L. Capranica

Relationship between blood lactate and cortical excitability between taekwondo athletes and non-athletes after hand-grip exercise

Abstract Objectives: In taekwondo competitions, fatigue has a large influence on performance. Recent studies have reported that the excitability in the primary hand motor cortex, investigated with transcranial magnetic stimulation (TMS), is enhanced at the end of a maximal exercise and that this improvement correlates with blood lactate. The aim of the present study was to investigate the relationship between blood lactate and cortical excitability in taekwondo athletes and non-athletes. Methods: The excitability of the primary motor cortex was measured before and after fatiguing hand-grip exercise by TMS. Capillary blood lactate was measured at rest (pre-test), at the end (0u2009min), and at 3 and 10u2009min after the exercise by using a “Lactate Pro” portable lactate analyzer. Results: Significant differences in cortical excitability between the two groups were found after the exercise (pu2009<u20090.05). Furthermore, we found a significant relationship between cortical excitability and blood lactate (pu2009<u20090.01). Conclusion: The present findings showed changes in the excitability in the athletes group and also in the non-athletes group. However, blood lactate seems to have the greater effect in trained subjects compared to untrained subjects. In fact, it appears that, during extremely intensive exercise in taekwondo athletes, lactate may delay the onset of fatigue not only by maintaining the excitability of muscle, but also by increasing the excitability of the primary motor cortex more than in non-athletes.

Relationship between RPE and Blood Lactate after Fatiguing Handgrip Exercise in Taekwondo and Sedentary Subjects

Purpose: To get information on the effort during vigorous exercise there are different ways and, the most popular, is the scale to measure subjective exertion or the rating of perceived exertion (RPE), such as the Borg scale. This scale is an effective methods to quantify and monitor the intensity of the exercise The aims of this study were to investigate the association between RPE, blood lactate concentration and maximal voluntary handgrip (MVG) force, after fatiguing exercise in athletes and non-athletes. Method: Twelve right-handed male taekwondo athletes (age: 27 ± 5 years) and 12 matched controls (age: 26 ± 5 years) were recruited. Peak force was measured and, after a subsequent rest, subjects were asked to reproduce 30% of their MVG for 4 s, then relax for 2 s, and then repeat this sequence for 10 minutes. Blood lactate was measured at rest (pre), at the end (0 min) as well as 3 and 10 min of the recovery. The RPE for the work performed were measured at the end of fatiguing handgrip exercise with Borg scale (range: 6-20). Conclusion: The results of this study show significant correlation between RPE and blood lactate peak (p<0.01), RPE and MVG post exercise (p<0.01) and between RPE and Δ blood lactate (blood lactate post-blood lactate pre; p<0.01).

Differences in corticospinal system activity and reaction response between karate athletes and non-athletes

The aim of this study was to verify the hypothesis that transcranial magnetic stimulation (TMS) parameters over the hand region of the motor cortex, such as resting motor threshold (rMT) and motor evoked potential (MEP) latency, predict the behavioural performance of karate athletes in the response time (RT) test. Twenty-five male karate athletes (24.9xa0±xa04.9xa0years) and 25 matched non-athletes (26.2xa0±xa04.5xa0years) were recruited. Using TMS, we investigated cortico-spinal system excitability. Compared with controls, the athletes showed faster RT (pxa0<xa00.001), lower rMT (pxa0<xa00.01), shorter MEP latency (pxa0<xa00.01), and higher MEP amplitude (pxa0<xa00.01); moreover, there was a significant positive linear correlation between RT and rMT (pxa0<xa00.001), between RT and MEP latency (pxa0<xa00.0001), and a negative correlation between RT and MEP amplitude (pxa0<xa00.001). The practice of competitive sports affects both the central and peripheral nervous system. Subjects that showed higher cortical excitability showed also higher velocity, at which the neural signal is propagated from the motor cortex to the muscle and consequently better RT. The lower rMT and the shorter MEP latency observed in athletes support the effects of training in determining specific brain organizations to meet specific sport challenges.