Grant: Project Grant - PA: Sex and Gender in Health Research (Bridge funding)

At six months post-stroke about 65% of affected persons continue to have hand paralysis that profoundly affects their independence, however recovery varies widely. The reason for variability in recovery remains unclear. We propose that having higher cardiorespiratory (or aerobic) fitness will enhance brain plasticity contributing to motor recovery. Exercise training has direct effects on beneficial neurotrophins that support brain remodelling. We have shown that having higher levels of fitness lessens corticospinal inhibition, a brain condition that limits capacity for plasticity. There is a surprising gap in our understanding of the role of fitness on brain recovery during stroke rehabilitation. Research suggests that females are less likely to achieve independence after rehabilitation and a recent Canadian report supports that females had longer lengths of stay and were less likely to be discharged home. There is evidence in healthy older adults that the relationships between fitness and brain function could be sex dependent and more robust in males. This project will identify whether there are sex and gender differences in fitness, plasticity and upper limb recovery after stroke. Transcranial magnetic stimulation (TMS) is a reliable research tool to map the motor cortex. Using TMS mapping we will register the location and extension of the brain area responsible for control of the paralyzed hand. We will measure (at 2 weeks, 3 and 6 months) upper limb recovery, cardiorespiratory fitness and brain reorganization in 175 people recovering from stroke. This proposal focuses on the impact of cardiorespiratory fitness on the ability of the brain to reorganize after stroke. Our core hypothesis is that higher levels of cardiorespiratory fitness (measured 2 weeks after stroke) will enable efficient motor map modifications leading to greater upper limb restoration in the first 6 months after stroke.