This study aims to investigate the effect of isometric handgrip training on brain blood vessel function in physically inactive adults. Isometric handgrip training is a promising strategy for lowering blood pressure and improving vascular health, but no previous investigations have studied the effect of training on markers of brain blood vessel function. Based on previous work showing improvements in vascular function after isometric handgrip training, we hypothesize that isometric handgrip training will improve key markers of cerebrovascular function.

The incidence of cerebrovascular diseases is expected to increase. Early life sets the stage for vascular health outcomes later in life. Regular exercise is recommended for improving cerebrovascular health outcomes, but a lack of time or inadequate facilities are common exercise barriers. Not getting enough exercise is associated with worse cardiovascular and cerebrovascular health outcomes. There is a critical need for time-efficient strategies that require minimal equipment for improving cardiovascular and cerebrovascular health. Isometric handgrip (IHG) training is an effective strategy for improving cardiovascular health. Despite IHG's usefulness for improving vascular health through blood pressure reductions and improvements in endothelial function, almost nothing is known about IHG training and cerebrovascular function. Therefore, this project aims to test the hypothesis that 8 weeks of IHG training will improve cerebrovascular blood flow regulation and total cerebrovascular blood flow among adult humans who are not meeting the physical activity recommendations. We will measure middle cerebral artery blood velocity (MCAv) via transcranial Doppler ultrasound and assess MCAv dynamic autoregulation and MCAv reactivity to high and low carbon dioxide. We will also measure total cerebral blood flow, central artery stiffness, and MCAv pulsatility index. Understanding the effect of IHG on cerebrovascular health could inform exercise recommendations.

Inclusion Criteria:

• 18 to 35 years old
• Body mass index ≤30 kg/m2 (without obesity)
• Physically inactive (not meeting the current recommendations of ≥150 minutes per week of moderate-to-vigorous aerobic exercise and not ≥2 days per week of resistance training) in last 6 months
• Have a smartphone and are willing to download mobile applications used in this project

Exclusion Criteria:

• Having an overt chronic condition (e.g., cardiovascular, cerebrovascular, etc.)
• Being pregnant, planning to become pregnant, or breastfeeding/lactating
• Regular use of nicotine products in the past 6 months
• Recent head injury/trauma or concussion