Author(s): CUI, S.1, WU, X.1, ZHAO, T.1, Institution: BEIJING RESEARCH INSTITUTE OF SPORT SCIENCE, Country: CHINA, Abstract-ID: 1104

INTRODUCTION:
Exercise-induced fatigue involves not only peripheral fatigue but also central fatigue. Near-infrared spectroscopy (NIRS) allows noninvasive monitoring of central changes in oxygenation and may provide valuable insight into the factors affecting fatigue.Transcranial magnetic stimulation (TMS) can evoked motor-evoked potentials (MEP),which can assess human muscle fatigue. Therefore, this study aims to better understand the impact of endurance exercise on central brain function by measuring changes in oxygenated hemoglobin concentration in the prefrontal cortex, as well as alterations in motor evoked potentials and central conduction time, before and after an acute high-intensity 5km run.
METHODS:
Nine trained healthy subjects (mean ± SE: age 20.6±4.1 years, body mass 64.1 ±2.2 kg, training years 5.9±1.9 years ). Performed an acute high-intensity 5000-meter running Before and after running ,the Prefrontal cortex oxygenation were measured by Near-infrared spectroscopy(NIRS). Transcranial magnetic stimulation was applied to stimulate the primary motor cortex and the peripheral Erb's point, respectively. The motor evoked potentials were recorded via surface electromyography, and the central conduction time（CCT） was calculated based on the lag time between the two evoked potentials. Blood lactate levels were measured immediately after exercise and again at 3 minutes post-exercise. Finally, the participants completed the Profile of Mood States questionnaire.
RESULTS:
The average time was 16.6 ± 0.9 minutes, average heart rate of 192.25 ± 8.96 bpm. blood lactate levels reached or exceeded 11.8 mmol/L. The average oxygenated hemoglobin concentration in the prefrontal cortex decreased significantly after exercise compared to the pre-exercise level (P < 0.05). After exercise, the MEP max amplitude increased compared to pre-exercise levels (1.42 ± 0.98 mV vs. 2.06 ± 1.35 mV), showing a statistically significant difference (p < 0.05). The negative peak amplitude exhibited a highly significant increase after exercise (1.66 ± 0.96 mV) compared to pre-exercise (1.02 ± 0.60 mV) (P < 0.01). The total area of the MEP showed a slight increase, but there was no significant difference (P > 0.05).The mean CCT was slightly higher after exercise (10.1 ± 0.99 ms) compared to pre-exercise (9.4 ± 0.79 ms), but there was no significant difference (P > 0.05).
CONCLUSION:
The present results demonstrate that 5km running increased the corticospinal excitability ,compared with primary motor cortex, prefrontal cortex play more important in the endurance exercise induced central fatigue. In the application of brain neuromodulation to enhance athletic performance or quick recovery, the Prefrontal cortex is an important intervention target.