If a patient's lower extremity hurts during exercise with pain in both plantar and dorsiflexion, what condition might they have?

The condition indicated by pain in both plantar and dorsiflexion during exercise suggests an issue with the Achilles tendon. Achilles tendonitis is characterized by pain and stiffness in the back of the heel and lower leg, especially during activities that involve ankle movement such as walking, running, or jumping. This condition arises from overuse or strain on the Achilles tendon, leading to inflammation and discomfort during movements that require both plantarflexion (pointing the toes down) and dorsiflexion (lifting the toes up).

Pain during these motions specifically points to dysfunction in the posterior chain, where the Achilles tendon plays a critical role in stabilizing and facilitating movement. In contrast, the other options typically present with more localized symptoms or different patterns of pain. For example, plantar fasciitis primarily causes heel pain and stiffness, shin splints are often associated with pain along the shin rather than the heel or ankle, and a hamstring strain typically results in pain in the back of the thigh, not the lower leg or ankle. Thus, the characteristics of the pain described align most closely with Achilles tendonitis.