebral cortex, in particular, of the motor cortex. The aim of the present study was to examine the effects of high blood lactate levels, induced with a maximal cycling or with an intravenous infusion, on motor cortex excitability. The study was carried out on 17 male athletes; all the subjects performed a maximal cycling test on a mechanically braked cycloergometer, whereas 6 of them were submitted to the intravenous infusion of a lactate solution (3 mg/kg in 1 min). Before the exercise or the injection, at the end, as well as 5 and 10 min after the conclusion, venous blood lactate was measured and excitability of the motor cortex was evaluated by using the transcranial magnetic stimulation. In both of these experimental conditions, it was observed that an increase of blood lactate is associated with a decrease of motor threshold, that is, an enhancement of motor cortex excitability. We conclude by hypothesizing that in the motor cortex the lactate could have a protective role against fatigue.

Attentional processes and blood lactate levels

The accumulation of lactate in the blood after a high-intensity exercise is associated to an increase of lactate extractions by the brain. However, no information has been provided about the influences of blood lactate on cognitive performances and, in particular, on attention. The present study was carried out to examine the association of high blood lactate levels, induced with a maximal cycling, with two different attentional tasks. The study was carried out on 17 male sprinters who performed exhaustive exercise. Before the exercise, as well as 5 and 10 min after the exhaustion, blood lactate was measured and intensity as well as selectivity of attention of each subject were evaluated. Same measurements were performed on 6 out of 17 subjects who accepted to receive an intravenous infusion of a lactate solution. In both experimental conditions, an inverse relation between scores in both aspects of attention and blood lactate levels was observed.

The second-to-fourth digit ratio correlates with aggressive behavior in professional soccer players

The aim of this study was to test the hypothesis that high levels of testosterone during prenatal life, testified by a low second-to-fourth digit ratio (2D:4D), as well as in adulthood affect the aggressive behavior of professional soccer players. Using 18 male professional players from a first level Italian Soccer Team we calculated: i) the 2D:4D ratio of the right hand, ii) the number of yellow and red cards per game, iii) the mean salivary testosterone concentration (Sal/T) and iv) the handling of aggressive impulses as assessed by the Picture Frustration test (PFT). Soccer players with a lower 2D:4D ratio had a higher number of fouls per game. A significant negative correlation was observed between Sal/T and 2D:4D ratio, as well as between 2D:4D ratio and the aggressiveness of players. By contrast, a significant positive correlation of Sal/T and fouls/game score and PFT was detected. No significant correlation was detected between 2D:4D or Sal/T and the playing position of players. Results of this study revealed that in professional soccer players, aggressive behavior, with the consequent increased risk of fouls during the game, is more likely to occur in individuals with high testosterone levels, not only in adulthood, but also during their intrauterine life.

The second-to-fourth digit ratio correlates with the rate of academic performance in medical school students

Prenatal androgens have important organizing effects on the development and future behavior of the brain. The second-to-fourth digit length ratio (2D:4D) has been proposed as a marker of these prenatal androgen effects, with a relatively longer fourth finger indicating higher prenatal androgen exposure. 2D:4D has been shown to predict the success of men who play sports and of financial traders. However, to date little is known regarding the effects of prenatal androgens on academic performance, for example, admission to and success in a highly competitive university system such as the state-run Italian medical schools. Here, we report the findings of a study conducted at the University of Catania Medical School, Italy, in which the 2D:4D ratio was sampled in a group of 48 male students. The 2D:4D ratios were found to be correlated with the performance of the students on the admission test to the medical school, their salivary testosterone levels and their aggressiveness; however, no correlation was observed with the mean score on exams during the course of study. Our results suggest that pre and/or postnatal androgens increase performance in situations that require prompt decision-making and the ability to take risks, but do not influence performance when a more analytical and planned approach is called for.

