Which of the following is NOT a cause of edema?

Edema is the medical term for swelling caused by an excess accumulation of fluid in the body's tissues. Conditions that lead to fluid retention and subsequent edema are typically linked to underlying issues with the heart, liver, or kidneys.

In the context of the given options, heart failure, liver disease, and kidney issues are all conditions that are known to cause edema. Heart failure can lead to increased pressure in the blood vessels, causing fluid to leak into surrounding tissues. Liver disease, particularly cirrhosis, can disrupt the normal production of proteins such as albumin, which helps maintain oncotic pressure and keeps fluid within the vessels. Similarly, kidney issues can cause the body to retain excess sodium and water, leading to swelling.

Exercise, on the other hand, typically promotes better circulation and can actually help prevent edema in a healthy individual. While intense or prolonged exercise may lead to temporary swelling in specific areas due to increased blood flow or microtrauma in muscles, it does not cause the generalized edema that is associated with the other conditions. Therefore, exercise is not a cause of chronic edema as seen in the context of the other conditions listed.