COMPLEMENTARY ACTIVATION IN THE IPSILATERAL TO THE CONTRALATERAL PRIMARY MOTOR CORTEX DURING HIGH-INTENSITY EXHAUSTIVE PINCHING EXERCISE IN WELL-TRAINED ATHLETES

Abstract

Knowledge about the functioning of the motor cortex during muscle fatigue is important to appropriately understand the condition, and it is also important in improving the competitive skills of endurance competitors. This study aimed to examine the time-course oxygenation of the bilateral motor cortex during a high-intensity exhaustive pinching task in well-trained athletes. Twelve healthy right-handed male athletes participated in the present study. Near-infrared spectroscopy (NIRS), positioned over the bilateral motor cortices, measured the activation/oxygenation throughout the pinching task until voluntary exhaustion. Subjects sustained 80% of maximal voluntary contraction (MVC) during the task until peak voluntary exhaustion. After the start of the motor task, contralateral motor cortex oxygenation increased significantly compared with the resting values (p < 0.05). However, with time, when exhaustion occurred, it significantly decreased to the lower value compared with the resting level (p < 0.01). In contrast, in the ipsilateral motor cortex, no change was observed in oxygenation/activation immediately after the start of exercise. However, in the latter phase of the motor task, oxygenation/activation significantly increased compared with the resting level (p < 0.001). These results suggest that complementary activation in the ipsilateral motor cortex to activation in the contralateral motor cortex occurs during fatiguing exercise in well-trained athletes.Keywords: muscle fatigue; bilateral hemisphere interaction; top athletes