Abstract Body (Do not enter title and authors here): Introduction: Ischemic conditioning (IC), a procedure where the limb is exposed to recurrent bouts of blood flow occlusion followed by reperfusion, is clinically relevant for stroke rehabilitation as a neuromodulatory adjunct. Similar modalities (i.e., ischemic nerve block) revealed that peripheral blood flow restriction initiated neuroplastic changes in the motor cortex. Yet, this is unconfirmed with IC.

Aims: To quantify changes in corticomotor excitability (CME) and transcallosal inhibition (TCI) of the paretic and nonparetic tibialis anterior (TA) muscle representations alongside changes in motor performance after one session of IC compared to sham ischemic conditioning (sham-IC), and aerobic exercise.

Methods: Fifteen chronic stroke survivors will participate in three sessions: one involving IC, one involving sham-IC, and one involving aerobic exercise, with a one-week washout period between sessions. During the IC and sham-IC sessions, participants will undergo three 10-minute cycles, totaling 30 minutes. Each cycle will consist of 5 minutes of occlusion with cuff pressure set at either 225mmHg (IC) or 25mmHg (sham-IC), followed by 5 minutes of reperfusion with cuff pressure set at 0mmHg. The aerobic exercise session will involve 30 minutes of moderate-intensity recumbent stepper cycling. Before (pre), after (post) and 30 minutes after (post-30) each intervention, CME and TCI will be assessed using transcranial magnetic stimulation in addition to paretic ankle strength and reaction time (RT).

Results: Pilot data from five males (mean ± SD: age = 62.4 ± 9.9 years; years since stroke = 8.4 ± 4.6) showed that after IC, CME increased by 31% (post) and 15% (post-30) and TCI increased by 12% (post) and 13% (post-30). After aerobic exercise, CME decreased by 8% (post) and increased by 5% (post-30) whereas TCI increased by 14% (post) and 16% (post-30). Sham-IC had negligible results. Strength improved by 19% (post) and 25% (post-30) following IC and by 16% (post) and 15% (post-30) following aerobic exercise. RT increased by 11% after IC but only by 2% after exercise and <1% after sham-IC.

Conclusion: Initial results reveal IC is superior to sham-IC and aerobic exercise for enhancing motor and neurophysiological outcomes in chronic stroke. We expect to confirm these results with full data collection.