Different Blood Pressure Response To Isometric Exercise And Its Effect On Cognitive Function.

Aerobic exercise is well-known for its cognitive benefit, and recent research has highlighted that isometric handgrip (HG) exercise also reduces reaction time in cognitive tasks. It is noteworthy that isometric exercise elicits a higher blood pressure response compared to dynamic exercise, potentially posing greater risks of cerebral and cardiovascular diseases despite cognitive benefits. PURPOSE: This study aimed to investigate how individual variations in blood pressure response to exercise, known as exercise pressor reflex (EPR), impact cerebral circulation and cognitive function in young healthy individuals. METHODS: Thirty young participants (age 21 ± 1 years) completed an interval HG exercise protocol, which comprised four trials of 2-minute HG exercise at 25% of their maximum voluntary contraction, with a 3-minute recovery period between each trial. Middle cerebral artery mean blood velocity (MCA Vm), mean arterial pressure (MAP), and partial pressure of end-tidal carbon dioxide (PETCO2) were measured throughout the IHG exercise protocol. Furthermore, a Go/No-Go task was administered to evaluate cognitive function before and after the IHG exercise protocol. To investigate the impact of individual differences in EPR, 16 out of the 30 subjects were divided into two groups; the high EPR group (n = 8, +35.9 ± 3.4 mmHg) and the low EPR group (n = 8, +8.6 ± 4.9 mmHg, P = 0.001). RESULTS: The increase in MCA Vm during exercise was significantly higher in the high EPR group compared to the low EPR group (11.1 ± 14.8 mmHg and -4.2 ± 9.8 mmHg, respectively, P = 0.028). Conversely, the change in PETCO2 during exercise showed no significant difference between the groups (High and Low; -1.8 ± 3.5 and -1.1 ± 1.6 mmHg, P = 0.616). Interestingly, cognitive function exhibited enhancement by the isometric HG protocol in the low EPR group (-23.8 ± 18.6 msec, P = 0.008), while it remained unchanged in the high EPR group (-4.7 ± 15.6 msec, P = 0.424). CONCLUSIONS: These findings suggest that individuals with high EPR have greater sensitivity of cerebral blood flow to arterial blood pressure responses during isometric exercise. Additionally, the lower arterial blood pressure responses during exercise might highlight exercise-induced improvements in cognitive function in young individuals compared to those with high EPR.