Which of the following is a contraindication for isolated strengthening?

Isolated strengthening, which typically focuses on targeting a specific muscle group or joint without involving other parts of the body, may not be advisable in certain medical conditions. Acute rheumatoid arthritis of the affected joint is a contraindication for this type of strengthening because it involves inflammation of the joint that can lead to pain, swelling, and further joint damage. Engaging in isolated strengthening in the presence of acute inflammation can exacerbate symptoms and hinder recovery.

In contrast, while acute knee injury, chronic tendinitis, and overuse injuries may involve pain and dysfunction, they may still allow for some forms of exercise or rehabilitation that do not target the inflamed or poorly functioning joint specifically. It is crucial to consider the overall state of the joint and systemic implications of conditions like rheumatoid arthritis before implementing any strengthening protocols.