What is the most effective angle to apply an armbar to isolate the elbow joint?

The most effective angle to apply an armbar, a submission hold that hyperextends the elbow joint, to isolate the elbow joint is approximately 45 degrees relative to the opponent's torso. At this angle, the applied force is optimally aligned to stress the ligaments and tendons of the elbow joint, maximizing the likelihood of a submission. When the arm is perfectly perpendicular (90 degrees) to the torso, the force may be distributed across the entire arm, reducing the stress specifically on the elbow joint. If the arm is nearly parallel (close to 0 degrees) with the torso, the force may primarily affect the shoulder rather than the elbow. The 45-degree angle provides the ideal leverage point to isolate the elbow, making it the most effective for applying the armbar.