Which of the following would be a key characteristic of ankylosing spondylitis pain?

Ankylosing spondylitis is a type of inflammatory arthritis that primarily affects the spine and the sacroiliac joints. One of the hallmark characteristics of the pain associated with ankylosing spondylitis is that it typically improves with physical activity. This is in contrast to mechanical pain from other causes, which usually worsens with activity.

The reason for the improvement in pain with movement lies in the underlying inflammation. Exercise can help reduce stiffness and maintain flexibility in the joints, which can provide symptomatic relief. Additionally, physical activity can stimulate the production of endorphins, the body's natural pain relievers, which can further alleviate pain.

Patients with ankylosing spondylitis commonly report that their pain is worse during periods of inactivity or prolonged rest, such as after a night’s sleep or sitting for extended periods. Therefore, the pain improves with physical activity, making it a key characteristic of the condition.