How does isometric exercise affect the haemodynamics of the brain?

Objective: Brain responses during exercise are rarely studied because movement limits imaging techniques. With the development of functional near-infrared spectroscopy (fNIRS), it is assumed that the change in brain oxygenation could be accepted as a change in brain haemodynamics. In terms of exercise studies, aerobic exercise was the main topic. However, isometric exercise significantly increases body wellness, and therefore it began to be a suggested exercise model, especially for the elderly population. Despite these physiologic effects, the haemodynamic effects of isometric exercise in the brain remained unknown. The aim of this study was to show the brain haemodynamic changes during isometric exercises. Methods: Seven healthy males (mean age: 24.71±3.33 years), who trained regularly, were enrolled in the study. fNIRS measurements were recorded from the forehead, where prefrontal cortex activity is reflected. The participants underwent three different exercises: handstand, squat, and plank. The oxygenation levels collected from the pre-, during-, and post-exercise conditions were evaluated. Results: According to the fNIRS results, brain oxygenation in the prefrontal cortex increased during exercise in all positions (p<0.05). Additionally, the post exercise oxygenation values were observed higher than the pre-exercise conditions. Conclusion: Haemodynamic changes during isometric exercise have been shown in this study. Brain oxygenation was increased during isometric exercise. In future studies, the brain haemodynamics of positional changes could be investigated as a factor to determine the positional effect during exercises. Also, the cognitive effects of isometric exercise could be a future research topic.