Plasticity in Recovery From Surgery: The Effects of Exercise "Prehabilitation" on Cognitive and Functional Recovery After Shoulder Replacement in Older Adults

This randomized clinical trial will determine whether aerobic exercise training (AET) before total shoulder replacement (TSR) surgery reduces the incidence of post-operative delirium (POD) and shortens time to recovery in elderly patients. Delayed recovery affects up to 30% of surgical patients and imposes enormous costs on patients, caregivers, and society. Patients over 65 are four times more likely to experience POD, a form of sudden change in mental function that could be experienced after undergoing surgery. POD is associated with impaired daily functioning, longer hospital stay, more frequent institutionalization, and increased mortality.

Prevention of POD is a high clinical priority. Evidence suggests that an exaggerated inflammatory response contributes to POD. Human studies show that AET may exert anti-inflammatory effects. Furthermore, recent animal data show that AET attenuates the inflammatory response to surgery and prevents associated cognitive dysfunction.

The trial will enroll elderly patients undergoing TSR surgery to examine whether a low-cost intervention before surgery can improve clinical outcomes (reduction in POD and decrease recovery time). The effects of a 4-week AET program, specifically a type known as high-intensity interval training (HIIT), on the incidence of POD and time to recovery from fatigue and functional impairment. We will also analyze patients' immune state before and after surgery with modern techniques (high-dimensional mass cytometry). Understanding the immune-modulatory effects of AET will reveal mechanisms that can be targeted by interventions other than or in addition to exercise, which may benefit patients who are physically disabled or require urgent surgery, and help identify non-surgical diseases that may benefit from exercise.