This translates to the loss of one's cardiac reserve, or the ability of the heart to work harder during strenuous physical activity.

Long-term mild excess of thyroid hormone can thus cause impaired cardiac reserve and exercise capacity.

For certain operations, such as Cesarean section, or in hypovolemic patients or patients with minimal cardiac reserve, the anesthesia provider may aim to provide "light anesthesia" and should discuss this with the patient to warn them.

ADF in rats "prolongs life span and promotes numerous health benefits in rodents, including tissue protection from ischemic damage" but also has negative effects including causing "myocardial hypotrophy, cardiac fibrosis, diastolic dysfunction, and a reduction of cardiac reserve."