Gender differences in changes of motor cortex excitability during elevated blood lactate levels

Gender differences in cortical excitability have been detected by using transcranial magnetic stimulation (TMS). The present study was carried out to compare the effects of high blood lactate levels, induced by performing a maximal exhausting exercise, on the excitability of the primary motor cortex in young male and female athletes. The study was carried out on 21 young males and 20 females from the Middle Distance Track Team of our university. Before the exercise, at the end, as well as 5 and 10 min after the conclusion, venous blood lactate and glucose were measured and excitability of the motor cortex was evaluated by using TMS. We observed a similar enhancement of excitability of primary motor cortex, concomitantly with an increase of blood lactate, in both young male and female athletes. However, the improvement was significantly higher (p < 0.05) in women (37.4% ± 3.97) than in men (42.0% ± 6.43), suggesting a greater sensitiveness of female cerebral cortex to blood lactate.

Brainstem excitability is not influenced by blood lactate levels

The influence of blood lactate on brainstem excitability was tested by using the blink reflex (BR) recovery cycle on 18 sprinters. Blood lactate was measured before maximal cycling, at the end, as well as 5 and 10 min after the exhaustion. Blood lactate was associated with a decrement of R2 whereas only small changes were observed after an intravenous infusion of lactate. It seems, therefore, that lactate influences BR mainly by acting at the cortical level.

Spinal cord excitability is not influenced by elevated blood lactate levels

The aim of the present study was to examine the association of high blood lactate levels, induced with a maximal cycling or with an intravenous infusion, with spinal cord excitability. The study was carried out on 17 male athletes; all the subjects performed a maximal cycling test on a mechanically braked cycloergometer, while 6 of them were submitted to the intravenous infusion of a lactate solution (3 mg/kg in 1 min). Before the exercise or the injection, also at the end as well as 5 and 10 min after the conclusion, venous blood lactate was measured and excitability of the spinal α-motoneurons was evaluated by using the H reflex technique. In both experimental conditions, it has been observed that an exhaustive exercise is associated with a strong increase of blood lactate (but not of blood glucose) and with a significant reduction of spinal excitability. Since a similar augment of blood lactate induced by an intravenous infusion, in subjects not performing any exercise, is not associated with significant changes of spinal excitability, it can be concluded that the increase of blood lactate levels during a maximal exercise is not per se capable of modifying the excitability of spinal α-motoneurons.

Changes in cortical excitability and blood lactate after a fatiguing hand-grip exercise

Abstract Excitability of primary hand motor cortex (PHMC), evaluated with transcranial magnetic stimulation by using the “1 mV resting motor threshold” method, and capillary blood lactate were measured at the end, as well as 5 and 10 min after a fatiguing hand-grip exercise. The relation between blood lactate and the amplitudes of motor-evoked potentials showed a significant direct proportionality. Blood lactate seems to exert a protective role on PHMC against fatigue reduction during extremely intensive isometric exercises.

Anthropometrics Related to the Performance of a Sample of Male Swimmers

The main purpose of the present investigation of 21 elite male swimmers was to assess whether the Ape Index (the ratio between the individuals arm span and height) and/or the second-to-fourth digit length ratio (2D:4D), i.e., the ratio between the length of the second and the fourth fingers of the right hand, are associated with the performance of high-level swimmers, when mood and / or executive function are covaried. The results showed no statistically significant correlation between the Ape Index and 2D:4D ratio, performance, executive function, or mood. In contrast, statistically significant correlations were found between 2D:4D ratio and performance, executive function, and mood. Regressions indicated that 2D:4D ratio and not Ape Index is related to the performances of a sample of male swimmers.

Effects of an exhaustive exercise on motor skill learning and on the excitability of primary motor cortex and supplementary motor area

AbstractWe examined, on 28 healthy adult subjects, the possible correlations of an exhaustive exercise, and the consequent high blood lactate levels, on immediate (explicit) and delayed (implicit) motor execution of sequential finger movements (cognitive task). Moreover, we determined with transcranial magnetic stimulation whether changes in motor performance are associated with variations in excitability of primary motor area (M1) and supplementary motor area (SMA). We observed that, after an acute exhaustive exercise, the large increase of blood lactate is associated with a significant worsening of both explicit and implicit sequential visuomotor task paradigms, without gender differences. We also found that, at the end of the exhaustive exercise, there is a change of excitability in both M1 and SMA. In particular, the excitability of M1 was increased whereas that of SMA decreased and, also in this case, without gender differences. These results support the idea that an increase of blood lactate after an exhaustive exercise appears to have a protective effect at level of primary cortical areas (as M1), although at the expense of efficiency of adjacent cortical regions (as SMA).